Background

[0001] Microfluidic devices are revolutionizing testing in the healthcare industry. Some microfluidic devices comprise digital microfluidic technology, which may employ circuitry to move fluids.

Brief Description of the Drawings

[0002] FIG. 1 is a diagram including a side view schematically representing an example device and/or example method of controlling electrowetting movement via airborne charges in association with an example consumable microfluidic receptacle.

[0003] FIG. 2 is a diagram including a top plan view schematically representing an example consumable microfluidic receptacle.

[0004] FIG. 3A is a diagram including a side view schematically representing an example consumable microfluidic receptacle including a substrate, which includes an anisotropic conductivity layer.

[0005] FIGS. 3B and 3C are each a diagram including a side view schematically representing an example conductive element including an array of conductive particles.

[0006] FIG. 4 is a diagram including a side view schematically representing an example consumable microfluidic receptacle including a substrate, which includes a passive electrode array.

[0007] FIG. 5 is an isometric view schematically representing an example addressable airborne charge depositing unit including a needle within a cylinder. [0008] FIG. 6A is a diagram including a side view schematically representing an example addressable airborne charge depositing unit, including first and second charge units. [0009] FIG. 6B is a diagram including a side view schematically representing an example addressable airborne charge depositing unit, including a charge building element and a pair of charge neutralizing elements.

[0010] FIG. 6C is a diagram including a side view schematically representing an example two-dimensional addressable charge depositing unit in charging relation to a portion of a consumable microfluidic receptacle.

[0011] FIG. 7A is diagram including a sectional end view schematically representing an example addressable airborne charge depositing unit, including a corona wire and array of individually controllable electrode nozzles.

[0012] FIG. 7B is a diagram including a top view schematically representing an example array of individually controllable electrode nozzles of an example addressable airborne charge depositing unit.

[0013] FIG. 8A is a diagram including a side view schematically representing an example electrode control element.

[0014] FIG. 8B is a diagram including a side view schematically representing an example electrode control element in releasable contact with an example consumable microfluidic receptacle.

[0015] FIG. 8C is a diagram including an isometric view schematically representing an example two-dimensional array of individually controllable electrodes, prior to releasable contact relative to, a portion of a consumable microfluidic receptacle.

[0016] FIG. 9A is a block diagram schematically representing an example fluid operations engine.

[0017] FIG. 9B is a block diagram schematically representing an example control portion.

[0018] FIG. 9C is a block diagram schematically representing an example user interface.

[0019] FIG. 10 is a flow diagram schematically representing an example method of applying charges to cause electrowetting movement of droplets. Detailed Description

[0020] In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific examples in which the disclosure may be practiced. It is to be understood that other examples may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense. It is to be understood that features of the various examples described herein may be combined, in part or whole, with each other, unless specifically noted otherwise.

[0021] At least some examples of the present disclosure are directed to providing a consumable microfluidic receptacle by which digital microfluidic operations can be performed in an inexpensive manner. In some examples, a charge applicator may be brought into charging relation to a plate (e.g. a second plate) of the consumable microfluidic receptacle, whereby the charge applicator is to apply (e.g. deposit) charges onto the second plate to cause an electric field which induces electrowetting movement of a droplet within and through the microfluidic receptacle. In some examples, the charge applicator may comprise an addressable airborne charge depositing unit which may be brought into spaced apart, charging relation to the plate (e.g. second plate) of the receptacle in order to deposit airborne charges onto the plate. In some examples, the charge applicator may comprise an electrode control element which may be brought into releasable contact with, and charging relation to, the plate (e.g. second plate) in order to deposit charges onto the plate of the receptacle.

[0022] In one aspect, “charges” as used herein refers to ions (+/-) or free electrons. In some examples, the addressable airborne charge depositing unit may sometimes be referred to as a non-contact charge depositing unit, as a non-contact charge head, and the like. In some examples, the electrode control element may sometimes be referred to as a releasable contact, electrode control element. In some examples, the plate may sometimes be referred to as a sheet, a wall, a portion, and the like. Moreover, it will be apparent that in some examples, the consumable microfluidic receptacle may form part of and/or comprise a microfluidic device. In some examples, the consumable microfluidic receptacle may sometimes be referred to as a single use microfluidic receptacle, or as being a disposable microfluidic receptacle.

[0023] In some examples, the plate (e.g. the second plate) may comprise dielectric properties to substantially preserve, for a period of time, a voltage differential across at least a dielectric layer of the plate which is caused, in part, by the deposited airborne charges. This arrangement may sometimes be expressed as a voltage differential parameter, such as a voltage differential preservation parameter. Preserving the voltage differential may facilitate droplet movement within a microfluidic receptacle according to a target velocity and/or desired movement initiation and movement termination parameters. In one aspect, via this arrangement a voltage differential across the second plate is substantially preserved over a predetermined period of time during which the droplet moves from a first position to a second position. This time period may sometimes be referred to as a droplet-movement time period or droplet- movement actuation time period. In some examples, this droplet-movement time period also may sometimes be referred to as an electrowetting movement time period. In some examples, the voltage differential parameter also may be expressed as a voltage decay prevention parameter by which decay of the voltage differential is substantially prevented or as a charge retention parameter by which deposited charges are retained at the second plate (as further described below) at least during the droplet-movement time period.

[0024] In some examples, the desired dielectric properties of the second plate (to substantially preserve a voltage differential) may be implemented, at least in part, via a dedicated dielectric layer (e.g. coating) interposed between a hydrophobic layer (e.g. coating) and a substrate of the second plate. In some such examples, in addition to the dedicated dielectric layer, at least the substrate of the second plate also may exhibit some dielectric properties, as further described below.

[0025] In some examples, the dielectric layer of the second plate may be implemented according to certain thicknesses, types of materials, dielectric strength, target applied voltages, droplet-movement time period, etc. In some examples, each type of material of the dielectric layer may be paired with a hydrophobic coating suited to the particular type of material.

[0026] In some examples, the substrate of the second plate may comprise a passive electrode array or an anisotropic conductivity layer, which may facilitate migration of charges across the second plate.

[0027] In some examples, each droplet comprises a small, single generally spherical mass of fluid, such as may be dropped into the consumable microfluidic receptacle. As described above, the entire droplet is sized to be movable via electrowetting forces. In sharp contrast, dielectrophoresis may cause movement of particles within a fluid, rather than movement of an entire droplet of fluid. Some further example details are provided below.

[0028] In some examples, the charge applicator (e.g. addressable airborne charge depositing unit or electrode control element) may apply the charges having a first polarity and/or an opposite second polarity, depending on whether the charge applicator is to build charges on the plate or is to neutralize charges on the plate. The first polarity may be positive or negative depending on the particular goals, while the second polarity will be the opposite of the first polarity. [0029] In some examples, the movement of droplets (caused by electrowetting forces) may occur between adjacent target positions along passageways within a microfluidic receptacle of a microfluidic device, with the target positions corresponding to locations at which the airborne charges are directed from one of the example charge applicators.

[0030] Via such example arrangements, the consumable microfluidic receptacle (of a microfluidic device) may omit control electrodes (e.g. electrically active electrodes) which would otherwise be used to cause microfluidic operations such as moving, merging, and/or splitting droplets within a microfluidic device. Moreover, by providing the example charge applicator to cause an electric field on a portion of the consumable microfluidic receptacle, the consumable microfluidic receptacle may omit inclusion of a printed circuit board and circuitry (e.g. active control circuitry) typically associated with digital microfluidic devices. This arrangement may significantly reduce the cost of the consumable microfluidic receptacle of the microfluidic device and/or significantly ease its recyclability.

[0031] Moreover, because the consumable microfluidic receptacle omits such electrically active control electrodes (for causing electrowetting movement) and omits complex circuitry which is typically directly connected to the control electrodes via conductive traces, the example consumable microfluidic receptacle of the present disclosure is not limited by the limited space constraints typically arising from a one-to-one correspondence between control electrodes and the complex control circuitry. Absent such space constraints, a greater number of target positions along the passageways of the microfluidic receptacle may be used, which may increase the precision by which microfluidic operations are performed, with a resolution (e.g. number of target positions for a given area) of such target positions corresponding to the capabilities (e.g. resolution) that the example charge applicator (e.g. non-contact addressable charge depositing unit or electrode control element) can deposit charges. By being able to re-use the example charge applicator over-and-over again with a supply of disposable or consumable microfluidic receptacles, this example arrangement greatly reduces the overall, long term cost of using digital microfluidic devices while significantly conserving valuable electrically conductive materials.

[0032] In some examples, the consumable microfluidic receptacle may be used to perform microfluidic operations to implement a lateral flow assay and therefore may sometimes be referred to as a lateral flow device. In some examples, the consumable microfluidic receptacle also may be used for other types of devices, tests, assays which rely on or include digital microfluidic operations, such as moving, merging, splitting, etc. of droplets within internal passages within the microfluidic device.

[0033] In at least some examples, when the plate (e.g. a second plate) is not conductive, at least some example charge applicators of the present disclosure stand in sharp contrast to some digital microfluidic devices which include an on board, array of control electrodes (connected to a power supply) which operate at a constant voltage and which are constantly changing the number of charges in the electrodes to maintain a desired voltage while the droplet is pulled into the induced electric field. However, via at least some example charge applicators of the present disclosure, charges are deposited on an exterior portion of a second plate of a consumable microfluidic receptacle such that a generally constant amount of charges may be maintained while a voltage at this second plate changes when a liquid droplet propagates into an induced, electric field zone and, at the same time, changes its intensity.

[0034] These examples, and additional examples, are further described and illustrated below in association with at least FIGS. 1-10.

[0035] FIG. 1 is a diagram including a side view schematically representing an example arrangement 100 (and/or example method) to control electrowetting movement via airborne charges. In some examples, the arrangement 100 may comprise a consumable microfluidic receptacle 102 and a non-contact charge depositing unit 140, either of which may be provided separately. While FIGS. 1- 7B are described primarily with respect to a charge applicator embodied as an example charge depositing unit (e.g. 140), it will be understood that other example charge applicators, such as the example electrode control element 1050, 1150 (described in association with at least FIGS. 8A-8C) may be used to apply charges in charging relation to a consumable microfluidic receptacle to cause electrowetting movement in the manner described throughout at least some examples of the present disclosure.

[0036] As shown in FIG. 1 , the consumable microfluidic receptacle 102 comprises a first plate 110 and a second plate 120 spaced apart from the first plate 110, with the spacing between the respective plates 110, 120 sized to receive and allow movement of a liquid droplet 130, such as a polar liquid droplet (e.g. conducive droplet). In some examples, the consumable microfluidic receptacle may form a portion of a microfluidic device, and according sometimes may be referred to as a microfluidic device or portion thereof.

[0037] As shown in FIG. 1 , in some examples each of the respective first and second plates 110 comprise an interior surface 111 , 121 , respectively, and each of the respective first and second plates 110, 120 comprise an exterior surface 112, 122, respectively.

[0038] In some examples, at least the interior surface 111 , 121 of the respective plates 110, 120 may comprise a planar or substantially planar surface. However, it will be understood that the passageway 119 defined between the respective first and second plates 110, 120 may comprise side walls, which are omitted for illustrative simplicity. The passageway 119 may sometimes be referred to as a conduit, cavity, and the like.

[0039] It will be understood that the first and second plates 110, 120 may form part of, and/or be housed within a frame, such as the frame 205 of the microfluidic device 200 shown in FIG. 2.

[0040] In some examples, the interior of the passageway 119 (between plates 110, 120) may comprise a filler such as a dielectric oil, while in some examples, the filler may comprise air. In some such examples, the filler may comprise other liquids which are immiscible and/or which are electrically passive relative to the droplet 130 and/or relative to the respective plates 110, 120. In some examples, the filler may affect the pulling forces (F), may resist droplet evaporation, and/or facilitate sliding of the droplet and maintaining droplet integrity.

