WO2022251646A1

WO2022251646A1 - Disinfection of live plants via plasma-charged microdroplets

Info

Publication number: WO2022251646A1
Application number: PCT/US2022/031358
Authority: WO
Inventors: Gregory Fridman; Randy Richard COX; III Charles Christopher Bailey; Mark A. Stibich
Original assignee: Xenex Disinfection Services, Inc.; Aa Plasma Llc.
Priority date: 2021-05-28
Filing date: 2022-05-27
Publication date: 2022-12-01

Abstract

Cold plasma disinfection devices and systems for application with live plants and other perishable items as well as methods of their use are provided. In particular, an agricultural treatment device includes a sprayer bar and multiple cold plasma disinfection devices spaced along the sprayer bar such that plasma charged microdroplets are discharged into an ambient of the device. A cold plasma disinfection device is provided which includes a microdroplet chamber configured to formulate a distribution of microdroplets having a smaller average diameter at an end of the chamber than a distribution of microdroplets introduced into the chamber. In some cases, the disinfection device may include carrier feature/s for facilitating manual portability of the device. In other embodiments, the disinfection device may be attached to or arranged within an enclosure such that plasma charged microdroplets generated by the disinfection device are discharged onto the containers of plants within the enclosure.

Description

Patent Application for

DISINFECTION OF LIVE PLANTS VIA PLASMA-CHARGED MICRODROPLETS

PRIORITY CLAIM

This application claims priority to U.S. Provisional Patent Application Nos. 63/202,161 filed May 28, 2021 and 63/264,746 filed December 1, 2021.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to devices for sanitization, disinfection, and/or sterilization of perishable items and, more particularly, devices for sanitization, disinfection, and/or sterilization of live plants, including but not limited to those which produce on a field or in a greenhouse.

2. Description of the Related Art

Farmers and farming of produce serves as the backbone of all modern societies. Without farms and produce, modem industrial life does not exist. The advent of farming machinery, such as tractors, and various trucks and other machines have enabled an expansion of the speed and quantity of materials that can be grown and harvested. Such advancements, however, can be limited by plants and produce being infected by pathogens prior to being harvested. Although chemical pesticides are commonly used for reducing the pathogenic loads on crops, the health effects and environmental impact of using such pesticides have shown to be detrimental·

Thus, it would be beneficial to develop devices, systems and methods for disinfecting produce and plants before they are harvested to prevent cross-contamination into the environment and to create safer cut produce. SUMMARY OF THE INVENTION

Disinfection devices and systems for application with live plants and other perishable items as well as methods of their use are provided. The following description of various embodiments of the apparatuses and methods is not to be construed in any way as limiting the subject matter of the appended claims.

Embodiments of an agricultural treatment device include a sprayer bar, a plurality of disinfection devices spaced along the sprayer bar, at least one air moving device for moving air into the plurality of disinfection devices, and at least one fluid reservoir and at least one pump for supplying fluid to the plurality of disinfection devices. Each of the plurality of disinfection devices include a cold plasma generator, a microdroplet introduction chamber arranged upstream or downstream from the cold plasma generator, at least one atomizer for introducing microdroplets into at least one intake port of the microdroplet introduction chamber, and an outlet. Each of the plurality of disinfection devices is arranged on the sprayer bar such that plasma charged microdroplets are discharged from the outlet into an ambient of the agricultural treatment device.

Embodiments of a disinfection device includes an inlet comprising an air filter, an air moving device for drawing air from an ambient of the disinfection device through the air filter, and a cold plasma generator arranged to receive filtered air from the inlet. The disinfection device further includes a microdroplet introduction chamber arranged upstream or downstream from the cold plasma generator and at least one atomizer for introducing microdroplets into at least one intake port of the microdroplet introduction chamber. The microdroplet introduction chamber is configured to formulate a distribution of microdroplets having a smaller average diameter at an end of the microdroplet introduction chamber than a distribution of microdroplets introduced into the microdroplet introduction chamber at the at least one intake port. The disinfection device further includes an outlet disposed downstream from the microdroplet introduction chamber and the cold plasma generator for discharging plasma charged microdroplets into an ambient of the disinfection device. In addition, the disinfection device includes a fluid reservoir and a pump for supplying fluid to the at least one atomizer as well as a power supply, wherein the power supply, the fluid reservoir, the pump, the at least one atomizer, the microdroplet introduction chamber, the cold plasma generator, the air moving device and the air filter comprise a portable cohesive unit. Moreover, the disinfection device includes one or more carrier features for facilitating manual portability of the cohesive unit, wherein the one or more carrier features comprise a handle and/or one or more shoulder straps.

Embodiments of an enclosure for growing plants includes containers of plants and a disinfection device attached to or arranged within the enclosure such that plasma charged microdroplets generated by the disinfection device are discharged onto the containers of plants. The disinfection device includes an air moving device for drawing air from an ambient of the disinfection device into the disinfection device, a cold plasma generator, a microdroplet introduction chamber arranged upstream or downstream from the cold plasma generator, and at least one atomizer for introducing microdroplets into at least one intake port of the microdroplet introduction chamber. In addition, the disinfection device includes an outlet disposed downstream from the microdroplet introduction chamber and the cold plasma generator for discharging plasma charged microdroplets into an ambient of the disinfection device.

Embodiments of a container for growing plants includes a cold plasma disinfection device attached to the container such that plasma charged microdroplets generated by the cold plasma disinfection device are discharged into an ambient of the container. The cold plasma disinfection device includes an air moving device for drawing air from an ambient of the container into the disinfection device, a cold plasma generator, and a microdroplet introduction chamber arranged upstream or downstream from the cold plasma generator. In addition, the cold plasma disinfection device includes at least one atomizer for introducing microdroplets into at least one intake port of the microdroplet introduction chamber and an outlet disposed downstream from the microdroplet introduction chamber and the cold plasma generator for discharging plasma charged microdroplets into an ambient of the disinfection device.

Embodiments of a method to reduce pathogenic loads on live plants includes introducing air into a plasma generator to generate reactive oxygen and nitrogen species and introducing microdroplets into a microdroplet chamber. The method further includes formulating a distribution of microdroplets having a smaller average diameter at a discharge end of the microdroplet chamber than a distribution of microdroplets introduced into the microdroplet chamber, mixing the microdroplets with the reactive oxygen and nitrogen species to form charged microdroplets, and discharging the charged microdroplets onto live plants.

BRIEF DESCRIPTION OF THE FIGURES

Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the accompanying drawings in which:

Fig. 1A illustrates a schematic view of a disinfection device configured to generate plasma charged microdroplets;

Fig. IB illustrates a schematic view of a different disinfection device configured to generate plasma charged microdroplets;

Fig. 2 illustrates a schematic view of an example electrode configuration for a plasma generator of the disinfection devices depicted in Figs. 1A and IB;

Fig. 3 illustrates a schematic view of a flow of fluid through a microdroplet introduction cavity of the disinfection device depicted in Fig. 1A;

Fig. 4A illustrates a perspective view of a microdroplet introduction chamber of the disinfection device depicted in Fig. 1A;

Fig. 4B illustrates a cross-sectional view of the microdroplet introduction chamber depicted in Fig. 4A taken along line 4B-4B of Fig. 4A;

Fig. 5 illustrates a perspective view of the microdroplet introduction chamber depicted in Fig. 4A taken from its opposite end;

Fig. 6A illustrates a schematic view of yet another disinfection device configured to generate plasma charged microdroplets; Fig. 6B illustrates a perspective view of a microdroplet introduction chamber of the disinfection device depicted in Fig. 6A;

Fig. 7A illustrates a tractor with a spray boom having individual disinfection devices configured to generate plasma charged microdroplets spaced along the spray boom;

Fig. 7B illustrates a tractor having a centralized system configured to generate plasma charged microdroplets and connected to nozzles spaced along a spray boom; and

Fig. 8 illustrates a schematic view of an enclosure having a disinfection device attached thereto and configured to generate plasma charged microdroplets and discharge them into the enclosure.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure details devices and systems for generating reactive oxygen and nitrogen species using cold plasma, dissolving the species into microdroplets, which protects the highly unstable and reactive species and then expressing the microdroplets onto live plants for sanitization, disinfection, and/or sterilization thereof. The charged microdroplets, when sprayed onto plants deactivate or kill pathogens on the surfaces of the plants. Spraying before plants are harvested or cut for sale allows the plants to have greatly reduced pathogen contamination as compared to unsprayed plants, thereby reducing the risk of pathogens in the food supply chain. The devices, systems and methods described herein are also suited for sanitizing, disinfecting, and/or sterilizing perishable items other than live plants in order to disinfect them before storage, transporting, or use. Further yet, the device, systems, and methods described herein may be used to sanitize, disinfect, and/or sterilize surfaces of non- perishable items, particularly ones suspected of being contaminated with one or more pathogens.

