CROSS-REFERENCE TO RELATED APPLICATIONS

[001] This application claims priority to

United States Patent Application No. 63/121 ,135, filed on December s, 2020, and titled “Air Filtering Device With Sensor System”, and

United States Patent Application No. 63/121 ,143, filed on December 3, 2020, and titled “Photochemical Activated Air Filtering Device”, the entire contents of which are herein incorporated by reference.

TECHNICAL FIELD

[002] The following generally relates to an air filtering device.

DESCRIPTION OF THE RELATED ART

[003] Airborne contaminants, fungal spores, pathogens, bacteria and viruses, herein rereferred to as aerosols, travel through buildings and enclosed spaces. These aerosols travel through ventilation systems and can be recirculated through the building or enclosed space.

[004] United States Patent No. 8,038,777 (the ‘777 patent) discusses an air sterilization device with low aerosol bounce. It includes an air conditioning pipe that has within it an ultraviolet (UV) light upstream from a porous filter media having irregularly distributed channels. The ‘777 patent also teaches that since the aerosols are captured by the porous filter media and killed by the UV light, there is no need to use photocatalysis for increasing the sterilization effect.

[005] It is herein recognized however that the material for porous filter media could degrade with UV light exposure.

[006] It is also herein recognized that it is desirable to track the operation of air sterilization devices. BRIEF DESCRIPTION OF THE DRAWINGS

[007] Embodiments will now be described by way of example only with reference to the appended drawings wherein:

[008] FIG. 1 is a perspective view of an air filtering device, according to an example embodiment.

[009] FIG. 2A shows ultraviolet (UV) light sources positioned upstream from an air filter assembly inside the body of the air filtering device, according to an example embodiment.

[0010] FIG. 2B shows, in the order from upstream to downstream airflow in the air filtering device, a first set of UV light sources, an air filter assembly, followed by a second set of UV light sources, according to another example embodiment.

[0011] FIG. 2C shows, in the order from upstream to downstream airflow in the air filtering device, a first set of UV light sources, a first air filter assembly, a second set of UV light sources, followed by a second air filter assembly, according to another example embodiment.

[0012] FIG. 3A shows a schematic of a mesh assembly that includes a first mesh material and a second mesh material, with the first mesh material positioned closer to the UV light sources, according to an example embodiment.

[0013] FIG. 3B shows a schematic of a mesh assembly that includes two layers of first mesh material that sandwich a layer of second mesh material, with the first mesh material positioned closer to the UV light sources, according to an example embodiment.

[0014] FIG. 3C shows the same mesh assembly shown in FIG. 3B, and further includes a second UV light source positioned downstream the mesh assembly, according to an example embodiment.

[0015] FIG. 3D is similar to the embodiment shown in FIG. 3C, and further includes a second mesh assembly positioned downstream from the second UV light source. The second mesh assembly includes a first layer of mesh comprising a first material and positioned closer to the second UV light source, and a second layer of mesh comprising a second material positioned further downstream from the second UV light source, according to an example embodiment. [0016] FIG. 3E shows a schematic, in the order from upstream to downstream airflow in the air filtering device, a first set of UV light sources, a first air filter assembly, a second set of UV light sources, a second air filter assembly, followed by a third set of UV light sources, according to another example embodiment. Each of the air filter assemblies include two layers of first mesh material that sandwich an inner layer of second mesh material.

[0017] FIG. 4 is a schematic diagram showing the flow of an air, aerosols and free radicals in a mesh assembly, while being exposed to UV light, according to an example embodiment.

[0018] FIG. 5 is a perspective view of an air filtering device, according to another example embodiment.

[0019] FIG. 6 shows the inner components of the air filtering device of FIG. 5, including UV light sources positioned upstream from a mesh assembly inside the body of the air filtering device, and upstream and downstream sensors, according to an example embodiment.

[0020] FIG. 7 is a perspective view of an air filtering device that includes an indicator substance deployment mechanism, according to an example embodiment.

[0021] FIG. 8 shows the inner components of the air filtering device of FIG. 7, including sensors for detecting the indicator substance downstream from the mesh assembly, according to an example embodiment.

[0022] FIG. 9 shows the inner components of the air filtering device of FIG. 3, including sensors that are positioned both upstream and downstream from the mesh assembly, according to an example embodiment.

[0023] FIGs. 10A, 10B, 10C and 10D show different views of an air filtering device with an access door to insert and remove a mesh assembly and a light assembly, according to an example embodiment.

[0024] FIG. 11 shows a system diagram of components for the air filtering device, including a control module, sensors, lights and data connection to one or more external devices. DETAILED DESCRIPTION

[0025] It will be appreciated that for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the example embodiments described herein. However, it will be understood by those of ordinary skill in the art that the example embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the example embodiments described herein. Also, the description is not to be considered as limiting the scope of the example embodiments described herein.

[0026] Within this specification, different structural entities (which may variously be referred to as “component”, “circuit”, “system”, “processor”, “module”, “interface”, “device”, other components, etc.) may be described or claimed as “configured” to perform one or more tasks or operations. This formulation - [entity] configured to [perform one or more tasks] - is used herein to refer to structure (i.e., something physical, such as an electronic circuit). More specifically, this formulation is used to indicate that this structure is arranged to perform one or more tasks during operation. A structure can be said to be “configured to” perform some task even if the structure is not currently being operated. A “sensor module configured to collect temperature information” is intended to cover, for example, circuitry that performs this function during operation, even if the circuitry in question is not currently being used (e.g., a power supply is not powering it). Thus, an entity described or recited “configured to” perform some task refers to something physical, such as a device, circuit, memory storing program instructions executable to implement the task, etc. This phrase is not used herein to refer to something intangible.