[0041] In some examples, the distance (D1) between the respective plates 110, 120 may comprise between about 50 to about 500 micrometers, between about 100 to about 150 micrometers, or about 200 micrometers. In some examples, the droplet 130 may comprise a volume of about less than a microliter, such as between about 10 picoliters and about 30 microliters. However, it will be understood that in some examples, the consumable microfluidic device 102 is not strictly limited to such example volumes or dimensions.

[0042] In some examples, the first plate 110 may be grounded, i.e. electrically connected to a ground element 113, which is also later shown in other FIGS, such as element 113 in FIGS. 3A, 4, etc. In some examples, the first plate 110 may comprise a thickness (D4) of about 100 micrometers to about 3 millimeters, and may comprise a plastic or polymer material. In some examples, the first plate 100 may comprise a glass-coated, indium tin oxide (ITO). As noted later in association with at least FIG. 2, the thickness (D4) of first plate 110 may be implemented to accommodate fluid inlets (e.g. 221 A, 223A, etc. in FIG. 2), to house and/or integrate sensors into the first plate 110, and/or to provide structural strength. In some examples, the sensors may sense properties of the fluid droplets, among other information.

[0043] As further shown in FIG. 1 , instead of the entire first plate 110 being electrically conductive to serve as (or connect to ground), in some examples, the first plate 110 of the consumable microfluidic receptacle 102 may comprise an electrically conductive layer 115, by which the first plate 110 may be electrically connected to a ground element 113. In some such examples, the electrically conductive layer 115 may comprise a material such an indium titanium oxide (ITO) which is transparent and may have a thickness D8 on the order of a few tens of nanometers.

[0044] As further shown in FIG. 1 , in some examples, microfluidic receptacle 102 may comprise a first coating 137 on interior surface 111 of first plate 110 and/or a second coating 136 on interior surface 121 of second plate 120, with such coatings arranged to facilitate electrowetting movement of droplets 130 through a passageway 119 defined between the respective plates 110, 120. [0045] In some examples, at least one of the respective coatings 137,136 may comprise a hydrophobic coating, while in some examples, at least one of the respective coatings 137,136 may comprise a low contact angle hysteresis coating. In some examples, a low contact angle hysteresis coating may correspond to contact angle hysteresis of less than about 30, 29, 28, 27, 26, 25, 24, 23, 22, 21 , or 20 degrees. In some examples, the contact angle hysteresis may comprise less than about 20, 19, 18, 17, 16, or 15 degrees. In some example implementations including coatings 137,136, an oil filler is provided within the passageways 219A-219E, which further enhances the effect of the coatings 137,136. In some examples, the coating 137 and coating 136 may have respective thicknesses of D6, D7 on the order of one micrometer, but in some examples the thicknesses D6, D7 can be less than one micrometer, such as a few tens of nanometers. In some examples, the thicknesses can be greater than one micrometer, such as a few micrometers. [0046] As further shown in FIG. 1 , in some examples the second plate 120 may further comprise a dielectric layer 134 interposed between the coating 136 and a substrate 132. In some examples, the substrate 132 may comprise an anisotropic conductivity layer or a passive electrode array, as further described later in association with at least FIGS. 3A and 4, respectively. At least some examples of the dielectric layer 134 are described below in context with, at least, how the dielectric layer 134 may facilitate maintaining a voltage differential across the second plate 120 as part of inducing electrowetting movement of droplet 130.

[0047] As further shown in FIG. 1 , in some examples, the addressable charge depositing unit 140 may be brought into a spaced apart relationship relative to the exterior surface 122 of the second plate 120 of the example arrangement 101 , as represented by the distance D2. In some examples, the distance D5 may comprise about 0.25 millimeters (e.g. 0.23, 0.24, 0.25, 0.26, 0.27) to about 2 millimeters (e.g. 1.9, 1.95, 2, 2.05. 2.1). In some such examples, the addressable charge depositing unit 140 may be supported by, or within, a frame 133 and the consumable microfluidic receptacle 102 may be releasably supportable by the frame 133 to place the consumable microfluidic receptacle 102 and the addressable charge depositing unit 140 into charging relation to each other.

[0048] As further shown in FIG. 1 , upon the consumable microfluidic receptacle 102 and the addressable charge depositing unit 140 being appropriately positioned relative to each other, the addressable charge depositing unit 140 may emit airborne charges 142 toward and onto the exterior surface 122 of the second plate 120, which may then be referred to as deposited charges 144A. In some examples, the deposited charges 144A exhibit a first voltage V1 , which may sometimes be referred to as an applied voltage.

[0049] As shown in FIG. 1 , the emitted charges 142 are directed to a target position shown in dashed lines T1 , which is immediately adjacent to the droplet 130. In some such examples, this target position may sometimes be referred to as a virtual electrode, at least to the extent that the dimensions/shape of the area over which the charges are deposited (and the applied voltage resides) may be viewed as being analogous to the dimensions/shape of an electrode pad, such as one of the electrode pads (e.g. 444A) of a respective one of the electrodes 442A, etc. of the passive electrode array 440 shown in FIG. 4.

[0050] As further represented in FIG. 1 , the deposited charges 144A at exterior surface 122 of second plate 120 migrate through the substrate 132 of the second plate 120 to an interface 135 between the substrate 132 (e.g. an inner surface of substrate 132) and the dielectric layer 134 (e.g. an inner surface of the dielectric layer 134), as represented by charges 144B. Upon such migration to interface 135, the charges 144B exhibit substantially the same voltage (e.g. V1) at the interface 135 as the charges 144A at exterior surface 122.

[0051] With first plate 110 being grounded, counter negative charges 146A develop at the first plate 110 to cause an electric field (E) between the respective first and second plates 110, 120, which creates a pulling force (F) to draw the droplet 130 forward into the target position T1. In some examples, at least part of this arrangement includes the liquid droplet 130 being conductive (i.e. polar) in at least some examples, such that counter-charges 146B develop within the droplet 130 relative to charges 146A (at first plate 111) and counter charges 144C develop within the droplet 130 relative to charges 144B at interface 135 (between the dielectric layer 134 and the substrate 132) within the second plate 120. At least because of the charge differential between the charges 144B and 144C and between the charges 146A and 146B (which corresponds to a voltage differential between V1 and V2), a pulling force is created to pull the droplet 130 from the position (e.g. TO) into the target position T 1. Stated differently, the droplet 130 is moved from one virtual electrode to the next/adjacent virtual electrode. Among other aspects, parameters (e.g. dielectric strength, thickness, etc.) associated with the dielectric layer 134 help to maintain the desired charge differential (or voltage differential) which induces the desired droplet movement.

[0052] In some examples, the pulling force (F), which causes movement of droplet 130 upon inducing the electric field (E), may comprise electrowetting forces. In some such examples, the electrowetting forces may result from: (1) modification of the wetting properties of the interior surface 121 of second plate 120 and/or surface 111 of plate 111 upon application of the electric field (E); (2) counter charges introduced in the droplet 130, which may result from electrical conductivity within the droplet 130 in some examples and/or from induced dielectric polarization within the droplet 130 in some examples; and/or (3) a minimization of the electrical potential energy due to charges in the system including as an example the minimization of the energy due to the counter charges 146 (e.g. negative) and the charges 144A (144B) (e.g. positive) in the case of a non-conductive droplet.

[0053] In some examples, the deposited charges 144A at second plate 120 may comprise between on the order of tens of volts and on the order of a few hundred volts of charges on the second plate 120. In some examples, the deposited charges 144A may comprise 1000 Volts. In some examples, the deposited charges 144A will dissipate, e.g. discharge upon the addressable charge depositing unit 140 emitting opposite charges (e.g. negative charges). As the droplet 130 moves into the area of the charges (i.e. the target position T1), the electric field E drops due to an increased dielectric constant occurring in the effective capacitor which is formed between the respective first and second plates 110, 120.

[0054] It will be further understood that charges (e.g. 144A) deposited on the second plate 120 (by the charge depositing unit 140) will be significantly discharged or at least be discharged to a level at which their voltage is significantly lower than the voltage to be applied before the next electrowetting- caused pulling movement of the droplet 130 occurs to the next target position T2.

[0055] At least some aspects of implementing discharge of the charges (e.g. 144A, 144B) are further described later in association with at least FIGS. 5-8 regarding example implementations of the charge depositing unit 140.

[0056] In some examples, the substrate 132 may comprise a plastic material, such as but not limited to, materials such as polypropylene, Nylon, polystyrene, polycarbonate, polyurethane, epoxies, or other plastic materials which are low cost and available in a wide range of conductivities. In some examples, the second plate 120 may comprise a transparent material. [0057] In some examples, the substrate 132 of the second plate 120 may comprise a resistivity of less than 10 ⁹ Ohm-cm in a z-direction so as to be electrically conductive in the z-direction (e.g. directional arrow B in FIG. 3A) while preserving charge separation laterally (e.g. directional arrow C in FIG. 3A) via a larger lateral resistivity (e.g. lateral conductivity) of at least 10 ¹¹ Ohm-cm. At least some such example implementations of the substrate 132 are described further below in association with at least FIGS. 3A, 4. In some such examples, with this resistivity the second plate 120 may sometimes be referred to as being partially electrically conductive, partially conductive, and the like. In some examples, a conductivity within the desired range noted above may be implemented via mixing into a plastic material some conductive carbon molecules, carbon black pigments, carbon fibers, or carbon black crystal.

[0058] In some examples, the response time and behavior of the second plate 120 may be related to, and/or expressed in association with, a voltage differential parameter, which may depend, at least in part, on the dielectric properties of the dielectric layer 134, which contribute to the overall dielectric properties of the second plate 120. In some such examples, at least some aspects of the voltage differential parameter may be implemented in association with a voltage differential engine 1230 of a fluid operations engine 1200 (FIG. 9A), which in turn may comprise part of or be implemented in association with, control portion 1300 of FIGS. 9B-9C. Various aspects associated with the voltage differential parameter are described further below and throughout various examples of the present disclosure.

[0059] In some examples, the electric properties (e.g. resistivity, etc.) of second plate 120 (which contribute to implementation of the voltage differential parameter via engine 1230 in FIG. 9A) are defined, at least in part, by the dedicated dielectric layer 134 of second plate 120. In some examples, the dielectric layer 134 may be an insulating material, comprising a resistivity of at least 10 ¹¹ Ohm-cm, and in some examples, at least 10 ¹³ Ohm-cm.

[0060] In some examples, the dielectric layer 134 may comprise a dielectric strength of at least 50 V/micrometers (e.g. 49.5, 49.6, 49.7, 49.8, 49.9, 50.1 , 50.2, 50.3, 50.4, 50.5), while in some examples, the dielectric layer may comprise at least 100 V/micrometers (e.g. 99.5, 99.6, 99.7, 99.8, 99.9, 100.1, 100.2, 100.3, 100.4, 100.5). In some examples, the dielectric layer may comprise at least about 200 V/micrometers (e.g. 199.5, 199.6, 199.7, 199.8, 199.9, 200.1 , 200.2, 200.3, 200.4, 200.5). In some examples, the dielectric layer may comprise at least about 300 V/micrometers (e.g. 299.5, 299.6, 299.7, 299.8, 299.9, 300.1 , 300.2, 300.3, 300.4, 300.5).

[0061] In some examples, second plate 120 (including the dedicated dielectric layer 134) may implement the above-mentioned voltage differential parameter which corresponds to the extent to which a voltage differential across at least the dielectric layer 134 of second plate 120 is substantially preserved (i.e. maintained with a significant magnitude) during a predetermined, droplet- movement time period. In some such examples, this voltage differential parameter may sometimes also be expressed as substantially preventing a decay of the voltage differential across the second plate 120 (including the dielectric layer 134).