The terms sanitize, disinfect, and sterilize mean to reduce the quantities of pathogens by an x-log amount, wherein the value of x differs for the different terms depending on the targeted pathogen, particularly that the terms sanitize, disinfect, and sterilize each require increasingly higher reduction of a given pathogen, respectively. As used herein, the term “pathogen” shall refer to any one or more of bacterial spores, mycobacteria, viruses, nonlipid or small viruses, fungi, vegetative bacteria, and lipid or medium size viruses. The term “kill,” as used herein, means to cause the death of an organism. In contrast, the term “deactivate,” as used herein, means to render an organism unable to reproduce without killing. As such, a germicide which is configured to deactivate a microorganism, as used herein, refers to an agent which renders a microorganism unable to reproduce but leaves the organism alive.

As used herein, a “live growing plant” means a plant that is being grown. Examples of growth environments in which the devices and methods described herein may be used to treat plants may include but are not limited to a field, a community farm, a garden, or a container (such as but not limited to a pot, tray, or a structure for vertical farming). The growth environments may be outdoor (e.g., field farming and gardens) or indoor (e.g., greenhouses, warehouses, and homes). In addition, the devices and methods described herein may be used to treat plants grown in soil and/or water. Examples of live growing plants which may be disinfected with the devices and/or methods disclosed herein include but are not limited to trees, bushes, shrubs, and crops. Although the devices and methods disclosed herein were initially tested for disinfecting plants that grow produce, it is contemplated that the devices and methods may be applied to other perishable items, including live growing plants that do not grow produce. Examples of plants that do not grow produce which may be considered for disinfection by the devices and methods disclosed herein include but are not limited to trees, floricultural plants, tobacco, and cannabis.

As used herein, a “perishable item” means items which are prone to decay by the action of a pathogen. The term is inclusive to live growing plants, edible items and items harvested from plants (i.e., both edible and non-edible items harvested from plants). Edible items which are considered perishable include but are not limited to produce, meats, mushrooms, and eggs. As used herein “meats” means red meat including but not limited to beef, buffalo, and similar meat, white meat including but not limited to pork, goat, venison, poultry, and fish. As described below, the term “produce” is inclusive to both harvested produce and unharvested produce. Examples of perishable items harvested from plants, include but not limited to produce, seeds, flowers, flower buds, leaves and stalks.

As used herein “produce” means a raw agricultural edible commodity that is grown from a live growing plant, particularly a food in its raw or natural state as grown from its plant or after being washed, colored, cut, or otherwise treated in its unpeeled state. The term is inclusive to unharvested produce and harvested produce. As used herein, “unharvested produce” refers to produce which has not been cut, picked, or otherwise separated from its source live growing plant. As used herein “harvested produce” refers to produce which has been cut, picked, or otherwise separated from its source live growing plant. Examples of produce include but are not limited to fruits, vegetables, tubers, legumes, sprouts, nuts, herbs, grain, and other edible food materials which are grown on a plant. It is noted that the term “produce” is inclusive to edible items which are intended to be consumable products as is and edible items which are intended to be processed into different edible or non-edible products (e.g., vineyard grapes, soybeans, corn, and wheat).

Disinfection devices disclosed herein include a cold plasma generator. The term “cold plasma” as used herein refers to a plasma which is not in thermodynamic equilibrium, particularly that the temperature of the electrons is much higher than the temperature of ions and neutrals. The term “cold plasma” as used herein is synonymous with the terms “nonthermal plasma” and “nonequilibrium plasma.” The cold plasma generators of the disinfection devices disclosed herein may include any generator known to generate a cold plasma. Examples of cold plasma generators which may be used for the disinfection devices disclosed herein include but are not limited to glow discharge, corona discharge, atmospheric pressure plasma jet, dielectric barrier discharge, micro-hollow cathode discharge, plasma needle and low-pressure plasma. Furthermore, the cold plasma generators considered for the disinfection devices disclosed therein may include pulsed cold plasma generators or continuous wave cold plasma generators.

Both pulsed and continuous-wave dielectric barrier discharge cold plasma generators may be considered for the disinfection devices disclosed herein. Advantages of dielectric barrier discharge cold plasma generators is small size, making them easily configured, and deployed into an enclosure. Continuous wave dielectric barrier discharge cold plasma generators are advantageous due to their availability and lower costs as compared to pulsed dielectric barrier discharge cold plasma generators. Yet, a disadvantage of employing continuous wave dielectric barrier discharge cold plasma generators in some applications is that they generate considerably more ozone in a given disinfection process as compared to pulsed dielectric barrier discharge cold plasma generators. In particular, the amount of ozone generated from a cold plasma generator may need to be taken into consideration for applications in which items in enclosed structures are disinfected, particularly structures for which ready access by individuals may be desirable. However, the amount of ozone generated from a cold plasma generator for applications of disinfecting a crop field or an enclosure in which ready access is not needed may not be a concern due to such applications facilitating a sufficient environment and/or allowing sufficient timing for the dissipation and/or decomposition of ozone.

Each of the disinfection devices disclosed herein also preferably includes a nozzle device for generating microdroplets, preferably microdroplets having an average diameter at or below 10 microns. For example, an atomizer or a nebulizer can be utilized to generate these small microdroplets. While any type of atomizer or nebulizer may be used in the disinfection devices disclosed herein, it preferable to utilize a nebulizer or atomizer that is configured to generate droplets having an average diameter of 5 pm or smaller. (The size of the microdroplets follows a bell curve on the size distribution, and thus there is variance in the size of the microdroplets.) In particular, small droplets increase the rate of transmission of the reactive oxygen and nitrogen species (RONS) species into the droplets because of the high surface area of the droplets. Thus, the smaller particle sizes are significantly more effective at reducing viral or bacterial loads as compared to larger fluid droplets. In any case, the cold plasma disinfection devices disclosed herein include a battery or a power cord for supplying power to various components, such as but not limited to the plasma generator and the air moving device. In addition, the cold plasma disinfection devices disclosed herein include an operating system and, in some cases, a computer-controlled operating system to control the various electrical components, valves, fans, and the like, which can be connected via wire or wireless connection.

Fig. 1A details an overview of an embodiment of a disinfection device of the present disclosure. Beginning on the left, air filter 1 is provided with replaceable filter media 15. Air filter 1 is positioned adjacent to air moving device 2, having fan blade 12. Alternatively, air moving device may be an air pump. Together, air filter 1 and air moving device 2 work to pull air through the air filter and provide clean air at an appropriate rate to plasma generator 3. Plasma generator 3 includes at least one electrode and, in some cases, may include upper electrodes 13 and lower electrodes 21 stacked upon one another as described in more detail below with respect to Fig. 2. As further depicted in Fig. 1A, plasma generator 3 may, in some cases, include a second set of electrodes in line with the first set, namely rear upper electrode 42 and rear lower electrode 43. In any case, plasma generator 3 creates a nonthermal plasma including reactive oxygen and nitrogen species (RONS) as air is passed over the upper electrodes and lower electrodes and a high voltage is applied to the electrodes. The electrodes can be sized and the voltage appropriately modified based on the necessary output of plasma. For example, voltage of between 15 and 30 kV at 25-40 kHz, with a 100% duty cycle can generate a nonthermal plasma. Appropriate voltage and amplitude are paired with airflow rate and the size and number of electrodes to yield appropriate quantities of plasma to generate reactive species within a given time period. Those of ordinary skill in the art will recognize that the voltage and frequency, as well as the pulse time and duration can be modified to meet the design specifications of the device.

