CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 62/536774, filed on July 25, 2017, entitled "SKEWING PADS FOR IMPEDANCE MEASUREMENT," and UK Patent Application No. 1803496.7, filed on March 5, 2018, entitled "SKEWING PADS FOR IMPEDANCE MEASUREMENT," each of which is incorporated herein in its entirety.

FIELD

[0002] Embodiments of the present disclosure relate to apparatuses, systems, and methods for the treatment of tissues via sensor-enabled monitoring in communication with various therapy regimes.

BACKGROUND

[0003] Nearly all areas of medicine may benefit from improved information regarding the state of the tissue, organ, or system to be treated, particularly if such information is gathered in real-time during treatment. Many types of treatments are still routinely performed without the use of sensor data collection; instead, such treatments rely upon visual inspection by a caregiver or other limited means rather than quantitative sensor data. For example, in the case of wound treatment via dressings and/or negative pressure wound therapy, data collection is generally limited to visual inspection by a caregiver and often the underlying wounded tissue may be obscured by bandages or other visual impediments. Even intact, unwounded skin may have underlying damage that is not visible to the naked eye, such as a compromised vascular or deeper tissue damage that may lead to an ulcer. Similar to wound treatment, during orthopedic treatments requiring the immobilization of a limb with a cast or other encasement, only limited information is gathered on the underlying tissue. In instances of internal tissue repair, such as a bone plate, continued direct sensor-driven data collection is not performed. Further, braces and/or sleeves used to support musculoskeletal function do not monitor the functions of the underlying muscles or the movement of the limbs. Outside of direct treatments, common hospital room items such as beds and blankets could be improved by adding capability to monitor patient parameters.

[0004] Therefore, there is a need for improved sensor monitoring, particularly through the use of sensor-enabled substrates which can be incorporated into existing treatment regimes.

SUMMARY

[0005] The present disclosure provides an improved wound monitoring and/or therapy apparatus which enables application an electrical signal to a wound or wound periphery. A wound monitoring and/or therapy apparatus according to some embodiments can include a plurality of excitation sensors configured to apply an electrical signal to a wound. The plurality of excitation sensors can be configured to be positioned proximate the wound. The apparatus can further include a plurality of measurement sensors configured to be positioned in or proximate the wound. The plurality of measurement sensors can be configured to, in response to the application of the electrical signal, measure a voltage indicative of a voltage difference between at least one of the plurality of excitation sensors and at least one measurement sensor of the plurality of measurement sensors or between a pair of measurement sensors of the plurality of measurement sensors. The at least one measurement sensor can be positioned or the pair of measurement sensors can be positioned such that a measurement path along which the voltage is measured is not perpendicular to an excitation path along which the electrical signal is applied.

[0006] The apparatus of the preceding paragraph may also include any combination of the following features described in this paragraph, among others described herein. The apparatus can include a wound dressing configured to be positioned in contact with the wound. The wound dressing can support the plurality of excitation sensors and/or the plurality of measurement sensors. The wound dressing can include a substantially flexible wound contact layer that supports the plurality of excitation sensors and the plurality of measurement sensors. The plurality of excitation sensors can include a first and second excitation sensor. The plurality of measurement sensors can include a first, second, third, and fourth sensor.

[0007] The apparatus of any of the preceding paragraphs may also include any combination of the following features described in this paragraph, among others described herein. The voltage difference between the at least one of the plurality of excitation sensors and the at least one of the plurality of measurement sensors can be different for every excitation sensor. In some cases, the electrical signal does not substantially stimulate or perturb wound tissue. The apparatus can include a processor configured to determine at least one of a bioelectrical impedance, bioelectrical resistance, bioelectrical reactance, bioelectrical phase angle, body cell mass (BCM), extra cellular mass (ECM), extracellular fluid (ECF), extracellular water (ECW), fat-free mass (FFM), fat mass (FM), total body water (TBW), electrolyte composition, cell membrane mass, or cell membrane function based at least in part on the measured voltage difference. The excitation signal can include an alternating current (AC) signal with intensity of about 5V.

[0008] The apparatus of any of the preceding paragraphs may also include any combination of the following features described in this paragraph, among others described herein. The apparatus can include a multiplexor configured to select a pair of excitation sensors from the plurality of excitation sensors to apply the electrical signal along the excitation path and/or select the at least one measurement sensor or the pair of measurement sensors from the plurality of measurement sensors to measure the voltage along the measurement path. The plurality of measurement sensors can be positioned between the plurality of excitation sensors.

[0009] The present disclosure also provides a method of performing any of the steps associated with any of the features of the preceding paragraphs.

[0010] The present disclosure also provides a method of determining a physiological characteristic associated with a wound. In some embodiments, the method can include applying an electrical signal to a wound via a plurality of excitation sensors positioned proximate the wound, and can further include measuring a voltage indicative of a voltage difference between at least one of the plurality of excitation sensors and at least one measurement sensor of a plurality of measurement sensors or between a pair of measurement sensors of the plurality of measurement sensors. The plurality of measurement sensors can be configured to be positioned in or proximate the wound. The at least one measurement sensor can be positioned or the pair of measurement sensors can be positioned such that a measurement path along which the voltage is measured is not perpendicular to an excitation path along which the electrical signal is applied. The method can further include determining, by a processor, based at least in part on the voltage, a physiological characteristic corresponding to the wound site.

[0011] The method of the preceding paragraph may also include any combination of the following steps or features described in this paragraph, among others described herein. The physiological characteristic can include an impedance of the wound. The plurality of excitation sensors and/or the plurality of measurement sensors can be supported by a wound dressing configured to be positioned in contact with the wound. The wound dressing can include a substantially flexible wound contact layer supporting the plurality of excitation sensors and the plurality of measurement sensors. The measurement path can correspond to a line connecting the pair of measurement sensors. The excitation path can correspond to a line connecting the excitation sensors. In some cases, the electrical signal does not substantially stimulate or perturb wound tissue.

[0012] The method of any of the preceding paragraphs may also include any combination of the following steps or features described in this paragraph, among others described herein. The method can include determining, by the processor, at least one of a bioelectrical resistance, bioelectrical reactance, bioelectrical phase angle, body cell mass (BCM), extra cellular mass (ECM), extracellular fluid (ECF), extracellular water (ECW), fat-free mass (FFM), fat mass (FM), total body water (TBW), electrolyte composition, cell membrane mass, or cell membrane function. The excitation signal can include an alternating current (AC) signal with intensity of about 5V. The physiological characteristic can include biological impedance.

[0013] The method of any of the preceding paragraphs may also include any combination of the following steps or features described in this paragraph, among others described herein. The method can include selecting, using a multiplexer, a pair of excitation sensors from the plurality of excitation sensors to apply the electrical signal along the excitation path and/or selecting, using the multiplexer, the at least one measurement sensor or the pair of measurement sensors from the plurality of measurement sensors to measure the voltage along the measurement path. [0014] The method of any of the preceding paragraphs may also include any combination of the following steps or features described in this paragraph, among others described herein. The measurement path can be a first measurement path, the voltage can be a first voltage, the electrical signal can be a second electrical signal, and the physiological characteristic can be a first physiological characteristic. The method can further include measuring a second voltage indicative of a voltage difference between at least a second one of the plurality of excitation sensors and at least a second measurement sensor of a plurality of measurement sensors or between a second pair of measurement sensors of the plurality of measurement sensors. The at least a second measurement sensor can be positioned or the second pair of measurement sensors can be positioned such that a second measurement path along which the second voltage is measured is not perpendicular to a second excitation path along which the second electrical signal is applied. The method can further include determining, based at least in part on the second voltage, a second physiological characteristic corresponding to the wound. The first voltage and the second voltage can be the same or different.

[0015] The present disclosure also provides a wound monitoring and/or therapy system, which can include any feature or step as shown and/or described herein or in the corresponding figures. The present disclosure also provides a wound dressing apparatus, which can include any feature or step as shown and/or described herein or in the corresponding figures. The present disclosure also provides a method of using a wound monitoring and therapy, which can include any feature or step as shown and/or described herein or in the corresponding figures.

[0016] Any of the features, components, or details of any of the arrangements or embodiments disclosed in this application, including without limitation any of the pump embodiments and any of the negative pressure wound therapy embodiments disclosed below, are interchangeably combinable with any other features, components, or details of any of the arrangements or embodiments disclosed herein to form new arrangements and embodiments. Details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, the drawings, and the claims. Neither this summary nor the following detailed description purports to define or limit the scope of the inventive subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Embodiments of the present disclosure will now be described hereinafter, by way of example only, with reference to the accompanying drawings in which:

[0018] FIG. 1A illustrates a negative pressure wound treatment system according to some embodiments;

[0019] FIG. 1 B illustrates a wound dressing according to some embodiments;

[0020] FIG. 1 C illustrates a negative pressure wound treatment system employing a flexible fluidic connector and a wound dressing capable of absorbing and storing wound exudate according to some embodiments;

[0021] FIG. 1 D illustrates a negative pressure wound treatment system employing a flexible fluidic connector and a wound dressing capable of absorbing and storing wound exudate according to some embodiments;

[0022] FIG. 1 E illustrates a negative pressure wound treatment system employing a flexible fluidic connector and a wound dressing capable of absorbing and storing wound exudate according to some embodiments;

[0023] FIG. 1 F illustrates of a negative pressure wound therapy system according to some embodiments;

[0024] FIG. 1 G illustrates a wound treatment system employing a wound dressing capable of absorbing and storing wound exudate to be used without negative pressure according to some embodiments;

[0025] FIG. 2 illustrates a sensor array illustrating the sensor placement incorporated into a wound dressing according to some embodiments;

[0026] FIG. 3A illustrates a flexible sensor array including a sensor array portion, a tail portion and a connector pad end portion according to some embodiments;

[0027] FIG. 3B illustrates flexible circuit boards with different sensor array geometries according to some embodiments; [0028] FIG. 3C illustrates the sensor array portion of a sensor array shown in FIG. 3B;

[0029] FIG. 3D illustrates a flexible sensor array incorporated into a perforated wound contact layer according to some embodiments;

[0030] FIG. 3E illustrates a control module according to some embodiments;

[0031] FIG. 4 illustrates an example schematic configuration for measuring bioelectrical impedance in or around a wound of a patient according to some embodiments;

[0032] FIG. 5 illustrates an example schematic configuration for measuring bioelectrical impedance in or around a wound of a patient according to some embodiments;

[0033] FIG. 6 illustrates an example schematic configuration for measuring bioelectrical impedance in or around a wound of a patient according to some embodiments;

[0034] FIG. 7 illustrates an example schematic configuration for measuring bioelectrical impedance in or around a wound of a patient according to some embodiments;

[0035] FIG. 8A illustrates a sensor array configured to take measurements of one or more areas of a wound;

[0036] FIG. 8B illustrates various example drive paths and example measurement paths of the sensor array of FIG. 8A;

[0037] FIG. 8C illustrates an example sensor array having the sensor array geometry of the sensor array of FIG. 8A;

[0038] FIG. 9A illustrates a sensor array configured to take measurements of one or more areas of a wound;

[0039] FIG. 9B illustrates various example drive paths and example measurement paths of the sensor array of FIG. 9A;

[0040] FIG. 9C illustrates an example sensor array having the sensor array geometry of the sensor array of FIG. 9A; and [0041] FIG. 10 illustrates a process for measuring bioelectrical impedance and/or determining bioelectrical impedance parameter in or around a wound of a patient according to some embodiments.

DETAILED DESCRIPTION

[0042] Embodiments disclosed herein relate to apparatuses and methods of monitoring and treating biological tissue with sensor-enabled substrates. The embodiments disclosed herein are not limited to treatment or monitoring of a particular type of tissue or injury, instead the sensor-enabled technologies disclosed herein are broadly applicable to any type of therapy that may benefit from sensor- enabled substrates. Some implementations utilize sensors and data collection relied upon by health care providers to make both diagnostic and patient management decisions.

[0043] Some embodiments disclosed herein relate to the use of sensors mounted on or embedded within substrates configured to be used in the treatment of both intact and damaged human or animal tissue. Such sensors may collect information about the surrounding tissue and transmit such information to a computing device or a caregiver to be utilized in further treatment. In certain embodiments, such sensors may be attached to the skin anywhere on the body, including areas for monitoring arthritis, temperature, or other areas that may be prone to problems and require monitoring. Sensors disclosed herein may also incorporate markers, such as radiopaque markers, to indicate the presence of the device, for example prior to performing an MRI or other technique.

[0044] The sensor embodiments disclosed herein may be used in combination with clothing. Non-limiting examples of clothing for use with embodiments of the sensors disclosed herein include shirts, pants, trousers, dresses, undergarments, outer-garments, gloves, shoes, hats, and other suitable garments. In certain embodiments, the sensor embodiments disclosed herein may be welded into or laminated into/onto the particular garments. The sensor embodiments may be printed directly onto the garment and/or embedded into the fabric. Breathable and printable materials such as microporous membranes may also be suitable. [0045] Sensor embodiments disclosed herein may be incorporated into cushioning or bed padding, such as within a hospital bed, to monitor patient characteristics, such as any characteristic disclosed herein. In certain embodiments, a disposable film containing such sensors could be placed over the hospital bedding and removed/replaced as needed.

[0046] In some implementations, the sensor embodiments disclosed herein may incorporate energy harvesting, such that the sensor embodiments are self-sustaining. For example, energy may be harvested from thermal energy sources, kinetic energy sources, chemical gradients, or any suitable energy source.

[0047] The sensor embodiments disclosed herein may be utilized in rehabilitation devices and treatments, including sports medicine. For example, the sensor embodiments disclosed herein may be used in braces, sleeves, wraps, supports, and other suitable items. Similarly, the sensor embodiments disclosed herein may be incorporated into sporting equipment, such as helmets, sleeves, and/or pads. For example, such sensor embodiments may be incorporated into a protective helmet to monitor characteristics such as acceleration, which may be useful in concussion diagnosis.

[0048] The sensor embodiments disclosed herein may be used in coordination with surgical devices, for example, the NAVIO surgical system by Smith & Nephew Inc. In implementations, the sensor embodiments disclosed herein may be in communication with such surgical devices to guide placement of the surgical devices. In some implementations, the sensor embodiments disclosed herein may monitor blood flow to or away from the potential surgical site or ensure that there is no blood flow to a surgical site. Further surgical data may be collected to aid in the prevention of scarring and monitor areas away from the impacted area.

[0049] To further aid in surgical techniques, the sensors disclosed herein may be incorporated into a surgical drape to provide information regarding tissue under the drape that may not be immediately visible to the naked eye. For example, a sensor embedded flexible drape may have sensors positioned advantageously to provide improved area-focused data collection. In certain implementations, the sensor embodiments disclosed herein may be incorporated into the border or interior of a drape to create fencing to limit/ control the surgical theater. [0050] Sensor embodiments as disclosed herein may also be utilized for pre-surgical assessment. For example, such sensor embodiments may be used to collect information about a potential surgical site, such as by monitoring skin and the underlying tissues for a possible incision site. For example, perfusion levels or other suitable characteristics may be monitored at the surface of the skin and deeper in the tissue to assess whether an individual patient may be at risk for surgical complications. Sensor embodiments such as those disclosed herein may be used to evaluate the presence of microbial infection and provide an indication for the use of antimicrobials. Further, sensor embodiments disclosed herein may collect further information in deeper tissue, such as identifying pressure ulcer damage and/or the fatty tissue levels.

[0051] The sensor embodiments disclosed herein may be utilized in cardiovascular monitoring. For example, such sensor embodiments may be incorporated into a flexible cardiovascular monitor that may be placed against the skin to monitor characteristics of the cardiovascular system and communicate such information to another device and/or a caregiver. For example, such a device may monitor pulse rate, oxygenation of the blood, and/or electrical activity of the heart. Similarly, the sensor embodiments disclosed herein may be utilized for neurophysiological applications, such as monitoring electrical activity of neurons.

[0052] The sensor embodiments disclosed herein may be incorporated into implantable devices, such as implantable orthopedic implants, including flexible implants. Such sensor embodiments may be configured to collect information regarding the implant site and transmit this information to an external source. In some embodiments, an internal source may also provide power for such an implant.

[0053] The sensor embodiments disclosed herein may also be utilized for monitoring biochemical activity on the surface of the skin or below the surface of the skin, such as lactose buildup in muscle or sweat production on the surface of the skin. In some embodiments, other characteristics may be monitored, such as glucose concentration, urine concentration, tissue pressure, skin temperature, skin surface conductivity, skin surface resistivity, skin hydration, skin maceration, and/or skin ripping. [0054] Sensor embodiments as disclosed herein may be incorporated into Ear, Nose, and Throat (ENT) applications. For example, such sensor embodiments may be utilized to monitor recovery from ENT-related surgery, such as wound monitoring within the sinus passage.