[0027] Reciting in the appended claims that a structure is “configured to” perform one or more tasks is intended not to be interpreted as having means-plus-function elements.

[0028] Throughout the specification and the claims, the following terms take at least the meanings explicitly associated herein, unless the context clearly dictates otherwise. The term "or" is intended to mean an inclusive "or." Further, the terms "a," "an," and "the" are intended to mean one or more unless specified otherwise or clear from the context to be directed to a singular form.

[0029] In this specification, numerous specific details have been set forth. It is to be understood, however, that implementations of the disclosed technology may be practiced without these specific details. In other instances, well-known methods, structures, and techniques have not been shown in detail in order not to obscure an understanding of this description. References to “for example”, "some examples," "other examples," "one example," "an example," "various examples," "one embodiment," "an embodiment," "some embodiments," "example embodiment," “an example aspect”, "various embodiments," "one implementation," "an implementation," "example implementation," "various implementations," "some implementations," etc., indicate that the implementation(s) of the disclosed technology so described may include a particular feature, structure, or characteristic, but not every implementation necessarily includes the particular feature, structure, or characteristic. Further, repeated use of the phrases "in one example," "in one embodiment," or "in one implementation" does not necessarily refer to the same example, embodiment, or implementation, although it may.

[0030] As used herein, unless otherwise specified the use of the ordinal adjectives "first," "second," "third," etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.

[0031] It is herein recognized that UV light interacting with non-photoreactive mesh material can still degrade the mesh material over time. For example, a mesh material with channels that have nickel surfaces (e.g., nickel mesh) are used to mechanically trap aerosols. The stopping or slowing of the aerosols in the channels of the mesh material then allows sufficient exposure time for the UV light rays to kill the aerosols (e.g., bacteria, pathogens, viruses, spores, etc.).

[0032] It is herein desirable, however, to reduce the amount of time that UV light rays interact with the non-photoreactive mesh to improve the operating life of the mesh, while still sterilizing aerosols. It is also herein desirable, for example, to also disintegrate other gasses and substances, such as volatile organic compounds (VOCs).

[0033] According to an example embodiment of the invention described herein, a protective mesh material shields a second mesh that is prone to degradation by UV light. The protective mesh is positioned closer to the UV light and absorbs the UV light, while the second mesh is positioned further away from the UV light. The protective mesh and the second mesh are made from different material. In an example embodiment, the protective mesh comprises a metallic material. Nonlimiting examples of metallic material include aluminum and Titanium dioxide. In an example embodiment, the second mesh is made from a metallic material or a non- metallic material. A non-limiting example of non-metallic material includes polyurethane.

[0034] According to another example of the invention described herein, photoreactive mesh material shields the non-photoreactive mesh. The photoreactive mesh traps and slows down some of the unwanted airborne material (e.g., aerosols, bioaerosols, spores, bacteria, viruses, VOCs, etc.), which are disintegrated by UV light. The photoreactive mesh also reacts with the UV light to produce free radicals that are blown downstream and are trapped in the non-photoreactive mesh. The free radicals and the unwanted airborne material are mechanically trapped in the non-photoreactive mesh, giving more exposure time for the unwanted airborne material and free radicals to interact. The free radicals sterilize the unwanted airborne material by punching electron holes in the material.

[0035] In an example aspect, the photoreactive mesh material blocks some of the UV light from hitting the non-photoreactive mesh material, which improves the operation life of the non-photoreactive mesh. In another example aspect, even after the UV light is turned off, the sterilization process still takes effect because the free radicals, which were produced during the activation by the UV light, continue to be trapped and persist in the non-photoreactive mesh even when the UV light is turned off. In other words, unwanted airborne material that interacts with the free radicals will be sterilized. In an example aspect, this allows sterilization to occur with a reduced amount of time that the light is turned on. This in turn increases the operational life of the mesh. [0036] FIG. 1 shows a body 101 of an air filtering device 100 that includes an inlet 102 and an outlet 103 for airflow. The device 100 can be part of an air ventilation system in a building, a house, a room, a vehicle, etc. For example, the device is part of an air conditioning system.

[0037] FIG. 2A shows internal components of the device 100. The body 100 defines therein a hollow space to facilitate air flow from the inlet to the outlet. The body 100 also houses one or more UV light sources 200 and a porous filter assembly 201 , also herein called a mesh assembly. The mesh assembly includes at least a first layer of porous filter media that includes a first material and a second layer of porous filter media that includes a second material. In an example aspect, the first layer protects the second layer from the UV light and is unreactive to UV light.

[0038] In an alternative example embodiment, the first material reacts with the UV light to product free radicals. The second material is not photochemically reactive to UV light. There may be more than two layers of the first material and the second material. The first layer that includes the first material is positioned closer to the UV light.