Referring now to Fig. 2, an example configuration of plasma generator 3 is depicted in a side profile view with air 30 being depicted as flowing from left to right. As shown, plasma generator 3 includes stacks of electrodes, namely, upper electrodes 13 and lower electrodes 21. In Fig. 2, upper electrodes 13a and 13b are stacked with each having an attached wiring harness 25a and 25b and connected to power source 22. The entire upper set of electrodes is attached to an upper wall 26, which allows for air to pass adjacent to the electrodes within the chamber. The lower or bottom portion is a mirror image, with a lower electrode set 21a and 21b each having wiring harness 24a and 24b and connected to a power source 23, which is all connected to a lower wall 27. Here, four electrodes are positioned stacked side by side to one another with air and/or microdroplets passing between electrodes. In general, stacking electrodes as depicted in Fig. 2 allows for one efficient way to increase the surface area of the electrodes with the passing air, while allowing the plasma generator 3 to be relatively compact. However, a second or third set of electrodes, or more, as necessary, can be positioned adjacent to the first set, to be in line with the flow of air, or alternatively, positioned parallel within a wider plasma generator. For example, this is depicted in Figs. 1A and IB, with a first set (13 and 21) and a second set (42 and 43), positioned adjacent to each other. In other embodiments, electrodes may be additionally or alternatively placed along the sidewalls of plasma generator 3.

In some cases, the shape of plasma generator 3 may be varied to accommodate additional electrodes along its sidewalls. For example, in some cases plasma generator 3 may be open-ended rectangular, but in other cases plasma generator 3 may include more than four sidewalls to accommodate more electrodes around a given communal area of the generator. For instance, plasma generator may be open-ended hexagonal in some cases to enable an arrangement of six electrodes (or six sets of electrodes) substantially uniformly around a communal area. The total number of sets of electrodes will depend on the volume of air passing over the electrodes and the total amount of plasma necessary to fill the space in any container, in order to reach between 0.1 and 10,000 ppm of plasma, inclusive of all numbers and ranges therein. In some cases, a measurement of plasma concentration may be correlated to ozone concentration. In a preferred embodiment, a concentration is >5 ppm of ozone as dissolved into microdroplets of fluid conserves and stabilize the RONS species. In certain embodiments, the concentration is >6, >7, >8, >9, and >10 ppm ozone. The size of the generators and the total flow of air will depend on the time necessary to fill the space to reach the necessary sanitizing, disinfecting or sterilizing concentration. In some cases, the cold plasma disinfection devices may be modified to include a plurality of plasma generators either in parallel or in series to reach a desired concentration of ozone.

Returning to Fig 1A., microdroplet introduction cavity 41 is shown coupled to a discharge end of plasma generator 3 such that charged air particles including reactive oxygen and nitrogen species (RONS) generated by plasma generator 3 pass into the microdroplet introduction cavity. RONS species such as ozone (O3), hydroxyl radical (OH), hydrogen peroxide (H2O2), singlet oxygen (O2^*), peroxynitrite radical (ONOO^*), and others are generated by the plasma generator 3 and these species are conserved and protected by being dissolved into the fluid microdroplets. Microdroplet introduction cavity 41 includes at least one intake port but is depicted here with three intake ports (i.e., 4a, 4b, and 4c), which are openings in microdroplet introduction cavity 41. In some cases, the openings may contain atomizer nozzles or nebulizers, such as shown by atomizer nozzles 81 in Fig. 3. Atomizer nozzles 81 are connected via tubing 10 to pump 8, which is connected to fluid reservoir 7. Pump 8 and fluid reservoir 7 are connected with tubing 9 to draw fluid from fluid reservoir 7 to pump 8. Pump 8 forces the fluid through the atomizer nozzles, which can be connected via the tubing 10 in series or individually to generate microdroplets, preferably at 10 pm or less in size.

Drain line 11 is attached to microdroplet introduction cavity 41 to capture fluids that collect at the bottom of the microdroplet introduction cavity to return the fluids back to fluid reservoir 7 or to a drain as appropriate. The fluids coming from drain line 11 are charged with the reactive species (RONS) and the fluid retains the dissolved RONS. This allows fluid that is nebulized or atomized from the reservoir to already have some charges and to be more easily saturated with reactive species when such is used with a recirculating system. Alternatively, the fluid can be drained to a further storage tank, where the charged fluid can be used for other processing. Finally, the fluid can simply be drained out of the system to waste or to irrigate, wash, or rinse plants which are being disinfected by the device.

Microdroplets are expressed through the atomizer or nebulizer through the nozzle and then forced into the microdroplet mixing cavity 5. As shown in Fig. 1A, microdroplet mixing cavity 5 and microdroplet introduction cavity 41 together are referenced as a microdroplet introduction chamber 60. Microdroplet mixing cavity 5 includes a helical blade 14 (i.e., an auger-like blade) within its interior extending along at least a portion of a length of the cavity and, in some cases, extending along a majority length of the cavity or along substantially the entire length of the cavity. Helical blade 14 may generally be centered within microdroplet mixing cavity 5 as taken with respect a width-wise cross-section of the cavity, but an off- center position of the helical blade may be considered. In some cases, helical blade 14 may be attached to an interior central post extending along at least a portion of the length of microdroplet mixing cavity 5. Alternatively, helical blade 14 may be attached to the interior sidewalls of microdroplet mixing cavity 5 (i.e., the outer periphery of the blades may be directly attached to the interior sidewalls of microdroplet mixing cavity 5 or helical blade may be suspended from the interior sidewalls of microdroplet mixing cavity 5). Regardless of its attachment within microdroplet mixing cavity 5, helical blade 14 may be cylindrically helical (i.e., having a cylindrical outer form) or may be conically helical (i.e., having a conical outer form).

In any case, the shape of helical blade 14 forces a spiral flow of air and microdroplets as they traverse through microdroplet mixing cavity 5, facilitating more contact between the RONS and the microdroplets. As a result, more RONS are dissolved into the microdroplets. In addition, the spiral motion causes larger microdroplets (i.e., generally microdroplets having a diameter greater than 10 microns) to coalesce or condense along helical blade 14 and along the interior sidewalls of the microdroplet mixing cavity 5. The coalesced or condensed fluid descends to the bottom of microdroplet mixing cavity 5 and is drained into drain line 11. As shown in Fig. 1, the bottom of microdroplet mixing cavity 5 may be sloped to enhance a flow of fluid to drain line 11. In general, microdroplets of over ten microns in diameter are typically those which are impacted by gravity and centrifugal forces. Thus, smaller droplets that are too small to coalesce within the microdroplet mixing cavity 5 (i.e., generally microdroplets having a diameter less than 10 microns) pass around helical blade 14 and are expelled through outlet 6 primarily as charged microdroplets, having been combined with the RONS generated by the plasma generator. These microdroplets can then be utilized to sanitize, disinfect, and/or sterilize perishable items.