[0055] As described in greater detail below, the sensor embodiments disclosed herein may encompass sensor printing technology with encapsulation, such as encapsulation with a polymer film. Such a film may be constructed using any polymer described herein, such as polyurethane. Encapsulation of the sensor embodiments may provide waterproofing of the electronics and protection from local tissue, local fluids, and other sources of potential damage.

[0056] In certain embodiments, the sensors disclosed herein may be incorporated into an organ protection layer such as disclosed below. Such a sensor- embedded organ protection layer may both protect the organ of interest and confirm that the organ protection layer is in position and providing protection. Further, a sensor-embedded organ protection layer may be utilized to monitor the underlying organ, such as by monitoring blood flow, oxygenation, and other suitable markers of organ health. In some embodiments, a sensor-enabled organ protection layer may be used to monitor a transplanted organ, such as by monitoring the fat and muscle content of the organ. Further, sensor-enabled organ protection layers may be used to monitor an organ during and after transplant, such as during rehabilitation of the organ.

[0057] The sensor embodiments disclosed herein may be incorporated into treatments for wounds (disclosed in greater detail below) or in a variety of other applications. Non-limiting examples of additional applications for the sensor embodiments disclosed herein include: monitoring and treatment of intact skin, cardiovascular applications such as monitoring blood flow, orthopedic applications such as monitoring limb movement and bone repair, neurophysiological applications such as monitoring electrical impulses, and any other tissue, organ, system, or condition that may benefit from improved sensor-enabled monitoring. Wound Therapy

[0058] Some embodiments disclosed herein relate to wound therapy for a human or animal body. Therefore, any reference to a wound herein can refer to a wound on a human or animal body, and any reference to a body herein can refer to a human or animal body. The disclosed technology embodiments may relate to preventing or minimizing damage to physiological tissue or living tissue, or to the treatment of damaged tissue (for example, a wound as described herein) wound with or without reduced pressure, including for example a source of negative pressure and wound dressing components and apparatuses. The apparatuses and components comprising the wound overlay and packing materials or internal layers, if any, are sometimes collectively referred to herein as dressings. In some embodiments, the wound dressing can be provided to be utilized without reduced pressure.

[0059] Some embodiments disclosed herein relate to wound therapy for a human or animal body. Therefore, any reference to a wound herein can refer to a wound on a human or animal body, and any reference to a body herein can refer to a human or animal body. The disclosed technology embodiments may relate to preventing or minimizing damage to physiological tissue or living tissue, or to the treatment of damaged tissue (for example, a wound as described herein).

[0060] As used herein the expression "wound" may include an injury to living tissue may be caused by a cut, blow, or other impact, typically one in which the skin is cut or broken. A wound may be a chronic or acute injury. Acute wounds occur as a result of surgery or trauma. They move through the stages of healing within a predicted timeframe. Chronic wounds typically begin as acute wounds. The acute wound can become a chronic wound when it does not follow the healing stages resulting in a lengthened recovery. It is believed that the transition from acute to chronic wound can be due to a patient being immuno-compromised.

[0061] Chronic wounds may include for example: venous ulcers (such as those that occur in the legs), which account for the majority of chronic wounds and mostly affect the elderly, diabetic ulcers (for example, foot or ankle ulcers), peripheral arterial disease, pressure ulcers, or epidermolysis bullosa (EB). [0062] Examples of other wounds include, but are not limited to, abdominal wounds or other large or incisional wounds, either as a result of surgery, trauma, sterniotomies, fasciotomies, or other conditions, dehisced wounds, acute wounds, chronic wounds, subacute and dehisced wounds, traumatic wounds, flaps and skin grafts, lacerations, abrasions, contusions, bums, diabetic ulcers, pressure ulcers, stoma, surgical wounds, trauma and venous ulcers or the like.

[0063] Wounds may also include a deep tissue injury. Deep tissue injury is a term proposed by the National Pressure Ulcer Advisory Panel (NPUAP) to describe a unique form of pressure ulcers. These ulcers have been described by clinicians for many years with terms such as purple pressure ulcers, ulcers that are likely to deteriorate and bruises on bony prominences.

[0064] Wound may also include tissue at risk of becoming a wound as discussed herein. For example, tissue at risk may include tissue over a bony protuberance (at risk of deep tissue injury/insult) or pre-surgical tissue (for example, knee tissue) that may has the potential to be cut (for example, for joint replacement/surgical alteration/reconstruction).

[0065] Some embodiments relate to methods of treating a wound with the technology disclosed herein in conjunction with one or more of the following: advanced footwear, turning a patient, offloading (such as, offloading diabetic foot ulcers), treatment of infection, systemix, antimicrobial, antibiotics, surgery, removal of tissue, affecting blood flow, physiotherapy, exercise, bathing, nutrition, hydration, nerve stimulation, ultrasound, electrostimulation, oxygen therapy, microwave therapy, active agents ozone, antibiotics, antimicrobials, or the like.

[0066] Alternatively or additionally, a wound may be treated using topical negative pressure and/or traditional advanced wound care, which is not aided by the using of applied negative pressure (may also be referred to as non-negative pressure therapy).

[0067] Advanced wound care may include use of an absorbent dressing, an occlusive dressing, use of an antimicrobial and/or debriding agents in a wound dressing or adjunct, a pad (for example, a cushioning or compressive therapy, such as stockings or bandages), or the like. [0068] In some embodiments, treatment of such wounds can be performed using traditional wound care, wherein a dressing can be applied to the wound to facilitate and promote healing of the wound.

[0069] Some embodiments relate to methods of manufacturing a wound dressing comprising providing a wound dressing as disclosed herein.

[0070] The wound dressings that may be utilized in conjunction with the disclosed technology include any known dressing in the art. The technology is applicable to negative pressure therapy treatment as well as non-negative pressure therapy treatment.

[0071] In some embodiments, a wound dressing comprises one or more absorbent layer(s). The absorbent layer may be a foam or a superabsorbent.

[0072] In some embodiments, wound dressings may comprise a dressing layer including a polysaccharide or modified polysaccharide, a polyvinylpyrrolidone, a polyvinyl alcohol, a polyvinyl ether, a polyurethane, a polyacrylate, a polyacrylamide, collagen, or gelatin or mixtures thereof. Dressing layers comprising the polymers listed are known in the art as being useful for forming a wound dressing layer for either negative pressure therapy or non-negative pressure therapy.

[0073] In some embodiments, the polymer matrix may be a polysaccharide or modified polysaccharide.

[0074] In some embodiments, the polymer matrix may be a cellulose. Cellulose material may include hydrophilically modified cellulose such as methyl cellulose, carboxymethyl cellulose (CMC), carboxymethyl cellulose (CEC), ethyl cellulose, propyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, carboxyethyl sulphonate cellulose, cellulose alkyl sulphonate, or mixtures thereof.

[0075] In certain embodiments, cellulose material may be cellulose alkyl sulphonate. The alkyl moiety of the alkyl sulphonate substituent group may have an alkyl group having 1 to 6 carbon atoms, such as methyl, ethyl, propyl, or butyl. The alkyl moiety may be branched or unbranched, and hence suitable propyl sulphonate substituents may be 1 - or 2-methyl-ethylsulphonate. Butyl sulphonate substituents may be 2-ethyl-ethylsulphonate, 2,2-dimethyl-ethylsulphonate, or 1 ,2-dimethyl- ethylsulphonate. The alkyl sulphonate substituent group may be ethyl sulphonate. The cellulose alkyl sulphonate is described in W010061225, US2016/1 14074, US2006/0142560, or US 5,703,225, the disclosures of which are hereby incorporated by reference in their entirety.

[0076] Cellulose alkyl sulfonates may have varying degrees of substitution, the chain length of the cellulose backbone structure, and the structure of the alkyl sulfonate substituent. Solubility and absorbency are largely dependent on the degree of substitution: as the degree of substitution is increased, the cellulose alkyl sulfonate becomes increasingly soluble. It follows that, as solubility increases, absorbency increases.

[0077] In some embodiments, a wound dressing also comprises a top or cover layer.

[0078] The thickness of the wound dressing disclosed herein may be between 1 to 20, or 2 to 10, or 3 to 7 mm.

[0079] In some embodiments, the disclosed technology may be used in conjunction with a non-negative pressure dressing. A non-negative pressure wound dressing suitable for providing protection at a wound site may comprise:

[0080] an absorbent layer for absorbing wound exudate and

[0081] an obscuring element for at least partially obscuring a view of wound exudate absorbed by the absorbent layer in use.

[0082] The obscuring element may be partially translucent.

[0083] The obscuring element may be a masking layer.

[0084] The non-negative pressure wound dressing may further comprise a region in or adjacent the obscuring element for allowing viewing of the absorbent layer. For example, the obscuring element layer may be provided over a central region of the absorbent layer and not over a border region of the absorbent layer. In some embodiments, the obscuring element is of hydrophilic material or is coated with a hydrophilic material.

[0085] The obscuring element may comprise a three-dimensional knitted spacer fabric. The spacer fabric is known in the art and may include a knitted spacer fabric layer. [0086] The obscuring element may further comprise an indicator for indicating the need to change the dressing.

[0087] In some embodiments, the obscuring element is provided as a layer at least partially over the absorbent layer, further from a wound site than the absorbent layer in use.

[0088] The non-negative pressure wound dressing may further comprise a plurality of openings in the obscuring element for allowing fluid to move therethrough. The obscuring element may comprise, or may be coated with, a material having size-exclusion properties for selectively permitting or preventing passage of molecules of a predetermined size or weight.

[0089] The obscuring element may be configured to at least partially mask light radiation having wavelength of 600 nm and less.

[0090] The obscuring element may be configured to reduce light absorption by 50% or more.

[0091] The obscuring element may be configured to yield a CIE L ^* value of 50 or more, and optionally 70 or more. In some embodiments, the obscuring element may be configured to yield a CIE L ^* value of 70 or more.

[0092] In some embodiments, the non-negative pressure wound dressing may further comprise at least one of a wound contact layer, a foam layer, an odor control element, a pressure-resistant layer and a cover layer.

[0093] In some embodiments, the cover layer is present, and the cover layer is a translucent film. Typically, the translucent film has a moisture vapour permeability of 500g/m2/24hours or more.

[0094] The translucent film may be a bacterial barrier.

[0095] In some embodiments, the non-negative pressure wound dressing as disclosed herein comprises the wound contact layer and the absorbent layer overlies the wound contact layer. The wound contact layer carries an adhesive portion for forming a substantially fluid tight seal over the wound site.

[0096] The non-negative pressure wound dressing as disclosed herein may comprise the obscuring element and the absorbent layer being provided as a single layer. [0097] In some embodiments, the non-negative pressure wound dressing disclosed herein comprises the foam layer, and the obscuring element is of a material comprising components that may be displaced or broken by movement of the obscuring element.

[0098] In some embodiments, the non-negative pressure wound dressing comprises an odor control element, and in another embodiment the dressing does not include an odor control element. When present, the odor control element may be dispersed within or adjacent the absorbent layer or the obscuring element. Alternatively, when present the odor control element may be provided as a layer sandwiched between the foam layer and the absorbent layer.

[0099] In some embodiments, the disclosed technology for a non-negative pressure wound dressing comprises a method of manufacturing a wound dressing, comprising: providing an absorbent layer for absorbing wound exudate; and providing an obscuring element for at least partially obscuring a view of wound exudate absorbed by the absorbent layer in use.

[0100] In some embodiments, the non-negative pressure wound dressing is may be suitable for providing protection at a wound site, comprising: an absorbent layer for absorbing wound exudate; and a shielding layer provided over the absorbent layer, and further from a wound-facing side of the wound dressing than the absorbent layer. The shielding layer may be provided directly over the absorbent layer. In some embodiments, the shielding layer comprises a three-dimensional spacer fabric layer.

[0101] The shielding layer increases the area over which a pressure applied to the dressing is transferred by 25% or more or the initial area of application. For example the shielding layer increases the area over which a pressure applied to the dressing is transferred by 50% or more, and optionally by 100% or more, and optionally by 200% or more.

[0102] The shielding layer may comprise 2 or more sub-layers, wherein a first sub-layer comprises through holes and a further sub-layer comprises through holes and the through holes of the first sub-layer are offset from the through holes of the further sub-layer. [0103] The non-negative pressure wound dressing as disclosed herein may further comprise a permeable cover layer for allowing the transmission of gas and vapour therethrough, the cover layer provided over the shielding layer, wherein through holes of the cover layer are offset from through holes of the shielding layer.

[0104] The non-negative pressure wound dressing may be suitable for treatment of pressure ulcers.

[0105] A more detailed description of the non-negative pressure dressing disclosed hereinabove is provided in WO2013007973, the entirety of which is hereby incorporated by reference.

[0106] In some embodiments, the non-negative pressure wound dressing may be a multi-layered wound dressing comprising: a fibrous absorbent layer for absorbing exudate from a wound site; and a support layer configured to reduce shrinkage of at least a portion of the wound dressing.

[0107] In some embodiments, the multi-layered wound dressing disclosed herein, further comprises a liquid impermeable film layer, wherein the support layer is located between the absorbent layer and the film layer.

[0108] The support layer disclosed herein may comprise a net. The net may comprise a geometric structure having a plurality of substantially geometric apertures extending therethrough. The geometric structure may for example comprise a plurality of bosses substantially evenly spaced and joined by polymer strands to form the substantially geometric apertures between the polymer strands.

[0109] The net may be formed from high density polyethylene.

[0110] The apertures may have an area from 0.005 to 0.32 mm2.

[0111] The support layer may have a tensile strength from 0.05 to 0.06

Nm.

[0112] The support layer may have a thickness of from 50 to 150 μηη.

[0113] In some embodiments, the support layer is located directly adjacent the absorbent layer. Typically, the support layer is bonded to fibers in a top surface of the absorbent layer. The support layer may further comprise a bonding layer, wherein the support layer is heat laminated to the fibers in the absorbent layer via the bonding layer. The bonding layer may comprise a low melting point adhesive such as ethylene-vinyl acetate adhesive. [0114] In some embodiments, the multi-layered wound dressing disclosed herein further comprises an adhesive layer attaching the film layer to the support layer.

[0115] In some embodiments, the multi-layered wound dressing disclosed herein further comprises a wound contact layer located adjacent the absorbent layer for positioning adjacent a wound. The multi-layered wound dressing may further comprise a fluid transport layer between the wound contact layer and the absorbent layer for transporting exudate away from a wound into the absorbent layer.

[0116] A more detailed description of the multi-layered wound dressing disclosed hereinabove is provided in GB patent application filed on 28 October 2016 with application number GB1618298.2, the entirety of which is hereby incorporated by reference.

[0117] In some embodiments, the disclosed technology may be incorporated in a wound dressing comprising a vertically lapped material comprising: a first layer of an absorbing layer of material, and a second layer of material, wherein the first layer being constructed from at least one layer of non-woven textile fibers, the non-woven textile fibers being folded into a plurality of folds to form a pleated structure. In some embodiments, the wound dressing further comprises a second layer of material that is temporarily or permanently connected to the first layer of material.

[0118] Typically the vertically lapped material has been slitted.

[0119] In some embodiments, the first layer has a pleated structure having a depth determined by the depth of pleats or by the slitting width. The first layer of material may be a moldable, lightweight, fiber-based material, blend of material or composition layer.

[0120] The first layer of material may comprise one or more of manufactured fibers from synthetic, natural or inorganic polymers, natural fibers of a cellulosic, proteinaceous or mineral source.

[0121] The wound dressing may comprise two or more layers of the absorbing layer of material vertically lapped material stacked one on top of the other, wherein the two or more layers have the same or different densities or composition. [0122] The wound dressing may in some embodiments comprise only one layer of the absorbing layer of material vertically lapped material.

[0123] The absorbing layer of material is a blend of natural or synthetic, organic or inorganic fibers, and binder fibers, or bicomponent fibers typically PET with a low melt temperature PET coating to soften at specified temperatures and to act as a bonding agent in the overall blend.

[0124] In some embodiments, the absorbing layer of material may be a blend of 5 to 95 % thermoplastic polymer, and 5 to 95 wt % of a cellulose or derivative thereof.

[0125] In some embodiments, the wound dressing disclosed herein has a second layer comprises a foam or a dressing fixative.

[0126] The foam may be a polyurethane foam. The polyurethane foam may have an open or closed pore structure.

[0127] The dressing fixative may include bandages, tape, gauze, or backing layer.

[0128] In some embodiments, the wound dressing as disclosed herein comprises the absorbing layer of material connected directly to a second layer by lamination or by an adhesive, and the second layer is connected to a dressing fixative layer. The adhesive may be an acrylic adhesive, or a silicone adhesive.

[0129] In some embodiments, the wound dressing as disclosed herein further comprises layer of a superabsorbent fiber, or a viscose fiber or a polyester fiber.

[0130] In some embodiments, the wound dressing as disclosed herein further comprises a backing layer. The backing layer may be a transparent or opaque film. Typically the backing layer comprises a polyurethane film (typically a transparent polyurethane film).