[0039] The UV light sources 200 are shown as three horizontal rows. In an example embodiment, a single UV light source is provided. In another example, multiple UV light sources are provided. UV light sources can be arranged in different configurations other than rows. Alternatives include rings, columns, grids, etc. The UV light sources can be bulbs or can be light emitting diodes, or a combination thereof.

[0040] In an example aspect, the UV light sources 200 emit UV-C light. For example, the UV light sources emit light at a 254 nanometer wavelength. In another example, the UV light sources emit light in the range of 100 to 280 nanometers. In another example aspect, the UV light sources 200 emit far-UVC light in the wavelength range of 207 to 222 nanometers. In another example aspect, the UV light sources 200 emit UV-A light. For example, the UV light sources emit light in the range of 315 to 400 nanometers.

[0041] FIG. 2B shows another embodiment of an air filtering device 100. From the order starting from upstream to downstream, the components include: one or more UV light sources 200, a mesh assembly 201 , and another set of one or more UV light sources 200.

[0042] FIG. 2C shows another embodiment of an air filtering device 100. From the order starting from upstream to downstream, the components include: a first one or more UV light sources 200, a first mesh assembly 201 , a second one or more UV light sources 200, and a second mesh assembly 201. In an example embodiment, the first and the second mesh assemblies are the same. In another example embodiment, the first and the second mesh assemblies are different from each other.

[0043] Turning to FIG. 3A, an example embodiment of a mesh assembly 201 is shown from a side view and the mesh assembly 201 includes a photoreactive layer 301 and a non-photoreactive layer 302.

[0044] The photoreactive layer 301 includes an entering surface 301 E for the air to enter, a leaving surface 301 L for air to leave, and multiple irregularly distributed channels 301 C connecting the entering surface 301 E to the leaving surface 301 L. As shown in the close-up view, the surface material 301 M of the porous media can be a coating on fibers, or the material of fiber and the surface material 301 M are the same. In an example embodiment, the surface material 301 M reacts to the UV light from the light sources 200 to produce free radicals.

[0045] The non-photoreactive layer 302 includes an entering surface 302E for air to enter, a leaving surface 302L for air to leave, and multiple irregularly distributed channels 302C that connect the entering surface 302E to the leaving surface 302L. As shown in the close-up view, the surface material 302M of the porous media can be a coating on fibers, or the material of fiber and the surface material 302M are the same. In an example embodiment, the surface material 302M does not react to the UV light and does not produce free radicals.

[0046] The entering surface 302E of the non-photoreactive layer 302 faces the leaving surface 301 L of the photoreactive layer 301. In an example embodiment, the entering surface 302E of the non-photoreactive layer 302 is in contact with the leaving surface 301 L of the photoreactive layer 301.

[0047] In an example aspect, the photoreactive layer 301 includes Titanium dioxide. For example, the surface material 301 M is Titanium dioxide. The Titanium dioxide reacts with the UV light to generate hydroxyl radicals (OH ), which disintegrate bacteria, viruses, pathogens, fungal spores, VOCs, etc. It will be appreciated that other photocatalytic materials can be used that will generate free radicals in a photochemical reaction.

[0048] In an example aspect, the non-photoreactive layer 302 includes Nickel. For example, the surface material 302M is Nickel. This Nickel material helps to mechanically trap and slow down aerosols. In another example aspect, the non- photoreactive layer 302 includes Copper. In another example aspect, the non- photoreactive layer 302 includes Aluminum. Other types of material that have low aerosol bounce can be used.

[0049] In an example aspect, the number of pores per inch (PPI) in the photoreactive layer 301 is lower than the PPI in the non-photoreactive layer 302. In an example aspect, the layer 301 has a PPI of less than 80 PPI and the layer 302 has a PPI of greater than 80 PPI. In an example embodiment, the layer 302 has between 80 and 100 PPI. It will be appreciated that different PPI can be used for the mesh, which are applicable to the principles described herein. For example, a mesh can have more than 100 PPI.

[0050] The higher the PPI, the more restricted the air flow through the mesh assembly, which creates energy strain on the air ventilation. Therefore, in an example embodiment, the photoreactive layer have a lower PPI to reduce air resistance.

[0051] In an alternative example embodiment, the photoreactive layer 301 has a higher PPI count than the non-photoreactive layer 302.

[0052] The photoreactive layer 301 produces free radicals that flow along the airstream into the non-photoreactive layer 302. The layer 302 has a higher PPI to hold and trap the unwanted airborne material (e.g., aerosols, bioaerosols, spores, bacteria, viruses, VOCs, etc,) for a longer period of time, along with the free radicals. This allows more time for the unwanted airborne material to be sterilized by the free radicals. Furthermore, for the UV light that penetrates the photoreactive layer 301 , the penetrating UV light also reacts with the unwanted airborne material trapped in the non-photoreactive layer 302. [0053] It will also be appreciated that unwanted airborne material trapped in the photoreactive layer 301 will also be sterilized by the mechanism of exposure to the UV light, and another mechanism of exposure to free radicals released by the photoreactive layer 301.

[0054] While the figures show irregularly distributed channels in the mesh, which help to reduce the aerosol bounce, in other example embodiments, the channels are arranged in a repeated pattern. For example, the pores and channels are hexagonal shaped and extend through the entering surface and the leaving surface of the mesh. Other uniform patterns of the channels are applicable to the principles herein.