Thus, microdroplet mixing cavity 5 serves to essentially sort the microdroplets by size via the rotation of the microdroplets as facilitated by helical blade 14. In general, the amount of rotation of microdroplets as they traverse through microdroplet mixing cavity 5 may depend on the angle (a.k.a., spacing or tightness) and length of helical blade 14 and will vary depending on the design specifications of the device. In some cases, it may be beneficial for helical blade 14 to be dimensionally configured to facilitate at least 360 degrees of microdroplet rotation within microdroplet mixing cavity 5 and, in some cases, at least 720 degrees of microdroplet rotation within microdroplet mixing cavity 5. In particular, such rotation targets were found, during the development of the devices disclosed herein, to aid in discharging of very fine mist of small microdroplet from the devices. For instance, a helical blade facilitating 720 degrees of microdroplet rotation was found to generate a discharge of sub-micron sized microdroplets.

Fig. IB provides a variation of the embodiment of Fig. 1 A, which essentially swaps the position of plasma generator 3 and microdroplet introduction chamber 60. Notably, in this embodiment, microdroplets are introduced and sorted in microdroplet introduction chamber 60 and then any microdroplets not coalesced or condensed in microdroplet mixing cavity 5 pass through plasma generator 3. In such a device configuration, it is important to ensure that the microdroplets entering plasma generator 3 are small enough to not impact and short out the plasma generator. It has been found that droplets having a diameter of less than 10 pm can travel through a dielectric barrier discharge cold plasma generator without shorting its electrodes, particularly since the viscosity of air can oppose gravity for droplets of this size. In other words, droplets having a diameter of less than 10 pm can generally stay suspended in air (such as a mist) and, thus, can move freely with air through the plasma generator without depositing on its electrodes. Such a phenomenon, however, dissipates with droplets of greater diameters. As such, microdroplets of over ten microns in size are generally considered large enough to cause a short in a dielectric barrier discharge cold plasma generator. In addition, as noted above, microdroplets of over ten microns in size are typically those which are impacted by gravity and centrifugal forces. As such, microdroplet mixing cavity 5 in the device depicted in Fig. IB will aid in inhibiting large microdroplets from entering plasma generator 3, particularly by coalescing or condensing the large microdroplets via centrifugal force such that they expel out of drain line 11 instead of outlet 6.

In some cases, a device having microdroplets routed through a plasma generator may include an additional measure to ensure that the microdroplets entering the plasma generator are small enough to not impact and short out plasma generator 3, particularly by having atomizer nozzles 81 displaced below intake ports 4a, 4b and 4c as is shown in the device depicted in FIG. IB and described in more detail below. It is noted, however, that the centrifugal force generated in microdroplet mixing cavity 5 in the device depicted in Fig. IB may be sufficient to ensure large microdroplets are not routed into plasma generator 3 and, thus, atomizer nozzles 81 may be alternatively arranged at intake ports 4a, 4b and 4c for the device configuration depicted in Fig. IB as is described in reference to Fig. 3 for the device configuration of Fig. 1A. In addition, it is noted atomizer nozzles 81 may be alternatively displaced apart from intake ports 4a, 4b, 4c in the device configuration of Fig. 1 A, such as described below in relation to Fig. IB.

As noted above, the device depicted in Fig. IB differs from the device depicted in Fig. 1A in that atomizer nozzles 81 are displaced below intake ports 4a, 4b and 4c. In particular, atomizer nozzles 81 are positioned in tubing 10 below microdroplet introduction cavity 41 with a distance D of tubing 10 between atomizer nozzles 81 and microdroplet introduction cavity 41. The distance D is typically between 0.01 and 3 meters, and most preferably about 0.1 to about 1 meter. Although Fig. IB shows atomizer nozzles 81 spaced apart from pump 8, it may alternatively be arranged adjacent the output of pump 8 within distance D to microdroplet introduction cavity 41. In some cases, the device may include a single atomizer nozzle 81 in tubing 10 to feed intake ports 4a, 4b, and 4c. In other embodiments, tubing 10 may be split into different channels after pump 8 and each channel may include an atomizer nozzle 81 within distance D to intake ports 4a, 4b, and 4c.

In any case, pump 8 forces fluids through atomizer nozzles 81 to create microdroplets. By passing the microdroplets vertically through tubing 10, smaller microdroplets (i.e., generally microdroplets having a diameter less than 10 microns) will flow through to microdroplet introduction cavity 41, while larger droplets (i.e., generally microdroplets having a diameter greater than 10 microns) will be sufficiently impacted by gravity and coalesce and thus will not pass into the microdroplet introduction cavity 41. As noted above, microdroplets of over ten microns in diameter are typically those which are impacted by gravity and centrifugal forces. However, even if some microdroplets over ten microns in diameter are introduced through atomizer nozzles 81 , the act of routing the microdroplets along helical blade 14 in microdroplet mixing cavity 5 will force any droplets greater than 10 pm in diameter to coalesce to the sides of the cavity, removing them from the air flow, thereby allowing only particles, less than 10 pm in diameter, to pass into the plasma generator 3. The plasma generator 3 will charge the microdroplets as they pass therethrough and cause explosions or fissure of the microdroplets, further reducing the size of the microdroplets, particularly to sub-micron sizes. Such a process advantageously increases the available surface area for the RONS to dissolve into, which increases the germicidal efficacy of the disinfection process.

Fig. 3 details the introduction of microdroplets into microdroplet introduction cavity 41 of Fig. 1A. In general, the purpose of microdroplet introduction cavity 41 is to receive microdroplets 82 of fluid which are expelled into the cavity at intake ports 4a, 4b, and 4c. Notably, microdroplet introduction cavity 41 is a continuous space between plasma generator 3 on one end and microdroplet mixing cavity 5 on the other end and with intake ports 4a, 4b, and 4c therebetween as shown in Fig. 1A. As described above, microdroplet mixing cavity 5 serves to essentially sort the microdroplets by size via the rotation of the microdroplets as facilitated by helical blade 14. If and when larger droplets are coalesced or condensed, amassed fluid therefrom flows to drain 83 and exits through the drain line 11. The drain line can revert back to the fluid reservoir 7 and the pump 8 can draw fluid from the reservoir via tubing 9 as shown in Fig. 3 or the drain line can be coupled to a storage tank or a waste drain. Although Fig. 3 illustrates drain 83 along microdroplet introduction cavity 41, it may be alternatively arranged along microdroplet mixing cavity 5.

Figs. 4A, 4B, and 5 detail microdroplet introduction chamber 60 with specificity. Fig. 4A shows a perspective view showing helical blade 14, which functions like an auger blade around central post 31. In sidewall 45 are three openings 32 which correlate to intake ports 4a, 4b and 4c of Fig. 1A, where atomization nozzles 81 are placed to release microdroplets. The section including sidewall 45 between openings 32 and helical blade 14 is microdroplet introduction cavity 41. As shown, sidewall 45 is circular in shape from one end to the other, but other shapes may be considered. Microdroplet mixing cavity 5 with helical blade 14 arranged in its interior is arranged on the opposing end of microdroplet introduction cavity 41 extending to outlet 6 at the discharge end of microdroplet introduction chamber 60. A portion of microdroplet mixing cavity 5 has a conical shape to facilitate the flow of fluid amassed from droplets coalesced or condensed in the cavity to drain 83 (not shown in Fig.

4A) when microdroplet introduction chamber 60 is oriented to discharge charged microdroplets sideways, but other shapes may be considered. These aspects are also shown in Fig. 4B, illustrating a cross-sectional view of microdroplet introduction chamber 60 as taken along line 4B-4B of Fig. 4A and oriented to discharge charged microdroplets downward.

Fig. 5 shows a side perspective view microdroplet introduction chamber 60 from its discharge end including outlets 6. In general, outlets 6 serve to expel microdroplets to their ultimate destination, whether to plants or to plasma generator 3 (as in the configuration of the device depicted in Fig. IB) to charge the microdroplets. Although there are three outlets shown in Fig. 5, any number of outlets may be employed in the device. Furthermore, the periphery of outlets 6 need not be circular. As shown, outlets 6 may, in some cases, have a width narrower than preceding sections of the microdroplet introduction chamber. In other embodiments, however, microdroplet introduction chamber 60 may include a single outlet having a width wider than the widest section of the microdroplet introduction chamber upstream of the outlet.