[0131] A more detailed description of the multi-layered wound dressing disclosed hereinabove is provided in GB patent applications filed on 12 December 2016 with application number GB1621057.7; and 22 June 2017 with application number GB1709987.0, the entirety of each of which is hereby incorporated by reference. [0132] In some embodiments, the non-negative pressure wound dressing may comprise an absorbent component for a wound dressing, the component comprising a wound contacting layer comprising gel forming fibers bound to a foam layer, wherein the foam layer is bound directly to the wound contact layer by an adhesive, polymer based melt layer, by flame lamination or by ultrasound.

[0133] The absorbent component may be in a sheet form.

[0134] The wound contacting layer may comprise a layer of woven or non- woven or knitted gel forming fibers.

[0135] The foam layer may be an open cell foam, or closed cell foam, typically an open cell foam. The foam layer is a hydrophilic foam.

[0136] The wound dressing may comprise the component that forms an island in direct contact with the wound surrounded by periphery of adhesive that adheres the dressing to the wound. The adhesive may be a silicone or acrylic adhesive, typically a silicone adhesive.

[0137] The wound dressing may be covered by a film layer on the surface of the dressing furthest from the wound.

[0138] A more detailed description of the wound dressing of this type hereinabove is provided in EP2498829, the entirety of which is hereby incorporated by reference.

[0139] In some embodiments, the non-negative pressure wound dressing may comprise a multi layered wound dressing for use on wounds producing high levels of exudate, characterized in that the dressing comprising: a transmission layer having an MVTR of at least 300 gm2/24 hours, an absorbent core comprising gel forming fibers capable of absorbing and retaining exudate, a wound contacting layer comprising gel forming fibers which transmits exudate to the absorbent core and a keying layer positioned on the absorbent core, the absorbent core and wound contacting layer limiting the lateral spread of exudate in the dressing to the region of the wound.

[0140] The wound dressing may be capable of handling at least 6g (or 8g and 15g) of fluid per 10cm2 of dressing in 24 hours. [0141] The wound dressing may comprise gel forming fibers that are chemically modified cellulosic fibers in the form of a fabric. The fibers may include carboxymethylated cellulose fibers, typically sodium carboxymethylcellulose fiber.

[0142] The wound dressing may comprise a wound contact layer with a lateral wicking rate from 5mm per minute to 40mm per minute. The wound contact layer may have a fiber density between 25gm2 and 55gm2, such as 35gm2.

[0143] The absorbent core may have an absorbency of exudate of at least 10g/g, and typically a rate of lateral wicking of less the 20mm per minute.

[0144] The absorbent core may have a blend in the range of up to 25% cellulosic fibers by weight and 75% to 100% gel forming fibers by weight.

[0145] Alternatively, the absorbent core may have a blend in the range of up to 50% cellulosic fibers by weight and 50% to 100% gel forming fibers by weight. For example the blend is in the range of 50% cellulosic fibers by weight and 50% gel forming fibers by weight.

[0146] The fiber density in the absorbent core may be between 150gm2 and 250gm2, or about 200 gm2.

[0147] The wound dressing when wet may have shrinkage that is less than 25 % or less than 15 % of its original size/dimension.

[0148] The wound dressing may comprise a transmission layer and the layer is a foam. The transmission layer may be a polyurethane foam laminated to a polyurethane film.

[0149] The wound dressing may comprise one or more layers selected from the group comprising a soluble medicated film layer; an odor-absorbing layer; a spreading layer and an additional adhesive layer.

[0150] The wound dressing may be 2mm and 4mm thick.

[0151] The wound dressing may be characterized in that the keying layer bonds the absorbent core to a neighboring layer. In some embodiments, the keying layer may be positioned on either the wound facing side of the absorbent core or the non-wound facing side of the absorbent core. In some embodiments, the keying layer is positioned between the absorbent core and the wound contact layer. The keying layer is a polyamide web. [0152] A more detailed description of the wound dressing of this type hereinabove is provided in EP1718257, the entirety of which is hereby incorporated by reference.

[0153] In some embodiments, the non-negative pressure wound dressing may be a compression bandage. Compression bandages are known for use in the treatment of oedema and other venous and lymphatic disorders, for example, of the lower limbs.

[0154] A compression bandage systems typically employ multiple layers including a padding layer between the skin and the compression layer or layers. The compression bandage may be useful for wounds such as handling venous leg ulcers.

[0155] The compression bandage in some embodiments may comprise a bandage system comprising an inner skin facing layer and an elastic outer layer, the inner layer comprising a first ply of foam and a second ply of an absorbent nonwoven web, the inner layer and outer layer being sufficiently elongated so as to be capable of being wound about a patient's limb. A compression bandage of this type is disclosed in WO99/58090, the entirety of which is hereby incorporated by reference.

[0156] In some embodiments, the compression bandage system comprises: a) an inner skin facing, elongated, elastic bandage comprising: (i) an elongated, elastic substrate, and

[0157] (ii) an elongated layer of foam, said foam layer being affixed to a face of said substrate and extending 33% or more across said face of substrate in transverse direction and 67% or more across said face of substrate in longitudinal direction; and b) an outer, elongated, self-adhering elastic bandage; said bandage having a compressive force when extended; wherein, in use, said foam layer of the inner bandage faces the skin and the outer bandage overlies the inner bandage. A compression bandage of this type is disclosed in WO2006/1 10527, the entirety of which is hereby incorporated by reference.

[0158] In some embodiments other compression bandage systems such as those disclosed in US 6,759,566 and US 2002/0099318, the entirety of each of which is hereby incorporated by reference. Negative Pressure Wound Dressing

[0159] In some embodiments, treatment of such wounds can be performed using negative pressure wound therapy, wherein a reduced or negative pressure can be applied to the wound to facilitate and promote healing of the wound. It will also be appreciated that the wound dressing and methods as disclosed herein may be applied to other parts of the body, and are not necessarily limited to treatment of wounds.

[0160] It will be understood that embodiments of the present disclosure are generally applicable to use in topical negative pressure ("TNP") therapy systems. Briefly, negative pressure wound therapy assists in the closure and healing of many forms of "hard to heal" wounds by reducing tissue oedema; encouraging blood flow and granular tissue formation; removing excess exudate and may reduce bacterial load (and thus infection risk). In addition, the therapy allows for less disturbance of a wound leading to more rapid healing. TNP therapy systems may also assist on the healing of surgically closed wounds by removing fluid and by helping to stabilize the tissue in the apposed position of closure. A further beneficial use of TNP therapy can be found in grafts and flaps where removal of excess fluid is important and close proximity of the graft to tissue is required in order to ensure tissue viability.

[0161] Negative pressure therapy can be used for the treatment of open or chronic wounds that are too large to spontaneously close or otherwise fail to heal by means of applying negative pressure to the site of the wound. Topical negative pressure (TNP) therapy or negative pressure wound therapy (NPWT) involves placing a cover that is impermeable or semi-permeable to fluids over the wound, using various means to seal the cover to the tissue of the patient surrounding the wound, and connecting a source of negative pressure (such as a vacuum pump) to the cover in a manner so that negative pressure is created and maintained under the cover. It is believed that such negative pressures promote wound healing by facilitating the formation of granulation tissue at the wound site and assisting the body's normal inflammatory process while simultaneously removing excess fluid, which may contain adverse cytokines or bacteria. [0162] Some of the dressings used in NPWT can include many different types of materials and layers, for example, gauze, pads, foam pads or multi-layer wound dressings. One example of a multi-layer wound dressing is the PICO dressing, available from Smith & Nephew, includes a wound contact layer and a superabsorbent layer beneath a backing layer to provide a canister-less system for treating a wound with NPWT. The wound dressing may be sealed to a suction port providing connection to a length of tubing, which may be used to pump fluid out of the dressing or to transmit negative pressure from a pump to the wound dressing. Additionally, RENASYS-F, RENASYS-G, RENASYS-AB, and RENASYS-F/AB, available from Smith & Nephew, are additional examples of NPWT wound dressings and systems. Another example of a multi-layer wound dressing is the ALLEVYN Life dressing, available from Smith & Nephew, which includes a moist wound environment dressing that is used to treat the wound without the use of negative pressure.

[0163] As is used herein, reduced or negative pressure levels, such as -X mmHg, represent pressure levels relative to normal ambient atmospheric pressure, which can correspond to 760 mmHg (or 1 atm, 29.93 inHg, 101.325 kPa, 14.696 psi, etc.). Accordingly, a negative pressure value of -X mmHg reflects absolute pressure that is X mmHg below 760 mmHg or, in other words, an absolute pressure of (760- X) mmHg. In addition, negative pressure that is "less" or "smaller" than X mmHg corresponds to pressure that is closer to atmospheric pressure (such as, -40 mmHg is less than -60 mmHg). Negative pressure that is "more" or "greater" than -X mmHg corresponds to pressure that is further from atmospheric pressure (such as, -80 mmHg is more than -60 mmHg). In some embodiments, local ambient atmospheric pressure is used as a reference point, and such local atmospheric pressure may not necessarily be, for example, 760 mmHg.

[0164] The negative pressure range for some embodiments of the present disclosure can be approximately -80 mmHg, or between about -20 mmHg and -200 mmHg. Note that these pressures are relative to normal ambient atmospheric pressure, which can be 760 mmHg. Thus, -200 mmHg would be about 560 mmHg in practical terms. In some embodiments, the pressure range can be between about - 40 mmHg and -150 mmHg. Alternatively a pressure range of up to -75 mmHg, up to -80 mmHg or over -80 mmHg can be used. Also in other embodiments a pressure range of below -75 mmHg can be used. Alternatively, a pressure range of over approximately -100 mmHg, or even -150 mmHg, can be supplied by the negative pressure apparatus.

[0165] In some embodiments of wound closure devices described herein, increased wound contraction can lead to increased tissue expansion in the surrounding wound tissue. This effect may be increased by varying the force applied to the tissue, for example by varying the negative pressure applied to the wound over time, possibly in conjunction with increased tensile forces applied to the wound via embodiments of the wound closure devices. In some embodiments, negative pressure may be varied over time for example using a sinusoidal wave, square wave, or in synchronization with one or more patient physiological indices (such as, heartbeat). Examples of such applications where additional disclosure relating to the preceding may be found include U.S. Patent No. 8,235,955, titled "Wound treatment apparatus and method," issued on August 7, 2012; and U.S. Patent No. 7,753,894, titled "Wound cleansing apparatus with stress," issued July 13, 2010. The disclosures of both of these patents are hereby incorporated by reference in their entirety.

[0166] Embodiments of the wound dressings, wound dressing components, wound treatment apparatuses and methods described herein may also be used in combination or in addition to those described in International Application No. PCT/IB2013/001469, filed May 22, 2013, published as WO 2013/175306 A2 on November 28, 2013, titled "APPARATUSES AND METHODS FOR NEGATIVE PRESSURE WOUND THERAPY," U.S. Patent Application No. 14/418,908, filed January 30, 2015, published as US 2015/0190286 A1 on July 9, 2015, titled "WOUND DRESSING AND METHOD OF TREATMENT," the disclosures of which are hereby incorporated by reference in their entireties. Embodiments of the wound dressings, wound dressing assembly, wound dressing components, wound treatment apparatuses and methods described herein may also be used in combination or in addition to those described in U.S. Patent Application No. 13/092,042, filed April 21 , 201 1 , published as US201 1/0282309, titled "WOUND DRESSING AND METHOD OF USE," and U.S. Patent Application No. 14/715,527, filed May 18, 2015, published as US2016/0339158 A1 on November 24, 2016, titled "FLUIDIC CONNECTOR FOR NEGATIVE PRESSURE WOUND THERAPY," the disclosure of each of which is hereby incorporated by reference in its entirety, including further details relating to embodiments of wound dressings, the wound dressing components and principles, and the materials used for the wound dressings.

[0167] Additionally, some embodiments related to TNP wound treatment comprising a wound dressing in combination with a pump or associated electronics described herein may also be used in combination or in addition to those described in International Application PCT/EP2016/059329 filed April 26, 2016, published as WO 2016/174048 on November 3, 2016, entitled "REDUCED PRESSURE APPARATUS AND METHODS," the disclosure of which is hereby incorporated by reference in its entirety.

NPWT System Overview

[0168] FIG. 1A illustrates an embodiment of a negative or reduced pressure wound treatment (or TNP) system 102 comprising a wound filler 108 placed inside a wound cavity 104, the wound cavity sealed by a wound cover 106. The wound filler 108 in combination with the wound cover 106 can be referred to as wound dressing. A single or multi lumen tube or conduit 1 12 is connected the wound cover 106 with a pump assembly 1 14 configured to supply reduced pressure. The wound cover 106 can be in fluidic communication with the wound cavity 104. In any of the system embodiments disclosed herein, as in the embodiment illustrated in FIG. 1A, the pump assembly can be a canisterless pump assembly (meaning that exudate is collected in the wound dressing or is transferred via tube 1 12 for collection to another location). However, any of the pump assembly embodiments disclosed herein can be configured to include or support a canister. Additionally, in any of the system embodiments disclosed herein, any of the pump assembly embodiments can be mounted to or supported by the dressing, or adjacent to the dressing.

[0169] The wound filler 108 can be any suitable type, such as hydrophilic or hydrophobic foam, gauze, inflatable bag, and so on. The wound filler 108 can be conformable to the wound cavity 104 such that it substantially fills the cavity. The wound cover 106 can provide a substantially fluid impermeable seal over the wound cavity 104. The wound cover 106 can have a top side and a bottom side, and the bottom side adhesively (or in any other suitable manner) seals with wound cavity 104. The conduit 1 12 or lumen or any other conduit or lumen disclosed herein can be formed from polyurethane, PVC, nylon, polyethylene, silicone, or any other suitable material.

[0170] Some embodiments of the wound cover 106 can have a port (not shown) configured to receive an end of the conduit 1 12. For example, the port can be Renays Soft Port available from Smith & Nephew. In other embodiments, the conduit 1 12 can otherwise pass through or under the wound cover 106 to supply reduced pressure to the wound cavity 104 so as to maintain a desired level of reduced pressure in the wound cavity. The conduit 1 12 can be any suitable article configured to provide at least a substantially sealed fluid flow pathway between the pump assembly 1 14 and the wound cover 106, so as to supply the reduced pressure provided by the pump assembly 1 14 to wound cavity 104.

[0171] The wound cover 106 and the wound filler 108 can be provided as a single article or an integrated single unit. In some embodiments, no wound filler is provided and the wound cover by itself may be considered the wound dressing. The wound dressing may then be connected, via the conduit 1 12, to a source of negative pressure, such as the pump assembly 1 14. The pump assembly 1 14 can be miniaturized and portable, although larger conventional pumps such can also be used.

[0172] The wound cover 106 can be located over a wound site to be treated. The wound cover 106 can form a substantially sealed cavity or enclosure over the wound site. In some embodiments, the wound cover 106 can be configured to have a film having a high water vapour permeability to enable the evaporation of surplus fluid, and can have a superabsorbing material contained therein to safely absorb wound exudate. It will be appreciated that throughout this specification reference is made to a wound. In this sense it is to be understood that the term wound is to be broadly construed and encompasses open and closed wounds in which skin is torn, cut or punctured or where trauma causes a contusion, or any other surficial or other conditions or imperfections on the skin of a patient or otherwise that benefit from reduced pressure treatment. A wound is thus broadly defined as any damaged region of tissue where fluid may or may not be produced. Examples of such wounds include, but are not limited to, acute wounds, chronic wounds, surgical incisions and other incisions, subacute and dehisced wounds, traumatic wounds, flaps and skin grafts, lacerations, abrasions, contusions, burns, diabetic ulcers, pressure ulcers, stoma, surgical wounds, trauma and venous ulcers or the like. The components of the TNP system described herein can be particularly suited for incisional wounds that exude a small amount of wound exudate.

[0173] Some embodiments of the system are designed to operate without the use of an exudate canister. Some embodiments can be configured to support an exudate canister. In some embodiments, configuring the pump assembly 1 14 and tubing 1 12 so that the tubing 1 12 can be quickly and easily removed from the pump assembly 1 14 can facilitate or improve the process of dressing or pump changes, if necessary. Any of the pump embodiments disclosed herein can be configured to have any suitable connection between the tubing and the pump.

[0174] The pump assembly 1 14 can be configured to deliver negative pressure of approximately -80 mmHg, or between about -20 mmHg and 200 mmHg in some implementations. Note that these pressures are relative to normal ambient atmospheric pressure thus, -200 mmHg would be about 560 mmHg in practical terms. The pressure range can be between about -40 mmHg and -150 mmHg. Alternatively a pressure range of up to -75 mmHg, up to -80 mmHg or over -80 mmHg can be used. Also a pressure range of below -75 mmHg can be used. Alternatively a pressure range of over approximately -100 mmHg, or even 150 mmHg, can be supplied by the pump assembly 1 14.