[0055] FIG. 3B shows another example embodiment that shows a mesh assembly 201 that includes two photoreactive layers 301 that sandwich a non- photoreactive layer 302. In other words, the entering surface of the non- photoreactive layer 302 abuts a leaving surface of a first photoreactive layer 301 , and the leaving surface of the non-photoreactive layer abuts an entering surface of a second photoreactive layer 301.

[0056] FIG. 3C shows another example embodiment that shows a mesh assembly with two photoreactive layers 301 that sandwich a non-photoreactive layer 302. A second downstream UV light 200 is positioned in the air filtering device. In other words, both of the photoreactive layers 301 are irradiated with UV light. This improves the sterilization effect.

[0057] In the example shown in FIG. 3C, the thickness of non-photoreactive layer 302 is illustrated to be thicker than the thickness of the photoreactive layers 301. The thicker the layer, the longer an unwanted airborne material is trapped in the layer. The photoreactive layer can be thinner so as to reduce air resistance. Also, in an example embodiment, the photoreactive layer is not primarily used to trap smaller unwanted airborne material, so it can be thinner.

[0058] The thickness of the mesh can be varied in the manufacturing of the mesh or can be varied by using multiple layers. For example, a thicker mesh can be formed by assembling multiple thin layers together.

[0059] It will be appreciated that the thickness of the layers 301 and 302 can vary. [0060] FIG. 3D shows another example embodiment that includes a second mesh assembly 201 . The second mesh assembly 201 is placed downstream from the second UV light 200, and it includes a photoreactive mesh layer 301 and a non- photoreactive mesh layer 302. The photoreactive mesh layer 301 is positioned closer to the second UV light 200. It will be appreciated that the first and the second mesh assemblies differ from each other.

[0061] FIG. 3E shows another example embodiment that includes an air filtering device. In the direction of the airflow, moving from upstream to downstream, the components include: a first UV light source 200, a first mesh assembly 201 , a second UV light source 200, a second mesh assembly 201 , and a third UV light source 200. The mesh assemblies 201 are the same in this example. Each mesh assembly includes a thicker layer of non-photoreactive mesh 302 that is sandwiched by thinner layers of photoreactive mesh 301.

[0062] In these examples, the non-photoreactive mesh is not directly exposed to UV light.

[0063] In FIG. 3E, the inner surfaces of the body 101 are shown being covered with a liner L. In an example embodiment, the liner L is a photoreactive material, such as a coating that includes Titanium dioxide. This liner L increases the photocatalytic surface area that reacts with the UV light. For example, this helps to increase the ability to destroy VOCs and bioaerosols. For example, the inner surfaces, or inner side walls, of the body 101 are coated with Titanium dioxide in the form of a paint. Other forms of applying Titanium dioxide to line the inner surfaces of the body 101 can be used.

[0064] In another example, the liner L is a reflective material, such as a mirror or mirror-like material. This reflects the UV light within the body 101 , thereby increasing the exposure of airborne contaminants to the UV light.

[0065] It will be appreciated that the liner L described with respect to FIG. 3 can be combined with any of the other embodiments of the air filtering device 100 described herein.

[0066] Turning to FIG. 4, another schematic diagram is shown that includes the airflow 400 carrying aerosols 402 in the body 101 of the air filtering device 100. When the UV light source 200 is turned on, UV light rays 401 shine on the photoreactive mesh layer 301 , which produces free radicals 403. The free radicals 403 and the unwanted airborne material are trapped in the non-photoreactive mesh layer 302.

[0067] Therefore, aerosols are sterilized by the UV light in the mesh layer 301 , and by the free radicals in the mesh layer 301. Unwanted airborne material is also sterilized by the free radicals in the mesh layer 302. For UV light rays 401 that reach the mesh layer 302, unwanted airborne material in the mesh layer 302 is sterilized by the UV light rays.

[0068] In another example embodiment, an air filtering device with sensors is herein provided to disintegrate unwanted airborne material (e.g., aerosols, bioaerosols, spores, bacteria, viruses, VOCs, etc.).

[0069] FIG. 5 shows a body 101 of an air filtering device 100 that includes an inlet 102 and an outlet 103 for airflow. The device 100 can be part of an air ventilation system in a building, a house, a room, a vehicle, etc. For example, the device 100 is part of an air conditioning system and is connected to ducts 110 and 111.

[0070] The device 100 also includes a control module 502 for controlling the UV lights, obtaining data from sensors and communicating data. In an example embodiment, the control module 102 is positioned on an external surface of the body 101 for easier access. The control module can also include operator devices (e.g., display, control buttons, etc.).

[0071] FIG. 6 shows internal components of the device 100. The body 100 defines therein a hollow space to facilitate air flow from the inlet to the outlet. The body 100 also houses one or more UV light sources 200 and a porous filter assembly 201 , also herein called a mesh assembly. In an example embodiment, the mesh assembly includes a single layer of mesh. In another example embodiment, the mesh assembly includes multiple layers of mesh. In another example embodiment, the mesh assembly includes multiple layers of mesh that are made from different types of material (e.g., a first mesh layer is made from a first material and a second mesh layer is made from a second material).

[0072] The UV light sources 200 are shown as three horizontal rows. In an example embodiment, a single UV light source is provided. In another example, multiple UV light sources are provided. UV light sources can be arranged in different configurations other than rows. Alternatives include rings, columns, grids, etc. The UV light sources can be bulbs or can be light emitting diodes, or a combination thereof.