[0062] In considering the behavior of a voltage differential across at least the dielectric layer 134 of second plate 120, it will be understood that in at least some examples the droplet 130 is generally electrically conductive and therefore droplet 130 generally sits at a voltage close to ground. In some such examples, in this context the droplet 130 may be considered to be conductive, having a resistivity less than 10 ⁷ ohm-cm. Given this general conductivity of the droplet 130, it will be further understood that the above-described, the applied voltage differential occurs entirely (or substantially entirely) across material within the second plate 120 which exhibits dielectric properties, such as the dielectric layer 134.

[0063] Moreover, as noted elsewhere among the various examples, of the present disclosure, materials of the dielectric layer 134 may exhibit compatibility with hydrophobic layer 136, as further described later.

[0064] In some examples, the dielectric layer 134 may comprise a dielectric material having a thickness of at least about 10 micrometers (e.g. 9.7, 9.8, 9.9, 10.1, 10.2, 10.3). In some examples, the dielectric layer 134 may comprise a dielectric material having a thickness of at least about 20 micrometers (e.g. 19.7, 19.8, 19.9, 20.1 , 20.2, 20.3). In some examples, the dielectric layer 134 may comprise a dielectric material having a thickness of at least about 50 micrometers (e.g. 49.7, 49.8, 49.9, 50.1, 50.2, 50.3).

[0065] In some such examples, the dielectric material comprise a combination (e.g. hybrid) of organic material and inorganic materials, which may comprise coatings provided in liquid form and cured via many possible routes. In some such examples, the dielectric material of layer 134 may comprise monomers/prepolymers that contain inorganic silicon-oxygen groups as well as reactive organic functional groups. In at least some example implementations of such materials, the dielectric layer 134 may comprise a thickness of at least about 10 micrometers, about 20 micrometers, and so on as noted above.

[0066] In some examples, the dielectric materials which comprise a silicon- oxygen group may comprise a silsesquioxane group.

[0067] In some examples, dielectric materials comprising a silsesquioxane group may comprise a polyhedral oligomeric silsesquioxane material. In some such examples, the silsesquioxane material may be a colorless solid that adopts cage-like or polymeric structures with Si-O-Si linkages and tetrahedral Si vertices. In some such examples, the silsesquioxane materials may be known as members of polyoctahedral silsesquioxane group of materials, which is sometimes known as a POSS® material as further explained below. In some examples, diverse substituents (R) can be attached to the Si centers of the silsesquioxane group materials.

[0068] In some examples, the previously-mentioned reactive functional organic groups may comprise epoxide groups and methacrylic/acrylic groups but also may comprise other functional groups such amines, in some examples.

[0069] In examples in which the dielectric material (of layer 134) comprises a silsesquioxane group material with a reactive functional group, some example formulations may comprise an epoxycyclohexylethyl POSS® material, a glycidyl POSS® material, a methacrylic POSS® material, and an acrylic POSS® material. At least some of these example materials may be obtained from Hybrid Plastics, Inc. of Hattiesburg, Mississippi under the tradename POSS® material, which refers to a polyhedral oligomeric silsesquioxane material. [0070] In some examples, the dielectric materials which comprise a silicon- oxygen group may comprise a siloxane group material, which comprises a Si-O- Si linkage. In examples in which the dielectric material (of layer 134) comprises a siloxane group material as a coating with reactive functional groups, some example formulations may comprise a monophenyl functional tris(epoxy terminated polydimethylsiloxane) material, a dimethylsiloxane copolymer material (e.g. an epoxycyclohexylethyl methylsiloxane dimethylsiloxane), or methylsiloxane - dimethylsiloxane copolymers (e.g. an acryloxypropyl methylsiloxane - dimethylsiloxane). At least some of these example materials may be obtained from Gelest, Inc. of Morrissville, Pennsylvania.

[0071] In some examples in which the reactive functional group is an epoxide, the liquid may be polymerized in a number of different ways. For instance, in some examples, a hardener such as an amine or imidazole can be added, as per a two-part formulation. Alternatively, in some examples, a latent curing agent such as dicyandiamide may be added to yield a one-pack heat curable formulation. In addition, in some examples one may add a cationic photoinitiator such as those based on sulfonium or iodonium salts in combination with sensitizers such as isopropylthioxanthone to yield a one-pack UV curable formulation.

[0072] In some examples in which the reactive functional group comprises a methacrylic or acrylic, either a thermal or photo initiator may be used to incite polymerization. At least some examples of such thermal initiators may comprise azo initiators such as azobisisobutyronitrile or peroxide initiators such as benzoyl peroxide. At least some examples of such photo initiators may comprise alpha-aminoalkylphenones or benzophenones.

[0073] In at least some of the foregoing example combination of organic and inorganic materials to form a dielectric layer, solvent(s) may be used to enable the liquid coating process, for viscosity adjustment, etc.

[0074] One example implementation an inorganic-organic combination of material for dielectric layer 134, such as a dielectric coating, may comprise a formulation including: (1) 94 parts of a resin and solvent, such as 70% epoxycyclohexylethyl POSS® EP0408 resin from Hybrid Plastics, Inc. and 30% propylene glycol monomethyl ether acetate; (2) 4 parts of a cationic photoinitiator, such as Omnicat 250 from IGM resins; and (3) 2 parts of an UV- curable photosensitizer, such as Omnirad ITX from IGM resins. In some examples, this example liquid coating formulation is then spin-coated onto a substrate at 1000 rpm for 30 seconds and then cured in the following way: (1) bake at 100 degrees C for 30 minutes; (2) UV cure with UVA of about 2000 mJ/cm ² ; and (3) post-bake at 190 degrees C for 30 minutes. In some such examples, the dielectric layer (e.g. coating) may comprise a dielectric strength of at least 100 V/micrometer and have a thickness of about 20 microns.

[0075] In some examples, the dielectric layer 134 may comprise other materials different from the above-described combination of inorganic material and inorganic materials. In some such examples, a dielectric layer 134 comprising these other materials may comprise a thickness of at least about 10 micrometers (e.g. 9.7, 9.8, 9.9, 10.1 , 10.2, 10.3). In some examples, these other materials may comprise a polyimide material, which may comprise a polyimide material such as a Kapton® material obtainable from DuPont de Nemours, Inc. In some examples, the other materials (from which dielectric layer 134 may be formed) may comprise a polyetherimide (PEI) material.

[0076] In some examples, the other materials (from which dielectric layer 134 may be formed) may comprise films in a fluoropolymer class of materials, and may comprise a perfluoroalkoxy alkane (PFA) material, an ethylene tetrafluorotethylene (ETFE) material, a polychlorotrifluoroethylene (PCTFE) material, or a fluorinated ethylene propylene (FEP) material. In some examples, these films may comprise a dielectric strength of at least 50 V/micrometers and are intrinsically compatible with many fluorinated-based hydrophobic coatings. [0077] In some examples, these films can be adhered to the substrate in a variety of methods. First, the film may be commercially available with an adhesive backing, with typical adhesives being in the silicone or acrylic family. Second, a curable adhesive may be applied between the substrate and the film. The adhesive can be cured by either a hardener (two-pack epoxy or two-pack silicone system for example) or by a UV source as for a UV-curable adhesive. For all the cases above, one surface of the dielectric film may be surface treated by a variety of methods (e.g. corona, oxygen plasma, and UV ozone) to enhance adhesion.

[0078] In one example implementation of the above-described arrangement, the dielectric layer 134 may comprise a combined film and adhesive structure having a thickness of about 25 micrometers. For instance, the dielectric layer 134 may comprise a polyimide material in form of a tape, such as a Kapton® tape, including a silicone adhesive. One such example may comprise a film/adhesive combination available from Caplinq of Ottawa, Ontario, Canada. The polyimide film may comprise a thickness of about 12.5 micrometers. Meanwhile, the silicone adhesive portion may comprise a thickness of about 12.5 micrometers and is suitable for laminating via pressure to a substrate (e.g. a PCB, other). In some examples, with a thickness of 12.5 micrometers, the dielectric strength of the polyimide film comprises about 300 V/micro meters. During the charging of the ion head and deposit of charges 144A at exterior surface 122 of the second plate 120, the ground current is close to zero (e.g. at droplet 130) because the relatively high dielectric strength (and thickness) of the dielectric layer 134 substantially eliminates or prevents migration of charges through to ground. In some examples, shortly (e.g. 2 seconds) after charging of the exterior surface 122 of second plate 120 ends, a magnitude of the second voltage V2 (e.g. - 700 Volts) adjacent the interior surface 121 of the second plate 120 (such as within a portion of droplet 130) is substantially the same as a magnitude of the first voltage V1 (e.g. about 700 Volts) at the exterior surface 122 of the second plate 120, which also appears at the interface 135 (between the substrate 132 and the dielectric layer 134). In this arrangement, the voltage differential between the interface 135 and a portion of the droplet 130 (adjacent the interior surface 121 of the second plate 120) easily meets the voltage differential preservation parameter of V2=0.5 x V1 because the V2 of 700 significantly exceeds 350, which is 0.5 x 700 (V1).

[0079] In a related aspect, the second voltage V2 remains substantially stable at least during the droplet-movement time period. In some examples, a velocity of droplet movement may comprise between about 1 mm/second and 30 mm/second. Accordingly, in some examples which an electrode has a length (e.g. D2 in FIG. 1) of about 3 millimeters, one example droplet-movement time period may comprise between about 0.1 and about 3 seconds. In one example, the time period may comprise about 2 seconds.

[0080] With further reference to FIG. 1 and the deposited charges 144B at interface 135 in some examples, the addressable charge depositing unit 140 also may be used to neutralize charges at interface 135 (or also on exterior surface 122 of) second plate 120, such as after a desired droplet movement has occurred. In particular, in some arrangements, , the addressable charge depositing unit 140 may be used to neutralize residual charges so as to prepare the microfluidic receptacle (e.g. portion of a microfluidic device) to receive a deposit of fresh charges (e.g. 144A) in preparation of causing further electrowetting movement of the droplet 130 to a next target position (e.g. T2). [0081] It will be understood that in some examples, the addressable charge depositing unit 140 may be mobile and the microfluidic receptacle 102 may be stationary while performing microfluidic operations, while in some examples, the addressable charge depositing unit 140 may be stationary and the microfluidic receptacle 102 is moved relative to the addressable charge depositing unit 140 during microfluidic operations. In some examples, the frame 133 (FIG. 1) may including portions, mechanisms, etc. which may facilitate relative movement between the consumable microfluidic receptacle 102 and the charge depositing unit 140. At least some such examples may be implemented in association with one of the addressable charge depositing units as described in association with at least FIGS. 5-8.

[0082] In some examples, both of the addressable charge depositing unit 140 and the microfluidic receptacle 102 are stationary during microfluidic operations, with the addressable charge depositing unit 140 being arranged in a two- dimensional array to deposit charges in any desired target area of the microfluidic receptacle in order to perform a particular microfluidic operation or sequence of microfluidic operations. At least some example implementations of such a two-dimensional array may comprise at least some of the substantially the same features and attributes as described in association with at least FIGS. 6C and/or 8. [0083] In some examples, such microfluidic operations to be performed via the consumable microfluidic receptacle 102 and an addressable charge depositing unit (e.g. 140 in FIG. 1) may be implemented in association with a control portion, such as but not limited to control portion 1300 in FIG. 9B and/or in association with a fluid operations engine 1200 in FIG. 9A.

[0084] FIG. 2 is a diagram including top plan view schematically representing an example microfluidic device 200. In some examples, the microfluidic device 200 comprises at least some of substantially the same features and attributes as the consumable microfluidic receptacle 102 in FIG. 1. In particular, in some examples, the microfluidic receptacle 102 in FIG. 1 may comprise at least a portion of the example microfluidic device 200.

