WO2024006463A1 - Activated and catalytic low temperature plasma air purifiers - Google Patents

Abstract

Exemplary systems and methods for a plasma-activated catalytic air-purifier that includes a direct or variable frequency, low-temperature, non-thermal plasma discharge region. The plasma discharge region is in contact with or in line with thermal and plasma-activated catalyst beds. The plasmas can be either dielectric-barrier discharge (DBD), micro-hollow-cathode-discharge (MHCD), or a plasma jet (PJ) array. Exemplary devices include transportable devices or devices implemented into large-scale air handling systems.

Description

ACTIVATED AND CATALYTIC LOW TEMPERATURE PLASMA AIR

PURIFIERS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. Provisional Patent Application No. 63/356,697 filed June 29, 2022, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] The present disclosure generally relates to air purification devices employing low- temperature plasma.

BACKGROUND

[0003] Current air treatment systems rely largely on mechanical filtering means (e.g., traditional fiber, cotton, or HEPA filters). Other air treatment systems employ ultraviolet (UV) light to treat bio-materials. However, UV light has limitations in that it is primarily surficial and line-of-sight. Existing air treatment systems generally have limitations in the removal of airborne pathogens, pollutants, spores, etc.

[0004] Plasma technology is known to be used for sterilization (e.g., medical wound healing). Low-temperature non-thermal plasmas can be produced with a distribution of species, including radicals, anions, cations, and secondary electrons. Reactive oxygen species and ozone are known to be among the active entities involved in deactivating and killing biological pathogens. However, plasma discharges operating in air or oxygen produce hydroxyl radicals, reactive nitrogen oxides, and ozone, which are not safe for discharge into certain environments (e.g., classrooms and buildings where humans frequent).

[0005] Therefore, there is a need for an enhanced air treatment system that can mitigate the discharge of hazardous substances while maintaining efficacy.

SUMMARY

[0006] Exemplary systems and methods are described for a plasma-activated catalytic air purifier, including a direct or variable frequency, low-temperature, and non-thermal plasma discharge region. [0007] The plasma discharge region is in contact with or in line with thermal and plasma- activated catalyst beds. The plasmas can be either dielectric-barrier discharge (DBD), micro- hollow-cathode-discharge (MHCD), or plasma jet (PJ) arrays. These plasmas can function alone, in contact with catalysis, or followed by one or more thermally and/or electrically activated filter and catalytic zones that contain nanoparticles and nanosheets to deactivate and collect viruses and particles while mitigating any excess hazardous gas-phase products (i.e., ozone, nitrogen oxides, etc.) formation and release.

[0008] The systems, methods, and devices of this disclosure may be used, for example, in the cleaning of enclosed air spaces in buildings, aircraft, hospitals, classrooms, residential apartments, homes, hotels, etc.

[0009] In an aspect, a plasma-activated catalytic air-purifier device is disclosed comprising: at least one plasma generation unit, including a first plasma generation unit comprising: a first electrode separated a first distance from a second electrode, wherein the first distance is less than 1 mm; an insulator (e.g., dielectric or glass) disposed in between the first electrode and the second electrode; a catalyst coating disposed on the first and second electrode, and a voltage source in electrical communication with the first electrode and the second electrode, the voltage source configured to provide an electrical potential difference across the first and second electrodes to generate a low-temperature plasma, wherein air stream flowing through the first plasma generation unit interacts with the low-temperature plasma to remove or deactivate contaminants or bio-contaminants from the air stream.

[0010] In some embodiments, the device includes a second plasma generation unit arranged adjacent to the first plasma generation unit to form a plasma stack or array.

[0011] In some embodiments, the plasma generation unit is a dielectric barrier discharge (DBD) unit, wherein the first electrode is a plate having a first hole therethrough, and the second electrode is a needle disposed within the first hole.

[0012] In some embodiments, the plasma generation unit is a micro-hollow-cathode-discharge (MHCD) unit wherein the first electrode is a first conductive plate having a first hole therethrough and the second electrode is a second conductive plate having a second hole therethrough, wherein the insulator placed between the two plates has a third hole therethrough aligning with each of the first hole and the second hole such that the plasma is generated in the gap space between the first plate and the second plate and the plasma may overflow out of at least one of the first hole and the second hole.

[0013] In some embodiments, the device includes a magnetic field confinement device, the magnetic field confinement device having permanent magnets disposed around the first plasma generation unit.

[0014] In some embodiments, the plasma generation unit is a nested glass capillary unit wherein the first electrode is a first conductive coating on an outer surface of a first glass tube, and the second electrode is a second conductive coating on an inner surface of a second glass tube disposed around the first glass tube, wherein a plurality of first and second glass tubes are arranged or stacked adjacent to each other to form the first plasma generation unit.

[0015] In some embodiments, the catalyst coating is disposed on the inner surface of the first glass tube and an outer surface of the second glass tube.

[0016] In some embodiments, the plasma array is a plasma jet (PJ) array.

[0017] In some embodiments, the catalyst coating comprises at least one of reduced graphite oxide (rGO) and/or manganese cerium oxide (MnCeOx).

[0018] In some implementations, the device further includes a coated filter comprising a laser- reduced graphite oxide (LrGO) polymer configured to, along with low-temperature plasma, capture and eliminate viruses and bacteria from the air stream.

[0019] In some implementations, the reduced graphite oxide (rGO) is used as a conductive coating configured to be heated by residual resistance.

[0020]

[0021] In some embodiments, the voltage source provides the electrical potential difference in a direct or variable frequency.

[0022] In some embodiments, the device includes an input side for the air stream and an output side for the air stream, wherein the plasma array is disposed in between the input side and the output side such that the fluid is forced to interact with or flow through at least a portion of the plasma array.

[0023] In some embodiments, the device includes an air motivator (e.g., a fan or turbine) disposed along one or both of the input side and the output side of the device and is configured to force air through the device. [0024] In some embodiments, the device includes a UV light source configured to remove or destroy pathogens from the air stream flowing through the device (e.g., via photocatalysis). [0025] In some embodiments, the device includes a mechanical filter (e.g., HEPA filter) disposed closer to the input side of the device than the plasma array.

[0026] In some embodiments, the device is configured for use in a personal device (e.g., a headset or mask device).

[0027] In some embodiments, the device is configured for use in an enclosed space (e.g., an office or classroom).

[0028] In some embodiments, the device is configured for use in an HVAC system.

[0029] In some embodiments, the first plasma generation unit of the device is configured for use as a HEPA filter to capture particles in the air stream.

[0030] In another aspect, an air filtration and purification system is disclosed comprising: a plasma array generation device comprising a plasma array generation device comprising: a first electrode separated a first distance from a second electrode, wherein the first distance is less than 1 mm; an insulator (e.g., dielectric or glass) disposed in between the first electrode and the second electrode; a voltage source in electrical communication with the first electrode and the second electrode, the voltage source configured to provide an electrical potential difference across the first and second electrodes to generate a low-temperature plasma; and a catalyst coating disposed on the first and second electrodes, the catalyst coating configured to capture or remove particles or byproducts; an air stream inlet comprising a mechanical filter and an air steam fluid outlet spaced apart from the air stream inlet; and an internal chamber defined by side walls and disposed between the fluid inlet and the fluid outlet, wherein the plasma array generation device extends from the side walls into the internal chamber, and wherein a fluid flowing through the system interacts with the plasma array to remove or deactivate contaminants or bio-contaminants from the fluid.