It is further noted that outlet 6 need not be at the end of microdroplet introduction chamber 60. On the contrary, the disinfection device disclosed in Fig. 1A may, in some cases, include a connection duct between an end of microdroplet introduction chamber 60 and outlet 6. Similarly, the disinfection device disclosed in Fig. IB may, in some cases, include a connection duct at the end of plasma generator 3 rather than the device having its outlet at the end of plasma generator 3. As such, the disinfection devices of Figs. 1A and IB may generally be referred to as having an outlet disposed downstream from microdroplet introduction chamber 60 and plasma generator 3. Furthermore, either of the disinfection devices disclosed in Figs. 1A and IB may include a connection duct between plasma generator 3 and microdroplet introduction chamber 60. An example of a disinfection device having a connection duct between similar of such components is shown and described in more detail below with respect to Fig. 6A.

An alternative configuration of a disinfection device which may be considered for disinfecting items, particularly perishable items and, more particularly, live plants is a device having the components of the device depicted in Fig. 1A, except that microdroplet introduction cavity 41 and microdroplet mixing cavity 5 are in separate chambers. In addition, the components of the alternative disinfection device may be arranged such that plasma generator 3 and a chamber comprising microdroplet introduction cavity 41 are arranged in parallel and their discharge merge at or before flowing into a chamber comprising microdroplet mixing cavity 5, particularly with helical blade 14.

Yet another device which may be considered for disinfecting items, particularly perishable items and, more particularly, live plants is shown in Fig. 6A. The device shown in Fig. 6A differs from the devices shown and described in reference to Figs. 1A and IB in many ways as described in more detail below, particularly the omission of a helical blade to cause a spiral flow of microdroplets, the shape of its microdroplet introduction chamber, and the size of its discharge outlet relative to preceding portions of its microdroplet introduction chamber. In particular, it was discovered during the development of the devices described herein that a helical blade to cause a spiral flow of microdroplets may not be needed for the disinfection of some or all perishable items. More specifically, it was discovered that the device shown and described in reference to Fig. 6A may achieve comparable disinfection results on live growing plants in a farm field as those achieved by conventional hydrogen peroxide bactericides.

It is contemplated that the device shown and described in Fig. 6A may achieve comparable positive results on other perishable items as well, including but not limited to plants growing in a different environment, plant parts separated from its source plant and non-plant perishable items. Furthermore, it is contemplated that the device shown and described in Fig. 6A may achieve comparable positive results on other non-perishable items. In any case, it is contemplated that a disinfection device which generates plasma-charged microdroplets but does not have a helical blade may offer a further benefit of irrigating, rinsing and/or washing the items being treated. Such an added benefit may be particularly applicable for live growing plants and harvested produce. As described above, it is contemplated that the device described in reference to Fig. 5 may be incorporated on any moveable device or a stationary device and may be configured as a stand-alone device.

As shown in Fig. 6A, disinfection device 90 is shown including intake air duct 92, plasma generator 94 and microdroplet introduction chamber 96. As similarly described for the devices discussed in reference to Figs. 1A and IB, intake air duct 92 may, in some cases, include an air filtering media and/or an air moving device (e.g., a fan or an air pump) to provide clean air at an appropriate rate to plasma generator 94. In any case, plasma generator 94 is a cold plasma generator that creates a plasma of reactive oxygen and nitrogen species (RONS) as air is passed over its electrodes. A definition of the term cold plasma generator and examples of such are provided above in reference to Figs. 1A and IB and not reiterated for the sake of brevity. The air charged in plasma generator 94 passes into the microdroplet introduction chamber 96 to combine with microdroplets therein.

Microdroplet introduction chamber 96 may include any number of intake ports for supplying microdroplets but is depicted in Fig. 6A with two intake ports 98a and 98b. In some cases, intake ports 98a and 98b are openings each containing an atomizer nozzle. In other cases, disinfection device 90 may include one or more atomizer nozzles in tubing 99 which supplies fluid to intake ports 98a and 98b, particularly along each of the portions of tubing 99 respectively leading to intake ports 98a and 98b or along the communal portion of tubing 99 before it splits into the portions respectively leading to intake ports 98a and 98b. In any case, the atomizer nozzle/s are configured to generate microdroplets having an average size at or below 10 microns in diameter and, in some configuration, an average diameter of 5 pm or smaller. As further shown in Fig. 6A, disinfection device 90 includes fluid reservoir 91 and pump 93 connected to tubing 99 to supply liquid to the atomizer nozzle/s. As noted above, disinfection device 90 differs from the devices shown and described in reference to Figs. 1 A and IB by the omission of a helical blade. As such, the plasma- charged microdroplets formed in microdroplet introduction chamber 96 pass to outlet 100 without impediment of centrifugal force. As a result, a vast majority of the plasma-charged microdroplets formed in microdroplet introduction chamber 96, including microdroplets of 10 microns in diameter and larger, will be discharged out of outlet 100 and onto the perishable item/s being disinfected. Due to their size, larger microdroplets take longer to evaporate than smaller microdroplets and, thus, disinfection device 90 will generally make items being disinfected and areas around the items more wet and for longer than what may occur with use of the devices shown and described in reference to Figs. 1A and IB. In some cases, such increased water discharge may be beneficial, such as but not limited to irrigating live plants as well as rinsing or washing other perishable items. In some cases, additional wetness may not necessarily be needed or desired for a particular perishable item but yet may not hinder the item and, thus, use of the disinfection device 90 may be additionally or alternatively beneficial over the devices shown and described in reference to Figs. 1A and IB, particularly by being a cheaper and/or a smaller device. On the contrary, the devices shown and described in reference to Figs. 1A and IB may provide benefit over disinfection device 90 for applications in which wetness is not desirable, such as when irrigation is not needed or when the presence of water may cause a hinderance to the item being disinfected, or when it is desirable to reduce the overall size distribution of the microdroplets discharged from the device.

A further benefit of disinfection device 90 not having a helical blade is that the orientation of the device during its operation is less of a concern than the devices disclosed in Figs. 1A and IB. In particular, disinfection device 90 does not include a drain to discharge coalesced droplets as the devices described in reference to Figs. 1A and IB do and, thus, the orientation of disinfection device 90 need not be considered to drain coalesced droplets therefrom. As a result, use of disinfection device 90 in the orientation shown in Fig. 6A may be readily considered for disinfecting items (i.e., oriented downward to disinfect item/s disposed directly beneath the device). Several other orientations of disinfection device 90 may be considered as well to disinfect item/s, such as but not limited to a sideways orientation to disinfect item/s. It is noted that although the position of drain 83 in the devices disclosed in Figs. 1A and IB may need to be considered for the orientation of the devices to disinfect items, it is contemplated that the devices may be designed such that multiple orientations may be possible, including but not limited to orientations that allow for the disinfection of item/s directly beneath the device.

As noted above, the device shown in Fig. 6A further differs from the devices shown and described in reference to Figs. 1A and IB by the size of its outlet relative to preceding portions of its microdroplet introduction chamber. As shown, outlet 100 is wider than preceding sections of microdroplet introduction chamber 96. Such a configuration is generally advantageous to widen the dispersal of discharge from disinfection device 90, which may be advantageous when item/s to be disinfected span a relatively large area. As shown in Fig. 6A, microdroplet introduction chamber 96, as taken from a two-dimensional front view, is pie shaped having a convex edge at outlet 100. Microdroplet introduction chamber 96 and outlet 100, however, may include other shapes to facilitate outlet 100 being wider than preceding sections of microdroplet introduction chamber 96. For example, microdroplet introduction chamber 96 may be rectangular and/or the edge of outlet 100 may be straight. Furthermore, the edge of microdroplet introduction chamber 96 extending between connection duct 95 and outlet 100 need not be straight. For example, the edge of microdroplet introduction chamber 96 extending between connection duct 95 and outlet 100 may be stepped or concave.