[0085] As shown in FIG. 2, the microfluidic device 200 comprises a frame 205 within which is formed an array 215 of interconnected passageways 219A, 219B, 219C, 219D, 219E, with each respective passageway being defined by a series of target positions 217. In some examples, the respective passageways 219A-219E are defined between a first plate (like first plate 110 in FIG. 1) and a second plate (like second plate 120 in FIG. 1), with each target position 217 corresponding to a target position (e.g. T1 or T2) shown in FIG. 1 at which a droplet (e.g. 130 in FIG. 1) may be positioned. In some examples, each target position 217 may comprise a length of about 500 to about 1500 micrometers while in some examples the length may be about 750 to about 1250 micrometers. In some examples, the length may be about 1000 micrometers. Meanwhile, in some examples, each target position 217 may have a width commensurate with the length, such as the above-noted examples.

[0086] As previously noted in association with FIG. 1 , the respective target positions 217 and the passageways 219A-219E do not include active control electrodes (and related circuitry) for moving droplets 130. Rather, droplets 130 are moved through the various passageways 219A, 219B, 219B, 219D, 219E via electrowetting forces caused by directing airborne charges from the non- contact airborne charge depositing unit 140, as described in association with FIG. 1. Accordingly, via the use of such an externally-applied electric field, the droplet(s) 130 move through the passageways via electrowetting forces without any active control electrodes (and related circuitry) lining the paths defined by the various passageways 219A-219E.

[0087] As further shown in FIG. 2, at least some of the respective target positions 217, such as at positions 221 A, 221 B, 223A, and/or 223B may comprise an inlet portion which can receive a droplet 130 to begin entry into the passageways 219A-219E to be subject to microfluidic operations such as moving, merging, splitting, etc. In some examples, some of the example positions 221 A, 221 B, 223A, 223B may comprise an outlet portion, from which fluid may be retrieved after certain microfluidic operations.

[0088] It will be understood that in some examples, the consumable microfluidic device 200 may comprises features and attributes, in addition to those described in association with FIGS. 1-2. For example, in some instances, prior to receiving droplets 130, the microfluidic device 200 may comprise at least one fluid reservoir R at which various fluids (e.g. reagents, binders, etc.) may be stored and which may be released into at least one of the passageways 219A- 219E. In some examples, release of such reagents or other materials may be caused by the same externally-caused electrowetting forces as previously described to cause movement of droplet 130. Moreover, in some examples, at least some of the passageways 219A-219E may form or define a lateral assay flow device in which some reagents, etc. may already be present at various target positions 217 within a particular passageway (e.g. 219A-219E) such that upon movement of various droplets 130 relative to such target positions 217 may result in desired reactions to effect a lateral flow assay. Flowever, in some examples, the microfluidic device 200 does not store any liquids on board, and any liquids on which microfluidic operations are to be performed are added, such as in the example inlet locations 221 A, 221 B, 223A, 223B, as previously described.

[0089] Via the externally-caused electrowetting movement of the respective droplets within the passageways 219A-219E, various microfluidic operations of moving, merging, splitting may be performed within microfluidic device 200 to cause desired reactions, etc. With this in mind, in some examples a portion of the consumable microfluidic device 200 may comprise at least one sensor (represented by indicator S in FIG. 2) to facilitate tracking the status and/or position of droplets within a microfluidic device, as well as for determining a chemical or biochemical result ensuing from the various microfluidic operations, such as merging, splitting, etc. In some such examples, such sensors may be incorporated into the first plate 110 (FIG. 1) so as to not interfere with the deposit of charges, migration of charges, neutralization of charges, etc. occurring at or through the second plate 120 (FIG. 1). In some examples the sensor(s) may include external sensors, like optical sensors. In some such examples, such external sensors may be used to sense attributes of a fluid retrieved from an above-described outlet portion.

[0090] In some examples, such microfluidic operations to be performed via the microfluidic device 200 and an addressable charge depositing unit (e.g. 140 in FIG. 1) may be implemented in association with a control portion, such as but not limited to control portion 1300 in FIG. 9B and/or in association with a fluid operations engine 1200 in FIG. 9A.

[0091] As previously noted in association with FIGS. 1-2, it will be understood that an addressable charge depositing unit 140 may be used in a non-contact manner to apply charges to build charges (144A) on a second plate 120 (or to neutralize charges) to cause electrowetting movement of droplets through the microfluidic device 200, and it is understood that the addressable charge depositing unit 140 may be mobile or stationary while the microfluidic device 200 may be mobile or stationary as well. With this in mind, the addressable charge depositing unit 140 may comprise a wide variety of configurations, as further later described in association with at least FIGS. 4-8, in order to achieve such application of charges for building charges and/or neutralizing charges. [0092] In some examples, as shown in FIG. 1 , each target position (e.g. T1 ,T2, etc.) may comprise a length (D2) which may comprise a length expected to be approximately the same size (e.g. length D2) as the droplet 130 to be moved. In view of the example volumes of droplets noted above, the length (D2) of each target position (e.g. T1 , T2, etc.) may comprise between about 50 micrometers to about 5 millimeters, and may comprise a width similar to its length in some examples. In some examples, the target position also may sometimes be referred to as a droplet position. As also previously noted, each of the respective droplet positions also may sometimes be referred to as corresponding to the position, size, and/or shape of the above-described virtual electrodes of the second plate 120.

[0093] In some examples, the length (D2) of the droplet in passageway 119 may sometimes be referred as a length scale of the droplet (or target position of a droplet). In sharp contrast to some other devices which utilize an array of control electrodes and which involve spacing between adjacent control electrodes because of manufacturing limitations, in at least some examples of the present disclosure, the target positions (e.g. T1 , T2) may be immediately adjacent each other with virtually no spacing therebetween. Accordingly, at least some examples of the present disclosure do not face at least some of the challenges in moving droplets that may otherwise be posed by a distance between adjacent electrodes in such devices employing active control electrodes.

[0094] In some examples, the example arrangements of the present disclosure to cause electrowetting movement of droplets stand in sharp contrast to some microfluidic devices which rely on dielectrophoresis to produce movement of particles. At least some such dielectrophoretic devices comprise a distance between control electrodes (of a printed circuit board which form one of the microfluidic plates) which is substantially greater (e.g. 10 times, 100 times, etc. ) than a length scale (e.g. size) of a particle within a liquid to be moved. For instance, the distance between control electrodes (in some dielectrophoretic devices) may be on the order of hundreds (i.e. 100’s) of micrometers, whereas the length scale of such particles may comprise on the order of hundreds (i.e. 100’s) nanometers. In some such devices, the distance between electrodes in a dielectrophoretic device may sometimes be referred to as a length scale of such electrodes or as a length scale of the gradient (i.e. gradient length scale).

[0095] For comparison purposes to some dielectrophoretic devices, a droplet of liquid to be moved via electrowetting forces in at least some examples of the present disclosure may comprise a thickness between a first plate 110 and second plate 120 of about 200 micrometers, and a length (or width) extending across a target position (e.g. T1 , T2) (i.e. droplet position) of about 2 millimeters, in some examples. In sharp contrast, dielectrophoresis may cause movement of a particle within a mass of fluid, where such particle may be about 100 nanometers diameter (or length, width, or the like) and many particles may reside within a droplet of liquid. However, the dielectrophoretic device does not generally cause movement of an entire fluid mass.

[0096] FIG. 3A is a diagram including a side view schematically representing an example consumable microfluidic receptacle 300 which includes an anisotropic conductivity layer 340. In some examples, the example consumable microfluidic receptacle 300 may comprise, and/or be employed via, at least some of substantially the same features and attributes as the examples previously described in association with at least FIGS. 1-2. For instance, the example microfluidic receptacle 330 may comprise a substrate 322 of the second plate 320 (e.g. 120 in FIG. 1) being formed as an anisotropic conductivity layer 340. [0097] In some examples, as shown in FIG. 3A, the anisotropic conductivity layer 340 comprises a conductive-resistant medium 345 (e.g. partially conductive matrix) within which an array 332 of conductive elements 334 is oriented generally perpendicular to the plane (P2) through which the entire anisotropic conductivity layer 340 generally extends. In some examples, the conductive-resistant medium 345 (e.g. matrix) may comprise a bulk resistivity of about 10 ¹¹ Ohm-cm to about 10 ¹⁶ Ohm-cm. In some such examples, the conductive elements 334 may comprise a conductivity at least two orders of magnitude greater than a bulk conductivity of the conductive-resistant medium 345. In some examples, the resistant-conductive medium 345 of the layer 340 may comprise a plastic or polymeric materials, such as but not limited to, materials such as polypropylene, Nylon, polystyrene, polycarbonate, polyurethane, epoxies, or other plastic materials which are low cost and available in a wide range of conductivities. In some examples, a bulk conductivity (or bulk resistivity) within the desired range noted above may be implemented via mixing into the plastic material some conductive carbon molecules, carbon black pigments, carbon fibers, or carbon black crystal. In some examples, the conductive-resistant medium 345 may comprise a resistivity of less than 10 ⁹ Ohm-cm in the perpendicular direction (direction B) to P2 plane, and a larger lateral resistivity (e.g. lateral conductivity) of at least 10 ¹¹ Ohm-cm (direction C along plane P2). Accordingly, the lateral conductivity is at least two orders of magnitude less than the conductivity of the conductive- resistant medium 345 in the direction perpendicular to the plane P2 (FIG. 3B). [0098] In some examples, the relative permittivity of the conductive-resistant medium 345 of the anisotropic layer 340 may be greater than about 20. In some examples, the relative permittivity may be greater than about 25, 30, 35, 40, 45 50, 55, 60, 65, 70, or 75. In some instances, the relative permittivity may sometimes be referred to as a dielectric constant. Among other attributes, providing such relative permittivity may result in a lower voltage drop across the second plate 320. In some examples, the relative permittivity of the second plate 320 in the direction of the plane P2 may comprise lower than about 10. In some examples, it may comprise about 3.

[0099] As noted above, in some examples, the anisotropic layer 340 may comprise a low lateral conductivity (i.e. a conductivity along the plane P2, such as represented via directional arrow C) with resistivity of at least 10 ¹¹ Ohm-cm (similar to the bulk conductivity). In some examples, this resistivity along the plane P2 (i.e. lateral conductivity) may comprise about 10 ¹⁴ Ohm-cm.

[00100] In some examples, the anisotropic conductivity layer 340 may comprise a high conductivity perpendicular (direction B) to the plane P, such as a resistivity which is on the order of, or less than, 10 ⁹ Ohm-cm. In some examples, this resistivity may comprise 10 ⁶ Ohm-cm. In at least some examples, the resistivity perpendicular to the plane P2 is at least about two orders of magnitude different from (e.g. lower) than the resistively along or parallel to the plane P2. In some such examples, this relatively high conductivity perpendicular to the plane P2 may sometimes be referred to as vertical conductivity with respect to the plane P2.

[00101] In comparison to the relatively high conductivity of the conductive resistant medium 345 perpendicular to the plane P2 (direction B), the above- noted relatively low lateral conductivity (direction C) of the conductive resistant medium 345 may effectively force travel of the charges (applied by the addressable charge depositing unit 140) to travel primarily in a direction (B) perpendicular to the plane P, such that the electric field E acting within the passageway 119 (i.e. conduit) may comprise an area (e.g. x-y dimensions) which are similar to the area (e.g. x-y dimensions) of each application of charges from the charge depositing unit 140 directed to a specific target position (e.g. T1, T2, etc.).

[00102] As shown in FIG. 3A, via the example anisotropic conductivity layer 340 of second plate 320, the conductive elements 334 are aligned generally parallel to each other, in a spaced apart relationship, in an orientation generally the same as the direction (arrow B) which the charges 144A at the exterior surface 122 (of second plate 320) are to travel through substrate 322 of second plate 320 to reach the interface 135 of substrate 322 with the dielectric layer 134. While the respective conductive elements 334 are shown as being oriented perpendicular to the plane P2, it will be understood that in some examples the conductive elements 334 may be oriented at a slight angle (i.e. slanted) which not strictly perpendicular.