[0031] In some embodiments, the system includes a second plasma generation unit disposed within the internal chamber and in a staggered configuration with the plasma generation unit. [0032] In some embodiments, the plurality of plasma generation units are arranged in an alternating pattern such that an airflow distance between the fluid inlet and the fluid outlet increases and the residence time of the fluid in the internal chamber increases. [0033] In some embodiments, the system includes a UV light source emitting UV light into the internal chamber, wherein the side walls of the internal chamber comprise a reflective surface to scatter the UV light throughout the internal chamber, wherein the UV light non-thermally activates the catalyst coating.

[0034] In some embodiments, the system includes a heat exchanger system comprising: an internal heated plate in air stream communication with a portion of the internal chamber to thermally decontaminate a portion of the air stream; and an external plate configured to exchange heat from the internal heated plate to a cooling system and away from the air stream (e.g., Peltier heat exchanger, coolant, etc.).

[0035] Additional advantages will be set forth in part in the description which follows or may be learned by practice. The advantages will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIGs. 1A, IB, and 1C each shows an air-purifier device configured with a plasma- activated catalytic plasma generation unit, according to one implementation.

[0037] FIGs. 2A, 2B, 2C, and 2D each shows an example of a plasma generation unit, according to various implementations.

[0038] Fig. 3 shows another example of the plasma generation unit configured with 2D dielectric barrier discharge through holes, according to one implementation.

[0039] Figs. 4, 5, and 6 each shows another example of the air purifier device for air decontamination and purification, according to various implementations.

[0040] Figs. 7A, 7B, and 7C each shows an air purifier system that includes plasma generation units configured to generate a meandering air flow across the plasma generation units to improve the residence time of the air, according to various implementations.

[0041] Fig. 8 shows simulation results of air flowing through an example device having an alternating pattern of plasma array generation devices therein, according to one implementation. [0042] Fig. 9 shows a graph of the results of a study showing the log reduction of viruses with varied time application of plasma and filter types, according to one implementation. [0043] Figs. 10A, 10B, and 10C show examples of transportable and/or portable air purifiers that may be implemented using the exemplary plasma generation units, according to various implementations.

[0044] Various objects, aspects, features, and advantages of the disclosure will become more apparent and better understood by referring to the detailed description taken in conjunction with the accompanying drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements.

DETAILED DESCRIPTION

[0045] Low-temperature plasma refers to a partially ionized gas state that is generated at temperatures significantly lower than those required for traditional high-temperature plasmas. Its operation at near-ambient temperatures makes it suitable for a wide range of applications where high temperatures would be detrimental or impractical. Moreover, low-temperature plasma is known for its ability to efficiently generate reactive species, such as ions, electrons, and free radicals. The energy imparted to the electrons leads to increased electron impact dissociation and ionization and enhanced formation of secondary electrons that cause dissociated electron attachment (DEA) and dissociative recombination (DR). These reactive species can aid in chemical reactions and can be harnessed for various purposes. For instance, it can effectively eliminate bacteria, viruses, fungi, volatile organic vapors, and other airborne particles, making it a helpful tool in disinfection and decontamination processes.

[0046] For plasma discharge (e.g., dielectric-barrier discharge (DBD)), activated catalysis packed-bed low-temperature discharges can be used with various dielectric packing materials that are either catalysts or catalyst substrates. Non-thermal low-temperature plasmas allow for miniaturization in which appropriate electrode spacing and geometries allow for the operation at atmospheric pressure (and lower) with relatively low applied potentials, operating currents, and consumed power.

[0047] Referring generally to the figures, systems, methods, and devices for low-temperature plasma air purification are shown, according to various implementations. Particularly, cold plasma air purifiers may be operated with catalysts and discharge filters to be operated simultaneously or in tandem. The systems, methods, and devices of the present disclosure employ micro-hollow-cathode-discharge (MHCD), plasma jets (PI), and miniature dielectric- barrier discharge (DBD) needle arrays having electrode and filter zones coated with catalyst known to be effective for hydroxyl radical production, ozone removal, and sterilization purposes. The systems, methods, and devices may operate under various gas loads and treatment strategies with applications in classrooms or any enclosed space/environment. The systems, methods, and devices may operate directly in the space (e.g., classroom) or in a circulation system (e.g., HVAC system connected to a space. In some implementations, forced flow with fans or compressed gas cylinders may be used.

[0048] Example System #1

[0049] Figs. 1A and IB show an air-purifier device 100 (shown as 100a, 100b, respectively) (e.g., as a plasma-activated catalytic air-purifier device) configured with a plasma generation unit 102 (shown as 102a), according to one implementation. In the example shown in Figs.1 A and IB, the air-purifier device 100 is configured to remove or destroy contaminants from the air (e.g., in a room) via a plasma-activated catalyst to improve indoor air quality. The air-purifier device 100 includes a housing 104 that houses the plasma generation unit 102a. An air-moving component 106 (shown as “fan” 106) draws air 107 through first perforations 108 in the housing 104 located at a first end 114 of the device 100a and pushes the air through the plasma generation unit 102a. The plasma generation unit 102a is configured to generate plasma 109 within a set of through holes 110 and along on its surface 112 that extends over a set of through holes 110 (see diagram 102a’ and 102a”) through which the air traverses. The purified air 113 then exits the air purifier device 100a through a second set of perforations 116 disposed at a second end 118 in the housing 104. Fig. 1 A shows the air-purifier device 100a in a vertical configuration; Fig. IB shows the air-purifier device 100b in a horizontal configuration.

[0050] The device (e.g., 100) may be a tabletop device configured to filter and purify air in an enclosed environment (e.g., an office space, living room, bedroom, etc.).

[0051] As used herein, the term “plasma” refers to partially ionized gas consisting of electrons, ions, molecules, radicals, photons, and excited species.

[0052] In the example shown in Fig. 1A, the plasma generation unit 102a is shown as a micro- hollow-cathode-discharge (MHCD) unit having a metal-insulator-metal structure 120 with two or more conductor plates (shown as a first electrode 122a and a second electrode 122b) separated by an insulator or dielectric material 126, e.g., configured as a plate, having a small distance 127 less than 1mm (e.g., 100 micrometers or 10 micrometers). In Fig. 1A, and IB, each of the first electrode 122a, the second electrode 122b, and the insulator 126 have a plurality of holes 110 extending therethrough that are aligned with each other, and the electrode-insulator-electrode structure 120 is coated with a catalyst coating 124 (see diagram 102a”) that can be either thermally activated (by resistively heating the rGO coated electrode or non-thermally activated with the UV light). The conductor (e.g., 122, a 122b) may be made of any conductive materials copper, aluminum, nickel, or an alloy thereof. In other implementation, the conductor (e.g., 122a, 122b) is formed of carbon (e.g., graphite or graphene). The insulator 106 is preferably glass or other dielectric material. The catalyst coating 124 may be made of metal oxides such as manganese cerium oxide (MnCeOx) that coats the exterior surfaces of the electrode-insulator- electrode structure 120.

[0053] When a voltage source (AC or DC) is applied and an electrical potential difference is formed across the first electrode 122a and the second electrode 122b, a low- temperature plasma is generated in the holes 110 when the applied field exceeds the Paschen limit. The plasma may flow out of the holes 110 and extends out of the plasma generation unit 100a on either side. The catalyst coating 124 forms a plasma 109 that can then remove or deactivate contaminants or biocontaminants, including ozone gas, from an air stream.

[0054] In the example shown in Fig. 1 A, the components of the electrode-insulator-electrode structure 120 are configured as a circular plate or disc. In other embodiments, the electrodes and insulator may be configured as a planar structure having a square profile, rectangular profile, triangular profile, or other polygon-shaped profile. In some embodiments, the electrodeinsulator-electrode structure 120 and its subcomponents may be configured as a planar structure having a bend or angle. In other embodiments, the electrodes and insulator may be configured to be spherical or as a cube.