[0073] An upstream sensor module 602 is positioned upstream from the UV light sources 200. A downstream sensor module 603 is positioned downstream from the mesh assembly 201 .

[0074] In an example embodiment, the upstream sensor module 602 and the downstream sensor module have the same type of sensors. In another example embodiment, the sensor module 602 includes one type of sensor and the sensor module 603 includes a different type of sensor.

[0075] In an example embodiment, the sensor module 602 has one or more sensors. In another example embodiment, the sensor module 603 has one or more sensors. The sensors measure, for example, one or more of: chemical(s) concentration, VOC concentration, temperature, air flowrate, humidity, temperature, light intensity, light wavelength spectrum, etc. Data from the sensors is time stamped and stored or transmitted, or both, by the control module 102.

[0076] The sensor modules 602, 603 can be positioned in different areas of the space within the body. In the example shown, the sensor is positioned away from the inner surfaces of the body in order to avoid boundary layer effects of the airflow. For example, a support structure 604, such as a rod or a bracket, holds the sensor module 602 in spaced relation to the inner surface of the body 101. Alternatively, the sensor modules are mounted to the inner surface of the body 101 .

[0077] The control module 502 includes a data logger that stores the data measured by the sensors. Alternatively, the data logger is integrated into each of the sensor module 602 and 603.

[0078] Turning to FIGs. 7 and 8, another example embodiment of an air filtering device 100 is shown, which further includes an indicator substance module 701 that is positioned upstream from the UV light source 200 and the mesh assembly 201. The indicator substance module 701 releases the indicator substance 705 into the upstream airflow, and the indicator substance 705 is to be filtered and sanitized by the UV light and the mesh assembly 201. One or more downstream sensors 706 detect the amount or concentration of indicator substance remaining after the filtration. This sensed data, which is obtained by the control module 502, provides up-to-date feedback about the efficacy of the filtering.

[0079] In an example embodiment, the indicator substance module 701 includes a reservoir 702 to hold the indicator substance and a deployment mechanism 703 to deploy the indicator substance. For example, the indicator substance is stored in the reservoir as a liquid or a gas. In another example embodiment, the indicator substance is stored as a solid, and energizing mechanism (for example, a heater), transforms the solid into a liquid or a gas for release into the air stream of the air filtering device.

[0080] The reservoir 702, for example, is positioned on the exterior of the body 101 and is refillable. The deployment mechanism 703 includes, for example, a pump to dispense the indicator substance. In another example, the deployment mechanism 703 includes a heater to heat the indicator substance into a vapor form for deployment. For example, the heater is a heating wire, a ceramic heater, or some other heating mechanism. In another example, the deployment mechanism 703 includes an agitator (e.g., an ultrasonic agitator) to produce vapors of the indicator substance for deployment. A nozzle 704 is attached to the deployment mechanism 703 to disperse the indicator substance in an aerosol form or a gas form. The deployment mechanism and nozzle are also referred to as an atomizer. In an example embodiment, the nozzle tip is positioned away from the inner surface of the body 101 to avoid boundary layer effects caused by the airflow. For example, the nozzle tip is positioned at the end of a tube, which extends away from the inner surface of the body 101.

[0081] The nozzle releases or dispense the indicator substance in the form of an aerosol or gas. In an example embodiment, the indicator substance is released in the form of an aerosol, comprising aerosol particles. In an example aspect, the aerosol particles are smaller than 200 micrometers. In an example aspect, the aerosol particles are smaller than 100 micrometers. In an example aspect, the aerosol particles are smaller than 50 micrometers. In an example aspect, the aerosol particles are smaller than 10 micrometers. In an example aspect, the aerosol particles are smaller than 5 micrometers. In an example aspect, the aerosol particles are smaller than 1 micrometer. The size of the aerosol particles depends on the setting of the deployment mechanism. It will be appreciated that other sizes of aerosol particles can be used.

[0082] Examples of indicator substances include Ethanol, Alcohol, Acetone and Limonene. Other types of indicator substances can be used.

[0083] In an example embodiment, the deployment mechanism 703 releases 250 ppm or less of the indicator substance into the air stream of the air filtering device. In another example embodiment, the deployment mechanism 703 releases 100 ppm or less of the indicator substance into the air stream of the air filtering device. In another example embodiment, the deployment mechanism 703 releases 50 ppm or less of the indicator substance into the air stream of the air filtering device. In another example embodiment, the deployment mechanism 703 releases 10 ppm or less of the indicator substance into the air stream of the air filtering device. In another example embodiment, the deployment mechanism 703 releases 5 ppm or less of the indicator substance into the air stream of the air filtering device. In another example embodiment, the deployment mechanism 703 releases 1 ppm or less of the indicator substance into the air stream of the air filtering device. In another example embodiment, the deployment mechanism 703 releases 0.5 ppm or less of the indicator substance into the air stream of the air filtering device. In another example embodiment, the deployment mechanism 703 releases 0.1 ppm or less of the indicator substance into the air stream of the air filtering device. It will be appreciated that other concentrations of the indicator substance can be deployed into the air stream of the air filtering device.