[00103] Moreover, in some examples, as shown in FIG. 3B, each respective conductive element 334 may comprise an array 347 of smaller conductive particles 348 which are aligned in an elongate pattern to approximate a linear element of the type shown as element 334 in FIG. 3A. The array 347 of elements 348 (e.g. particles) may sometimes be referred to as a conductive path. In some examples, the conductive particles 348 may comprise metal beads with each bead ranging from 0.5 micrometers to about 5 micrometers in diameter (or a greatest cross-sectional dimension). In some such examples, these smaller conductive particles 348 may be aligned during formation of the anisotropic layer 340 via application of a magnetic field until the materials (e.g. conductive particles, conductive-resistant medium) solidify into their final form approximating the configuration shown in FIGS. 3B-3C. In contrast to the bulk resistivity of the conductive-resistant medium 345 of a resistivity of at least on the order of 10 ¹¹ Ohm-cm, the elongate pattern formed by array 347 of conductive particles 348 may comprise a resistivity of less than 10 ⁹ Ohm-cm in some examples. In some examples, the conductive particles 348 may comprise conductive materials, such as but not limited to iron or nickel. In some examples in which the conductive particles 348 are not in contact with each other, such particles 348 may be spaced apart by a distance F1 as shown in FIG. 3C, with such distances being on the order of a few nanometers in some examples. In some examples, the material (e.g. polymer) forming the conductive-resistant medium 345 of the anisotropic layer 340 of the second plate 320 is interposed between the respective conductive particles 348 of the array 347 (e.g. forming the elongate pattern) defining elements 334. In some such examples, because of this very small dimension F1 between at least some of the conductive particles 348, the conductive-resistance medium 345 interposed between the conductive particles 348 (and which would other exhibit a resistivity of at least on the order of 10 ¹¹ Ohm-cm in some examples) may comprise a conductive bridge (between adjacent particles 348) having a length less than about a micrometer and as such, may exhibit a much smaller resistivity which is several (e.g. 2, 3, or 4) orders of magnitude less than the resistivity otherwise exhibited by the conductive-resistant medium 345. Accordingly, even when some conductive resistant medium 345 is interspersed between some of the aligned conductive particles 348, the elongate pattern (e.g. array 347) of the conductive particles 348 still exhibits an overall conductivity perpendicular to the plane P2 (through which the second plate 120 extends) which comprises at least two orders of magnitude higher (e.g. greater) than the lateral conductivity along the plane P2.

[00104] In some examples, because of the anisotropic conductivity arrangement within the substrate 322 of the second plate 320, the second plate 320 exhibits a response time which is substantially faster than if the substrate 322 were otherwise made primarily dielectric material or made of a partially conductive material without the conductive elements 334.

[00105] In one aspect, the anisotropic conductivity configuration of the substrate 322 of second plate 320 either may enable faster electrowetting movement of droplets 130 through passageway 119 due to higher electrical field on the droplet resulting in higher pulling forces and/or may permit use of thicker second plates (e.g. 120 in FIG. 1 , 320 in FIG. 3A), as desired (i.e. increasing the thickness of second plate 120, 320). In one aspect, providing a relative thick/thicker (substrate 132 of the) second plate 120, 320 enables better structural strength, integrity, and/or better mechanical control of the gap between interior surface 111 of the first plate 110 and the interior surface 121 of the second plate 120, 320. In some examples, the second plate 120, 320 may comprise a thickness (D3) of about 30 micrometers to about 1000 micrometers. In some examples, the thickness (D3) may comprise about 30 micrometers to about 500 micrometers. In some examples, at least the substrate 132 of the second plate 120 may sometimes be referred to as a charge-receiving layer and sometimes may be referred to as an anisotropic conductivity layer.

[00106] In one aspect, the anisotropic conductivity configuration (e.g. layer 340) forming substrate 322 of second plate 320 in FIG. 3A stands in sharp contrast to at least some anisotropic conductive films (ACF) which may resemble a tape structure and involve the application of high heat and high pressure, which in turn may negatively affect the overall structure of the consumable microfluidic receptacle, such as but not limited to, any sensitive sensor elements or circuitry within the first plate 110. Moreover, at least some anisotropic conductive films (ACF) may be relatively thin and/or flexible such that they are unsuitable to stand alone as a bottom plate of a microfluidic device because they may lack sufficient structural strength and durability.

[00107]

[00108] As previously noted, the addressable charge depositing unit 140 (FIG. 1) may comprise a wide variety of configurations, depending on the particular type of consumable microfluidic receptacle 102, whether it is stationary or mobile, etc.

[00109] As further shown in FIG. 3A, in some examples, the consumable microfluidic receptacle 102 may comprise spacer element(s) 309 at periodic locations or non-periodic locations between the first plate 110 and the second plate 120 to maintain the desired spacing between the respective plates 110,120 and/or to provide structural integrity to the microfluidic receptacle 300. In some examples, the spacer element(s) 309 may be formed as part of forming one or both of plates 110, 120, such as via a molding process. It will be understood that such spacer element(s) 309 may form part of any of the other example microfluidic receptacles of the present disclosure.

[00110] FIG. 4 is a diagram including a side view schematically representing an example consumable microfluidic receptacle 400 which includes a passive electrode array layer 422. In some examples, the example consumable microfluidic receptacle 400 may comprise, and/or be employed via, at least some of substantially the same features and attributes as the examples previously described in association with at least FIGS. 1-3A. In one example implementation, the example microfluidic receptacle 400 comprises a second plate 420 (e.g. 120 in FIG. 1) in which a substrate 422 is formed as an array of passive electrodes, and hence may sometimes be referred to the passive electrode layer 422.

[00111] In some examples, as shown in FIG. 4, the passive electrode layer 422 comprises a conductive-resistant medium 447 (e.g. partially conductive matrix) within which an array 440 of electrodes 442A, 442B, 442C, 442D, 442E, 442F, etc. in which each respective electrode is oriented to be electrically conducive generally perpendicular to the plane (P2) through which the entire array 440 generally extends. In some examples, the conductive-resistant medium 447 (e.g. matrix) may comprise a bulk resistivity of about 10 ¹¹ Ohm-cm to about 10 ¹⁶ Ohm-cm. In some such examples, the electrically conductive electrodes (e.g. 442A, 442B, 442C, 442D, 442E, 442F) may comprise a conductivity at least two orders of magnitude greater than a bulk conductivity of the conductive-resistant medium 447.

[00112] In some such examples, the passive array 440 of electrodes (e.g. 442A, 442B, 442C, 442D, 442E, 442F) and matrix 447 may be formed as a printed circuit board or similar circuitry structure.

[00113] In some examples, each respective electrode (e.g. 442A, 442B, 442C, 442D, 442E, 442F) of the array 440 comprises a pair of pads 444A, 444B which are disposed at opposite ends of a column 445. In some instances, the column 445 of each respective electrode may be referred to as being interposed between the respective pads 444A, 444B of each respective electrode. As further shown in FIG. 4, in some examples the respective electrodes (e.g. 442A, 442B, etc.) of the array 440 are arranged in a side-by-side relationship and spaced apart from each other by a distance D12. In particular the outer edge of the pads (e.g. 444A, 444B) of one electrode (e.g. 442A) are spaced apart from the outer edge of the pads (e.g. 444A, 444B) of another electrode (e.g. 442B) by the distance D12, with a portion of the conductive-resistant medium 447 interposed between the outer edge of the pad (e.g. 444B) of one electrode (e.g. 442A) and the outer edge of the pad (e.g. 444B) of another electrode (e.g. 442B). Via this arrangement, each electrode (e.g. 442A-442F) of the array 440 is electrically independent of the other respective electrodes (e.g. 442A-442F) of the array 440.

[00114] In addition, each of the respective electrodes (e.g. 442A-442F) of the array 440 is passive, i.e. is not in electrical connection to (or communication with) any electrical circuitry, any power source, etc. Stated differently, each of the respective electrodes (e.g. 442A-442F) is isolated to be an independent electrically conductive element by which charges 144A may be conducted from exterior surface 122 of second plate 420 to interface 135 in order to create a voltage differential (across the dielectric layer 134) at a desired target position (e.g. T1 , T2, etc.) within the passageway 119 of the receptacle 400.

[00115] It will be understood that the electrodes 442A-442E shown in FIG. 4 are merely representative and that the electrodes of array 440 may extend in multiple orientations to comprise a two-dimensional array such as at least some of the examples, as described in association with at least FIGS. 2, 3A, 6C. [00116] As further shown in FIG. 4, in a manner similar to that shown in FIGS. 1 and 3A, in some examples a deposit of charges 144A (from a non- contact charge depositing unit 140, as in FIG. 1) onto a selected electrode 442C (at exterior surface 122 of second plate 420) results in charges 144B at interface 135 of second plate 420 to induce the electric field E between the first and second plates 110, 420 to cause electrowetting movement of droplet 130 from the position shown in FIG. 4A to the target position T1 in a manner similar to that described with respect to at least FIGS. 1 and 3A. In one aspect, the deposited charges 144A at exterior surface 122 at pad 444A of electrode 422C correspond to a first voltage V1 (e.g. similar to FIGS. 1 , 3A), while the charges 144B at interface 135 (aligned with pad 444B of electrode 422C) of second plate correspond to a second voltage V2 (e.g. similar to FIGS. 1 , 3A).

[00117] In further reference to the previously-described example of a dielectric layer 134 made of a polyimide material (having a dielectric strength of about 300 V /micrometer, thickness of 12.5 micrometers), in a further example this dielectric layer 134 may be coupled with a hydrophobic layer 136. In some such examples, the hydrophobic layer 136 may comprise a hydrophobic fluoropolymer material (e.g. PFC 1601V) available from CYTONIX, LLC of Beltsville, Maryland. Furthermore, when deployed in the arrangement of the consumable microfluidic receptacle 400 of FIG. 4, a charge depositing unit (e.g. 140 in FIG. 1 , 600 in FIG. 5, 645 in FIG. 6A, 675 in FIG. 6B, 715 in FIG. 6C, 800 in FIG. 7A) is positioned to deposit charges 144A at exterior surface 122 of second plate 420 to cause a first voltage V1 to be developed at exterior surface 122 at pad 444A of electrode 422C. As later described in association with at least FIGS. 5-8, this applied first voltage V1 may be achieved via developing an internal voltage (e.g. V3 in FIG. 1) within the charge depositing unit of sufficient strength (e.g. 2900V) such that with an electrode control voltage (VC) (e.g. via a grid, electrode hole, and the like) of the charge depositing unit (e.g. 140 in FIG. 1) set at a desired value (e.g. 700 V) for a selectable period of time (e.g. 0.625 seconds), the pad 444A of electrode 442C (at exterior surface 122 of second plate 420) becomes charged (via charges 144A) to the first voltage V1 of 700V (e.g. applied voltage). For at least the reasons previously described in association with at least FIGS. 1-3C, a voltage differential (VD) between the interface 135 and the droplet 130 adjacent the interior surface 121 of the second plate 420 results in the electric field E between the second plate 420 and the first plate 110, and this arrangement causes electrowetting movement of the droplet 130 from the position shown in FIG. 4 to the target position T1 aligned with pads 444B, 444A of electrode 442C of array 440.