[0055] The air-purifier unit 100a further includes a power supply system 128, as a power source, having one or more power supply units that provide low power AC or DC voltage to the first electrode 122a and the second electrode 122b of the plasma generation unit 102a to generate the plasma there at. The power supply system 128 also provides power to the air-moving component 106, a controller 130, and associated user interface 132. A power supply unit (referenced as 128a) of the power supply system 128 can generate a low voltage output of at least 50 V that can be provided as an electrical potential difference across the first electrode 122 and the second electrode 122b. To generate the plasma 109, the applied voltage is a function of the gap distance 127, the material and geometry of the conductors (e.g., 122, 122b), and the material and geometry of the insulator/dielectric 126. In some embodiments, the voltage output is 50 VDC, 55 VDC, 60 VDC, 65 VDC, 70 VDC, 75 VDC, 80 VDC, 85 VDC, 90 VDC, 95 VDC, 100 VDC. In other embodiments, the voltage output is 50 VAC(rms), 55 VAC, 60 VAC, 65 VAC, 70 VAC, 75 VAC, 80 VAC, 85 VAC, 90 VAC, 95 VAC, 100 VAC or higher. The voltage output is provided at low power (i.e., with low current), e.g., 5W, 10W, 15W, 20W, 25W, 30W, 35W, 40W. In other implementations, the device 100 includes batteries or local energy storage device and voltage amplifiers.

[0056] Example description for a micro-hollow-cathode-discharge (MHCD) unit may be found in R. H. Stark and K. H. Schoenbach, "Microhollow cathode discharges as plasma cathodes for atmospheric pressure glow discharges in air," IEEE Conference Record - Abstracts. 1999 IEEE International Conference on Plasma Science. 26th IEEE International Conference (Cat. NO.99CH36297), Monterey, CA, USA, 1999, pp. 198.

[0057] The controller 130, via mechanical and/or electrical buttons of the user interface 132, is configured to receive inputs for power on/off, fan speed, power levels (e.g., 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%), sleep mode settings, among other air purification commands. The interface 132 includes a display (e.g., LCD or LED) to provide outputs of the current settings (e.g., power, power level, fan speed, sleep mode, etc.). The controller 130 preferably include a microcontroller (e.g., consumer-product grade microcontroller) and corresponding electronics. In other embodiments, the controller 130 may be implemented with other processing units (e.g., microprocessors, ASICs, FPGA, CPLD, etc.). These can be integrated into a distributed sensor network with a central processing unit for autonomous control of a large area.

[0058] In the example shown in Figs. 1A and IB, the air purifier device 100a, 100b may include filters 134 at its inlets (e.g., 108). Examples of filters may include a high-efficiency particulate air (HEP A) filter or other pleated or mesh mechanical air filters.

[0059] Figs. 1 A and IB show the air purifier device 100 as a tabletop device configured to filter and purify the air in an enclosed environment (e.g., office space or bedroom) or employed in a building unit as described herein. Fig. 1C shows the air purifier device 100 (shown as 100c) as a building heating, ventilation, and air conditioning (HVAC) system. In Fig. 1C, the air purifier device 100c is shown installed at an inlet of the HVAC system to the duct of a building. Fig. 1C also shows the air purifier device 100c being installed within the duct.

[0060] Example Plasma Generation Unit #1

[0061] Figs. 2A, 2B, and 1C each show different configurations of the plasma generation unit 102a as a plasma-activated catalytic device for an air-purifier system (e.g., 100). The plasma generation unit 102a each includes 2 or more plasma generation units formed at or in proximity to the through holes 108 that generate the plasma. The plasma generation unit 102a can include any number of through holes 108, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10-14, 15-19, 20-24, 25-29, 30-34, 35-39, 40-44, 45-49, 50-54, 55-59, 60-64, 65-69, 70-74, 75-79, 80-84, 85-89, 90-94, 95-99, 1 GO- 199, 200-299, 300-399, 400-499, 500-599, 600-699, 700-799, 800-899, 900-999, 1000, or more. [0062] Fig. 2 A shows the plasma generation unit 102a (shown as 202) of Fig. 1A and IB as a plate structure in which the unit 202 to be placed directly in the path air stream to flow therethrough.

[0063] A fluid (e.g., air in a room) flows through the device 202 via the holes 1109. The fluid then interacts with the low-temperature plasma to remove or deactivate contaminants or biocontaminants from the fluid. In some embodiments, the fluid is a liquid.

[0064] Fig. 2B shows two plasma generation units 202, 204 (e.g., micro hollow-cathode- discharge (MHCD)) in an array configuration. In use, a voltage source applies an electrical potential difference across each set of electrodes in the first plasma generation unit 202 and the second plasma generation unit 202. The low-temperature plasma formed in each of the holes 110 may form a plasma array, connecting with the plasma generated in an adjacent hole. The result is a plasma array across a surface of the first electrode 122a and/or the second electrode 122b. In the example, the two units 202 and 204 may be connected to each other in a cylindrical device such that FIG. 2B would represent a longitudinal cross-sectional view. Thus, the space between the two units 202 and 204 would be defined by the inner diameter of a device.

[0065] Having two or more plasma generation units (e.g., 202, 204) through which the fluid flows increases the residence time of the fluid in the air purifier device (e.g., 100) thus increasing the decontamination efficacy of the device (e.g., 100).

[0066] In some embodiments, MHCDs can be stacked and coated with catalysts that can be thermally or non-thermally activated. [0067] MHCDs can be configured to use very little power (as described herein) and can be made portable. MHDs can be employed to provide high densities of energetic electrons and photons that can lead to plasma-activated catalysis,

[0068] In addition, DBD as described herein can also be stacked and coated with catalysts. DBDs discharge tips and gaps can be made small, so power dissipation is low. Small DBDs can function as plasma jets and be put into large arrays. DBDs can lead to plasma-activated catalysis.

[0069] In some configurations, the stack plasma generation units can also be used as a HEPA filter itself. The HEPA filter can be used in the plasma mode, heated mode, or static mode. When used in plasma mode, it can capture smaller particles than on the market filters since the filter traps charged particles and aerosols. Ionic radii are larger than the neutral radii.

[0070] Fig. 2C shows another configuration of the plasma generation unit 206 as a tubular structure 102b (shown as 206) that may be used to line a surface to generate a plasma-induced surface that can remove or deactivate contaminants or bio-contaminants, including ozone gas, from the air stream. The airflow direction 107 is perpendicular to the longitudinal axis of the holes 110.

[0071] In use, the same voltage source may be applied to the units 206 to produce a potential difference across the sets of electrodes there at. The resulting plasma array can form across the surface of each electrode that forms a tunnel-like structure. If the diameter of the units 206 is made small, the air stream flowing through the channel 208 can interact with the plasma array across a longer length and thus for a longer residence time, as compared to the device 202. The longer residence time can increase the efficacy of the decontamination process. The holes 110 also reduce the air pressure as an air stream flows through the tunnel due to the Venturi effect. This may have the additional benefit of effectively reducing the potential needed to start and maintain a plasma discharge layer.

[0072] Fig. 2D shows a combination of the plate plasma generation unit 202 and tubular plasma generation unit 206.

[0073] Catalyst and Filter Assemblies

[0074] The catalysts coatings described in the present disclosure may comprise a variety of catalysts targeted at specific byproducts (e.g., ozone). Many applications for trapping particles and removing ozone use activated charcoal to capture and convert the ozone. Such coatings/embodiments do not kill air-born viruses or bacteria, can be loaded up with particles and have to be exchanged. The electrode and tube materials of the present disclosure can be made out of carbon which can react to reduce the amount of ozone produced.