Despite the advantage to widen the dispersal of discharge from disinfection device 90, outlet 100 of disinfection device 90 may be alternatively sized to have approximately the same or smaller size than preceding sections of microdroplet introduction chamber 96. Such a configuration may be advantageous to concentrate the dispersal of discharge from disinfection device 90 within particular areal dimensions. It is further noted that outlet 100 need not be at the end of microdroplet introduction chamber 96. On the contrary, disinfection device 90 may, in some cases, include a connection duct between an end of microdroplet introduction chamber 96 and outlet 100. As such, disinfection device 90 may generally be referred to as having an outlet disposed downstream from microdroplet introduction chamber 96 and plasma generator 94. Furthermore, disinfection device 90 may be additionally or alternatively void of connection duct 95.

Fig. 6B shows an example configuration of microdroplet introduction chamber 96 as taken from a three-dimensional perspective side view. As shown in Fig. 6B, in addition to being pie-shaped as taken from a two-dimensional front view of microdroplet introduction chamber 96, microdroplet introduction chamber 96 is also wedge-shaped as taken from a three-dimensional perspective side view, particularly having a wider portion at its union with connection duct 95 and narrowing as it extends to outlet 100. As further shown in Fig. 6B, intake ports 98a and 98b are arranged in the narrower depth portion of the wedge (i.e., closer to outlet 100 than connection duct 95). Such a configuration may be advantageous to cause the microdroplets introduced into microdroplet introduction chamber 96 at intake ports 98a and 98b to hit the opposing interior side of microdroplet introduction chamber 96 and break into smaller sized microdroplets, reducing the size of some microdroplets discharged from disinfection device 90 and, thus, reduce the size distribution of the droplets. In addition, the collision of microdroplets against interior side of the microdroplet introduction chamber 96 may cause the microdroplets to rebound, increasing their exposure and availability to mix with charged particles routed from plasma generator 94 before being discharged through outlet 100. As a consequence, a higher concentration of charged microdroplets may be discharged from disinfection device 90.

Although the wedge-shape of microdroplet introduction chamber 96 enables such an advantage for the disinfection device shown in Fig. 6A, it is noted that microdroplet introduction chamber 96 need not be restricted to such a shape for disinfection device 90 to realize such a benefit. In particular, all of or a portion of connection duct 95 and/or an end portion of plasma generator 94 may be additionally or alternatively wedge-shaped and, thus, microdroplet introduction chamber 96 may not be wedged shape or, alternatively, may have a wedge-shape arranged in the opposite direction than what is shown in Fig. 6B. In any of such cases, the wedge shapes of an end portion of plasma generator 94 and/or of connection duct 95 may facilitate microdroplet introduction chamber 96 to have a relatively narrower depth at least at its entrance. If intake ports are arranged at narrow depth portions of such a microdroplet introduction chamber, the resulting disinfection device may realize the benefit of microdroplets hitting and rebounding off of interior walls of the microdroplet introduction chamber as described above. In cases in which a microdroplet introduction chamber has a relatively narrow section at its entrance, it may be advantageous to arrange intake ports closer to its entrance than its exit nozzle to further increase the travel time by which to mix the droplets with charge plasma particles, particularly if a majority length of the microdroplet introduction chamber is narrow to facilitate continual rebounding of microdroplets as it travels therethrough. A corollary of microdroplets breaking and rebounding off of interior walls of microdroplet introduction chamber 96 is that portions of the breaking microdroplets may stick to and drip down the interior walls, coalescing with other microdroplet remnants as they move down microdroplet introduction chamber 96. The coalesced microdroplet remnants contribute to wetting items and surrounding areas treated by disinfection device 90 as they exit outlet 100. In some cases, microdroplet introduction chamber 96 may include a drain to collect coalesced microdroplet remnants to reduce the amount of coalesced liquid discharged from discharge outlet 100 onto items being treated. In some of such cases, the coalesced liquid may be recycled to the reservoir supplying fluid to disinfection device 90, such as discussed in reference to the devices described in Figs. 1A and IB.

In some cases, disinfection device 90 may be configured such that no coalesced liquid or microdroplets having a diameter greater than 10 microns are discharged from outlet 100 onto items being treated. In this manner, the wetness of the items treated by disinfection device 90 may be minimized as is achieved by the devices described in Figs. 1A and IB. Configurations used to give such functionality to disinfection device 90 may include but are not limited to arranging intake ports at a narrower portion of microdroplet introduction chamber 96 (e.g., a portion having a depth of less than approximately 6 inches) and possibly closer to outlet 100 than connection duct 95, optimizing the length of the narrow portion of the microdroplet introduction chamber 96, placement of the drain, shape of microdroplet introduction chamber 96, design of the interior walls of microdroplet introduction chamber 96, and orientation of disinfection device 90 during use. If disinfection device 90 is designed such that no coalesced liquid or microdroplets having a diameter greater than 10 microns are discharged from outlet 100 onto items being treated, it is contemplated that microdroplet introduction chamber 96 may be placed upstream from plasma generator 94 as is discussed for the device described in Fig. IB relative to the device in Fig. 1A.

In any case, in configurations in which microdroplet introduction chamber 96 includes a drain, disinfection device 90 may be configured for its selective use. In particular, disinfection device 90 may be configured to open or close the drain based on user selection or based on feedback from a humidity sensor or a moisture sensor (air or soil) used in conjunction with disinfection device 90. In this manner, the functionality of disinfection device 90 to chiefly be used as a disinfection device without simultaneously providing irrigation, washing or rinsing functionality or to be used for simultaneously disinfecting an item as well as irrigating, washing or rinsing the item may be selected by a user of the device or may be based on the environment in which the item is arranged. Such selective functionality may also be incorporated into the device described in reference to Figs. 1A and IB if the unit is oriented to discharge charged microdroplets downward to disinfect item/s disposed directly beneath the device.

In any case, it is noted that the configuration of microdroplet introduction chamber 96 to have a narrow depth section to facilitate a higher concentration of microdroplets discharged from the device and a wide discharge outlet to provide a wide dispersal of microdroplets from the device are not mutually inclusive. In particular, microdroplet introduction chamber 96 may be designed to provide either function but not the other. As such, although microdroplet introduction chamber 96 may be pie-shaped and wedge-shaped as described above in references to Figs. 6 A and 6B, the microdroplet introduction chamber may just include one of such design configurations. Furthermore, as noted above, any portion of microdroplet introduction chamber 96 or connection duct 95 and/or an end portion of plasma generator 94 may be wedge-shaped to enable microdroplet chamber 96 to have a narrow depth section to facilitate a higher concentration of microdroplets discharged from the device. Other designs for such components to achieve such an objective, however, may be used. In particular, the components may include any shape or design to facilitate a portion having a relatively wide depth and a portion downstream therefrom having a relatively narrow depth, such as but not limited to less than approximately 6 inches. In any case, the depth of a narrow section of a microdroplet introduction chamber may be expressed in relation to the depth of the plasma generator of the device since a particular depth of the plasma generator is designed to generate a sufficient plasma to charge the microdroplets. For example, a ratio of a depth of a microdroplet introduction chamber at one of its intake ports and a depth of a portion of the plasma generator where its electrode/s are arranged may be approximately 1:3 or smaller.

Regardless of the design of the disinfection devices disclosed herein, the charged microdroplets discharged therefrom may be utilized to coat live plants for disinfection. For example, when the charged microdroplets are expelled from the device, they can be blown over growing plants, whether in a field, a greenhouse, or a vertical farming warehouse. By providing a sufficient density of charged microdroplets, the microdroplets are able to quickly and evenly cover the plants with the reactive microdroplets. In turn, the reactive microdroplets are thus able to disinfect, sanitize, and/or sterilize the plant surfaces they are contacting.