[0084] Two sensor modules 706 are shown in different positions along the downstream airflow. This provides confirmation of the accuracy of the data regarding the concentration of the indicator substance. The sensor modules 706 each include a chemical concentration sensor that is specific to the indicator substance 705.

[0085] In another example embodiment, only one sensor module 706 is positioned downstream to detect the indicator substance. In another example, more than two sensor modules 706 are positioned downstream to sample the air in different positions of the space defined within the body 101. [0086] In an example aspect, the sensor modules include sensors that detect the presence of the indicator substance and measures the concentration of the indicator substance. For example, the sensor is an electrochemical sensor or electronic sensor. In another example, the sensor includes a metal oxide semiconductor to detect the presence of the indicator substance. In another example, the sensor includes a conductive polymer composite to detect the presence of the indicator substance. In another example, the sensor includes a carbon nano-material to detect the presence of the indicator substance. Other types of sensors that detect the concentration of the indicator substance in the air stream can be used.

[0087] Turning to FIG. 9, similar to the embodiment shown in FIGs. 7 and 8, the air filtering device 100 includes an upstream sensor module 901 that detects the concentration of the indicator substance 705. The sensor module 901 is positioned upstream from the lights 200 and the mesh assembly 201 , and downstream from the nozzle 702 that releases the indicator substance 705.

[0088] One or more downstream sensor modules 902, positioned downstream from the mesh assembly 201 , also measure the concentration of the indicator substance 705. These sensor modules 901 and 902 are in data communication with the control module 502, for example, via data wires.

[0089] The difference in chemical concentrations from the upstream sensor module 901 and the downstream sensor module 902 is used to indicate the effectiveness of the UV light 200 and mesh assembly 201. For example, the concentration [A] of the indicator substance is measured by the sensor module 901 , and the concentration [B] of the indicator substance is measured by the sensor module or modules 902. The control module 502 computes Difference = [A]-[B] to obtain the difference of the detected concentration. If the control module 502 determines that the Difference is above a threshold value, then the control module determines that the filtering and sanitization operation is operating as expected. It will be appreciated that the threshold value, for example, is stored in memory of the control module.

[0090] The sensor modules 901 and 902 can also be equipped with other types of sensors, including and not limited to: chemical(s) concentration sensor, temperature sensor, air flowrate sensor, humidity sensor, temperature sensor, light intensity sensor, light wavelength spectrum sensor, etc.

[0091] In an example embodiment, the sensor modules and the control modules shown in the above figures are combined with the light sources 200 and mesh assembly 201 configurations described in FIGs. 2a to 4. In a further example embodiment, the indicator substance module 701 , which includes a reservoir 702 and deployment mechanism 703, is combined with the sensor modules, the control modules, and any one or more of the configurations of light sources 200 and mesh assembly 201 described in FIGs. 2a to 4.

[0092] T urning to FIGs. 10A, 10B, 10C and 10D, an example embodiment of an air filtering device 100 is shown that includes door 1000 that can be opened and closed to access one or more mesh assemblies 201 and one or more lights 200.

[0093] In FIG. 10A, the door 1000 is closed. In FIG. 10B, the door 1000 is opened. Slots 1002 hold a given mesh assembly 201 in place. The mesh assembly 201 can slide in and out of the slots 1002, as shown in FIG. 10C. In an example aspect, there is an upper slot and a corresponding lower slot to hold a given mesh assembly in place, which is best shown in FIG. 10D. The slots 1002 and the access door 1000 make it easier to replace, repair or perform maintenance on the mesh assembly 201.

[0094] In another example aspect, a light assembly 1001 includes one or more UV light sources 200. The light assembly 1001 operates in a plug-and-play manner. The light assembly includes a frame that holds the UV light sources 200. The frame provides electrical wiring to the UV light sources. The frame also includes electrical contacts that are connectable to electrical contacts within the body 101 or on the slots 1002. The electrical contacts within the body 101 or on the slots 1002 are eclectically connected to the control module 102. The light assembly can slide in and out of slots 1002. In this way, it is easier to replace, repair or perform maintenance on the light assembly 1001.

[0095] In another example aspect, a sensor (e.g., a switch) 1005 detects the position of the door 1000. When the door 1000 is detected to be in an open position, the control module 102 turns off the UV lights, or prevents the UV lights from being turned on. This is a safety measure for the maintenance personnel. [0096] T urning to FIG. 11 , a system diagram shows active components of an air filtering device 100. It includes a control module 502, which includes a processor, memory and a communication module. The communication module can be a wired communication device or a wireless communication device, or both. In an example aspect, the processor, memory and the communication module are electrical hardware components mounted onto a circuit board.

[0097] The control module 502 controls one or more UV light sources 200. For example, the control module stores determines the time that the UV lights are turned on and off. The control module 502, for example, stores in memory a schedule of when to turn on and turn off the UV lights for predetermined amounts of time. The control module 102 can selectively turn on some UV lights, while keeping other UV lights off.

[0098] The control module 502 also obtains data from one or more sensors 602, 603, 706, 901 , 902.

[0099] In an example aspect, the sensors used in the air filtering device 100 include one or more of: an indicator substance sensor; a humidity sensor; a temperature sensor; an airflow sensor; an air pressure sensor; a light intensity sensor; a light wavelength spectrum sensor; and a chemical concentration sensor.