[0075] In some embodiments, a laser-reduced graphite oxide (LrGO) polymer can be used to form a coated filter in conjunction with a plasma can also be used to capture and kill air-born viruses and bacteria. The very high surface area can provide sufficient LrGO trapping properties while the thermal stability allows heating to > 300 °C. This elevated temperature can decompose any trapped toxic molecules and biomaterials. Temperature cycling by simple joule-heating allows them to be self-cleaning. The LrGO may be implemented on ceramic monoliths that are embedded in the plasma or coated on the dielectric barrier and counter electrode. Additionally, graphene may be grown on a fine copper mesh for superior electrostatic filter material. The graphene-coated copper can also serve as an electrode material.

[0076] In some embodiments, rGO can be used as a conductive coating in which the residual resistance can allow it to be heated. The rGO can be coated onto fibers which can be used as the HEPA filter. The heated HEPA filter can both capture and destroy the volatile molecules and biomaterials. This rGO HEPA filter can be implemented independently of the operation in the plasma discharge mode described herein. rGO can be thermally activated (by resistively heating the rGO-coated electrode or non-thermally activated with UV light).

[0077] Other forms and coatings of reduced graphite-oxide (rGO) can be used as electrode and plasma reactor coatings. These can be dispersed rGO nanosheets, nanobelts, or nanoplatelets/plates or polymer matrices containing rGO nanosheets, nanobelts or nanop latelets/plates. The removal of oxidants, aldehydes, ketones, ozone, etc., down-stream and prior to exiting the plasma treatment zone can be facilitated by the use of manganese cerium oxide (MnCeOx) thin-films, particles or nanosheets, nanobelts or nanoplatelets/plates. This works due to the copious number of oxygen vacancies that are reactive and can generate terminal hydroxyl groups when water and ozone interact with the surface. Thus, these catalysts serve a dual purpose of removing ozone at room temperature while oxidizing and removing molecules such as formaldehyde which can form in the plasma.

[0078] The Mn oxides and MnCeOx oxides can also be integrated into the LrGO polymers so that filtering, trapping, and treatment can occur simultaneously. These can be either integrated into the plasma device or downstream from it. When used in an assembly, these can be used as a standalone unit or integrated into an array or network. MnCeOx embedded in the rGO can also be either thermally activated (by resistively heating the coated electrode or non-thermally activated with the UV light).

[0079] A UV photodiode detector can be combined with the UV light source in different positions in the plasma device and can be used to carry out in situ, real-time monitoring of the O3 concentrations. The power can be self-regulated with a feedback network providing operational and safety monitoring. The UV photodiode detector can be used for real time monitoring and self-awareness of the system and/or device.

[0080] Example Plasma Generation Unit #2

[0081] Fig. 3 shows another example of the plasma generation unit 102 (shown as 300) configured with 2D dielectric barrier discharge through holes 301, according to one implementation.

[0082] The 2D dielectric barrier discharge (DBD) through holes 301 includes two electrodes (122a, 122b) and a discharge barrier 302 and discharge pin 304 to define a discharge region 306, in the insulation layer 126, located between the electrodes 122a, 122b. The plasma generation unit 102 also includes through holes 303. Diagram 310 shows a cross-section of the device. Diagram 312 shows a detailed view of the cross-section.

[0083] The fine- tip electrode materials (e.g., of the discharge pin 304) can be made of a diamond coating or other negative electron affinity material and can be used as electron field emitters.

[0084] In the example shown in Fig. 3, the plasma generation unit 300 includes a first electrode 122a formed as a first plate having a plurality of holes 110 therethrough. The second electrode 122b is formed as the second plate 122b and a plurality of discharge pins 304 and extends from the second plate 122b into a discharge region 306 in the insulation layer 125. In the insulation layer 126, the discharge pins 204 is separated from the insulation layer 126 by the discharge barrier 302 formed of a glass capillary. The discharge barrier 302 as a glass capillary may be disposed within each hole 110 with a separation distance to allow fluid flow through the hole 212. As shown, the discharge barrier 302 has an outer diameter of 3mm, and the discharge pin 304 has an outer diameter of less than 0.5mm. [0085] Similar to Figs. 1 A and IB, the electrode-insulator-electrode structure of the plasma generation unit 300 is coated with the catalyst coating 124. The channels 314 of the electrodes 122a, 122b may also be coated with the catalyst coating 124.

[0086] The plasma discharge region created by the device 200 may be operated so as to minimize the formation of reactive nitrogen (RN) species which includes reactive nitrogen oxides (RNO). In some implementations, carbon-based filters at an outlet are impregnated with zeolites to trap and remove both O3, RN, and RNO.

[0087] Example Air Purifier System #3

[0088] Fig. 4 shows an example of the air purifier device 100 (shown as 102c) for air decontamination and purification. The air purifier 102c may implement the micro hollow- cathode-discharge (MHCD) unit of Figs. 1 A or IB or the plasma discharge device (DBD) of Fig. 3, among other catalytic low-temperature plasma devices described herein.

[0089] In Fig. 4, device lOOd includes a housing 404 defining an airflow channel 406 through which a fluid (e.g., air) flows from a first end 408 to a second end 410. The second end 410 of the device lOOd includes the plasma discharge device 102 (shown as 402) disposed within the housing 404 in the direct path of the airflow channel 406. An electrostatic trap 412 is disposed on the second end 410 covering the plasma discharge device 402. The electrostatic trap 412 is configured to be electrostatically charged to collect dust or other particles.

[0090] The device lOOd further includes a magnetic field confinement device 414 (e.g., permanent magnets) that surrounds the outside of the housing 404 to surround the plasma discharge device 402 and the associated plurality of plasma generating units.

[0091] In use, air flows from the first end 408 to the second end 410 through the airflow channel 406 of the device 1 OOd. A voltage (AC or DC as described herein) can be applied to the electrode plates of the plasma discharge device 402, which produces a plasma discharge in the plurality of holes or surfaces having the catalytic coating. As air flows through the holes of the plasma discharge device 402 and out of the device 1 OOd, the low-temperature plasma generated near the catalytic coating interacts with the air to destroy pathogens and eliminate contaminants therein. The magnetic field confinement device 414 helps to confine the plasma and increase the plasma density of the plasma discharge device 402. The electrostatic trap 412 removes larger particulates that may flow through as well as charged molecules (e.g., O3 and NOx species).

[0092] Example Air Purifier System #4 [0093] Fig. 5 shows an air filtration device 100 (shown as lOOd) configured with a stack-up array of plasma generation units 102, in accordance with an illustrative embodiment. The device lOOd may be a tabletop device configured to filter and purify air in an enclosed environment (e.g., an office space or bedroom) or employed in a building unit as described herein. The device lOOd has a first end 502 and a second end 504. The device lOOd is generally cylindrical; however, in other implementations, a variety of other shapes are possible.

[0094] The device lOOd includes a large-gauge filter 506 disposed on the first end 502 and configured to raise or separate the remainder of the device lOOd from a base surface (e.g., a tabletop). The device lOOd includes a fan 508 disposed adjacent to the large-gauge filter 506. The fan 508 is configured to draw a fluid (e.g., air) into the device lOOd via the large-gauge filter 506 and direct the fluid through the device lOOd from the first end 502 to the second end 504. [0095] The device lOOd further includes a method of producing ions and reactive radicals using carbon fiber bipolar ionizer filaments 510 disposed adjacent to the fan 508. An applied voltage to the carbon fiber bipolar ionizer filaments 510 is configured to release both positive and negative ions at the points of the carbon fibers. The positive and negative ions, as well as the neutral radicals produced, can help reduce volatile organic compounds.