Figs. 7 A and 7B detail an embodiment wherein a tractor is utilized to treat crops utilizing one or more of the disinfection devices described herein with Fig. 7 A depicting individual disinfection devices on the arms of the sprayer and Fig. 7B depicting a centralized disinfection device with openings on the sprayer arms. In embodiments involving a tractor, the sprayer bar may alternatively be referred to as a sprayer boom. The tractor in either embodiment of Figs. 7A and 7B can be replaced by other agricultural treatment devices including but not limited to rolling irrigation systems, crop dusters, airplanes, helicopters, drones, ATV vehicles, trucks, robotic vehicles, or any other movable vehicle, including one which is specifically designed and built to use one or more of the devices disclosed herein. In yet other embodiments, one or more of the disinfection devices described herein may be incorporated into a wheeled device other than a vehicle, movement of which may be manual or automated. Alternatively, the devices described herein may be attached to a stationary system, such a stationary irrigation system or any other stationary device or system, including one which is specifically designed and built to use one or more of the devices disclosed herein.

As shown in Fig. 7A, tractor 101 having sprayer bars 102 is utilized on a set of row crops 104. Sprayer bars 102 extend laterally from tractor 101, allowing numerous rows to be sprayed simultaneously. In Fig. 7A, the device is shown with five disinfection devices 103 on each of sprayer bars 102, however this number can be increased or decreased as needed for each particular use case. Each of disinfection devices 103 is positioned along the length of the sprayer bar 102 so as to be positioned at an appropriate distance to spray crop rows.

As the tractor moves along the length of the rows 104, the plants growing in the rows can be sprayed with microdroplets 105 being expelled from the disinfection device 103. Although Fig. 7A illustrate disinfection devices 103 discharging microdroplets 105 sideways, disinfection devices 103 may alternatively be oriented to discharge charged microdroplets 105 downward to disinfect item/s disposed directly beneath the systems.

In some cases, each of the disinfection devices 103 can independently carry fluids, pumps, air filters and air moving devices and, thus, in some embodiments, disinfection devices 103 can be inclusive to all of the components described for any of the disinfection devices described herein, particularly in reference to Figs. 1A, IB, 6A and 6B and any variants thereof. In other embodiments, tractor 101 and/or the spray boom may include a centralized fluid supply system and/or a centralized air supply system and, thus, disinfection devices 103 may include the components described for any of the disinfection devices described in reference to Figs. 1 A, IB, 6A and 6B except for a fluid reservoir, a pump, an atomizer, an air moving device, and/or an air filter. For instance, tractor 101 and/or the spray boom may include one or more communal fluid reservoirs 107 and one or more communal pumps 106 to pass microdroplets or just fluids to each of the disinfection devices 103 along the length of the sprayer bars 102. In addition or alternatively, tractor 101 and/or the spray boom may include one or more communal air moving devices 109 to pass air along a communal air duct which connects to each of disinfection devices 103. In some of such cases, the communal air duct may include communal air filter, but in other cases, each of disinfection devices 103 may include their own air filter.

Fig. 7B depicts a centralized approach, wherein the disinfection device 112 is located on tractor 101. Instead of having individual disinfection devices 103 along the length of the sprayer bars 102 as in Fig. 7A, lengths of tubing 108 are positioned along the length of the sprayer bars, and at each appropriate length along the sprayer bars 102, opening 110 (such as an atomizer or nebulizer, or just an opening) is provided to discharge the microdroplets onto the rows 104. This allows for the system to be centralized on the tractor 101 and to simply blow charged microdroplets along the length of the tubing 108 to spray them onto the rows 104 of plants. In such a configuration, disinfection system 112 may include all of the components described for any of the disinfection devices described herein, particularly in reference to Figs. 1A, IB, 6A and 6B and any variants thereof. The system can utilize a computer-controlled system to determine the required pressures and quantities of fluids, particularly for the air flow along tubing 108, as those in closer proximity to the tractor may require different volumes, pressures, and such in order to operate consistently among all of openings 110.

As noted above, the devices described herein may be attached to any agriculture treatment device for expressing charged microdroplet onto plants growing in crop field. However, the devices can also be used on live growing plants in other environments as well. For example, the disinfection devices described herein may be configured to facilitate manual portability of the device as a cohesive unit. For example, the disinfection devices described herein may be incorporated into a handheld device or may be contained within and/or attached to an exterior surface of a bag, such as but not limited to a backpack or a shoulder bag. In such cases, the disinfection devices may include one or more carrier features for facilitating manual portability of the device as a cohesive unit, such as a handle and/or one or more shoulder straps. In some of such cases, the device may be configured such that microdroplets are expelled from a handheld device (i.e., the outlet of the disinfection device is part of a handheld device) extending from a bag or other portable storage unit and the device may manually walked in a field or greenhouse setting.

In any of such cases, the concept of a cohesive unit refers to the components of the disinfection device being joined such that when the disinfection device is transported to a different location, the disinfection device as a whole is moved together. The concept is inclusive to embodiments in which components of the disinfection device are not moveable relative to each other as well as embodiments in which some of the components are moveable relative to each other. For instance, it is contemplated that a disinfection device may be configured as a cohesive unit in which all of its components are fixedly arranged relative to each other. In other cases, a disinfection device may include its output coupled to a moveable arm or moveable duct coupled to receive plasma charged microdroplets discharged from a microdroplet introduction chamber or a plasma generator of the device.

In yet other cases, the devices described herein and any variants thereof may be attached to or arranged within an enclosure in which one or more container of plants are disposed, particularly such that plasma charged microdroplets generated by the disinfection device are discharged onto the container of plants. Examples of enclosures include but are not limited to greenhouses and vertical framing warehouses. Fig. 8 details an example configuration of an enclosure having one of the cold plasma disinfection devices described herein attached thereto. In general, enclosure 70 can be of any size and shape. Although enclosure 70 is shown having a single door 57 on one end, the configuration of enclosures considered for the disinfection devices disclosed herein are not so limited. In particular, enclosure 70 may include any number and sizes of egresses, which are closable or not closable.

As shown in Fig. 8, enclosure 70 may include containers of plants 51, 52 and 53. Any number and type of containers and any number and type of plants may be disposed in enclosure 70. Attached on top of enclosure 70 is one of the cold plasma disinfection devices described herein for generating and discharging plasma charged microdroplets. In alternative embodiments, the cold plasma disinfection device may be attached to a different surface of enclosure 70, including interior or exterior surfaces and particularly exterior sidewalls, interior sidewalls, the interior ceiling, and the interior flooring of enclosure 70. In yet other embodiments, the cold plasma disinfection device may not be attached to surfaces of enclosure 70, but rather may be arranged within enclosure, such as but not limited to being on a cart, on a stand, on a shelf, on a suspension pole or hook, or as a free-standing unit. As set forth below, a cold plasma disinfection device may be attached to a container for growing plants, which may be arranged in an enclosure (e.g., a building) or outdoors.

As shown in Fig. 8, the cold plasma disinfection attached to enclosure 70 includes air filter 1, air moving device 2, cold plasma generator 3, microdroplet introduction chamber 60, which may optionally include a helical blade. Air filter 1 is as previously detailed in Figs. 1A and IB, as is air moving device 2, plasma generator 3, microdroplet introduction chamber 60 and the optional helical blade. In some cases, the cold plasma disinfection device attached to enclosure 70 may include a fluid reservoir, pump, and tubing coupled to microdroplet introduction chamber 60. In other embodiments, however, enclosure 70 may include its own fluid source and pump to which microdroplet introduction chamber 60 may be coupled. Such an embodiment may be particularly applicable when enclosure 70 is a building with a piped water supply. In some cases, the cold plasma disinfection device attached to enclosure 70 may include power source 87 connected to its other components in order to provide the necessary power to operate the components. In other embodiments, enclosure 70 may include its own power source to which cold plasma disinfection device may be coupled.