[0175] In operation, the wound filler 108 is inserted into the wound cavity 104 and wound cover 106 is placed so as to seal the wound cavity 104. The pump assembly 1 14 provides a source of a negative pressure to the wound cover 106, which is transmitted to the wound cavity 104 via the wound filler 108. Fluid (such as, wound exudate) is drawn through the conduit 1 12, and can be stored in a canister. In some embodiments, fluid is absorbed by the wound filler 108 or one or more absorbent layers (not shown). [0176] Wound dressings that may be utilized with the pump assembly and other embodiments of the present application include Renasys-F, Renasys-G, Renasys AB, and Pico Dressings available from Smith & Nephew. Further description of such wound dressings and other components of a negative pressure wound therapy system that may be used with the pump assembly and other embodiments of the present application are found in U.S. Patent Publication Nos. 201 1/0213287, 201 1/0282309, 2012/01 16334, 2012/0136325, and 2013/01 10058, which are incorporated by reference in their entirety. In other embodiments, other suitable wound dressings can be utilized.

Wound Dressing Overview

[0177] FIG. 1 B illustrates a cross-section through a wound dressing 155 according to some embodiments. FIG. 1 B also illustrates a fluidic connector 1 16 according to some embodiments. The wound dressing 155 can be similar to the wound dressing described in International Patent Publication WO2013175306 A2, which is incorporated by reference in its entirety. Alternatively, the wound dressing 155 can be any wound dressing embodiment disclosed herein or any combination of features of any number of wound dressing embodiments disclosed herein, can be located over a wound site to be treated. The wound dressing 155 may be placed as to form a sealed cavity over the wound, such as the wound cavity 104. In some embodiments, the wound dressing 155 includes a top or cover layer, or backing layer 220 attached to an optional wound contact layer 222, both of which are described in greater detail below. These two layers 220, 222 can be joined or sealed together so as to define an interior space or chamber. This interior space or chamber may comprise additional structures that may be adapted to distribute or transmit negative pressure, store wound exudate and other fluids removed from the wound, and other functions which will be explained in greater detail below. Examples of such structures, described below, include a transmission layer 226 and an absorbent layer 221.

[0178] As used herein the upper layer, top layer, or layer above refers to a layer furthest from the surface of the skin or wound while the dressing is in use and positioned over the wound. Accordingly, the lower surface, lower layer, bottom layer, or layer below refers to the layer that is closest to the surface of the skin or wound while the dressing is in use and positioned over the wound.

[0179] The wound contact layer 222 can be a polyurethane layer or polyethylene layer or other flexible layer which is perforated, for example via a hot pin process, laser ablation process, ultrasound process or in some other way or otherwise made permeable to liquid and gas. The wound contact layer 222 has a lower surface 224 (for example, facing the wound) and an upper surface 223 (for example, facing away from the wound). The perforations 225 can comprise through holes in the wound contact layer 222 which enable fluid to flow through the layer 222. The wound contact layer 222 helps prevent tissue ingrowth into the other material of the wound dressing. In some embodiments, the perforations are small enough to meet this requirement while still allowing fluid to flow therethrough. For example, perforations formed as slits or holes having a size ranging from 0.025 mm to 1.2 mm are considered small enough to help prevent tissue ingrowth into the wound dressing while allowing wound exudate to flow into the dressing. In some configurations, the wound contact layer 222 may help maintain the integrity of the entire dressing 155 while also creating an air tight seal around the absorbent pad in order to maintain negative pressure at the wound. In some embodiments, the wound contact layer is configured to allow unidirectional or substantially one-way or unidirectional flow of fluid through the wound contact layer when negative pressure is applied to the wound. For example, the wound contact layer can permit fluid to flow away from the wound through the wound contact layer, but not allow fluid to flow back toward the wound. In certain case, the perforations in the wound contact layer are configured to permit such one-way or unidirectional flow of fluid through the wound contact layer.

[0180] Some embodiments of the wound contact layer 222 may also act as a carrier for an optional lower and upper adhesive layer (not shown). For example, a lower pressure sensitive adhesive may be provided on the lower surface 224 of the wound dressing 155 whilst an upper pressure sensitive adhesive layer may be provided on the upper surface 223 of the wound contact layer. The pressure sensitive adhesive, which may be a silicone, hot melt, hydrocolloid or acrylic based adhesive or other such adhesives, may be formed on both sides or optionally on a selected one or none of the sides of the wound contact layer. When a lower pressure sensitive adhesive layer is utilized may be helpful to adhere the wound dressing 155 to the skin around a wound site. In some embodiments, the wound contact layer may comprise perforated polyurethane film. The lower surface of the film may be provided with a silicone pressure sensitive adhesive and the upper surface may be provided with an acrylic pressure sensitive adhesive, which may help the dressing maintain its integrity. In some embodiments, a polyurethane film layer may be provided with an adhesive layer on both its upper surface and lower surface, and all three layers may be perforated together.

[0181] A layer 226 of porous material can be located above the wound contact layer 222. This porous layer, or transmission layer, 226 allows transmission of fluid including liquid and gas away from a wound site into upper layers of the wound dressing. In particular, the transmission layer 226 can ensure that an open air channel can be maintained to communicate negative pressure over the wound area even when the absorbent layer has absorbed substantial amounts of exudates. The layer 226 can remain open under the typical pressures that will be applied during negative pressure wound therapy as described above, so that the whole wound site sees an equalized negative pressure. The layer 226 may be formed of a material having a three dimensional structure. For example, a knitted or woven spacer fabric (for example Baltex 7970 weft knitted polyester) or a non-woven fabric could be used.

[0182] In some embodiments, the transmission layer 226 comprises a 3D polyester spacer fabric layer including a top layer (that is to say, a layer distal from the wound-bed in use) which is a 84/144 textured polyester, and a bottom layer (that is to say, a layer which lies proximate to the wound bed in use) which is a 10 denier flat polyester and a third layer formed sandwiched between these two layers which is a region defined by a knitted polyester viscose, cellulose or the like monofilament fiber. Other materials and other linear mass densities of fiber could of course be used.

[0183] Whilst reference is made throughout this disclosure to a monofilament fiber it will be appreciated that a multistrand alternative could of course be utilized. The top spacer fabric thus has more filaments in a yarn used to form it than the number of filaments making up the yarn used to form the bottom spacer fabric layer.

[0184] This differential between filament counts in the spaced apart layers helps control moisture flow across the transmission layer. Particularly, by having a filament count greater in the top layer, that is to say, the top layer is made from a yarn having more filaments than the yarn used in the bottom layer, liquid tends to be wicked along the top layer more than the bottom layer. In use, this differential tends to draw liquid away from the wound bed and into a central region of the dressing where the absorbent layer 221 helps lock the liquid away or itself wicks the liquid onwards towards the cover layer where it can be transpired.

[0185] In some embodiments, to improve the liquid flow across the transmission layer 226 (that is to say perpendicular to the channel region formed between the top and bottom spacer layers, the 3D fabric may be treated with a dry cleaning agent (such as, but not limited to, Perchloro Ethylene) to help remove any manufacturing products such as mineral oils, fats or waxes used previously which might interfere with the hydrophilic capabilities of the transmission layer. An additional manufacturing step can subsequently be carried in which the 3D spacer fabric is washed in a hydrophilic agent (such as, but not limited to, Feran Ice 30g/l available from the Rudolph Group). This process step helps ensure that the surface tension on the materials is so low that liquid such as water can enter the fabric as soon as it contacts the 3D knit fabric. This also aids in controlling the flow of the liquid insult component of any exudates.

[0186] A layer 221 of absorbent material can be provided above the transmission layer 226. The absorbent material, which comprise a foam or non- woven natural or synthetic material, and which may optionally comprise a super- absorbent material, forms a reservoir for fluid, particularly liquid, removed from the wound site. In some embodiments, the layer 221 may also aid in drawing fluids towards the backing layer 220.

[0187] The material of the absorbent layer 221 may also prevent liquid collected in the wound dressing 155 from flowing freely within the dressing, and can act so as to contain any liquid collected within the dressing. The absorbent layer 221 also helps distribute fluid throughout the layer via a wicking action so that fluid is drawn from the wound site and stored throughout the absorbent layer. This helps prevent agglomeration in areas of the absorbent layer. The capacity of the absorbent material must be sufficient to manage the exudates flow rate of a wound when negative pressure is applied. Since in use the absorbent layer experiences negative pressures the material of the absorbent layer is chosen to absorb liquid under such circumstances. A number of materials exist that are able to absorb liquid when under negative pressure, for example superabsorber material. The absorbent layer 221 may typically be manufactured from ALLEVYN™ foam, Freudenberg 1 14-224-4 or Chem-Posite™1 1 C-450. In some embodiments, the absorbent layer 221 may comprise a composite comprising superabsorbent powder, fibrous material such as cellulose, and bonding fibers. In a some embodiments, the composite is an airlaid, thermally-bonded composite.

[0188] In some embodiments, the absorbent layer 221 is a layer of non- woven cellulose fibers having super-absorbent material in the form of dry particles dispersed throughout. Use of the cellulose fibers introduces fast wicking elements which help quickly and evenly distribute liquid taken up by the dressing. The juxtaposition of multiple strand-like fibers leads to strong capillary action in the fibrous pad which helps distribute liquid. In this way, the super-absorbent material is efficiently supplied with liquid. The wicking action also assists in bringing liquid into contact with the upper cover layer to aid increase transpiration rates of the dressing.

[0189] An aperture, hole, or orifice 227 can be provided in the backing layer 220 to allow a negative pressure to be applied to the dressing 155. In some embodiments, the fluidic connector 1 16 is attached or sealed to the top of the backing layer 220 over the orifice 227 made into the dressing 155, and communicates negative pressure through the orifice 227. A length of tubing may be coupled at a first end to the fluidic connector 1 16 and at a second end to a pump unit (not shown) to allow fluids to be pumped out of the dressing. Where the fluidic connector is adhered to the top layer of the wound dressing, a length of tubing may be coupled at a first end of the fluidic connector such that the tubing, or conduit, extends away from the fluidic connector parallel or substantially to the top surface of the dressing. The fluidic connector 1 16 may be adhered and sealed to the backing layer 220 using an adhesive such as an acrylic, cyanoacrylate, epoxy, UV curable or hot melt adhesive. The fluidic connector 1 16 may be formed from a soft polymer, for example a polyethylene, a polyvinyl chloride, a silicone or polyurethane having a hardness of 30 to 90 on the Shore A scale. In some embodiments, the fluidic connector 1 16 may be made from a soft or conformable material.

[0190] In some embodiments, the absorbent layer 221 includes at least one through hole 228 located so as to underlie the fluidic connector 1 16. The through hole 228 may in some embodiments be the same size as the opening 227 in the backing layer, or may be bigger or smaller. As illustrated in FIG. 1 B a single through hole can be used to produce an opening underlying the fluidic connector 1 16. It will be appreciated that multiple openings could alternatively be utilized. Additionally should more than one port be utilized according to certain embodiments of the present disclosure one or multiple openings may be made in the absorbent layer and the obscuring layer in registration with each respective fluidic connector. Although not essential to certain embodiments of the present disclosure the use of through holes in the super-absorbent layer may provide a fluid flow pathway which remains unblocked in particular when the absorbent layer is near saturation.

[0191] The aperture or through-hole 228 can be provided in the absorbent layer 221 beneath the orifice 227 such that the orifice is connected directly to the transmission layer 226 as illustrated in FIG. 1 B. This allows the negative pressure applied to the fluidic connector 1 16 to be communicated to the transmission layer

226 without passing through the absorbent layer 221. This ensures that the negative pressure applied to the wound site is not inhibited by the absorbent layer as it absorbs wound exudates. In other embodiments, no aperture may be provided in the absorbent layer 221 , or alternatively a plurality of apertures underlying the orifice

227 may be provided. In further alternative embodiments, additional layers such as another transmission layer or an obscuring layer such as described in International Patent Publication WO2014020440, the entirety of which is hereby incorporated by reference, may be provided over the absorbent layer 221 and beneath the backing layer 220.

[0192] The backing layer 220 is can be gas impermeable, but moisture vapor permeable, and can extend across the width of the wound dressing 155. The backing layer 220, which may for example be a polyurethane film (for example, Elastollan SP9109) having a pressure sensitive adhesive on one side, is impermeable to gas and this layer thus operates to cover the wound and to seal a wound cavity over which the wound dressing is placed. In this way an effective chamber is made between the backing layer 220 and a wound site where a negative pressure can be established. The backing layer 220 can be sealed to the wound contact layer 222 in a border region around the circumference of the dressing, ensuring that no air is drawn in through the border area, for example via adhesive or welding techniques. The backing layer 220 protects the wound from external bacterial contamination (bacterial barrier) and allows liquid from wound exudates to be transferred through the layer and evaporated from the film outer surface. The backing layer 220 can include two layers; a polyurethane film and an adhesive pattern spread onto the film. The polyurethane film can be moisture vapor permeable and may be manufactured from a material that has an increased water transmission rate when wet. In some embodiments the moisture vapor permeability of the backing layer increases when the backing layer becomes wet. The moisture vapor permeability of the wet backing layer may be up to about ten times more than the moisture vapor permeability of the dry backing layer.

[0193] The absorbent layer 221 may be of a greater area than the transmission layer 226, such that the absorbent layer overlaps the edges of the transmission layer 226, thereby ensuring that the transmission layer does not contact the backing layer 220. This provides an outer channel of the absorbent layer 221 that is in direct contact with the wound contact layer 222, which aids more rapid absorption of exudates to the absorbent layer. Furthermore, this outer channel ensures that no liquid is able to pool around the circumference of the wound cavity, which may otherwise seep through the seal around the perimeter of the dressing leading to the formation of leaks. As illustrated in FIG. 1 B, the absorbent layer 221 may define a smaller perimeter than that of the backing layer 220, such that a boundary or border region is defined between the edge of the absorbent layer 221 and the edge of the backing layer 220.

[0194] As shown in FIG. 1 B, one embodiment of the wound dressing 155 comprises an aperture 228 in the absorbent layer 221 situated underneath the fluidic connector 1 16. In use, for example when negative pressure is applied to the dressing 155, a wound facing portion of the fluidic connector may thus come into contact with the transmission layer 226, which can thus aid in transmitting negative pressure to the wound site even when the absorbent layer 221 is filled with wound fluids. Some embodiments may have the backing layer 220 be at least partly adhered to the transmission layer 226. In some embodiments, the aperture 228 is at least 1 -2 mm larger than the diameter of the wound facing portion of the fluidic connector 1 1 , or the orifice 227.

[0195] For example, in embodiments with a single fluidic connector 1 16 and through hole, it may be preferable for the fluidic connector 1 16 and through hole to be located in an off-center position. Such a location may permit the dressing 155 to be positioned onto a patient such that the fluidic connector 1 16 is raised in relation to the remainder of the dressing 155. So positioned, the fluidic connector 1 16 and the filter 214 may be less likely to come into contact with wound fluids that could prematurely occlude the filter 214 so as to impair the transmission of negative pressure to the wound site.

[0196] Turning now to the fluidic connector 1 16, some embodiments include a sealing surface 216, a bridge 21 1 with a proximal end (closer to the negative pressure source) and a distal end 140, and a filter 214. The sealing surface 216 can form the applicator that is sealed to the top surface of the wound dressing. In some embodiments a bottom layer of the fluidic connector 1 16 may comprise the sealing surface 216. The fluidic connector 1 16 may further comprise an upper surface vertically spaced from the sealing surface 216, which in some embodiments is defined by a separate upper layer of the fluidic connector. In other embodiments the upper surface and the lower surface may be formed from the same piece of material. In some embodiments the sealing surface 216 may comprise at least one aperture 229 therein to communicate with the wound dressing. In some embodiments the filter 214 may be positioned across the opening 229 in the sealing surface, and may span the entire opening 229. The sealing surface 216 may be configured for sealing the fluidic connector to the cover layer of the wound dressing, and may comprise an adhesive or weld. In some embodiments, the sealing surface 216 may be placed over an orifice in the cover layer with optional spacer elements 215 configured to create a gap between the filter 214 and the transmission layer 226. In other embodiments, the sealing surface 216 may be positioned over an orifice in the cover layer and an aperture in the absorbent layer 220, permitting the fluidic connector 1 16 to provide air flow through the transmission layer 226. In some embodiments, the bridge 21 1 may comprise a first fluid passage 212 in communication with a source of negative pressure, the first fluid passage 212 comprising a porous material, such as a 3D knitted material, which may be the same or different than the porous layer 226 described previously. The bridge 21 1 can be encapsulated by at least one flexible film layer 208, 210 having a proximal and distal end and configured to surround the first fluid passage 212, the distal end of the flexible film being connected the sealing surface 216. The filter 214 is configured to substantially prevent wound exudate from entering the bridge, and spacer elements 215 are configured to prevent the fluidic connector from contacting the transmission layer 226. These elements will be described in greater detail below.