[0096] The device lOOd further includes a first HEPA filter 512 disposed adjacent to the carbon fiber bipolar ionizer filaments 510. The first HEPA filter 512 is configured to trap contaminants in a mesh to filter the incoming air. The device lOOd further includes a first ultraviolet (UV) light-emitting diode (LED) assembly having a UV-LED 514 disposed adjacent to the first HEPA filter 512 and a second UV LED 516. The first UV LED 514 is configured to kill trapped pathogens while the second UV LED 516 is configured to generate reactive oxides in the flow path. The device further includes a photocatalyst layer 518 (e.g., a TiCh or ZrCh photocatalyst). Finally, the second end 504 of the device lOOd includes a second HEPA filter 520.

[0097] The device lOOd includes the plasma generation unit (e.g., 102), such as the dielectricbarrier discharge (DBD), micro-hollow-cathode-discharge (MHCD), or a plasma jet (PJ) array as described herein. The plasma discharge device would be disposed in line with, or replace one of, the other filtering components to filter and purify the air flowing therethrough.

[0098] Example Tubular Dielectric Barrier Discharge (DBD) Unit and Air Purifier System #5 [0099] Fig. 6 shows another air purifier system 100 (shown as lOOf) configured with a tubular dielectric barrier discharge (DBD) unit 600. The tubular dielectric barrier discharge (DBD) unit is formed of a nested glass capillary. Diagrams 601a shows an isometric view of a single tubular dielectric barrier discharge device 600, diagram 601b shows a cross-section view of device 600, and diagram 601c shows a diagram of multiple tubular dielectric barrier discharge devices 600 configured as a plasma generation unit 102 (shown as 102c).

[0100] In diagram 601a, the plasma generation unit 600 includes a first glass tube 602 disposed within a second glass tube 604. The first glass tube includes a first conductive coating 606 on the outer surface 608 of the first glass tube 602, the first conductive coating 606 acting as the first electrode. The second glass tube 604 includes a second conductive coating 610 on the inner surface 612 of the second glass tube 604, the first conductive coating 606 acting as the second electrode. The first glass tube 602 includes a first catalyst coating 614 on an inner surface 616 of the first glass tube 602. The second glass tube 604 includes a second catalyst coating 618 on the outer surface 620 of the second glass tube 604.

[0101] In use, a voltage applied to the first conductive coating 606 and/or the second conductive coating 610 produces a plasma discharge between the first glass tube 602 and the second glass tube 604.

[0102] Diagram 601c shows an assembly lOOf, which includes an array of nested tubes. The assembly lOOf includes a housing 632 and a plurality of plasma generation units 600 disposed therein. In use, air flows from the first end 634 of the housing 632, through the plurality of plasma generation units 600, and out through the second end 636 of the housing 632. Air interacting with the plasma discharge layers is thus filtered and purified as described in this disclosure. The array may include a single layer of plasma generation units 600 or a plurality of layers of plasma generation units 600 either in line longitudinally or offset to reduce the airflow and increase the fluid residence time. The first catalyst coating 614 and second catalyst coating 618 can function to remove unwanted noxious gas and other byproducts from the outflow of air. The assembly 1 OOf provides for a high throughput of air due to the larger gaps between the plasma discharge areas.

[0103] Example Air Purifier System #6 with Meandering Flow Plasma Generation Assembly [0104] Figs. 7A - 7D each shows an air purifier system 700 (shown as 700a) that includes plasma generation units (e.g., 102 and others described herein) configured to generate a meandering air flow across the plasma generation units to improve the residence time of the air flow and associated particulates are in contact with the plasma of the plasma generation units. [0105] Indeed, plasma generated in an array configuration by multiples of the exemplary device and placed as an assembly in flow fields of a labyrinth (stacking in staggered configurations in any geometry) coupled to a fan (push) or vacuum (pull) can yield vortices and high residence times.

[0106] In Fig. 7A, viewing from the top of the system, the air purifier system 700a includes multiple plasma array generation units 102 (shown as 702a, 702b, 702c, 702d, 702e, and 702f), e.g., as described in relation Figs. 1A-1C, 2A-2D, and 3-6. The system 700a includes an air flow inlet 704 on a first end of the system and an air flow outlet 706 spaced apart from the fluid inlet 704 on a second end of the system. The system 700a includes side walls 708 which define an internal chamber 710 between the fluid inlet 704 and the fluid outlet 706. A mechanical filter 712 (e.g., HEPA filter) is disposed on the air flow inlet 704, configured to capture dust and other large particles from a fluid (e.g., air) moving through the system 700a.

[0107] The plasma array generation units 702a, 702b, 702c, 702d, 702e, and 702f extend from the side walls 708 and into the internal chamber 710. The plasma array generation units (e.g., 702a-702f) are oriented and arranged in an alternating pattern within the internal chamber 710 such that an airflow distance between the fluid inlet 704 and the fluid outlet 706 is increased to increase the residence time of the fluid passing through the system 700a.

[0108] The system 700 further includes one or more UV light sources 714 disposed close to the fluid inlet 704 (or could be at the outlet) and configured to emit UV light (shown as beam 705) into the internal chamber 710. The side walls 708 of the system 700a may be highly reflective or may include an internal mirror to reflect and/or scatter the UV light throughout the internal chamber 710. A UV detector 716 is disposed closer to the fluid outlet 706 to detect the level of UV light intensity in the internal chamber 710. In other embodiments, additional UV sources may be provided at the outlet. The UV light can decontaminate and eliminate some pathogens from the air. Additionally, the UV light may lower the breakdown potential required by the applied fields of pathogens and/or contaminants, allowing the plasma discharge to decontaminate the fluid more easily. That is, the use of UV LED light sources (wavelength < 350 nm) can be used to treat bioaerosols and to stimulate photocatalysis. The multiple reflections and use with plasmas can lead to lowering the required applied field for the plasmas and enhance non-thermal catalysis.

[0109] In the example shown in Fig. 7A, the air purifier system 700a includes a heating filter 718 disposed at the fluid outlet 706, the filter 718 being coated with reduced graphite oxide configured to further trap and destroy any remaining pathogens.

[0110] In use, each of the plasma array generation units (e.g., 702a-702f) receives an applied voltage and generates a low-temperature plasma in the various through outs. A plasma surface is formed via the array of through holes and on the surface of the plasma generation unit (e.g., 702a-702f). The airflow is forced through the system 700a at the fluid inlet 704 (e.g., by a fan or turbine in an HVAC system).

[0111] Once the fluid enters the internal chamber 710, the alternating structural placement of the plasma generation units (e.g., 702a-702f) causes a turbulent flow and eddy air currents to form within the internal chamber 710. That is, the air stream flowing through the system 700a can not to take a straight path from the fluid inlet 704 to the fluid outlet 706. Thus, each portion of the airflow stays in the internal chamber 710 for a longer time, interacting with the plasma discharge from the plasma generation units (e.g., 702a-702f) for a longer time. The result is the increased residence time of the fluid in the internal chamber 710.

[0112] Fig. 8 shows a diagram of streamline velocities of air flowing through an example device (e.g., 700) with eddy currents trapped in the spaced adjacent to the alternating pattern of plasma generation units (e.g., 702a-702f). The fluid interacts with one or more plasma generation units (e.g., 702a-702f) as it flows towards the fluid outlet 706. The interaction removes or deactivates contaminants or bio-contaminants from the fluid. With the UV light source 714 acting as a secondary purification source, pathogens can be destroyed more quickly or more thoroughly.

[0113] Fig. 7A shows the air purifier system 700a configured with a heated filter 718 at the fluid outlet 706. The heating can assist with the air purification process.