[00118] Thereafter, in some examples, the charge depositing unit (e.g. 140 in FIG. 1 , 600 in FIG. 5, 645 in FIG. 6A, 675 in FIG. 6B, 715 in FIG. 6C, 800 in FIG. 7A) may be used to discharge the charges 144B at pad 444B at interface 135 (or the charges 144A at pad 444A of electrode 442C) by setting the internal voltage (e.g. V3 in FIG. 1) of the charge depositing unit to an elevated voltage of an opposite polarity (e.g. -1600V) and the control voltage (VC) to 0 Volts for a period of time (e.g. 0.62 seconds), which results in the pad 444 B at interface 135 being discharged to 0 Volts (or a minimal value). In order to move the droplet 130 from target position T1 to T2, the charge depositing unit (e.g. 140 in FIG. 1) is moved into a position to be aligned with the pad 444A of the next electrode 442D over a period of time (e.g. 0.52 seconds), and then the process (e.g. depositing fresh charges 144A to create a voltage differential and electric field E, electrowetting droplet movement) repeats in order to move droplet 130 from position T1 to position T2. With many iterations via this arrangement, a velocity of droplet movement may be achieved that falls within a range between about 0.5 mm/second and 200 mm/second. In some examples, the velocity of droplet movement may comprise between about 1 mm/second to about 30 mm/second. In some examples, the velocity of droplet movement may comprise between about 5 mm/second to about 20 mm/second. In some examples, the velocity of droplet movement may comprise at least about 10 mm/second. It will be understood that some example charge depositing units, such as the later described charge depositing unit 715 in FIG. 6C comprise a two-dimensional array 741 of charge depositing elements 742, may apply charges to the exterior surface (e.g. 122 in FIGS. 1 , 4 and 722 in FIG. 6C) of the second plate (e.g. 420 in FIG. 4, 720 in FIG. 6C) without moving the charge depositing unit 715.

[00119] In some example arrangements, in the context of electrowetting movement on dielectric (EWOD), an average velocity of movement of droplet e.g. droplet movement) within microfluidic device may be proportional to an applied voltage (e.g. V1 at exterior surface 122) squared and inversely proportional to a dielectric thickness, such as thickness of dielectric layer 134. In such example arrangements, if the dielectric thickness were quadrupled (e.g. 80 micrometers) relative to a reference thickness (e.g. 20 micrometers), then one can obtain the same average velocity of droplet movement by doubling the applied voltage (e.g. V1 at exterior surface 122). Accordingly, in at least some of the example arrangements of the present disclosure which may employ relatively high voltages (e.g. 700 V), an example dielectric layer may comprise a significantly greater thickness without comprising a desired velocity of droplet movement.

[00120] FIG. 5 is an isometric view schematically representing an example addressable charge depositing unit 600. In some examples, the addressable charge depositing unit 600 may comprise one example implementation of, and/or may comprise at least some of substantially the same features and attributes as, the addressable charge depositing units described in association with at least FIGS. 1-4.

[00121] As shown in FIG. 5, the addressable charge depositing unit 600 comprises a needle 607. The needle 607 extends at least partially through, and is exposed at, one end 605 of a cylinder 602, with the needle 607 being spaced apart from the inner wall surface 609 of the cylinder 602. Upon applying an electrical signal, a high voltage (e.g. V3 in FIG. 1) may be caused at the end of the needle 607, which in turn generates airborne charges 633 oriented to migrate toward a second plate (e.g. 120 in FIG. 1) of a consumable microfluidic receptacle 102. The generated airborne charges 633 may be positive (as shown) or negative, depending on the particular goals (e.g. building charge, neutralizing charge, etc.) for the consumable microfluidic receptacle 102. In some examples, the cylinder 602 may be electrically connected to a ground element 613 and a third voltage (e.g. V3) applied to the needle 607 may be at least one order of magnitude greater than a first voltage V1 (e.g. deposited charges 144A in FIG. 1) to occur at the exterior surface 122 of the second plate 120. In some such examples, the third voltage (V3) at needle 607 may comprise between about 1000 Volts to about 5000 Volts.

[00122] Flowever, in some examples, the cylinder 602 is not grounded but rather an electrical signal is applied to cause the cylinder 602 to exhibit an alternate first voltage, with the third voltage at the needle 607 being substantially greater than the alternate voltage. In one such example implementation, the third voltage at needle 607 may comprise about 4000 Volts while the alternate first voltage at the cylinder 602 may comprise about 1000 Volts, while the first plate 110 is grounded. [00123] The addressable charge depositing unit 600 may be mobile, and moved relative to a stationary microfluidic device (e.g. consumable microfluidic receptacle), or the addressable charge depositing unit 600 may be stationary, and the microfluidic device (e.g. consumable microfluidic receptacle) may be moved relative to the addressable charge depositing unit 600. In either case, via such relative movement, the addressable charge depositing unit 600 may selectively generate airborne charges 633 to cause electrowetting movement of droplets within and through a consumable microfluidic receptacle, with the addressable charge depositing unit 600 being operated to generate negative or positive charges, depending on particular goals to build charges or neutralize charges.

[00124] FIG. 6A is a diagram 640 including a side view schematically representing an example addressable charge depositing unit 645. In some examples, the addressable charge depositing unit 645 may comprise one example implementation of, and/or may comprise at least some of substantially the same features and attributes as, the addressable charge depositing units described in association with at least FIGS. 1-4. In some examples, the addressable charge depositing unit 645 comprises a first charge unit 652 and a second charge unit 654, each of which may generate airborne charges having a first polarity or an opposite second polarity, as desired. In some examples, the respective charge units 652, 654 may comprise and/or sometimes be referred to as an ion head, ion-generating head, and the like. For example, if the addressable charge depositing unit 645 were moved in a first direction (directional arrow M), the first charge unit 652 could emit airborne charges of a first polarity 653B (e.g. negative in some examples) to deposit charges in order to neutralize any residual charges present at second plate 120. Next, the following second charge unit 654 can emit airborne charges of an opposite second polarity 653A (e.g. positive in this example) to deposit and build charges at the exterior surface 122 of the second plate 120 in order to cause an electric field (as represented by directional arrow E) between the respective second and first plates 120, 110. This electric field (E) may induce electrowetting movement of droplets 130 within passageways of a consumable microfluidic receptacle for microfluidic operations.

[00125] Alternatively, upon moving the addressable charge depositing unit 645 in an opposite second direction (directional arrow N), the second charge unit 654 may generate airborne charges having the first polarity (e.g. negative) 653B to deposit charges in order to neutralize any residual charges present at second plate 120. Next, the following first charge unit 652 can emit airborne charges of an opposite second polarity (e.g. positive in this example) 653A to deposit and build charges at the exterior surface 122 of the second plate 120 in order to cause an electric field (between the respective second and first plates 120, 110) to induce electrowetting movement of droplets 130 within passageways of a consumable microfluidic receptacle of a microfluidic device. [00126] Accordingly, by altering the respective roles of the first and second charge units 652, 654 in view of the particular direction of movement of the addressable charge depositing unit 645, the addressable charge depositing unit 645 may generate the appropriate stream of airborne charges to either neutralize charges or build charges to control electrowetting movement of droplets within the microfluidic device as desired.

[00127] FIG. 6B is a diagram 670 including an isometric view schematically representing an example addressable charge depositing unit 675. In some examples, the addressable charge depositing unit 675 may comprise one example implementation of, and/or may comprise at least some of substantially the same features and attributes as, the addressable charge depositing units described in association with at least FIGS. 1-6A. In some examples, the addressable charge depositing unit 675 comprises a charge building element 684 and a pair of charge neutralizing elements 686A, 686B on opposite sides of the charge building element 684. In some examples, the respective charge building or neutralizing elements 684, 686A, 686B may comprise and/or sometimes be referred to as an ion head, ion-generating head, and the like.

[00128] In some examples, the charge building element 684 may generate airborne charges of a first polarity (e.g. positive) 692 to deposit and build charges 144A on an exterior surface 122 of a second plate 120 (e.g. FIG. 1) to cause an electric field to control electrowetting movement of droplets within a consumable microfluidic receptacle of a microfluidic device. However, prior to doing so, charges on the second plate 120 may be neutralized as desired via operation of the first or second charge neutralizing element 686A, 686B, depending on the direction of movement of the addressable charge depositing unit 675. For instance, upon moving in the first direction M, the first charge neutralizing unit 686A may emit charges 693A to neutralize charges on the second plate 120 (and first plate 110). In some examples, as shown in FIG. 6B, the charges 693A may comprise charges of both a first and second polarity (e.g. positive and negative) within an AC signal. The combination of opposite charges may more effectively neutralize any charges on the second plate 120 and/or the first plate 110. However, in some examples, the first charge neutralizing element 686A may emit airborne charges of a single polarity (e.g. negative) which are opposite the polarity (e.g. positive) of the charges 692 emitted by the charge building element 684.

[00129] Alternatively, upon moving the addressable charge depositing unit 675 in the opposite second direction N, the second charge neutralizing element 686B may emit charges 693B to deposit charges in order to neutralize residual charges on the second plate 120 (and first plate 110). In some examples, as shown in FIG. 6B, the charges 693B may comprise charges of both a first and second polarity (e.g. positive and negative) within an AC signal. The combination of opposite charges may effectively neutralize any charges on the second plate 120 and/or the first plate 110. However, in some examples, the second charge neutralizing element 686B may emit airborne charges of a single polarity (e.g. negative) which are opposite the polarity (e.g. positive) of the charges 692 emitted by the charge building element 684.

[00130] Accordingly, the addressable charge depositing unit 675 of FIG. 6B is equipped for efficient, effective charge neutralization and/or charge building regardless of the particular direction (e.g. M or N) of movement of the charge depositing unit 675 to control electrowetting movement of droplets within a microfluidic device. [00131] FIG. 6C is a diagram including a side view schematically representing an example two-dimensional addressable charge depositing unit 715 in charging relation to a second plate 720 of a consumable microfluidic receptacle (e.g. 102 in FIG. 1). In some examples, the addressable charge depositing unit 715 may comprise one example implementation of, and/or may comprise at least some of substantially the same features and attributes as, the addressable charge depositing units described in association with at least FIGS. 1-4. Meanwhile, the second plate 720 may comprise one example implementation of, and/or may comprise at least some of substantially the same features and attributes as, the consumable microfluidic receptacle 102 described in association with at least FIGS. 1-4.

[00132] As shown in FIG. 6C, addressable charge depositing unit 715 comprises a two dimensional array 741 of addressable charge depositing elements as represented by the arrows 742. The array 741 comprises a size and a shape to cause electrowetting movement of droplets 130 to any one target position (e.g. 217 in FIG. 2) of a corresponding array 718 of target droplet positions (e.g. 217 in FIG. 1) of the consumable microfluidic receptacle 720. In some examples, each addressable charge depositing element 742 may correspond to an addressable charge depositing unit 600 in FIG. 5, which may be operated to generate airborne charges (of a desired first polarity or opposite second polarity) in order to deposit and build charges on an exterior surface 722 of second plate 720 (of a consumable microfluidic receptacle) to cause a desired direction of movement of a droplet along a passageway (e.g. 219A- 219E in FIG. 2) within the consumable microfluidic receptacle. In some such examples, any one of the addressable charge depositing elements 742 also may be operated in a charge neutralizing mode, to emit single polarity charges (e.g. negative), or to emit charges of both a first and second polarity (e.g. negative, positive) via an AC signal in a manner similar to the first and second charge neutralizing units 686A, 686B shown in FIG. 6B, in some examples. [00133] Via the two-dimensional arrangement shown in FIG. 6C, both the second plate 720 of the microfluidic device and the addressable charge depositing unit 715 remain stationary while the array 741 of addressable charge depositing elements 742 may be selectively operated (e.g. individually controllable) to control electrowetting movement for any or all of the target positions (e.g. 217 in FIG. 2) of the second plate 720 of the consumable microfluidic receptacle (e.g. 102 in FIG. 1).

[00134] In some examples, the arrangement described in FIGS. 7A-7B may comprise one example by which the two-dimensional array 741 of addressable charge depositing elements 742 may be implemented.

[00135] FIG. 7A is a diagram 800 schematically illustrating an example addressable charge depositing unit 820. In some examples, the addressable charge depositing unit 820 may comprise at least some of substantially the same features and attributes as, the addressable charge depositing units described in association with at least FIGS. 1-6C. In some examples, the addressable charge depositing unit 820 may comprise one example implementation of at least a portion of the two-dimensional array of the addressable charge depositing unit in FIG. 6C.