[0197] Some embodiments may further comprise an optional second fluid passage positioned above the first fluid passage 212. For example, some embodiments may provide for an air leak may be disposed at the proximal end of the top layer that is configured to provide an air path into the first fluid passage 212 and dressing 155 similar to the suction adapter as described in U.S. Patent No 8,801 ,685, which is incorporated by reference herein in its entirety.

[0198] In some embodiment, the fluid passage 212 is constructed from a compliant material that is flexible and that also permits fluid to pass through it if the spacer is kinked or folded over. Suitable materials for the fluid passage 212 include without limitation foams, including open-cell foams such as polyethylene or polyurethane foam, meshes, 3D knitted fabrics, non-woven materials, and fluid channels. In some embodiments, the fluid passage 212 may be constructed from materials similar to those described above in relation to the transmission layer 226. Advantageously, such materials used in the fluid passage 212 not only permit greater patient comfort, but may also provide greater kink resistance, such that the fluid passage 212 is still able to transfer fluid from the wound toward the source of negative pressure while being kinked or bent.

[0199] In some embodiments, the fluid passage 212 may be comprised of a wicking fabric, for example a knitted or woven spacer fabric (such as a knitted polyester 3D fabric, Baltex 7970®, or Gehring 879®) or a nonwoven fabric. These materials selected can be suited to channeling wound exudate away from the wound and for transmitting negative pressure or vented air to the wound site, and may also confer a degree of kinking or occlusion resistance to the fluid passage 212. In some embodiments, the wicking fabric may have a three-dimensional structure, which in some cases may aid in wicking fluid or transmitting negative pressure. In certain embodiments, including wicking fabrics, these materials remain open and capable of communicating negative pressure to a wound area under the typical pressures used in negative pressure therapy, for example between -40 to -150 mmHg. In some embodiments, the wicking fabric may comprise several layers of material stacked or layered over each other, which may in some cases be useful in preventing the fluid passage 212 from collapsing under the application of negative pressure. In other embodiments, the wicking fabric used in the fluid passage 212 may be between 1.5 mm and 6 mm; more preferably, the wicking fabric may be between 3 mm and 6 mm thick, and may be comprised of either one or several individual layers of wicking fabric. In other embodiments, the fluid passage 212 may be between 1 .2-3 mm thick, and preferably thicker than 1.5 mm. Some embodiments, for example a suction adapter used with a dressing which retains liquid such as wound exudate, may employ hydrophobic layers in the fluid passage 212, and only gases may travel through the fluid passage 212. Additionally, and as described previously, the materials used in the system can be conformable and soft, which may help to avoid pressure ulcers and other complications which may result from a wound treatment system being pressed against the skin of a patient.

[0200] In some embodiments, the filter element 214 is impermeable to liquids, but permeable to gases, and is provided to act as a liquid barrier and to ensure that no liquids are able to escape from the wound dressing 155. The filter element 214 may also function as a bacterial barrier. Typically the pore size is 0.2μηη. Suitable materials for the filter material of the filter element 214 include 0.2 micron Gore™ expanded PTFE from the MMT range, PALL Versapore™ 200R, and Donaldson™ TX6628. Larger pore sizes can also be used but these may require a secondary filter layer to ensure full bioburden containment. As wound fluid contains lipids it is preferable, though not essential, to use an oleophobic filter membrane for example 1.0 micron MMT-332 prior to 0.2 micron MMT-323. This prevents the lipids from blocking the hydrophobic filter. The filter element can be attached or sealed to the port or the cover film over the orifice. For example, the filter element 214 may be molded into the fluidic connector 1 16, or may be adhered to one or both of the top of the cover layer and bottom of the suction adapter 160 using an adhesive such as, but not limited to, a UV cured adhesive.

[0201] It will be understood that other types of material could be used for the filter element 214. More generally a microporous membrane can be used which is a thin, flat sheet of polymeric material, this contains billions of microscopic pores. Depending upon the membrane chosen these pores can range in size from 0.01 to more than 10 micrometers. Microporous membranes are available in both hydrophilic (water filtering) and hydrophobic (water repellent) forms. In some embodiments, filter element 214 comprises a support layer and an acrylic copolymer membrane formed on the support layer. In some embodiments, the wound dressing 155 according to certain embodiments uses microporous hydrophobic membranes (MHMs). Numerous polymers may be employed to form MHMs. For example, the MHMs may be formed from one or more of PTFE, polypropylene, PVDF and acrylic copolymer. All of these optional polymers can be treated in order to obtain specific surface characteristics that can be both hydrophobic and oleophobic. As such these will repel liquids with low surface tensions such as multivitamin infusions, lipids, surfactants, oils and organic solvents.

[0202] MHMs block liquids whilst allowing air to flow through the membranes. They are also highly efficient air filters eliminating potentially infectious aerosols and particles. A single piece of MHM is well known as an option to replace mechanical valves or vents. Incorporation of MHMs can thus reduce product assembly costs improving profits and costs/benefit ratio to a patient.

[0203] The filter element 214 may also include an odor absorbent material, for example activated charcoal, carbon fiber cloth or Vitec Carbotec-RT Q2003073 foam, or the like. For example, an odor absorbent material may form a layer of the filter element 214 or may be sandwiched between microporous hydrophobic membranes within the filter element. The filter element 214 thus enables gas to be exhausted through the orifice. Liquid, particulates and pathogens however are contained in the dressing.

[0204] The wound dressing 155 may comprise spacer elements 215 in conjunction with the fluidic connector 1 16 and the filter 214. With the addition of such spacer elements 215 the fluidic connector 1 16 and filter 214 may be supported out of direct contact with the absorbent layer 220 or the transmission layer 226. The absorbent layer 220 may also act as an additional spacer element to keep the filter 214 from contacting the transmission layer 226. Accordingly, with such a configuration contact of the filter 214 with the transmission layer 226 and wound fluids during use may thus be minimized.

[0205] Similar to the embodiments of wound dressings described above, some wound dressings comprise a perforated wound contact layer with silicone adhesive on the skin-contact face and acrylic adhesive on the reverse. Above this bordered layer sits a transmission layer or a 3D spacer fabric pad. Above the transmission layer, sits an absorbent layer. The absorbent layer can include a superabsorbent non-woven (NW) pad. The absorbent layer can over-border the transmission layer by approximately 5mm at the perimeter. The absorbent layer can have an aperture or through-hole toward one end. The aperture can be about 10 mm in diameter. Over the transmission layer and absorbent layer lies a backing layer. The backing layer can be a high moisture vapor transmission rate (MVTR) film, pattern coated with acrylic adhesive. The high MVTR film and wound contact layer encapsulate the transmission layer and absorbent layer, creating a perimeter border of approximately 20 mm. The backing layer can have a 10 mm aperture that overlies the aperture in the absorbent layer. Above the hole can be bonded a fluidic connector that comprises a liquid-impermeable, gas-permeable semi-permeable membrane (SPM) or filter that overlies the aforementioned apertures.

[0206] FIGS. 1 C-1 D illustrate embodiments of a negative pressure wound treatment system 10 employing a wound dressing 100 in conjunction with a fluidic connector 1 10. Here, the fluidic connector 1 10 may comprise an elongate conduit, for example, a bridge 120 having a proximal end 130 and a distal end 140, and an applicator 180 at the distal end 140 of the bridge 120. An optional coupling 160 can be disposed at the proximal end 130 of the bridge 120. A cap 170 may be provided with the system (and can in some cases, as illustrated, be attached to the coupling 160). The cap 170 can be useful in preventing fluids from leaking out of the proximal end 130. The system 10 may include a source of negative pressure such as a pump or negative pressure unit 150 capable of supplying negative pressure. The pump may comprise a canister or other container for the storage of wound exudates and other fluids that may be removed from the wound. A canister or container may also be provided separate from the pump. In some embodiments, such as illustrated in FIGS. 1A-1 B, the pump 150 can be a canisterless pump such as the PICO™ pump, as sold by Smith & Nephew. The pump 150 may be connected to the coupling 160 via a tube 190, or the pump 150 may be connected directly to the coupling 160 or directly to the bridge 120. In use, the dressing 100 is placed over a suitably-prepared wound, which may in some cases be filled with a wound packing material such as foam or gauze. The applicator 180 of the fluidic connector 1 10 has a sealing surface that is placed over an aperture in the dressing 100 and is sealed to the top surface of the dressing 100. Either before, during, or after connection of the fluidic connector 1 10 to the dressing 100, the pump 150 is connected via the tube 190 to the coupling 160, or is connected directly to the coupling 160 or to the bridge 120. The pump is then activated, thereby supplying negative pressure to the wound. Application of negative pressure may be applied until a desired level of healing of the wound is achieved.

[0207] As shown in FIG. 1 E, the fluidic connector 1 10 comprises an enlarged distal end, or head 140 that is in fluidic communication with the dressing 100 as will be described in further detail below. In one embodiment, the enlarged distal end has a round or circular shape. The head 140 is illustrated here as being positioned near an edge of the dressing 100, but may also be positioned at any location on the dressing. For example, some embodiments may provide for a centrally or off-centered location not on or near an edge or corner of the dressing 100. In some embodiments, the dressing 10 may comprise two or more fluidic connectors 1 10, each comprising one or more heads 140, in fluidic communication therewith. In an embodiment, the head 140 may measure 30mm along its widest edge. The head 140 forms at least in part the applicator 180, described above, that is configured to seal against a top surface of the wound dressing. [0208] Turning to FIG. 1 F, treatment of other wound types, such as larger abdominal wounds, with negative pressure in certain embodiments uses a negative pressure treatment system 101 as illustrated schematically here. In this embodiment, a wound 126, illustrated here as an abdominal wound, may benefit from treatment with negative pressure. Such abdominal wounds may be a result of, for example, an accident or due to surgical intervention. In some cases, medical conditions such as abdominal compartment syndrome, abdominal hypertension, sepsis, or fluid edema may require decompression of the abdomen with a surgical incision through the abdominal wall to expose the peritoneal space, after which the opening may need to be maintained in an open, accessible state until the condition resolves. Other conditions may also necessitate that an opening— particularly in the abdominal cavity— remain open, for example if multiple surgical procedures are required (possibly incidental to trauma), or there is evidence of clinical conditions such as peritonitis or necrotizing fasciitis.

[0209] In cases where there is a wound, particularly in the abdomen, management of possible complications relating to the exposure of organs and the peritoneal space is desired, whether or not the wound is to remain open or if it will be closed. Therapy, preferably using the application of negative pressure, can be targeted to minimize the risk of infection, while promoting tissue viability and the removal of deleterious substances from the wound. The application of reduced or negative pressure to a wound has been found to generally promote faster healing, increased blood flow, decreased bacterial burden, increased rate of granulation tissue formation, to stimulate the proliferation of fibroblasts, stimulate the proliferation of endothelial cells, close chronic open wounds, inhibit burn penetration, and/or enhance flap and graft attachment, among other things. It has also been reported that wounds that have exhibited positive response to treatment by the application of negative pressure include infected open wounds, decubitus ulcers, dehisced incisions, partial thickness burns, and various lesions to which flaps or grafts have been attached. Consequently, the application of negative pressure to a wound106 can be beneficial to a patient.

[0210] Accordingly, certain embodiments provide for a wound contact layer 105 to be placed over the wound 126. The wound contact layer can also be referred to as an organ protection layer and/or a tissue protection layer. Preferably, the wound contact layer 105 can be a thin, flexible material which will not adhere to the wound or the exposed viscera in close proximity. For example, polymers such as polyurethane, polyethylene, polytetrafluoroethylene, or blends thereof may be used. In one embodiment, the wound contact layer is permeable. For example, the wound contact layer 105 can be provided with openings, such as holes, slits, or channels, to allow the removal of fluids from the wound 126 or the transmittal of negative pressure to the wound 126. Additional embodiments of the wound contact layer 105 are described in further detail below.

[0211] Certain embodiments of the negative pressure treatment system 101 may also use a porous wound filler 103, which can be disposed over the wound contact layer 105. This pad 103 can be constructed from a porous material, for example foam, that is soft, resiliently flexible, and generally conformable to the wound 126. Such a foam can include an open-celled and reticulated foam made, for example, of a polymer. Suitable foams include foams composed of, for example, polyurethane, silicone, and polyvinyl alcohol. Preferably, this pad 103 can channel wound exudate and other fluids through itself when negative pressure is applied to the wound. Some pads 103 may include preformed channels or openings for such purposes. In certain embodiments, the pad 103 may have a thickness between about one inch and about two inches. The pad may also have a length of between about 16 and 17 inches, and a width of between about 1 1 and 12 inches. In other embodiments, the thickness, width, and/or length can have other suitable values. Other embodiments of wound fillers that may be used in place of or in addition to the pad 103 are discussed in further detail below.

[0212] Preferably, a drape 107 is used to seal the wound 126. The drape 107 can be at least partially liquid impermeable, such that at least a partial negative pressure may be maintained at the wound. Suitable materials for the drape 107 include, without limitation, synthetic polymeric materials that do not significantly absorb aqueous fluids, including polyolefins such as polyethylene and polypropylene, polyurethanes, polysiloxanes, polyamides, polyesters, and other copolymers and mixtures thereof. The materials used in the drape may be hydrophobic or hydrophilic. Examples of suitable materials include Transeal® available from DeRoyal and OpSite® available from Smith & Nephew. In order to aid patient comfort and avoid skin maceration, the drapes in certain embodiments are at least partly breathable, such that water vapor is able to pass through without remaining trapped under the dressing. An adhesive layer may be provided on at least a portion the underside of the drape 107 to secure the drape to the skin of the patient, although certain embodiments may instead use a separate adhesive or adhesive strip. Optionally, a release layer may be disposed over the adhesive layer to protect it prior to use and to facilitate handling the drape 107; in some embodiments, the release layer may be composed of multiple sections.

[0213] The negative pressure system 101 can be connected to a source of negative pressure, for example a pump 1 14. One example of a suitable pump is the Renasys EZ pump available from Smith & Nephew. The drape 107 may be connected to the source of negative pressure 1 14 via a conduit 122. The conduit 122 may be connected to a port 1 13 situated over an aperture 109 in the drape 107, or else the conduit 122 may be connected directly through the aperture 109 without the use of a port. In a further alternative, the conduit may pass underneath the drape and extend from a side of the drape. U.S. Pat. No. 7,524,315 discloses other similar aspects of negative pressure systems and is hereby incorporated by reference in its entirety and should be considered a part of this specification.

[0214] In many applications, a container or other storage unit 1 15 may be interposed between the source of negative pressure 124 and the conduit 122 so as to permit wound exudate and other fluids removed from the wound to be stored without entering the source of negative pressure. Certain types of negative pressure sources— for example, peristaltic pumps— may also permit a container 1 15 to be placed after the pump 124. Some embodiments may also use a filter to prevent fluids, aerosols, and other microbial contaminants from leaving the container 1 15 and/or entering the source of negative pressure 124. Further embodiments may also include a shut-off valve or occluding hydrophobic and/or oleophobic filter in the container to prevent overflow; other embodiments may include sensing means, such as capacitive sensors or other fluid level detectors that act to stop or shut off the source of negative pressure should the level of fluid in the container be nearing capacity. At the pump exhaust, it may also be preferable to provide an odor filter, such as an activated charcoal canister.

[0215] FIG. 1 G illustrates various embodiments of a wound dressing that can be used for healing a wound without negative pressure. As shown in the dressings of FIG. 1 G, the wound dressings can have multiple layers similar to the dressings described with reference to FIGS. 1 C-1 F except the dressings of FIG. 1 G do not include a port or fluidic connector. The wound dressings of FIG. 1 G can include a cover layer and wound contact layer as described herein. The wound dressing can include various layers positioned between the wound contact layer and cover layer. For example, the dressing can include one or more absorbent layers and/or one or more transmission layers as described herein with reference to FIGS. 1 C-1 F. Additionally, some embodiments related to wound treatment comprising a wound dressing described herein may also be used in combination or in addition to those described in U.S. Application Publication No. 2014/0249495, filed May 21 , 2014, entitled "WOUND DRESSING AND METHOD OF TREATMENT" the disclosure of which are hereby incorporated by reference in its entirety, including further details relating to embodiments of wound dressings, the wound dressing components and principles, and the materials used for the wound dressings.

Wound Dressing with Sensors

[0216] A wound dressing that incorporates a number of sensors can be utilized in order to monitor characteristics of a wound as it heals. Collecting data from the wounds that heal well, and from those that do not, can provide useful insights towards identifying measurands to indicate whether a wound is on a healing trajectory.

[0217] In some implementations, a number of sensor technologies can be used in wound dressings or one or more components forming part of an overall wound dressing assembly. For example, as illustrated in FIGS. 2 and 3D, which depict wound dressings 250 and 320 with sensor arrays according to some embodiments, one or more sensors can be incorporated onto or into a wound contact layer, which may be a perforated wound contact layer as shown in FIG. 3D. The wound contact layer in FIGS. 2 and 3D is illustrated as having a square shape, but it will be appreciated that the wound contact layer may have other shapes such as rectangular, circular, oval, etc. In some embodiments, the sensor integrated wound contact layer can be provided as an individual material layer that is placed over the wound area and then covered by a wound dressing assembly or components of a wound dressing assembly, such as gauze, foam or other wound packing material, a superabsorbent layer, a drape, a fully integrated dressing like the Pico or Allevyn Life dressing, etc. In other embodiments, the sensor integrated wound contact layer may be part of a single unit dressing such as described herein.