[0114] The heat filter 718 may be a heat exchanger such as a Peltier cooler, a coolant system, or a traditional gas expansion device. The system may perform cooling so that the air exiting the system is not warmed up to an uncomfortable or undesirable temperature.

[0115] The system (e.g., 700) may be implemented into an HVAC system for a building to provide filtered and purified air to a plurality of environments. In other implementations, these systems may be implemented into a compact version for use in a single environment (e.g., a room-sized environment).

[0116] Fig. 7B shows another configuration of the planar plasma generation units 702 (shown as plasma generation unit assembly 702’) as an assembly formed of two planar plasma generation units 702 in an angled-shaped structure. The angle-shaped structure may be employed, e.g., in the meandering configuration of Fig. 7A to extend the residence time of the particles in the system (e.g., 700). In Fig. 7B, the planar plasma generation assembly 700b includes a UV LED light source 714a disposed inside of the angled-shaped structure 700a. The plasma discharge from the planar plasma generation assembly 700a and the UV light from the UV LED light source714a can operate concurrently to purify and disinfect air flowing through the device 700.

[0117] FIG. 7C shows another configuration of the air purifier system 700 (shown as 700b) that includes plasma generation units (e.g., 102 and others described herein) configured to generate a meandering air flow across the plasma generation units. In the example of Fig. 7C, the system 700, device 700c includes two internal chambers 710a and 710b, with corresponding fluid inlets 704a and 704b. Thus, two airflow paths are formed, each directed towards a central fan 740 (e.g., a high-volume squirrel cage fan), which draws air from each side of the device 700c. A heated filter 718 and heat exchanger 730 are disposed at the fluid outlet 706 of the device 700c. In such a heating mode, the air treatment is via thermal treatment, and the air may need to be cooled. In some embodiments, a cooling device or a pressure expansion (adiabatic cooling) could be employed downstream to the heated filter 718. In some embodiments, the heated gas is compressed first and then decompressed.

[0118] Experimental Results

[0119] A prototype device was created using a packed-bed dielectric barrier discharge (DBD) device. A study was conducted using the device to treat influenza viruses to a CDC-required log 3 met. In one test, 7.5 minutes of plasma treatment was performed in air at atmospheric pressure. FIG. 9 shows a graph of the results of a study showing the log reduction of viruses with varied time application of plasma and filter types.

[0120] Transportable or Portable Air Purifier and Particle Removal

[0121] Figs. 10A - 10C show examples of transportable or portable air purifiers that may be implemented using the exemplary plasma generation units described herein. Most popular air purifiers employ low-temperature plasmas and bi-polar ionization sources. Low-temperature plasmas have been shown to be effective in treating and destroying volatile organic vapors, mold, spores, bacteria, viruses, and other airborne particles [1, 2]. The reactive oxygen species and ozone are known to be among the active entities involved in deactivating and killing biological pathogens, etc. However, ozone cannot be released into the indoor air space due to other health hazards. Plasmas operating with volatile organic molecules and oxidants also produce particles and aerosols that can be hazardous. Thus, the use of reactive plasmas and ozone generators is typically not suitable for air purification in enclosed and occupied airspaces. [0122] Bi-polar ionization sources have been suggested to be effective in the deactivation and killing of bacteria and viruses, though most of these tests have been conducted under stagnant air conditions or involve particle trapping prior to treatment [3], Operating these devices in a manner that attempts to trap them in flow often requires high air circulation through-puts while also requiring deactivation times.

[0123] The use of a single pole device in the direct field emission mode can also be used to locally supply a stream of low energy electros, which interact with the ambient air and water vapor leading to the formation of solvated anion clusters, with O2'(H2O)n being the most prominent chemical species present. Solvated anions can serve as an electron transfer media for charging aerosols and particles, which can be removed by simple electrostatic attraction to any grounded or oppositely charged surface. Many devices use simple carbon whiskers as the field emitting material; however, many other materials, when in the proper nanometer shape and size regime, can be used as atmospheric pressure field emission sources that operate at lower applied potentials [4-6], There is a benefit to improving ionization-based air purification technologies to make them more localized and portable.

[0124] Fig. 10A shows a portable local miniature air purifier for, e.g., musical wind instruments, e.g., for orchestras and bands. The device is configured to be mountable, transportable, and miniature and has high efficiency at low power and can be manufactured at low-cost. The exemplary device is configured for ambient pressure electrostatic particle removal and charge particle surface interactions. The exemplary device can remove particles at the source and are more local, thus mitigating the particles before they are injected into and dispersed within indoor air spaces. Personal placement, distributed single deployments, and the use of locally network arrays can sidestep the throughput and large air mass handling needs. [0125] In some embodiments, the devices are configured to locally remove and collect airborne particles emanating from wind instruments, as well as speaking and singing individuals in enclosed in-door air spaces and systems with no hazardous gas-phase byproduct formation and release (e.g., ozone, nitrogen oxides, etc.).

[0126] In the example shown in Fig. 1, the device is powered by a 3-25 V battery which is amplified to up to 5 kV by a direct DC converter. The high-voltage wire is fed through a shielded hollow flexible metal tube and terminates at a tip containing an electron field emitting material. Electron-emitting materials may be incorporated into the device. Example of these material includes, but are not limited to, carbon whiskers, nano-pillars of graphite, nano-pillars of graphene, graphene foam, reduced graphite oxide, nano-pillars of ZnO with metal nanoparticles, WO pillars, H-BN films, sputtered nanostructured diamond thin-films, and other negative electron affinity material. Nanostructured emitted may beneficially reduce the required potential to operate the device.

[0127] In some embodiments, the application of UV light to the emitter may help further reduce the required applied potential.

[0128] In some embodiments, the device is configured with electron-emitting tips, which is attached to a re-attachable mount. In some embodiments, the tip can be replaceable. In some embodiments, the tip is configured with a shape selected from the group consisting of a 2D rectangle, a square, a circle, a 3D sphere, and a cube.

[0129] The electron-emitting filaments or material may be set in a plastic, ceramic, or nonconducting terminal end-cap. The ceramic materials can be doped with meals and metal clusters for electron beam-activated catalysis. These can be equipped with miniature high-speed battery- operated fans. The power supply may be operated with a timer and be switched off by current limiting circuits. The base may have a clip for mounting or be on a normal base stand that resembles a lamp. The battery pack can fit into the pocket of the musician, and the length of the connecting wire can vary from a few inches to tens of feet.

[0130] Indeed, the exemplary device has multiple embodiments, e.g., to provide for multiple modes of utilization in enclosed air spaces with high occupancies. In some embodiments, the exemplary device is configured for use with musical wind instruments. In some embodiments, the exemplary device is configured for use with musical stands. In some embodiments, the exemplary device is configured for use with choir singers. In some embodiments, the exemplary device is configured for use with speakers. In some embodiments, the exemplary device is configured for use with oration podiums. In some embodiments, the exemplary device is configured for use with room lighting fixtures. The exemplary devices can also be used synergistically with integrated miniature high-speed fans to provide additional aerosol and/or fine particulate removal.

[0131] Fig. 10B shows a stationary device to operate using a standard 120 VAC line and can clamp on music stands, a podium, or any other stationary source having a potential local source of particles. The stationary embodiment may be configured with various features, as discussed in relation to Fig. 10A. In Fig. 10B, the device may be configured to operate with AC power and include a plug receptacle. It may include a clamp to be put on music stands. In some embodiments, the device may be equipped with an in-line miniature high-speed fan (e.g., an inline drone motor). In some embodiments, an in-line drone motor is used and positioned behind the emitter or the reverse.