[00100] The control module 502 also controls the indicator substance sub-system, including, for example, the deployment mechanism 703. For example, a pump, an agitator, or a heater, or a combination thereof, are controlled by the control module 502. In the example embodiment in which the deployment mechanism includes a valve, the control module 502 also controls the valve.

[00101] In an example embodiment, a local operator system 1101 is positioned on the body 101 of the device 100. The local operator system 1101 includes one or more input devices (e.g., buttons, switches, etc.) and a visual feedback display. The display, for example, includes a display screen. In another example, indicator lights form the display. For example, the display provides feedback about one or more of: power; whether or not the UV lights 200 are turned on; the length of time that the UV lights 200 have been activated; sensor data; etc.

[00102] The control module 502 stores and transmits the sensed data. Nonlimiting examples of the data include: airflow, number of air exchanges made per hour within a room, amount of time that the air filtering device has been activated, temperature, temperature changes, humidity, humidity changes, light intensity, light intensity changes, pressure, pressure changes, pressure drop upstream and downstream from the mesh assembly, changes in pressure drop upstream and downstream the mesh assembly, chemical(s) concentration, chemical(s) concentration changes, chemical concentration difference upstream and downstream the mesh assembly, changes in chemical concentration difference upstream and downstream the mesh assembly, a light wavelength spectrum, light wavelength spectrum changes, etc.

[00103] The communication module is data connected to one or more external devices 1103 via a wired network or a wireless network 1102. The external devices include, for example, a dedicated display screen, a desktop computer, a mobile device (e.g., a phone, a tablet, a laptop, a smart speaker, etc.), and a server. These devices 1103 display data about the air filtering device 100. In other words, other devices can remotely monitor the health parameters of the air and the operating parameters of the air filtering device 100. In an example aspect, the external device 1103 can send and receive data with the control module 502 using the Internet.

[00104] In an example aspect, one or more of these external devices 1103 transmit commands that affect the control module 502. The commands, for example, are used to affect the operation of the UV lights, the operation of the sensors, or the operation of the indicator substance module, or a combination thereof.

[00105] Below are general example embodiments and related example aspects.

[00106] In a first general example embodiment, an air cleaning device is provided that comprises: a body comprising an air inlet and an air outlet, and a UV light source and a porous filter assembly positioned within the body between the air inlet and the air outlet; the porous filter assembly comprising a first mesh and a second mesh; the first mesh comprising an entering surface and a leaving surface, and a first plurality of irregularly distributed channels connect the first mesh’s entering surface and leaving surface, and the first plurality of irregularly distributed channels defined by a first set of surfaces that comprise a first material that photochemically reacts with UV light emitted by the UV light source to generate free radicals; the second mesh comprising an entering surface and a leaving surface, and a second plurality of irregularly distributed channels connect the second mesh’s entering surface and leaving surface, and the second plurality of irregularly distributed channels defined by a second set of surfaces that comprise a second material that is unreactive to the UV light emitted by the UV light source; and wherein the UV light source is positioned adjacent and upwind the entering surface of the first mesh, and the leaving surface of the first mesh faces the entering surface of the second mesh.

[00107] In an example aspect, the second mesh comprises the second plurality of irregularly distributed channels that define a pore size of at least 80 pores per inch (ppi), and the first mesh comprises the first plurality of irregularly distributed channels that define a pore size of less than 80 ppi.

[00108] In another example aspect, the second mesh comprises the second plurality of irregularly distributed channels that define a pore size of at least 80 pores per inch (ppi), and the first mesh comprises the first plurality of irregularly distributed channels that define a pore size of at least 80 ppi.

[00109] In another example aspect, the porous filter assembly further comprises a third mesh comprising an entering surface and a leaving surface, and a third plurality of irregularly distributed channels connect said third mesh’s entering surface and leaving surface, and the third plurality of irregularly distributed channels is defined by a third set of surfaces that comprise the first material that photochemically reacts with the UV light to generate free radicals; and the second mesh is sandwiched between the first mesh and the third mesh.

[00110] In another example aspect, a second UV light source is positioned downwind from the third mesh.

[00111] In another example aspect, the second mesh has a thickness greater than the first mesh.

[00112] In another example aspect, the second material of the second mesh comprises at least one of Nickel, Aluminum and Copper. [00113] In another example aspect, the first material of the first mesh comprises Titanium dioxide.

[00114] In another example aspect, the UV light source emits UV-C light.

[00115] In another example aspect, the UV light source emits far UV-C light.

[00116] In another example aspect, the air cleaning device further comprising: an upstream sensor module positioned upstream from the porous filter assembly; a downstream sensor module positioned downstream from the porous filter assembly; and a control module that controls the UV light source and uses a measurement from the upstream sensor module and a measurement from the downstream sensor module to compute a difference in sensor measurement across the porous filter assembly.

[00117] In another example aspect, the upstream sensor module and the downstream sensor module both measure volatile organic compound (VOC) concentration. In another example aspect, the upstream sensor module and the downstream sensor module both measure air pressure. In another example aspect, the upstream sensor module and the downstream sensor module both measure air flow. In another example aspect, the air cleaning device further comprising an indicator substance module mounted to the body, wherein the indicator substance module comprises a reservoir that holds an indicator substance and a deployment mechanism that releases the indicator substance upstream from the porous filter assembly. In another example aspect, the downstream sensor module comprises a sensor that measures concentration of the indicator substance. In another example aspect, the upstream sensor module comprises a sensor that also measures the concentration of the indicator substance. In another example aspect, the deployment mechanism includes a nozzle that dispenses the indicator substance away from inner surfaces of the body. In another example aspect, the control module controls a time period that the indicator substance module releases the indicator substance. In another example aspect, the reservoir is positioned on an external surface of the body.