[0218] The sensor-integrated wound contact layer can be placed in contact with the wound and will allow fluid to pass through the contact layer while causing little to no damage to the tissue in the wound. The sensor-integrated wound contact layer can be made of a flexible material such as silicone and can incorporate antimicrobials or other therapeutic agents known in the art. In some embodiments, the sensor-integrated wound contact layer can incorporate adhesives that adhere to wet or dry tissue. In some embodiments, the sensors or sensor array can be incorporated into or encapsulated within other components of the wound dressing such as the absorbent layer or spacer layer described above.

[0219] As shown in FIGS. 2 and 3D, five sensors can be used, including, for instance, sensors for temperature (such as, 25 thermistor sensors, in a 5 x 5 array, ~20mm pitch), oxygen saturation or Sp02 (such as, 4 or 5 Sp02 sensors, in a single line from the center of the wound contact layer to the edge thereof, 10mm pitch), tissue color (such as, 10 optical sensors, in 2 x 5 array, ~20mm pitch; not all 5 sensors in each row of the array need be aligned), pH (such as, by measuring colour of a pH sensitive pad, optionally using the same optical sensors as for tissue colour), and conductivity (such as, 9 conductivity contacts, in a 3 x 3 array, ~40mm pitch). As shown in FIG. 3A, the Sp02 sensors can be arranged in a single line from the center of or near the center of the wound contact layer to the edge of the wound contact layer. The line of Sp02 sensors can allow the sensor to take measurements in the middle of the wound, at the edge or the wound, or on intact skin to measure changes between the various regions. In some embodiments, the wound contact layer or sensor array can be larger than the size of the wound to cover the entire surface area of the wound as well as the surrounding intact skin. The larger size of the wound contact layer and/or sensor array and the multiple sensors can provide more information about the wound area than if the sensor was only placed in the center of the wound or in only one area at a time.

[0220] The sensors can be incorporated onto flexible circuit boards formed of flexible polymers including polyamide, polyimide (PI), polyester, polyethylene naphthalate (PEN), polyetherimide (PEI), along with various fluropolymers (FEP) and copolymers, or any material known in the art. The sensor array can be incorporated into a two-layer flexible circuit. In some embodiments, the circuit board can be a multi-layer flexible circuit board. In some embodiments, these flexible circuits can be incorporated into any layer of the wound dressing. In some embodiments, a flexible circuit can be incorporated into a wound contact layer. For example, the flexible circuit can be incorporated into a wound contact layer similar to the wound contact layer described with reference to FIG. 1 B. The wound contact layer can have cutouts or slits that allow for one or more sensors to protrude out of the lower surface of the wound contact layer and contact the wound area directly.

[0221] In some embodiments, the sensor-integrated wound contact layer can include a first and second wound contact layer with the flexible circuit board sandwiched between the two layers of wound contact layer material. The first wound contact layer has a lower surface intended to be in contact with the wound and an upper surface intended to be in contact with flexible circuit board. The second wound contact layer has a lower surface intended to be in contact with the flexible circuit board and an upper surface intended to be in contact with a wound dressings or one or more components forming part of an overall wound dressing assembly. The upper surface of the first wound contact layer and the lower surface of the second wound contact layer can be adhered together with the flexible circuit board sandwiched between the two layers.

[0222] In some embodiments, the one or more sensors of the flexible circuit board can be fully encapsulated or covered by the wound contact layers to prevent contact with moisture or fluid in the wound. In some embodiments, the first wound contact layer can have cutouts or slits that allow for one or more sensors to protrude out of the lower surface and contact the wound area directly. For example, the one or more Sp02 sensors as shown in FIG. 3D are shown protruding out the bottom surface of the wound contact layer. In some embodiments, the Sp02 sensors can be mounted directly on a lower surface of the first wound contact layer. Some or all of the sensors and electrical or electronic components may be potted or encapsulated (for example, rendered waterproof or liquid-proof) with a polymer, for example, silicon or epoxy based polymers. The encapsulation with a polymer can prevent ingress of fluid and leaching of chemicals from the components. In some embodiments, the wound contact layer material can seal the components from water ingress and leaching of chemicals.

[0223] In some embodiments, gathering and processing information related to the wound can utilize three components, including a sensor array, a control or processing module, and software. These components are described in more detail herein.

[0224] FIG. 3A illustrates a flexible sensor array circuit board 300 that includes a sensor array portion 301 , a tail portion 302, and a connector pad end portion 303 according to some embodiments. The sensor array portion 301 can include the sensors and associated circuitry. The sensor array circuit board 300 can include a long tail portion 302 extending from the sensor array portion 301. The connector pad end portion 303 can be enabled to connect to a control module or other processing unit to receive the data from the sensor array circuit. The long tail portion 302 can allow the control module to be placed distant from the wound, such as for example in a more convenient location away from the wound.

[0225] FIG. 3B illustrates embodiments of the flexible circuit boards with four different sensor array geometries 301 A, 301 B, 301 C, and 301 D according to some embodiments. The illustrated embodiments include tail portions 302A, 302B. 302C, and 302D. In some embodiments, four different sensor array geometries shown can be implemented in flexible circuits. While FIG. 3B show four different sensor array formats and configurations, the design 301 B and 302B also includes the connector pads end portion 303 configured to provide electrical or electronic connection between the sponsor array 301 B and a control module. One or more of the designs in 301 A, 301 C, or 301 D can also include a connector pads end portion, such as the portion 303, to allow flexible circuit boards 301A, 301 C, or 301 D to communicate with a control module or other processing unit. In some embodiments, the sensor array communicates with the control module wirelessly and the tail portion may be omitted.

[0226] FIG. 3C shows the sensor array portion 301 B of the sensor array design shown of FIG. 3B in more detail. In any one or more of the embodiments of FIGS 2 or 3A-3D, the sensor array portion can include a plurality of portions that extend either around a perimeter of a wound dressing component such as a wound contact layer, or inward from an outer edge of the wound dressing component. For example, the illustrated embodiments include a plurality of linearly extending portions that may be parallel to edges of a wound dressing component, and in some embodiments, follow the entire perimeter of the wound dressing component. In some embodiments, the sensor array portion may comprise a first plurality of parallel linearly extending portions that are perpendicular to a second plurality of parallel linearly extending portions. These linearly extending portions may also have different lengths and may extend inward to different locations within an interior of a wound dressing component. The sensor array portion preferably does not cover the entire wound dressing component, so that gaps are formed between portions of the sensor array. As shown in FIG. 2, this allows some, and possibly a majority of the wound dressing component to be uncovered by the sensor array. For example, for a perforated wound contact layer as shown in FIG. 2 and 3D, the sensor array portion 301 may not block a majority of the perforations in the wound contact layer. In some embodiments, the sensor array may also be perforated or shaped to match the perforations in the wound contact layer to minimize the blocking of perforations to fluid flow.

[0227] FIG. 3D illustrates a flexible sensor array incorporated into a perforated wound contact layer 320 according to some embodiments. As is illustrated, the sensor array can be sandwiched between two films or wound contact layers. The wound contact layers can have perforations formed as slits or holes as described herein that are small enough to help prevent tissue ingrowth into the wound dressing while allowing wound exudate to flow into the dressing. In some embodiments, the wound contact layers can have one or more slits that increase flexibility of the wound contact layer with integrated sensor array. In some embodiments, one of the wound contact layers can have extra cut outs to accommodate the sensors so that they can contact the skin directly.

[0228] Connectivity for the sensor array can vary depending on the various sensors and sensor array designs utilized. In some embodiments, for example as shown in FIG. 3B, a total of 79 connections can be used to connect the components of the sensor array. The sensor arrays can be terminated in two parallel 40-way 0.5mm pitch Flat Flexible Cable (FFC) contact surfaces, with terminals on the top surface, designed to be connected to an FFC connector such as Molex 54104-4031.

[0229] In some embodiments, one or more of thermistors, conductivity sensors, Sp02 sensors, or color sensors can be used on the sensor array to provide information relating to conditions of the wound. The sensor array and individual sensors can assist a clinician in monitoring the healing of the wound. The one or more sensors can operate individually or in coordination with each other to provide data relating to the wound and wound healing characteristics.

[0230] Temperature sensors can use thermocouples or thermistors to measure temperature. The thermistors can be used to measure or track the temperature of the underlying wound or the thermal environment within the wound dressing. The thermometry sensors can be calibrated and the data obtained from the sensors can be processed to provide information about the wound environment. In some embodiments, an ambient sensor measuring ambient air temperature can also be used to assist in eliminating problems associated with environment temperature shifts.

[0231] Optical sensors can be used to measure wound appearance using an RGB sensor (for example, a red, green, blue, and clear (RGBC) sensor or red, green blue, and white (RGBW) sensor) with an illumination source. In some embodiments, both the RGB sensor and the illumination source would be pressed up against the skin, such that light would penetrate into the tissue and take on the spectral features of the tissue itself.

[0232] Light propagation in tissue can be dominated by two major phenomena, scattering and attenuation. For attenuation, as light passes through tissue, its intensity may be lost due to absorption by various components of the tissue. Blue light tends to be attenuated heavily, whilst light at the red end of the spectrum tends to be attenuated least.

[0233] Scattering processes can be more complex, and can have various "regimes" which must be considered. The first aspect of scattering is based on the size of the scattering centre compared with the wavelength of incident light. If the scattering center is much smaller than the wavelength of light, then Rayleigh scattering can be assumed. If the scattering center is on the order of the wavelength of light, then a more detailed Mie scattering formulation must be considered. Another factor involved in scattering light is the distance between input and output of the scattering media. If the mean free path of the light (the distance between scattering events) is much larger than the distance travelled, then ballistic photon transport is assumed. In the case of tissue, scatting events are approximately 100 microns apart - so a 1 mm path distance would effectively randomise the photon direction and the system would enter a diffusive regime.

[0234] Ultra bright light emitting diodes (LEDs), an RGB sensor, and polyester optical filters can be used as components of the optical sensors to measure through tissue color differentiation. For example, because surface color can be measured from reflected light, a color can be measured from light which has passed through the tissue first for a given geometry. This can include color sensing from diffuse scattered light, from an LED in contact with the skin. In some embodiments, an LED can be used with an RGB sensor nearby to detect the light which has diffused through the tissue. The optical sensors can image with diffuse internal light or surface reflected light.

[0235] Additionally, the optical sensors can be used to measure autofluorescence. Autoflourescense is used because the tissue is absorbing light at one wavelength, and emitting at another. Additionally, dead tissue may not auto- fluoresce and so this could be a very strong indication as to if the tissue is healthy or not. Due to blue light (or even UV light) having such a short penetration depth, it may be very useful for example to have a UV light with a red sensitive photodiode nearby (or some other wavelength shifted band) to act as a binary test for healthy tissue, which would auto-fluoresce at a very particular wavelength. [0236] Conductivity sensors can be used to determine the difference between living and dead tissue or to show a change in impedance due to a wound being opened up in morbid tissue. Conductivity sensors can include Ag/AgCI electrodes and an impedance analyser. The conductivity sensors can be used to measure the change of impedance of a region of wound growth by measuring the impedance of the surrounding tissue/area. In some embodiments, the sensor array can utilize conductivity sensors to measure the change in conductivity on perimeter electrodes due to a wound size or wound shape change. In some embodiments, the conductivity sensors can be used in the wound bed or on the perimeter of the wound.

[0237] In some embodiments, pH changing pads can be used as a pH sensor. A spectrometer and a broadband white light source can be used to measure the spectral response of the pH dye. The illumination and imaging can be provided on the surface of the wound dressing that is in contact with the wound and at the same side as the fluid application, the bottom surface. Alternatively, in some embodiments, the illumination and imaging source can be provided on the surface of the wound dressing opposite the bottom surface and away from fluid application or the top surface of the dressing.

[0238] In some embodiments, pulse oximetry Sp02 sensors can be used. To measure how oxygenated the blood is and the pulsatile blood flow can be observed. Pulse oximetry measurements work by taking a time resolved measurement of light absorption / transmission in tissue at two different optical wavelengths. When hemoglobin becomes oxygenated, its absorption spectrum changes with regards to non-oxygenated blood. By taking a measurement at two different wavelengths, one gains a ratio metric measure of how oxygenated the blood is.

[0239] The components in the sensor array can be connected through multiple connections. In some embodiments, the thermistors can be arranged in groups of five. Each thermistor is nominally 10kQ, and each group of five has a common ground. There are five groups of thermistors, giving a total of 30 connections. In some embodiments, there can be nine conductivity terminals. Each conductivity terminal requires one connection, giving a total of 9 connections. In some embodiments, there can be five Sp02 sensors. Each Sp02 sensor requires three connections, plus power and ground (these are covered separately), giving a total of 15 connections. In some embodiments, there can be 10 color sensors. Each color sensor comprises an RGB LED and an RGB photodiode. Each color sensor requires six connections, however five of these are common to every sensor, giving a total of 15 connections. Power and ground are considered separately. In some embodiments, there can be 5 pH sensors. The pH sensors can be a color-change discs, and can be sensed using the color sensors described above. Therefore, the pH sensors require no additional connections. There can be three power rails, and seven ground return signals, giving a total of 10 common connections. In some embodiments, the sensor array can include 25 thermistor (Murata NCP15WB473E03RC), 9 conductivity terminal, 5 Sp02 (ADPD144RI), 10 RGB LED (such as KPTF-1616RGBC-13), 10 RGB Color Sensor, 10 FET, a printed circuit board (PCB), and an assembly.

[0240] A control module can be used to interface with the sensor array. In some embodiments, the control module can contain a power source, such as batteries, and electronics to drive the sensors. The control module can also log data at appropriate intervals and allow data transfer to an external computing device, such as a personal computer (PC). The control module can be customized to have various features depending on the sensors used in the sensor array and the data collected by the sensors. In some embodiments, the control module can be comfortable enough and small enough to be worn continuously for several weeks. In some embodiments, the control module can be positioned near the wound dressing or on the wound dressing. In some embodiments, the control module can be positioned in a remote location from the wound dressing and accompanying sensor array. The control module can communicate with the sensor array and wound dressing through electrical wires or through wireless communication whether positioned on the dressing, near the dressing, or remote from the wound dressing. In some embodiments, the control module can be adapted to be utilized with different sensor arrays and can enable easy replacement of the sensor array. [0241] In some embodiments, the control module can include various requirements and combination of features including but not limited to the features listed in Table 1 below.

TABLE 1. OPTIONAL FEATURES FOR CONTROL MODULE

7 day operation from a single set of batteries

28 day local, non-volatile, storage capacity

Easy to charge, or to replace battery

Wireless link to PC / tablet (such as Bluetooth)

Wired link to PC (optional, micro-USB)

Drive electronics for thermistors

Drive electronics for conductivity sensors

Drive electronics for optical sensors

Drive electronics for SpO2 sensors

Power management

Real Time Clock (RTC) to allow accurate data logging, and correlation with other measurands

Ability to change sample rates and intervals (useful for SpO2) for each sensor

Indication of status via LED, such as (Green : Awake; Flashing green :

Charging; Blue : Wireless link established; Flashing blue : Wireless data transfer; Yellow : Wired link established; Flashing yellow : Wired data transfer; Red : Battery low; Flashing red : Battery very low

[0242] FIG. 3E illustrates a block diagram 330 of a control module according to some embodiments. The block diagram of the control module includes a conductivity driver box 391 displaying features of the conductivity driver. Box 392 shows the features of the thermistor interface and box 393 shows the features of the optical interface. The control module can include a controller or microprocessor with features similar to those shown in box 394. Real time clock (RTC), Status LEDs, USB connector, Serial Flash, and Debug Connector can be included as features of the control module as shown in FIG. 3E.

[0243] In some embodiments, the microprocessor can have one or more of the following features: 2.4GHz or another suitable frequency radio (either integrated, or external); Supplied Bluetooth software stack; SPI interface; USB (or UART for external USB driver); I2C; 3 channel PWM; 32 GPIO; or 6-channel ADC. In some embodiments, the device can require at least 48 I/O pins or possibly more due to banking limitations. Bluetooth stack typically requires ~20kB on-board Flash, so a minimum of 32kB can be required. In some embodiment, 64kB can be required if complex data processing is considered. The processor core can be ARM Cortex M4 or a similar processor core. In some embodiments, the parts can include ST's STM32L433LC or STM32F302R8, which would require an external radio, or NXP's Kinetis KW range including integrated radio.

[0244] In some embodiment, the control module can include a memory component where the amount of local storage depends on the sample rate and resolution of the sensors. For example, an estimated data requirement of 256Mb (32MB) can be met by using a serial Flash device from a number of manufacturers (Micron, Spansion).