[0132] Three embodiments are configured for the in-line fan: (1) an in-line high-speed (> 10,000 rpm) miniature fan configured in-line (behind) with the emitters; (2) in-line high-speed (> 10,000 rpm) miniature fans configured in-line (in front) with the emitters; and (3) an air-purifier located in a gas-stream and can operate with ambient air. The air purifiers can be fed with a source gas.

[0133] In another configuration, the device is in a reverse configuration and has the emitting filament in the stem after the fan motor. In this case, the surface or stand-mounted device may include an input funnel and /or a venturi inlet.

[0134] Fig. 10C shows a headset purifier for singers, speakers, and non-mask wearers. The heat set may be equipped with a power supply configuration and up-converted power configuration as described in relation to Figs. 10A and 10B.

[0135] The device may include a high-voltage wire, e.g., as described in relation to Fig. 10B, that feeds through a flexible wire harness. The device may include an ear clip and a front termination port that has an electron-emitting source embedded and exposed as shown in Fig. 10C.

[0136] The device includes field emitter materials that can be put on graphene foam cover (similar to a microphone foam cover) and be replaced easily. 1 [0137] The field emitter in some embodiments employs a recessed charge emission region containing field emitters. In some embodiments, the field emitters are made of carbon whiskers, nano-pillars of graphite, nano-pillars of graphene, graphene foam, reduced graphite oxide, nanopillars of ZnO with metal nanoparticles, WO pillars, H-BN films, sputtered nanostructured diamond thin-films, a negative electron affinity material, or a combination thereof. The emitter in some embodiments is configured as a graphene foam covering that is positioned at a tip on the device.

[0138] In some embodiments, the emitter comprises a Cu metal mesh with chemically deposited graphene. In some embodiments, the emitter comprises a metal mesh with sputtered and reduced graphite-oxide films as electron emitter covers/tips that operate in ambient air and atmospheric pressure. In some embodiments, the emitter comprises nano-pillars of ZnO with metal nanoparticles as electron emitter covers/tips that operate in ambient air and atmospheric pressure. In some embodiments, the emitter comprises nano-pillars of WxOy films as electron emitter covers/tips that operate at in ambient air and atmospheric pressure. In some embodiments, the emitter comprises H-BN films as electron emitter covers/tips that operate in ambient air and atmospheric pressure. In some embodiments, the emitter comprises sputtered nanostructured diamond thin films as electron emitter covers/tips that operate in ambient air and atmospheric pressure. In some embodiments, the emitter comprises a charge emission region that contains metal meshes coated with sputtered reduced graphite oxide. In some embodiments, the emitter comprises a charge emission region that contains metal meshes coated WXOY films. In some embodiments, the emitter comprises a charge emission region that contains metal meshes coated H-BN films. In some embodiments, the emitter comprises a charge emission region that contains metal meshes coated with sputtered diamond films.

[0139] In some embodiments, existing microphone headsets may be retrofitted with the discussed emitters without significant sound quality degradation. The headset may have a second symmetric discharge end.

[0140] Although example embodiments of the present disclosure are explained in some instances in detail herein, it is to be understood that other embodiments are contemplated. Accordingly, it is not intended that the present disclosure be limited in its scope to the details of construction and arrangement of components set forth in the following description or illustrated in the drawings. The present disclosure is capable of other embodiments and of being practiced or carried out in various ways.

[0141] Additional embodiments

[0142] In some embodiments, the exemplary device is configured as a miniature battery- operated portable air purifier device that can be placed in, mounted on, or mounted near a musical wind instrument.

[0143] In some embodiments, the exemplary device is configured as a miniature battery- operated air purifier device that can be mounted on or near a musician's music stand.

[0144] In some embodiments, the exemplary device is configured as a miniature battery- operated air purifier device that can be mounted on or near a speaker podium, counter, table, desk-top, etc.

[0145] In some embodiments, the exemplary device is configured as a miniature portable air purifier device that can be placed in, mounted on or mounted near a musical wind instrument. [0146] In some embodiments, the exemplary device is configured as a miniature portable air purifier device that can be mounted on or near a musician's music stand.

[0147] In some embodiments, the exemplary device is configured as a miniature battery- operated portable air purifier device with a single emitter port that can be worn as a headset by singers, speakers, and the general public.

[0148] In some embodiments, the exemplary device is configured as a miniature battery- operated portable air purifier device with dual emitter ports that can be worn as a headset by singers, speakers, and the general public.

[0149] In some embodiments, the exemplary device is configured as a single unit that can be operated individually and separately. The single units can be linked together to comprise a purification network. The portable ones can also be made into hand-held units.

[0150] In some embodiments, the exemplary device comprises local air cleaning units that can be used in any enclosed air space, e.g., to provide point source mitigation or for HVAC applications.

[0151] It must also be noted that, as used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” or “ 5 approximately” one particular value and/or to “about” or “approximately” another particular value. When such a range is expressed, other exemplary embodiments include from the one particular value and/or to the other particular value.

[0152] By “comprising” or “containing” or “including” is meant that at least the name compound, element, particle, or method step is present in the composition or article or method, but does not exclude the presence of other compounds, materials, particles, method steps, even if the other such compounds, material, particles, method steps have the same function as what is named.

[0153] In describing example embodiments, terminology will be resorted to for the sake of clarity. It is intended that each term contemplates its broadest meaning as understood by those skilled in the art and includes all technical equivalents that operate in a similar manner to accomplish a similar purpose. It is also to be understood that the mention of one or more steps of a method does not preclude the presence of additional method steps or intervening method steps between those steps expressly identified. Steps of a method may be performed in a different order than those described herein without departing from the scope of the present disclosure. Similarly, it is also to be understood that the mention of one or more components in a device or system does not preclude the presence of additional components or intervening components between those components expressly identified.

[0154] The construction and arrangement of the systems and methods as shown in the various implementations are illustrative only. Although only a few implementations have been described in detail in this disclosure, many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes, and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.). For example, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. Accordingly, all such modifications are intended to be included within the scope of the present disclosure. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative implementations. Other substitutions, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of the implementations without departing from the scope of the present disclosure. [0155] The present disclosure contemplates methods, systems, and program products on any machine-readable media for accomplishing various operations. The implementations of the present disclosure may be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwired system. Implementations within the scope of the present disclosure include program products including machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures, and which can be accessed by a general purpose or special purpose computer or other machine with a processor. [0156] When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a machine, the machine properly views the connection as a machine-readable medium. Thus, any such connection is properly termed a machine-readable medium. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions include, for example, instructions and data which cause a general-purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions.

[0157] Although the figures show a specific order of method steps, the order of the steps may differ from what is depicted. Also, two or more steps may be performed concurrently or with partial concurrence. Such variation will depend on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure. Likewise, software implementations could be accomplished with standard programming techniques with rule-based logic and other logic to accomplish the various connection steps, processing steps, comparison steps and decision steps.

[0158] It is to be understood that the methods and systems are not limited to specific synthetic methods, specific components, or to particular compositions. It is also to be understood that the terminology used herein is for the purpose of describing particular implementations only and is not intended to be limiting.

[0159] As used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another implementation includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another implementation. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0160] “Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

[0161] Throughout the description and claims of this specification, the word “comprise” and variations of the word, such as “comprising” and “comprises,” means “including but not limited to,” and is not intended to exclude, for example, other additives, components, integers or steps. “Exemplary” means “an example of’ and is not intended to convey an indication of a preferred or ideal implementation. “Such as” is not used in a restrictive sense, but for explanatory purposes.