[00136] Addressable charge depositing unit 820 includes a corona generating device 822 to generate charges 826 and an electrode grid array 824. The term “charges” as used herein refers to ions (+/-) or free electrons, and in Figure 7 the corona generating device 822 generates charges 826, which may be positive (as shown) or negative, as desired. Electrode array 824 is held in spaced apart relation to device 822 by a distance D13. In one example, device 822 is a corona generating device, such as a thin wire that is less than 100 micrometers in diameter and operating above its corona generating potential. In some examples, while not shown in Figure 7, device 822 generates negative charges that move under existing electrical fields.

[00137] In some examples, electrode array 824 includes a dielectric film 828, a first electrode layer 830, and a second electrode layer 832. Dielectric film 828 has a first side 834 and a second side 836 that is opposite first side 834. Dielectric film 828 has holes or nozzles 838A and 838B that extend through dielectric film 828 from first side 834 to second side 836. In one example, each of the holes 838A and 838B is individually addressable to control the flow of electrons through each of the holes 838A and 838B separately. Accordingly, any one of the holes 838A, 838B or multiple holes 838A, 838B may be closed or opened, as desired.

[00138] First electrode layer 830 is on first side 834 of dielectric film 828 and second electrode layer 832 is on second side 836 of dielectric film 828. First electrode layer 830 is formed around the circumferences of holes 838A and 838B to surround holes 838A and 838B on first side 834. Second electrode layer 832 is formed into separate electrodes 832A and 832B, where electrode 832A is formed around the circumference of hole 838A to surround hole 838A on second side 836 and electrode 832B is formed around the circumference of hole 838B to surround hole 838B on second side 836. Via this juxtaposition with the electrodes, the holes 838A, 838B may sometimes be referred to as electrode nozzles or electrode holes.

[00139] In operation, an electrical potential between first electrode layer 830 and second electrode layer 832 controls the flow of charges 826 from device 822 through holes 838A, 838B in dielectric film 828. In one example, electrode 832A is at a higher electrical potential than first electrode layer 830 and the charges 826 (e.g. positive) are prevented or blocked from flowing through hole 838A. In one example, electrode 832B is at a lower electrical potential than first electrode layer 830 and the charges 826 flow through hole 838B and outwardly to be directed in an airborne manner onto a second plate 120 of a consumable microfluidic receptacle.

[00140] Because FIG. 7A presents an end view of the charge unit 820, it will be understood that the electrode nozzles 838A, 838B may be representative of a two-dimensional array of multiple electrode nozzles, each of which are individually controllable to selectively emit the airborne charges 826 of a particular selectable polarity (e.g. negative or positive) being generated by element 822.

[00141] FIG. 7B a diagram including a top view schematically representing an example array 937 of electrode nozzles 938 of an example addressable charge depositing unit 900. The array 937 may comprise one example implementation of an array of electrode nozzles (e.g. 838A, 838B in FIG. 7A) in which the electrode nozzles 938 in FIG. 7B generally correspond to the representative electrode nozzles 838A, 838B in FIG. 7A. Moreover, the example array 937 in FIG. 7B may comprise one example implementation of at least a portion of the two-dimensional array 741 in FIG. 6C in which each addressable charge depositing element 742 may correspond to a respective one of the electrode nozzles 938 in the example array 937 of FIG. 8. Similarly, in some examples the body 936 shown in FIG. 7B may comprise a supporting structure and elements which generally corresponds to the structures (e.g. dielectric film 828, electrode plates, etc.) which form the overall structure of electrode array 824 in FIG. 7A.

[00142] FIGS. 8A-8C relate to an example electrode control element 1050, 1150, which may be used instead of using a charge depositing unit, such as 140, to apply charges (e.g. 144A in FIG. 1 ) to a second plate (e.g. 120 in FIG. 1 , 320 in FIG. 3A, or 420 in FIG. 4) of a consumable microfluidic receptacle (e.g. 102 in FIG. 1 , 300 in FIG. 3A, 400 in FIG. 4) in order to cause migration of charges, a voltage differential, etc. (as previously described in association with FIGS. 1-4) in order to cause electrowetting movement of a droplet 130. Moreover, it will be further understood that such example electrode control elements 1050, 1150 may be operated in a manner consistent with at least some example arrangements in FIGS. 5-7B by which charges are built and/or neutralized, except with the electrode control element applying charges in a releasable contact manner instead of the airborne manner described in association with FIGS. 5-7B.

[00143] FIG. 8A is a diagram 1000 including a side view schematically representing an example electrode control element 1050. As shown in FIG. 8A, electrode control element 1050 comprises a base 1055 which may comprise an insulative material which houses circuitry (and/or conductive elements connectable to circuitry) for controlling generation and application of charges (e.g. 144A) via each of the addressable electrodes 1053. In some examples, the electrode control element 1050 may be implemented in the form of a printed circuit board (PCB) or similar structure.

[00144] In some examples, microfluidic operations to be performed via the consumable microfluidic receptacle (e.g. 102, 300, 400) and an addressable electrode control element (e.g. 1050, 1150 in FIGS. 8A-8C) may be implemented in association with a control portion, such as but not limited to control portion 1300 in FIG. 9B and/or in association with a fluid operations engine 1200 in FIG. 9A. Such operations may also comprise control of the later-described relative movement and/or other later-described operational aspects associated with the receptacle and/or electrode control element 1050, 1150.

[00145] In some examples, as shown in FIG. 8A, each electrode 1053 may comprise a length (X1) which may comprise a length expected to be approximately the same size as the droplet 130 to be moved, as shown in FIG. 8B. In view of the example volumes of droplets noted above, the length (X1) of each electrode 153 may comprise between about 50 micrometers to about 5 millimeters, and may comprise a width similar to its length in some examples. In some examples, the length (X1) of each electrode 153 may be commensurate with the length (D2 in FIG. 9B) of a droplet or target position (e.g. T1 , T2) of a droplet within the consumable microfluidic receptacle 300.

[00146] In some examples, the length (D2) of the droplet in passageway 119 (e.g. FIG. 1 , 3A, 8B) may sometimes be referred as a length scale of the droplet, or a length of a target position of a droplet. Meanwhile, the distance (X2) between adjacent electrodes 1053 as shown in FIG. 8A may sometimes be referred to as the length scale of the electrodes 1053. In some examples, the length scale (X2) between electrodes 1053 may comprise about 50 to about 75 micrometers (e.g. 2-3 mils) and also may sometimes be referred to as spacing between electrodes 1053.

[00147] As shown in FIG. 8B, in some examples the addressable electrode control element 1050 may be brought into releasable contact against the exterior surface 122 of the second plate 320 of the example consumable microfluidic receptacle 300. In some such examples, the addressable electrode control element 150 may be supported by or within a frame (e.g. 133 in FIG. 1) and the consumable microfluidic receptacle 300 may be releasably supportable by the frame to place the consumable microfluidic receptacle 300 and the addressable electrode contact element 1050 into releasable contact and charging relation to each other. In some examples, exterior surface 122 of second plate 300, and a first surface 1051 (e.g. top surface) of the control element 1050 are each planarized to facilitate establishing robust mechanical and electrical connectivity when brought and maintained in releasable contact together.

[00148] As further shown in FIG. 8B, upon the addressable electrode control element 1050 being brought into releasable contact against the consumable microfluidic receptacle 300, a selected electrode(s) 1053 of the addressable electrode control element 150 may apply charges directly onto the exterior surface 122 of the second plate 320, which may then be referred to as deposited charges 144A. As further shown in FIG. 8B, the electrode 1053 selected from array 1052 (of electrodes 1053) is aligned with a target position T1 (represented via dashed lines), which is immediately adjacent to the droplet 130 and to which the droplet 130 is to be moved.

[00149] After the charges 144A are deposited at surface 122 of second plate 320 of receptacle, the charges 144A behave in a manner substantially similar to that described in association with at least FIGS. 1-4 to cause electrowetting movement of droplet 130 within and through passageway 119 of receptacle 300.

[00150] In some examples, the addressable electrode control element 1050 also may be used to neutralize charges on second plate 320 so as to prepare the microfluidic receptacle 300 to receive an application of fresh charges from electrode control element in preparation of causing further controlled pulling movement of the droplet 130 to a next target position (e.g. T2). [00151] It will be further understood that charges (e.g. 144A) applied on the second plate 120 (by the electrode control element 1050) will be significantly discharged or at least be discharged to a level at which their voltage is significantly lower than the voltage to be applied before the next electrowetting- caused pulling movement of the droplet 130 occurs to the next target position T2.

[00152] In some examples, both of the addressable electrode control element 1050 and the consumable microfluidic receptacle 300 are stationary during microfluidic operations, with the addressable electrode control element 1050 being arranged in a two-dimensional array to apply charges in any desired target location (e.g. 217 in FIG. 2) of the microfluidic receptacle in order to perform a particular microfluidic operation or sequence of microfluidic operations. One example implementation of a two-dimensional array of such electrodes is described later in association with at least FIG. 8C.

[00153] Flowever, it will be understood that in some examples, the electrode control element 1050 may be mobile and the consumable microfluidic receptacle 300 may be stationary while performing microfluidic operations, while in some examples, the addressable electrode control element 1050 may be stationary and the consumable microfluidic receptacle 300 is moved relative to the addressable electrode control element 1050 during microfluidic operations. In some examples, a frame (e.g. frame 133 in FIG. 1) may include portions, mechanisms, etc. which may facilitate relative movement between the consumable microfluidic receptacle 300 and the electrode control element 1050. [00154] It will be further understood that while FIG. 8B depicts second plate 320 as comprising an anisotropic conductive layer as in FIG. 3A, in some examples the electrode control element 1050 may be brought into releasable contact with other example receptacles, such as into releasably contact with a second plate 420 of receptacle 400 of FIG. 4 to deposit charges 144A at a pad 444A (of an electrode such as 442C) in order to initiate the migration of charges, voltage differential, etc. (as previously described in association with FIGS. 1-4) in order to cause electrowetting movement of droplet 130.

[00155] FIG. 8C is a diagram including a side view schematically representing an example arrangement 1101 comprising a two-dimensional addressable electrode control element 1150 in charging relation to a second plate 1120 of a consumable microfluidic receptacle 1100. In some examples, the addressable electrode control element 1150 may comprise one example implementation of, and/or may comprise at least some of substantially the same features and attributes as, the addressable electrode control element described in association with at least FIGS. 8A-8B. Meanwhile, the second plate 1120 (and associated consumable microfluidic receptacle 1100) may comprise one example implementation of, and/or may comprise at least some of substantially the same features and attributes as, the second plate 120, 320, 420 (and associated consumable microfluidic receptacle 102, 300, 400) described in association with at least FIGS. 1 , 3A or 4.

[00156] As shown in FIG. 8C, the example addressable electrode control element 1150 comprises a two dimensional array 1171 of individually controllable (e.g. addressable) electrodes 1172. The array 1171 comprises a size and a shape to cause controlled movement of droplets 130 to any one target position (e.g. 217 in FIG. 2) of a corresponding array of target droplet positions (e.g. 217 in FIG. 2) implemented via the second plate 1120 of the consumable microfluidic receptacle 1100. In some examples, at least some of the respective example addressable electrodes 1172 of control element 1150 may correspond to the example electrodes 1053 shown in FIGS. 8A-8B, which may be operated to apply charges (of a desired first polarity or opposite second polarity) in order to deposit charges on an exterior surface 1122 of second plate 1120 (of the consumable microfluidic receptacle 1100) to ultimately cause a desired direction of movement of a droplet along a passageway (e.g. 219A- 219E in FIG. 2) within the consumable microfluidic receptacle 1100. In some such examples, any one of the addressable electrodes 1172 also may be operated in a charge neutralizing mode in which charges are emitted having a polarity (e.g. negative) opposite the polarity of the charges (e.g. positive) used to initiate an electrowetting movement of the liquid droplet 130.