[0245] The control module can utilize one or more analogue switches. In some embodiments, analogue switches with good on resistance and reasonable bandwidth can be used. For example, Analog Devices' ADG72 or NXP's NX3L4051 HR can be used. Based on the initial system architecture, 8 of these will be required.

[0246] The control module can incorporate a power source, such as a battery. For example a 300mWh/day battery can be used. For 7 days this is 2100mWh. This could be provided by: a 10 days, non-rechargeable, ER14250 (14.5mm diameter x 25mm) LiSOCI2 cell; or a 7 days, rechargeable, Li 14500 (14.5mm diameter x 500mm) Li-Ion.

[0247] The control module can incorporate a real time clock (RTC). The RTC can be chosen from any RTC devices with crystal. The control module can also include miscellaneous resistors, capacitors, connectors, charge controllers, and other power supplies.

[0248] The PCB of the control module can be a 4-layer board, approximately 50mm x 20mm, or 25mm x 40mm. The type of PCB used can be largely driven by connection requirements to sensor array. [0249] The enclosure of the control module can be a two part moulding, with clip features to allow easy access for changing sensor arrays or batteries.

[0250] The data collected through the sensor array can be passed through the control module and processed by host software. The software may be executed on a processing device. The processing device can be a PC, tablet, smartphone, or other computer capable of running host software. The processing device executing the software can be in communication with the control module through electrical wires or through wireless communication. In some embodiments, the software may be configured to provide access to the data held on the control module, but not to perform big-data analysis. The host software can include an interface to the control module via Bluetooth or USB. In some embodiments, the host software can read the status of control module, download logged data from control module, upload sample rate control to control module, convert data from control module into format suitable for processing by big-data analysis engine, or upload data to cloud for processing by analysis engine.

[0251] The software may be developed for PC (Windows / Linux), tablet or smartphone (Android / iOS), or for multiple platforms.

[0252] In some embodiments, a source of negative pressure (such as a pump) and some or all other components of the topical negative pressure system, such as power source(s), sensor(s), connector(s), user interface component(s) (such as button(s), switch(es), speaker(s), screen(s), etc.) and the like, can be integral with the wound dressing. In some embodiments, the components can be integrated below, within, on top of, or adjacent to the backing layer. In some embodiments, the wound dressing can include a second cover layer or a second filter layer for positioning over the layers of the wound dressing and any of the integrated components. The second cover layer can be the upper most layer of the dressing or can be a separate envelope that enclosed the integrated components of the topical negative pressure system.

[0253] As used herein the upper layer, top layer, or layer above refers to a layer furthest from the surface of the skin or wound while the dressing is in use and positioned over the wound. Accordingly, the lower surface, lower layer, bottom layer, or layer below refers to the layer that is closest to the surface of the skin or wound while the dressing is in use and positioned over the wound.

Pad Skew

[0254] FIG. 4 illustrates an example schematic configuration 400 for measuring one or more physiological characteristics at a wound site (for example, in or around a wound) of a patient according to some embodiments. As is shown, excitation sensors 420, 424 (sometimes referred to as drive pads or excitation electrodes) are configured to introduce or apply an electrical signal(s) (for example, voltage, current, frequency, or the like) to the wound site (not pictured). Measurement sensors 404, 408, 412, 416 (sometimes referred to as measurement pads or measurement electrodes) are positioned between the excitation sensors 420, 424 and configured to measure a voltage, current, frequency, or the like. This sensor arrangement can be used to determine one or more physiological characteristics, such as bioelectrical impedance characteristics of tissues and/or fluids at or near a wound and/or one or more physiological parameters, any of which can be indicative of how a wound is healing and/or effects of treatment on a wound.

[0255] Impedance can be characterized as a physical variable describing the resistance characteristics acting on an electric current. Bioelectrical impedance is based on the principle that tissues and/or fluids of a patient have different impedances, that is, opposition to the flow of the electric current, which in turn may be dependent on variables such as water and electrolyte content, to name a few. Using a bioelectrical impedance analysis as a diagnostic tool to examine the electrical or resistive characteristics of tissues provides information on a noninvasive, invasive, and/or continuous basis. For example, a bioelectrical impedance analysis can be made using measurement supported on a wound dressing or otherwise positioned in contact with a wound of the patient.

[0256] Mathematically, bioelectrical impedance can be represented as a complex number including a real component (resistance) and an imaginary dimension (reactance). The electrical impedance (Z) consists of two components, resistance (R) and reactance (X), and can be calculated using Equation 1 below.

Z = R +jX (Equation 1) [0257] In some instances, a number of physiological characteristics or parameters can be calculated or estimated using determined bioelectrical impedance characteristics, such as body cell mass (BCM), extra cellular mass (ECM), extracellular fluid (ECF), extracellular water (ECW), fat-free mass (FFM), fat mass (FM), total body water (TBW), electrolyte composition, cell membrane mass, cell membrane function and the like. In addition, other bioimpedance variables such as phase angle can be useful in determining physiological characteristics. For example, phase angle can be calculated as the arc tangent of reactance over resistance (X/R) and can be expressed in degrees. By determining these bioelectrical parameters and/or monitoring cellular changes over time, physiological characteristics such as wound healing can be assessed, and other determinations can be made such as prognoses in malnutrition and/or chronic disease.

[0258] Biological tissues can have complex electrical impedance which is dependent, for instance, on the frequency of the electrical applied field (for example, rings 436) or tissue cellular structure. Therefore, the electrical impedance of tissue is a function of its structure and it can be used to differentiate tissues, such as those in a healed state from those in a partially healed state. For example, patterns or changes in bioelectrical impedance or bioelectrical impedance variables can be monitored to develop various models indicative of wound healing. As a non-limiting example, changes in resistance (R) over time may be suggestive of healing. For instance, an increase in resistance may indicate healing while decreases may characterize a lack of healing, or vice versa.

[0259] Referring to FIG. 4, the excitation sensors 420, 424 apply an electrical signal to the wound site (not shown). The excitation sensors 420, 424 can be capacitive-coupled with no conductive pathway to the patient. The measurement sensors 404, 408, 412, or 416 are positioned between the excitation sensors 420, 424 such that each of the measurement sensors 404, 408, 412, or 416 can measure characteristics of the excitation signal as it passes from, for example, excitation sensor 420 to excitation sensor 424, or vice versa. For example, the measurement sensors 404, 408, 412, or 416 can measure a voltage, current, frequency, magnetic field, etc., which can be indicative of a voltage difference across tissue or a biological impedance of a tissue, to name a few. [0260] The excitation sensors 420, 424 can provide at least one of various excitation voltages, currents, frequencies, and/or fields. As described above, in some cases, the excitation sensors 420, 424 are capacitive-coupled. In addition, in some embodiments, an excitation signal(s) can be used that does not substantially stimulate or perturb tissues. As such, measurements can be taken while providing little to no discomfort to the patient. However, it should be noted that, in some cases, an excitation signal may be provided which stimulates and/or perturbs the tissues.

[0261] The frequency of the excitation signal can include at least one of various frequencies, such as a low, medium, or high frequency. In some instances, the excitation signal is a spectrum of frequencies or frequency modulation. For example, the excitation frequency can be any of a broad range of frequencies, such as any frequency in the range of about 5kHz to about 1200kHz or in the range of about 37kHz to about 70kHz. In some cases, the excitation frequency can be any of about 5, 10, 30, 37, 40, 45, 50, 55, 60, 65, 70, 80, 90, 100, 300, 500, 700, 900, or 1200 kHz.

[0262] The voltage of the excitation signal can include at least one of various AC or DC voltages, such as a low, medium, or high voltage. The excitation voltage can be any of a broad range of voltages, such as any voltage in the range of about 0.1 mV to about 10,000 V. In some cases, the excitation voltage can be any of about 1 , 2, 5, 10, 30, 50, 60, 100, 300, 500, or 800 mV or about 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 30, 50, 60, 100, 500, 1000, or 10,000 volts. In some embodiments, a peak-to- peak voltage of the excitation signal is less than approximately 3.3V or less than approximately 1V.

[0263] The current of the excitation signal can include at least one of various currents. The excitation current can be any of a broad range of currents, such as any current in the range of about 0.1 μΑ to about 1 A. In some cases, the excitation current can be any of about 0.1 , 1 , 2, 5, 10, 30, 50, 60, 100, 300, 500, 800, or 1000 μΑ. In some cases, the excitation current can be any of about 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 30, 50, 60, 100, 500, 1000 mA.

[0264] The pads 404, 408, 412, 416, 420, 424 can be held in place in a variety of ways. For example, the pads may be attached directly to the patient, incorporated into a wound dressing, as described herein, a flexible circuit, or the like. In some embodiments, at least some of the pads 404, 408, 412, 416, 420, 424 can be soldered or otherwise electrically connected to electronic connections, such as electrical connections within wound dressing (for example, wound dressing 1 10 of FIG. 1A). In some embodiments, adhesive is applied to securely affix or attach one or more of the pads 404, 408, 412, 416, 420, 424 to the wound dressing, patient, etc.

[0265] In certain implementations, it can be advantageous to position the excitation sensors 420, 424 and/or measurement sensors 404, 408, 412, 416 such that a measurable potential difference exists between each of the measurement sensors 404, 408, 412, 416 and/or the excitation sensors 420, 424. For example, by providing a measurable difference between the measurement sensors 404, 408, 412, 416, more impedance measurements can be taken, which can result in a more accurate or precise wound healing determination.

[0266] However, in some embodiments, such as illustrated in FIG. 4, little or no potential difference is measurable between measurement sensors 404, 408, 412, 416. For example, because the a measurement paths (for example, the path from pad 404 to pad 408, the path from pad 408 to pad 412, the path from pad 404 to pad 412, etc.) are perpendicular to the line 432 connecting the drive pads 420, 424, an approximately equal electric field 436 will reach each of the measurement pads or sensors, thereby causing the voltages measured at the measurement sensors 404, 408, 412, 416 to be approximately the same. As a non-limiting example, if a 5V excitation signal was introduced by the excitation sensors 420, 424, each of the measurement sensors 404, 408, 412, 416 would measure approximately the same voltage (for example, about 2.5V). As shown in Table 2, the potential difference between any two of the measurement sensors is approximately 0V.

TABLE 2. APPROXIMATE POTENTIAL DIFFERENCES OF FIG. 4

[0267] FIG. 5 illustrates an example schematic configuration 500 for measuring bioelectrical impedance at a wound site of a patient according to some embodiments. Similar to FIG. 4, the system 500 includes excitation sensors 520, 524 which are configured to introduce or apply an electrical signal(s) and sensors 504, 508, 512, 516 which are positioned between the excitation sensors 520, 524 and are configured to measure a voltage, current, frequency, or the like. However, unlike, the electrode arrangement of FIG. 4, a potential difference is measurable between each of measurement sensors 504, 508, 512, 516. As a non-limiting example, if a 5V excitation signal was introduced by the excitation sensors 520, 524, the measurement sensors 504, 508, 512, 516 would measure different voltages, such as those listed in Table 3.

TABLE 3. APPROXIMATE POTENTIAL DIFFERENCES OF FIG. 5

[0268] While the arrangement in FIG. 5 can achieve a measurable potential difference between each of the measurement sensors 504, 508, 512, 516, in some cases, the configuration may only achieve the desired results when the measurement sensors are in a straight line. Thus, in order to take measurements at various locations across a wound site, multiple straight line configurations would need to be utilized. Accordingly, rather than using a single pair of excitation electrodes, multiple pairs of excitation electrodes may be required. While multiple excitation electrodes may be utilized in some embodiments, the additional excitation electrodes might add unnecessary complexity to the system.

[0269] FIG. 6 illustrates an example schematic configuration 600 for measuring bioelectrical impedance in or around a wound of a patient according to some embodiments. Similar to FIGS. 4 and 5, the system 600 includes excitation sensors 620, 624 which are configured to apply an electrical signal(s) and sensors 604, 608, 612, 616 which are positioned between the excitation sensors 620, 624 and are configured to measure a voltage, current, frequency, or the like. However, in this configuration, unlike the configuration of FIG. 4, the excitation sensors 620, 624 are skewed such that no measurement path (for example, indicated by line 628) is perpendicular to the line 632 connecting the drive pads 620. Accordingly, all measurement sensors 604, 608, 612, 616 are at different potentials.

[0270] Returning to the non-limiting example described in FIGS. 4 and 5, if a 5V excitation signal was introduced by the excitation sensors 520, 524, the measurement sensors 604, 608, 612, 616 would each measure different voltages, such as those listed in Table 4. For example, with reference to a 0V ground (for example, pad 6), pads 1 , 2, 3, 4, 5, and 6 measure approximately 5, 4.2, 3.5, 1.5, 0.8, and 0 volts respectively. Accordingly, a valid measurement can be made between any of the measurement sensors 604, 608, 612, 616 and/or drive pads 620, 624.

TABLE 4. APPROXIMATE POTENTIAL DIFFERENCES OF FIG. 6

[0271] FIG. 7 illustrates an example schematic configuration 700 for measuring bioelectrical impedance in or around a wound of a patient according to some embodiments. The system 700 includes excitation sensors 720, 724 which are configured to introduce or apply an electrical signal(s) and sensors 702, 704, 706, 708, 710, 712, 714, 716 which are positioned between the excitation sensors 720, 724 and are configured to measure a voltage, current, frequency, or the like. As is illustrated, sensors 702 to 708 are positioned proximate the wound, and sensors 710 to 716 are positioned in the wound. A measurement path (for example, paths 730, 732, 734, 736, 738, 740, 743, 744, 746, 748) can exist between any two of the measurement sensors 702, 704, 706, 708, 710, 712, 714, 716 or excitation sensors 720, 724. As illustrated, the excitation sensors 720, 724 are skewed such that none of the measurement paths 730, 732, 734, 736, 738, 740, 743, 744, 746, 748 are perpendicular to a line 750 connecting the excitation sensors 720, 724. Because of this skewing, each of the sensors 702, 704, 706, 708, 710, 712, 714, 716 is at different potential, and therefore a valid measurement exists between each measurement path (for example, paths 730, 732, 734, 736, 738, 740, 743, 744, 746, 748). It should be noted that while only measurement paths 730, 732, 734, 736, 738, 740, 743, 744, 746, 748 are illustrated, a measurement path can exists between any two measurement sensors 702, 704, 706, 708, 710, 712, 714, 716 and/or excitation sensors 720, 724. Accordingly, some measurement paths can overlap with other measurement paths.

[0272] The sensors can be arranged in a variety of arrangements. For example, in some instances the measurement sensors can arranged in a line (for example, as illustrated in FIGS. 4-6), a two-by-two arrangement, a 4 + 4 arrangement (as illustrated in FIG. 7), a 4 + 4 + 4 arrangement, etc. In some embodiments, the measurement sensors, such as measurement sensors 702, 704, 706, 708, 710, 712, 714, 716, can be arranged in any configuration such that no measurement path between any of the measurement sensors is perpendicular to a line 750 connecting the excitation sensors.

[0273] In addition, although illustrated as a the-dimensional arrangement, it should be noted that a three-dimensional arrangement is contemplated. For example, one or more of the sensors 702, 704, 706, 708, 710, 712, 714, 716, 720, 724 can be arranged such that it is not aligned on the same 2-dimensional plane (for example, it is higher or lower than another pad) as each of the other pads. Similar to as described above, in a three-dimensional embodiment, the measurement sensors can be arranged in any configuration such that no measurement path between any of the measurement sensors is orthogonal to a line connecting the excitation sensors.

[0274] Each of the sensors 702, 704, 706, 708, 710, 712, 714, 716, 720, 724 can be placed on the skin 760, such as on a perimeter of a wound, and/or on the wound 770 itself. For example, in some instances, the excitation sensors 720, 724 can be positioned a perimeter of a wound and the measurement sensors 702, 704, 706, 708, 710, 712, 714, 716, can be placed in or on the wound 770. However, it should be noted that any of the sensors 702, 704, 706, 708, 710, 712, 714, 716, 720, 724 can be placed in, on or around the wound 770.

[0275] It can be desirable to take measurements at various locations across a wound site. For example, certain portions of a wound may heal at different rates, and it can be desirable to determine how well one or more areas of the wound are healing. This can be determined, for example, by applying one or more electrical signals to the wound at various locations, and then measuring the responses of one or more areas of the wound.

[0276] In some cases, two excitation sensors may provide sufficient coverage for the wound. However, in some cases, a system can utilize two or more excitation sensors to apply one or more electrical signals. For example, the system can include two, three, four, five, or more excitation sensors positioned in or around a wound, such as near edges of the sensor array. The system can select two or more of the excitation sensors to apply the electrical signal in or around the wound. This allows for a broad coverage of the electrical signal and ultimately allows the system to measure multiple regions of the tissue associated with the wound.