[0162] Disclosed are components that can be used to perform the disclosed methods and systems. These and other components are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these components are disclosed that while specific reference of each various individual and collective combinations and permutation of these may not be explicitly disclosed, each is specifically contemplated and described herein, for all methods and systems. This applies to all aspects of this application including, but not limited to, steps in disclosed methods. Thus, if there are a variety of additional steps that can be performed it is understood that each of these additional steps can be performed with any specific implementation or combination of implementations of the disclosed methods.

[0163] The following patents, applications and publications as listed below and throughout this document are hereby incorporated by reference in their entirety herein.

[1] Akikazu Sakudo, Yoshihito Yagyu and Takashi Onodera, “Disinfection and Sterilization Using Plasma Technology: Fundamentals and Future Perspectives for Biological Applications”, Int. J. Mol. Sci. 2019, 20, 5216; doi: 10.3390/ijms20205216 www. [2] G. Nayak, et. al, “Rapid inactivation of airborne porcine reproductive and respiratory syndrome virus using an atmospheric pressure air plasma”, Plasma Process Polym. 2020;el900269 https://doi.org/10.1002/ppap.201900269.

[3] Shunpeng Chen, “Low temperature plasma air purifier with high speed ion- wind selfadsorption”, US Patent No. US 2017/0341088 Al.

[4] And Agural and J. G. E. Gardeniers, “Synthesis and atmosheric pressure field emission operation of W18049 nanorods”, J. Phys. Chem. C, 2008, 112, 15183-15189.

[5] S. Komatsu, E. Ohta, H. Tanaka, Y. Moriyoshi, K. Nakajima, T. Chikyo and M. Shiratani, “Electron field emission in air at an atmospheric pressure from -bonded microcones”, J. Appl. Physics, 101, 084904 (2007); https://doi.org/10.1063/L2717594.

[6] Nannan Li 1,2,*, Xiaozhao Li 1 and Baoqing, Zeng, Field Emission and Emission- Stimulated Desorption ofZnO Nanomaterials Appl. Sci. 2018, 8, 382; doi:10.3390/app8030382.

Claims

What is claimed is:

1. A plasma-activated catalytic air-purifier device, the device comprising: at least one plasma generation unit, including a first plasma generation unit comprising: a first electrode separated a first distance from a second electrode, wherein the first distance is less than 1 mm; an insulator disposed in between the first electrode and the second electrode; a catalyst coating disposed on the first and second electrodes, and a voltage source in electrical communication with the first electrode and the second electrode, the voltage source configured to provide an electrical potential difference across the first and second electrodes to generate a low-temperature plasma, wherein an air stream flowing through the first plasma generation unit interacts with the low-temperature plasma to remove or deactivate contaminants or bio-contaminants from the air stream.

2. The device of claim 1, further comprising a second plasma generation unit arranged adjacent to the first plasma generation unit to form a plasma stack or array.

3. The device of claim 1 or 2, wherein the at least one plasma generation unit is a dielectric barrier discharge (DBD) unit.

4. The device of any one of claims 1-3, wherein the first electrode is a plate having a first hole therethrough and the second electrode is a needle disposed within the first hole.

5. The device of any one of claims 1-4, wherein the at least one plasma generation unit is a micro-hollow-cathode-discharge (MHCD) unit wherein the first electrode is a first conductive plate having a first hole therethrough and the second electrode is a second conductive plate having a second hole therethrough, wherein the insulator placed between the two plates has a third hole therethrough aligning with each of the first hole and the second hole such that the plasma is generated in a gap space between the between the first plate and the second plate and the plasma may overflow out of at least one of the first hole and the second hole.

6. The device of any one of claims 1-5, further comprising a magnetic field confinement device, the magnetic field confinement device having permanent magnets disposed around the first plasma generation unit.

7. The device of any one of claims 1-6, wherein the at least one plasma generation unit is a nested glass capillary unit wherein the first electrode is a first conductive coating on an outer surface of a first glass tube and the second electrode is a second conductive coating on an inner surface of a second glass tube disposed around the first glass tube, wherein a plurality of first and second glass tubes are arranged or stacked adjacent to each other to form the first plasma generation unit.

8. The device of claim 6, wherein the catalyst coating is disposed on an inner chamber surface of the first electrode.

9. The device of any one of claims 1-8, wherein the plasma array is a plasma jet (PJ) array.

10. The device of any one of claims 1-9, wherein the catalyst coating comprises at least one of reduced graphite oxide (rGO) and manganese cerium oxide (MnCeOx).

11. The device of any one of claims 1-10, wherein the catalyst coating forms a coated filter configured to, along with low-temperature plasma, capture and eliminate viruses and bacteria from the air stream.

12. The device of claim 10 or 11, wherein the reduced graphite oxide (rGO) is used in the catalyst coating as a conductive coating, wherein residual resistance of the conductive coating is employed to heat the first plasma generation unit to, along with low-temperature plasma, capture and eliminate viruses and bacteria from the air stream .

13. The device of any one of claims 1-12, wherein the voltage source provides the electrical potential difference in a direct or variable frequency.

14. The device of any one of claims 1-13, further comprising an input side for the air stream and an output side for the air stream, wherein the plasma is disposed in between the input side and the output side such that the air flow is forced to interact with or flow through at least a portion of the plasma.

15. The device of claim 14, further comprising an air motivator disposed one or both of the input side and the output side of the device configured to force air through the device.

16. The device of any one of claims 1-15, further comprising a UV light source configured to remove or destroy pathogens from the air stream flowing through the device.

17. The device of any one of claims 1-16, further comprising a mechanical filter disposed closer to the input side of the device than the plasma.

18. The device of any one of claims 1-17, wherein the device is configured for use in a personal device.

19. The device of any one of claims 1-17, wherein the device is configured for use in an enclosed space.

20. The device of any one of claims 1-19, wherein the device is configured for use in an HVAC system.

21. The device of any one of claims 1-20, wherein the first plasma generation unit of the device is configured for use as a HEPA filter to capture particles in the air stream.

22. An air filtration and purification system comprising: a plasma generation unit comprising: a first electrode separated a first distance from a second electrode, wherein the first distance is less than 1 mm; an insulator disposed in between the first electrode and the second electrode; a voltage source in electrical communication with the first electrode and the second electrode, the voltage source configured to provide an electrical potential difference across the first and second electrodes to generate a low-temperature plasma; and a catalyst coating disposed on the first and second electrodes, the catalyst coating configured to capture or remove particles or byproducts; an air stream inlet comprising a mechanical filter and an air steam outlet spaced apart from the air stream inlet; and an internal chamber defined by side walls and disposed between the air stream inlet and the air stream outlet, wherein the plasma generation unit extends from the side walls into the internal chamber, and wherein an air flow flowing through the system interacts with plasma to remove or deactivate contaminants or bio-contaminants from the air flow.

23. The system of claim 22, further comprising a second plasma generation unit disposed within the internal chamber and in a staggered configuration to the plasma generation unit.

24. The system of claim 22 or 23, wherein the plasma generation unit and the second plasma generation unit are arranged in an alternating pattern such that an airflow distance between the air stream inlet and the air stream outlet increases and a residence time of the air flow in the internal chamber increases.

25. The system of any one of claims 22-24, comprising a UV light source emitting UV light into the internal chamber, wherein the side walls of the internal chamber comprise a reflective surface to scatter the UV light throughout the internal chamber, wherein the UV light non-thermally activate the catalyst coating.

26. The system of any one of claims 22-25, comprising a heat exchanger system comprising: an internal heated plate in air stream communication with a portion of the internal chamber to thermally decontaminate a portion of the air stream; and an external plate configured to exchange heat from the internal heated plate to a cooling system and away from the air stream.