[00118] In a second general example embodiment, an air cleaning device is provided that comprises: a body comprising an air inlet and an air outlet, and a UV light source and a porous filter assembly positioned within the body between the air inlet and the air outlet; the porous filter assembly comprising a first mesh and a second mesh; the first mesh having an entering surface and a leaving surface, and a first plurality of irregularly distributed channels connect the first mesh’s entering surface and the first mesh’s leaving surface, and the first plurality of irregularly distributed channels are defined by a first set of surfaces that comprise Titanium dioxide, and the Titanium dioxide photochemically reacts with UV light emitted by the UV light source to generate free radicals; the second mesh having an entering surface and a leaving surface, and a second plurality of irregularly distributed channels connect the second mesh’s entering surface and the second mesh’s leaving surface, and the second plurality of irregularly distributed channels are defined by a second set of surfaces that comprise Nickel; and wherein the UV light source is positioned adjacent and upwind the entering surface of the first mesh, and the leaving surface of the first mesh faces the entering surface of the second mesh.

[00119] In a third general example embodiment, an air cleaning device is provided that comprises: a body comprising an air inlet and an air outlet, and a UV light and a porous filter assembly positioned within the body between the air inlet and the air outlet; an upstream sensor module positioned upstream from the porous filter assembly; a downstream sensor module positioned downstream from the porous filter assembly; a control module that controls the UV light and uses a measurement from the upstream sensor module and a measurement from the downstream sensor module to compute a difference in sensor measurement across the porous filter assembly.

[00120] In an example aspect, the upstream sensor module and the downstream sensor module both measure volatile organic compound (VOC) concentration.

[00121] In an example aspect, the upstream sensor module and the downstream sensor module both measure air pressure.

[00122] In an example aspect, the upstream sensor module and the downstream sensor module both measure air flow. [00123] In an example aspect, the air cleaning device further comprising an indicator substance module mounted to the body, wherein the indicator substance module comprises a reservoir that holds an indicator substance and a deployment mechanism that releases the indicator substance upstream from the porous filter assembly.

[00124] In an example aspect, the downstream sensor module comprises a sensor that measures concentration of the indicator substance.

[00125] In an example aspect, the upstream sensor module comprises a sensor that also measures the concentration of the indicator substance.

[00126] In an example aspect, the deployment mechanism includes a nozzle that dispenses the indicator substance away from inner surfaces of the body.

[00127] In an example aspect, the control module controls a time period that the indicator substance module releases the indicator substance.

[00128] In an example aspect, the reservoir is positioned on an external surface of the body.

[00129] In a fourth general example embodiment, an air cleaning device is provided that comprises: a body comprising an air inlet and an air outlet, and a UV light source and a porous filter assembly positioned within the body between the air inlet and the air outlet; an indicator substance module mounted to the body, wherein the indicator substance module comprises a reservoir that holds an indicator substance and a deployment mechanism that releases the indicator substance upstream from the porous filter assembly; a downstream sensor module positioned downstream from the porous filter assembly; and a control module that controls the UV light source, the indicator substance module, and obtains measurements from the downstream sensor module.

[00130] In an example aspect, the downstream sensor module measures chemical concentration of the indicator substance. In an example aspect, the air cleaning device further comprising an upstream sensor module positioned upstream from the porous filter assembly, and the upstream sensor module comprises a sensor that also measures the chemical concentration of the indicator substance. In an example aspect, the control module computes a relative difference in the chemical concentration using measurements from the upstream sensor module and the downstream sensor module.

[00131] It will be appreciated that different features of the example embodiments of the system, the devices, and the components as described herein, may be combined with each other in different ways. In other words, different devices, modules, operations, functionality and components may be used together according to other example embodiments, although not specifically stated.

[00132] It will also be appreciated that the examples and corresponding system diagrams used herein are for illustrative purposes only. Different configurations and terminology can be used without departing from the principles expressed herein. For instance, components and modules can be added, deleted, modified, or arranged with differing connections without departing from these principles.

[00133] It will be appreciated that any module or component exemplified herein that executes instructions may include or otherwise have access to non-transitory computer readable media such as storage media, computer storage media, or data storage devices (removable and/or non-removable) such as, for example, memory chips, magnetic disks, optical disks. For example, the control module and the external device include non-transitory computer readable media. Computer storage media may include volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information, such as computer readable instructions, code, processor executable instructions, data structures, program modules, or other data. Examples of computer storage media include random access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), read-only memory (ROM), solid-state ROM, electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, or any other medium which can be used to store the desired information and which can be accessed by an application, module, or both. Any such computer storage media may be part of the servers or computing devices, or accessible or connectable thereto. Any application or module herein described may be implemented using computer readable/executable instructions that may be stored or otherwise held by such computer readable media. [00134] Although the above has been described with reference to certain specific embodiments, various modifications thereof will be apparent to those skilled in the art without departing from the scope of the claims appended hereto.