[0277] As described herein, little to no potential difference may exist between measurement sensors if a measurement path between those measurement sensors is perpendicular to a drive path between excitation sensors applying the electrical signal. Accordingly, the excitation sensors that apply one or more electrical signals can be selected to ensure that a measurable potential difference exists between desired measurement sensors.

[0278] FIG. 8A illustrates a sensor array 800A configured to take measurements of one or more areas of the wound. The configuration of the sensor array 800A illustrates an example of sensor placement that can be incorporated into a wound dressing. The sensor array 800A includes four excitation sensors 820, 822, 824, 826 positioned near outside corners of the sensor array 800A and six measurement sensors 802, 804, 806, 808, 810, 812. As described herein, any two or more excitation sensors 820, 822, 824, 826 can apply one or more electrical signals to a patient's wound. For example, the excitation sensors can be driven using a sinusoidal wave, a square wave, a pulse width modulation (PWM) pulse, or another signal. A measurement can be taken at one, or between two or more, of the measurement sensors 802, 804, 806, 808, 810, 812 to measure one or more of voltage, current, frequency, or the like. While four excitation sensors and six measurement sensors are illustrated in FIG. 8A, in other embodiments, other numbers and/or placement of the excitation and/or measurement sensors can be utilized. [0279] From the four excitation sensors 820, 822, 824, 826, any two or more excitation sensors can be chosen to apply the electrical signal. For example, two excitation sensors can be chosen to apply the electrical signal. A first excitation sensor of the excitation sensors 820, 822, 824, or 826 can operate at a first potential and a second excitation sensor (that is different from the first excitation sensor) can operate at a second potential. In some cases, one excitation sensor is selected as a power terminal and another excitation sensor is selected as a ground (or floating ground) terminal.

[0280] As another example, more than two excitation sensors can be selected to apply the electrical signal. For example, a first group (for example, one, two, or more than two) of excitation sensors can operate at a first potential, and a second group of excitations sensors can operate at a second potential. The system can then drive the electrical signal between the first group of excitation sensors and the second group of excitation sensors. For example, in FIG. 8A, excitation sensors 820 and 824 can operate at a first potential, and excitation sensors 822 and 826 can operate at a second potential.

[0281] In some cases, a multiplexer or other selection circuit (not shown) can be configured to select which, if any, of the excitation sensors 820, 822, 824, 826 are to be configured to apply the electrical signal. For example, a multiplexer can be coupled to an input of each of the excitation sensors 820, 822, 824, 826 and can be configured to select two or more excitation sensors to apply the electrical signal. The multiplexer can select a first excitation sensor. Alternatively, one of the excitation sensors can be hardwired at a particular potential. For example, the multiplexer can be coupled to an input of three of the four excitation sensors, while the other excitation sensor is operating at a first potential. Between the three excitation sensors, the multiplexer can select a select an excitation sensor to operate at a different potential. In some cases, the multiplexer can select excitation sensors operating at more than two different potentials. For example, the system can include a 3-phase power supply, where at least one excitation sensor is selected to operate at each of the three phases. For instance, each of the selected excitation sensors can follow an Xsinoot voltage magnitude, but the signals are phase shifted relative to each other. As another example, in some cases, a multiplexer can generate signals across multiple sets of excitation sensors. For example, one or more multiplexers can select a first excitation sensor to operate at a first potential, a second excitation sensor to operate at a second potential, a third excitation sensor to operate at a third potential, and a fourth excitation sensor to operate at a fourth potential.

[0282] The multiplexer can select the two or more excitation sensors that will be used to apply the electrical signal based at least in part on a desired region of tissue to be measured. For example, in some cases, the excitation sensors that are closest to the desired region of tissue may be selected. Similarly, in some cases, excitation sensors that are closest to particular measurement sensor(s) may be selected.

[0283] Furthermore, the multiplexer can select excitation sensors based at least in part on a desired measurement path. For example, as described herein, it can be desirable for the selected excitation sensors to be skewed relative to selected measurement sensors such that an excitation or drive path between the selected excitation sensors is not perpendicular a measurement path between selected measurement sensors. This can ensure that a measurable potential difference exists between the selected measurement sensors. Thus, a multiplexer can select a pair of excitation that would have a drive path that is not perpendicular to a measurement path between selected measurement sensors. The measurement sensors may have been selected, for example, based on their proximity to a region of tissue that a user desires to measure.

[0284] FIG. 8B illustrates various example drive paths and example measurement paths of the sensor array of FIG. 8A. A drive path, indicated by dashed lines 832, corresponds to a path of an electrical signal applied by a pair of excitation sensors and can exist between any two of the excitation sensors 820, 822, 824, 826. A measurement path, indicated by dashed lines 834, corresponds to a path between two measurement sensors, and can exist between any two of measurement sensors 802, 804, 806, 808, 810, 812. In some cases, a measurement path can also exist between any one excitation sensor and any one measurement sensor. [0285] The multiplexer can select the excitation sensor(s) based at least in part on the area of the wound that measurements are to be taken. In other words, excitation sensors can be selected based on the location of measurement sensors 802, 804, 806, 808, 810, 812. For example, as described herein, to ensure that the measurement sensors are at different potentials, it can be desirable for the multiplexer to select a pair of excitation sensors that have a drive path that is not perpendicular any measurement path.

[0286] As a non-limiting example, it may be desirable to obtain a measurement between measurement sensors 804 and 808. For example, it may be desirable to obtain a measurement associated with a left-center portion of the wound, and, among all possible sets of measurement sensors, a measurement between measurement sensors 804 and 808 may provide the best measurement associated with the left-center portion of the wound.

[0287] Based at least in part on the selected measurement sensors (for example, measurement sensors 804 and 808), the system (for example, via a multiplexer) can select excitation sensors to apply the signal. In this example, the measurement path between measurement sensors 804 and 808 is vertical. Accordingly, excitation sensors can be selected which have a drive path appropriately skewed with respect to the selected measurement sensors 804, 808. For example, the system may select excitation sensor pairs 820 and 826, 822 and 824, 820 and 824, or 822 and 826. In this example, the system might not choose excitation sensor pair 820 and 822 or pair 824 and 826, because each of these pairs have a drive path that is perpendicular to the measurement path between measurement sensors 804 and 808. However, in some cases, a measurable signal exists between excitation sensor pair 820 and 822 or pair 824 and 826.

[0288] FIG. 8C illustrates an example sensor array 800C having the sensor array geometry of the sensor array of FIG. 8A. As described in more detail with respect to FIGS, or 3A-3E, the sensor array 800C can include a plurality of portions that extend either around a perimeter of a wound dressing component such as a wound contact layer, or inward from an outer edge of the wound dressing component. For example, the illustrated embodiment includes a plurality of linearly extending portions that may be parallel to edges of a wound dressing, or in some embodiments, follow the entire perimeter of the wound dressing. In some embodiments, the sensor array 800C may include a first plurality of parallel linearly extending portions that are perpendicular to a second plurality of parallel linearly extending portions. These linearly extending portions may also have different lengths and may extend inward to different locations within an interior of a wound dressing. The sensor array 800C preferably does not cover the entire wound dressing, so that gaps are formed between portions of the sensor array. As shown in FIG. 2, this allows some, and possibly a majority of the wound dressing component to be uncovered by the sensor array. For example, for a perforated wound contact layer as shown in FIGS. 2 and 3D, the sensor array portion 800C may not block a majority of the perforations in the wound contact layer. In some embodiments, the sensor array may also be perforated or shaped to match the perforations in the wound contact layer to minimize the blocking of perforations to fluid flow.

[0289] FIG. 9A illustrates a sensor array 900A configured to take measurements of one or more areas of the wound. The configuration of the sensor array 900A illustrates an example of sensor placement that can be incorporated into a wound dressing. The sensor array 900A includes four excitation sensors 920, 822, 924, 926 positioned near outside corners of the sensor array 900A and six measurement sensors 902, 904, 906, 908, 910, 912. As described herein, two or more excitation sensors 920, 922, 924, 926 can apply an electrical signal to a patient's wound, and a measurement can be taken at one, or between two or more, of the measurement sensors 902, 904, 906, 908, 910, 912 to measure voltage, current, frequency, or the like.

[0290] FIG. 9B illustrates various example excitation or drive paths and example measurement paths of the sensor array of FIG. 9A. A drive path, indicated by dashed lines 932, corresponds to a path of an electrical signal applied by excitation sensors and can exist between any two or more of the excitation sensors 920, 922, 924, 926. A measurement path, indicated by dashed lines 934, corresponds to a path between two measurement sensors, and can exist between any two or more of measurement sensors 902, 904, 906, 908, 910, 912. In some cases, a measurement path can also exist between any one excitation sensor and any one measurement sensor. [0291] As described with respect to FIGS. 8A-8C, a multiplexer can select excitation sensors to apply an electrical signal into the wound. The selection can be based at least in part on the area of the wound that measurements are to be taken. As a non-limiting example, it may be desirable to obtain a measurement between measurement sensors 910 and 912. For example, it may be desirable to obtain a measurement associated with a bottom-center portion of the wound, and, among all possible sets of measurement sensors, a measurement between measurement sensors 910 and 912 may provide the best measurement associated with the bottom-center portion of the wound.

[0292] Based at least in part on the selected measurement sensors (for example, measurement sensors 910 and 912), the system (for example, via a multiplexer) can select excitation sensors to apply the signal. In this example, the measurement path between measurement sensors 910 and 912 is horizontal. Accordingly, excitation sensors can be selected such that they are appropriately skewed with respect to the selected measurement sensors 910, 912. In other words, excitation sensors can be selected that have a drive path that is perpendicular (for example, vertical) to the measurement path between measurement sensors 910 and 912. For example, the system can select excitation sensor pairs 920 and 922, 924 and 926, 920 and 926 or 924 and 922. Alternatively, in some cases, the system can choose excitation sensors having a vertical drive path, such as pair 920 and 924 or pair 922 and 926. For example, because equipotentials are not straight (as illustrated in FIG. 4), in some cases, a measureable signal can appear across measurement pads 912 and 910 when driven by pads excitation sensors 920 and 924. Furthermore, a non-homogeneity in the underlying tissue may cause a higher measureable signal to appear across these pads.

[0293] FIG. 9C illustrates an example sensor array 900C having the sensor array geometry of the sensor array of FIG. 9A. As described in more detail with respect to FIGS, or 3A-3E, the sensor array 900C can include a plurality of portions that extend either around a perimeter of a wound dressing such as a wound contact layer, or inward from an outer edge of the wound dressing. For example, the illustrated embodiments include a plurality of linearly extending portions that may be parallel to edges of a wound dressing. The sensor array 900C includes a plurality of parallel linearly extending portions that are perpendicular to base portion of the sensor array 900C. These linearly extending portions may also have different lengths and may extend inward to different locations within an interior of a wound dressing. The sensor array 900C preferably does not cover the entire wound dressing, so that gaps are formed between portions of the sensor array. As shown in FIG. 2, this allows some, and possibly a majority of the wound dressing component to be uncovered by the sensor array. For example, for a perforated wound contact layer as shown in FIG. 2 and 3D, the sensor array 900C may not block a majority of the perforations in the wound contact layer. In some embodiments, the sensor array may also be perforated or shaped to match the perforations in the wound contact layer to minimize the blocking of perforations to fluid flow.

[0294] FIG. 10 illustrates a process 1000 for measuring bioelectrical impedance and/or determining bioelectrical impedance parameter in or around a wound of a patient according to some embodiments. Process 1000 can be performed by hardware and/or software. In some embodiments, the process 1000 can be performed by a controller, such as the control module 330.

[0295] Process 1000 can begin in step or block 1002, in which excitation sensors introduce or apply one or more electrical signals to a wound site. The electrical signal can have any voltage, current or frequency as described herein. The excitation sensors can include one or more sets or pairs of excitation sensors configured to apply an electrical signal. In some cases, the excitation sensors can be capacitive-coupled with no conductive pathway to the patient. In addition, in some embodiments, the sets or pair of excitation sensors can apply simultaneous electrical signals or each set can apply an electrical signal at a different time.,

[0296] At block 1004, the process 1000 is configured to measure, along a first measurement path, a voltage differential between a first voltage at a first measurement pad and a second voltage at a second measurement pad. The first and second measurement pad are positioned proximate the wound site and between a pair of excitation sensors. In addition, first measurement path is not perpendicular to a line connecting the pair of excitation sensors.

[0297] At block 1006, the process 1000 is configured to measure, along a second measurement path, a voltage differential between a third voltage at a third measurement pad and a fourth voltage at a fourth measurement pad. The third and fourth measurement pad are positioned proximate the wound site and between the pair of excitation sensors. In addition, second measurement path is not perpendicular to the line connecting the pair of excitation sensors.

[0298] At block 1008, the process 1000 is configured to determine a physiological characteristic of the wound site. For example, based on the excitation signal, the first voltage differential, the second voltage differential, the first voltage, the second voltage, the third voltage, or the fourth voltage, the process 1000 can determine a physiological characteristic, such as a biological impedance of the tissue, for instance a tissue located between the first and second measurement sensors. In addition or alternatively, based at least in part on a measured voltage, current, frequency, or magnetic field, the process 1000 can determine any number of physiological characteristics.

Other Variations

[0299] Any value of a threshold, limit, duration, etc. provided herein is not intended to be absolute and, thereby, can be approximate. In addition, any threshold, limit, duration, etc. provided herein can be fixed or varied either automatically or by a user. Furthermore, as is used herein relative terminology such as exceeds, greater than, less than, etc. in relation to a reference value is intended to also encompass being equal to the reference value. For example, exceeding a reference value that is positive can encompass being equal to or greater than the reference value. In addition, as is used herein relative terminology such as exceeds, greater than, less than, etc. in relation to a reference value is intended to also encompass an inverse of the disclosed relationship, such as below, less than, greater than, etc. in relations to the reference value. Moreover, although blocks of the various processes may be described in terms of determining whether a value meets or does not meet a particular threshold, the blocks can be similarly understood, for example, in terms of a value (i) being below or above a threshold or (ii) satisfying or not satisfying a threshold.

[0300] Features, materials, characteristics, or groups described in conjunction with a particular aspect, embodiment, or example are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features or steps are mutually exclusive. The protection is not restricted to the details of any foregoing embodiments. The protection extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0301] While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of protection. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made. Those skilled in the art will appreciate that in some embodiments, the actual steps taken in the processes illustrated or disclosed may differ from those shown in the FIGS. Depending on the embodiment, certain of the steps described above may be removed, others may be added. For example, the actual steps or order of steps taken in the disclosed processes may differ from those shown in the FIG. Depending on the embodiment, certain of the steps described above may be removed, others may be added. For instance, the various components illustrated in the FIGS, may be implemented as software or firmware on a processor, controller, ASIC, FPGA, or dedicated hardware. Hardware components, such as controllers, processors, ASICs, FPGAs, and the like, can include logic circuitry. Furthermore, the features and attributes of the specific embodiments disclosed above may be combined in different ways to form additional embodiments, all of which fall within the scope of the present disclosure.

[0302] Although the present disclosure includes certain embodiments, examples and applications, it will be understood by those skilled in the art that the present disclosure extends beyond the specifically disclosed embodiments to other alternative embodiments or uses and obvious modifications and equivalents thereof, including embodiments which do not provide all of the features and advantages set forth herein. Accordingly, the scope of the present disclosure is not intended to be limited by the specific disclosures of preferred embodiments herein, and may be defined by claims as presented herein or as presented in the future.

[0303] Conditional language, such as "can," "could," "might," or "may," unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements, or steps. Thus, such conditional language is not generally intended to imply that features, elements, or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements, or steps are included or are to be performed in any particular embodiment. The terms "comprising," "including," "having," and the like are synonymous and are used inclusively, in an open-ended fashion, and do not exclude additional elements, features, acts, operations, and so forth. Also, the term "or" is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term "or" means one, some, or all of the elements in the list. Further, the term "each," as used herein, in addition to having its ordinary meaning, can mean any subset of a set of elements to which the term "each" is applied.

[0304] Conjunctive language such as the phrase "at least one of X, Y, and Z," unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require the presence of at least one of X, at least one of Y, and at least one of Z.

[0305] Language of degree used herein, such as the terms "approximately," "about," "generally," and "substantially" as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms "approximately", "about", "generally," and "substantially" may refer to an amount that is within less than 10% of, within less than 5% of, within less than 1 % of, within less than 0.1 % of, and within less than 0.01 % of the stated amount. As another example, in certain embodiments, the terms "generally parallel" and "substantially parallel" refer to a value, amount, or characteristic that departs from exactly parallel by less than or equal to 15 degrees, 10 degrees, 5 degrees, 3 degrees, 1 degree, or 0.1 degree.

[0306] The scope of the present disclosure is not intended to be limited by the specific disclosures of preferred embodiments in this section or elsewhere in this specification, and may be defined by claims as presented in this section or elsewhere in this specification or as presented in the future. The language of the claims is to be interpreted broadly based on the language employed in the claims and not limited to the examples described in the present specification or during the prosecution of the application, which examples are to be construed as nonexclusive.