[00157] Via the two-dimensional arrangement 1101 shown in FIG. 8C, both the second plate 1120 of the consumable microfluidic receptacle 1100 and the addressable electrode control element 1150 remain stationary while the various respective addressable electrodes 1172 (of array 1171) may be selectively operated (e.g. individually controlled) to control droplet movement for any or all of the target positions (e.g. 217 in FIG. 2) of the second plate 1120 of the consumable microfluidic receptacle 1100.

[00158] FIG. 9A is a block diagram schematically representing an example fluid operations engine 1200. In some examples, the fluid operations engine 1200 may form part of a control portion 1300, as later described in association with at least FIG. 9B, such as but not limited to comprising at least part of the instructions 1311. In some examples, the fluid operations engine 1200 may be used to implement at least some of the various example devices and/or example methods of the present disclosure as previously described in association with FIGS. 1-8 and/or as later described in association with FIGS. 9B-10. In some examples, the fluid operations engine 1200 (FIG. 9A) and/or control portion 1300 (FIG. 9B) may form part of, and/or be in communication with, an addressable charge depositing unit and/or a consumable microfluidic receptacle, such as the devices and methods described in association with at least FIGS. 1-8.

[00159] As shown in FIG. 9A, in some examples the fluid operations engine 1200 may comprise a moving function 1202, a merging function 1204, and/or a splitting function 1206, which may track and/or control electrowetting- caused manipulation of droplets within a microfluidic device, such as moving, merging, and/or splitting, respectively.

[00160] In some examples, the fluid operations engine 1200 may comprise a charge control engine 1220 to track and/or control parameters associated with operation of an addressable charge depositing unit to build charges (parameter 1222) or neutralize charges (parameter 1224) on a consumable microfluidic receptacle (of a microfluidic device), as well as to track and/or control the polarity (parameter 1224) of such charges. In some examples, a positioning parameter (1226) of the charge control engine 1220 is to track and/or control positioning (1226) of an addressable charge depositing unit and a consumable microfluidic receptacle relative to each other to implement such building or neutralizing of charges. In some examples, these parameters 1222, 1224, 1226 may be implemented according to at least some of the example implementations described in association with at least FIGS. 1-8 and 9B-10. [00161] In some examples, the charge control engine 1220 may comprise a voltage differential engine 1240 to implement a voltage differential parameter to cause a voltage differential across at least the dielectric layer (e.g. 134 in FIGS. 1 , 3A, 4) of the second plate of a consumable microfluidic receptacle. As previously noted, in some examples, the voltage differential parameter may be expressed as a voltage differential preservation parameter to the extent that a voltage differential across at least the dielectric layer is substantially preserved over a predetermined period of time during which the droplet is to move from a first position to a second position. This time period may sometimes be referred to as a droplet-movement time period or droplet-movement actuation time period. In some examples, the voltage differential parameter may be expressed as a voltage differential decay parameter to the extent that decay of a voltage differential across the second plate is substantially prevented over a predetermined period of time, such as the droplet-movement time period (or actuation time period).

[00162] In some examples, the voltage differential parameter may be expressed as a charge retention parameter to the extent that charges at an interface of the dielectric layer and the substrate of the second plate are substantially retained over the predetermined period of time during which the droplet is to move from a first position to a second position. Via this arrangement, a charge differential or voltage differential is retained between the charges at the interface (i.e. the interface of the dielectric layer and the substrate of the second plate) and a portion of the droplet (adjacent an interior surface of the second plate) at least during the droplet-movement time period. [00163] In some examples, the voltage differential parameter (implemented via engine 1240) comprises at least some of substantially the same features and attributes by which preservation of a voltage differential (or prevention of voltage decay, or retention of charge differential) across at least a dielectric layer of the second plate are described in association with at least FIGS. 1-8 and/or 9B-10. With this in mind, in some examples the voltage differential engine 1240 may control or manage a voltage differential according to parameters regarding a material type (1242), a thickness (1244), a dielectric strength (1246), an applied voltage (1248) (e.g. V1 at 122, V1 at 135), and a time period (1250). In some examples, parameters (1242, 1244, 1246) regarding the material type (1242), thickness (1244), and dielectric strength (1246) may be implemented with regard to solely the dielectric layer (e.g. 134) while in some examples, these parameters may be implemented with regard to the second plate (e.g. 120, etc.) as a whole including the dielectric layer 134. In some examples, the parameters regarding the material type, thickness, and dielectric strength may be implemented with regard to both the dielectric layer (e.g. 134) and the hydrophobic layer 136. In some examples, parameters regarding voltage (1248) and time period (1250) may depend on the other parameters (1242, 1244, 1246), desired performance, type of microfluidic operations, or other factors. In some examples, the voltage parameter 1248 also may include control or specification of voltages such as internal voltages (e.g. V3) of a charge depositing unit, control voltages (VC) of the charge depositing unit (which are used to set the applied voltage V1 , etc.

[00164] It will be understood that various functions and parameters of fluid operations engine 1200 may be operated interdependently and/or in coordination with each other, in at least some examples.

[00165] FIG. 9B is a block diagram schematically representing an example control portion 1300. In some examples, control portion 1300 provides one example implementation of a control portion forming a part of, implementing, and/or generally managing the example microfluidic devices, as well as the particular portions, components, addressable charge depositing units, electrode control elements, consumable microfluidic receptacle, dielectric layers, hydrophobic layers, substrates, microfluidic operations, control portion, instructions, engines, functions, parameters, and/or methods, as described throughout examples of the present disclosure in association with FIGS. 1-9A and 9C-10. In some examples, control portion 1300 includes a controller 1302 and a memory 1310. In general terms, controller 1302 of control portion 1300 comprises at least one processor 1304 and associated memories. The controller 1302 is electrically couplable to, and in communication with, memory 1310 to generate control signals to direct operation of at least some of the example portions, components, etc. of the addressable charge depositing units, electrode control elements, consumable microfluidic receptacle, dielectric layers, hydrophobic layers, substrates, microfluidic operations, control portion, instructions, engines, functions, parameters, and/or methods, as described throughout examples of the present disclosure. In some examples, these generated control signals include, but are not limited to, employing instructions 1311 stored in memory 1310 to at least direct and manage microfluidic operations via electrowetting movement in the manner described in at least some examples of the present disclosure, including controlling a voltage differential across at least a dielectric layer of a microfluidic receptacle. In some instances, the controller 1302 or control portion 1300 may sometimes be referred to as being programmed to perform the above-identified actions, functions, etc.

[00166] In response to or based upon commands received via a user interface (e.g. user interface 1320 in FIG. 9C) and/or via machine readable instructions, controller 1302 generates control signals as described above in accordance with at least some of the examples of the present disclosure. In some examples, controller 1302 is embodied in a general purpose computing device while in some examples, controller 1302 is incorporated into or associated with at least some of the example microfluidic devices, as well as the particular portions, components, addressable charge depositing units, electrode control elements, consumable microfluidic receptacles, dielectric layers, hydrophobic layers, substrates, microfluidic operations, control portion, instructions, engines, functions, parameters, and/or methods, etc. as described throughout examples of the present disclosure.

[00167] For purposes of this application, in reference to the controller 1302, the term “processor” shall mean a presently developed or future developed processor (or processing resources) that executes machine readable instructions contained in a memory or that includes circuitry to perform computations. In some examples, execution of the machine readable instructions, such as those provided via memory 1310 of control portion 1300 cause the processor to perform the above-identified actions, such as operating controller 1302 to implement microfluidic operations, including causing electrowetting movement of droplets, via the various example implementations as generally described in (or consistent with) at least some examples of the present disclosure. The machine readable instructions may be loaded in a random access memory (RAM) for execution by the processor from their stored location in a read only memory (ROM), a mass storage device, or some other persistent storage (e.g., non-transitory tangible medium or non-volatile tangible medium), as represented by memory 1310. The machine readable instructions may include a sequence of instructions, a processor-executable machine learning model, or the like. In some examples, memory 1310 comprises a computer readable tangible medium providing non-volatile storage of the machine readable instructions executable by a process of controller 1302. In some examples, the computer readable tangible medium may sometimes be referred to as, and/or comprise at least a portion of, a computer program product. In other examples, hard wired circuitry may be used in place of or in combination with machine readable instructions to implement the functions described. For example, controller 1302 may be embodied as part of at least one application-specific integrated circuit (ASIC), at least one field- programmable gate array (FPGA), and/or the like. In at least some examples, the controller 1302 is not limited to any specific combination of hardware circuitry and machine readable instructions, nor limited to any particular source for the machine readable instructions executed by the controller 1302.

[00168] In some examples, control portion 1300 may be entirely implemented within or by a stand-alone device.

[00169] In some examples, the control portion 1300 may be partially implemented in one of the example microfluidic operation devices (e.g. addressable charge depositing unit and/or consumable microfluidic receptacle) and partially implemented in a computing resource separate from, and independent of, the example microfluidic operation devices (e.g. addressable charge depositing unit and/or consumable microfluidic receptacle) but in communication with the example microfluidic operation devices. For instance, in some examples control portion 1300 may be implemented via a server accessible via the cloud and/or other network pathways. In some examples, the control portion 1300 may be distributed or apportioned among multiple devices or resources such as among a server, a microfluidic operation device (e.g. addressable charge depositing unit and/or consumable microfluidic receptacle), and/or a user interface. [00170] In some examples, control portion 1300 includes, and/or is in communication with, a user interface 1320 as shown in FIG. 9C. In some examples, user interface 1320 comprises a user interface or other display that provides for the simultaneous display, activation, and/or operation of at least some of the example microfluidic devices, as well as the particular portions, components, addressable charge depositing units, electrode control elements, consumable microfluidic receptacles, dielectric layers, hydrophobic layers, substrates, microfluidic operations, control portion, instructions, engines, functions, parameters, and/or methods, etc., as described in association with FIGS. 1-9B and 10. In some examples, at least some portions or aspects of the user interface 1320 are provided via a graphical user interface (GUI), and may comprise a display 1324 and input 1322.

[00171] FIG. 10 is a flow diagram of an example method 1400. In some examples, method 1400 may be performed via at least some of the devices, components, example microfluidic devices, addressable charge depositing units, electrode control elements, consumable microfluidic receptacles, dielectric layers, hydrophobic layers, substrates, microfluidic operations, instructions, control portions, engines, functions, parameters, and/or methods, etc. as previously described in association with at least FIGS. 1-9C. In some examples, method 1400 may be performed via at least some of the devices, components, example microfluidic devices, as well as the particular portions, components, addressable charge depositing units, electrode control elements, consumable microfluidic receptacles, dielectric layers, hydrophobic layers, substrates, microfluidic operations, instructions, control portions, engines, functions, parameters, and/or methods, etc. other than those previously described in association with at least FIGS. 1-9C.

[00172] As shown at 1412 in FIG. 10, in some examples method 1400 comprises placing a liquid droplet between a first plate and a second plate of a replaceable fluid cavity, the second plate comprising an at least partially conductive substrate defining an exterior surface, a hydrophobic layer defining an interior surface, and a dielectric layer sandwiched between the substrate and the hydrophobic layer. As further shown at 1414 in FIG. 10, in some examples method 1400 comprises selectively applying charges to the exterior surface of the second plate to cause an electric field between the second plate and the first plate, to control electrowetting movement of the droplet through a passageway between the respective first and second plates. As further shown at 1416 in FIG. 10, method 1400 may comprise substantially preserving, via at least the dielectric layer, a voltage differential across the at least the dielectric layer due to the applied charges at the second plate during an electrowetting movement time period in which the droplet is to move from a first position to a second position.

[00173] Although specific examples have been illustrated and described herein, a variety of alternate and/or equivalent implementations may be substituted for the specific examples shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific examples discussed herein.