Such an embodiment may be particularly applicable when enclosure 70 is a building with a mains power supply. As further shown in Fig. 8, the cold plasma disinfection device includes operating system 84 to control the various electrical components, valves, fans, and the like. Each of the components can be connected via wire or wireless connection, as understood by one of ordinary skill in the art.

In FIG. 8, the cold plasma disinfection device is fluidly connected with opening 54 of enclosure 70 by connection feature 61 to allow for transfer of plasma charged microdroplets 85 from the cold plasma disinfection device into the enclosure 70. Connection feature 61 may be a valve or gasket or may be tubing or piping. In some cases, enclosure 70 may include one or more fans 71-74 within enclosure 70 to aid in the mixing and circulation 86 of plasma charged microdroplets 85 within enclosure 70. This provides additional airflow to help the plasma charged microdroplets 85 to cover and saturate the live plants within enclosure 70. In some cases, enclosure 70 may include a plurality of the cold plasma disinfection devices disclosed herein in order to supply and distribute a sufficient amount of plasma charged microdroplets onto plants or other perishable items in enclosure 70.

In some embodiments, enclosure 70 may include a vacuum pump and a vacuum opening extending through a sidewall of the enclosure or its roof. In such cases, the cold plasma disinfection device on or within the enclosure may be void of air moving device 2 and, instead, utilize the flow of air from a vacuum created and released in enclosure 70. In this embodiment, the device works without the use of a fan or other air generator as it utilizes negative pressure created by the vacuum to draw air through the system. More specifically, when a vacuum is pulled within the enclosure 70 and then released at the opening 54, air will be pulled through air filter 1, plasma generator 3, microdroplet introduction chamber 60, and then through the connection apparatus 61, which expels the plasma charged microdroplets 85 into the enclosure 70. These microdroplets will then be circulated 86 throughout the enclosure 70 and cover the contents of the enclosure, i.e., coating the growing plants within the enclosure with the reactive species within microdroplets 85.

As set forth below, any of the cold plasma disinfection devices disclosed herein and variants thereof may be attached to a container for growing plant/s, which may be arranged in an enclosure (e.g., a building) or outdoors. Examples of containers which may include a cold plasma disinfection device attached thereto include but are not limited to plant pots, plant trays and vertical farming structures. An example of a container having a cold plasma disinfection device attached thereto is shown in Fig. 8 by cold plasma disinfection device 88 attached to container 53. It is noted that enclosure 70 need not include a plant container with a cold plasma disinfection device attached to it, nor does cold plasma disinfection device 88 need to be attached to a plant container arranged in an enclosure. Thus, the description of either of such scenarios are not necessarily inclusive to the other.

In general, cold plasma disinfection device 88 may be attached to container 53 in any manner and to any part of container 53 such that discharge from cold plasma disinfection device 88 is projected into an ambient of the disinfection device. More specifically, cold plasma disinfection device 88 may be attached to container 53 in any manner and to any part of container 53 such that the outlet of cold plasma disinfection device is directed or can be manipulated to be directed to plant/s growing in container 53 or the area of container 53 in which plant/s may be planted. In some cases, cold plasma disinfection device 88 may be detachable from container 53 such that it may be moved to different parts of container to disinfect different surfaces of plant/s growing therein. In addition or alternatively, cold plasma disinfection device 88 may be attached to container 53 such that the disinfection device may be moved (i.e., either manually or automatically) when it is attached to container 53 such that it may oriented to disinfect different surfaces of plant/s growing therein. In some cases, either of such movement capabilities may be advantageous for placing the disinfection device in a position to maximize the distribution of plasma charged microdroplets over the plant/s growing in the container during a disinfection cycle but then be able to move the disinfection device so that light is not blocked from directly exposing the plant/s.

Cold plasma disinfection device 88 may include any of the disinfection devices disclosed herein and variants thereof. In particular, cold plasma disinfection device 88 includes an air moving device for drawing air from an ambient of the container into the disinfection device, a cold plasma generator, a microdroplet introduction chamber arranged upstream or downstream from the cold plasma generator, and an optional helical blade. In addition, cold plasma disinfection device 88 includes at least one atomizer for introducing microdroplets into at least one intake port of the microdroplet introduction chamber and an outlet disposed downstream from the microdroplet introduction chamber and the cold plasma generator for discharging plasma charged microdroplets into an ambient of the disinfection device. In some cases, cold plasma disinfection device 88 may include a fluid reservoir, pump, and tubing coupled to the microdroplet introduction chamber. In other embodiments, however, the environment in which container 53 is arranged (i.e., either indoors or outdoors) may include its own fluid source and pump to which the microdroplet introduction chamber may be coupled. Such an embodiment may be particularly applicable when the fluid source is a piped water supply. In some cases, cold plasma disinfection device 88 may include its own power source to provide the necessary power to operate its components. In other embodiments, cold plasma disinfection device 88 may be configured to couple to an auxiliary power source. Furthermore, cold plasma disinfection device 88 may include an operating system to control operation of its various components, which can be connected via wire or wireless connection.

A method to reduce a pathogenic load on live plants utilizing any one of the cold plasma disinfection devices disclosed herein includes introducing air into a plasma generator to generate reactive oxygen and nitrogen species. Because air contains both oxygen and nitrogen compounds, when these air molecules pass the electrodes of the plasma generatore a variety of reactive species are generated. However, these reactive species are typically unstable. Accordingly, there is a need to stabilize the reactive species so that they can then attack pathogenic materials. As such, the method further introducing microdroplets into a microdroplet chamber and mixing the microdroplets with the reactive oxygen and nitrogen species to form charged microdroplets. In some cases, the microdroplets may be mixed with the reactive oxygen and nitrogen species in the microdroplet chamber. In other embodiments, the microdroplets may be mixed with the reactive oxygen and nitrogen species in the plasma generator. In yet other cases, the microdroplets may be mixed with the reactive oxygen and nitrogen species downstream of the microdroplet chamber and the plasma generator. In any case, when combined with the atomized microdroplets, species such as ozone (O3), hydroxyl radical (OH), hydrogen peroxide (H2O2), singlet oxygen (O2^*), peroxynitrite radical (ONOO^*), and others from the plasma are conserved and protected by being dissolved into fluid droplets. It is these radicals, most specifically the ozone, peroxides, and peroxynitrite which are the key effectors in reducing bacterial and viral loads.

The fluid used to form the microdroplets for the method and devices disclosed described herein is preferably non-DI or RO-DI water, such as tap water, well water, natural flowing water or any other water source, or otherwise reconstituted water containing metallic ions. Thus, the iron and/or other multivalent metals, as required for Fenton’s reaction will be present in the fluid to allow for Fenton’ s mechanism to proceed. Furthermore, additional metallic ions will be present in tap or well water and which also stabilize RONS species. In some cases, the fluid used to form the microdroplets for the method and devices disclosed described herein may include additional excipients such as: acids, bases, buffer solutions (comprising a conjugate acid and base), peroxide solutions, bleach, peracetic acid, etc. In some cases, the fluid may include 0.1% to 25% of an additional excipient, with the remaining portion being water. It is particularly noted that applications comprising about 10% of an excipient with 90% water led to a 1-2 log increase in killing power over 100% of an excipient, or 100% of water. Accordingly, the combination is not merely additive, but exponentially improved.

A key feature of the atomized microdroplets is their size. While a typical atomizer may be effective in generating droplets of fluid, these are typically variable in size between 5-100 microns. However, by reducing the size of the microdroplets to below ten microns or even to a sub-micron size, the total surface area of the microdroplets can be dramatically increased. Furthermore, by reducing the size of the microdroplets, the number of microdroplets generally increases which aid in ensuring there are sufficient quantities and density of microdroplets to saturate the surface of the materials being disinfected. As such, the method disclosed herein further includes formulating a distribution of microdroplets having a smaller average diameter at a discharge end of the microdroplet chamber than a distribution of microdroplets introduced into the microdroplet chamber (i.e., compared to a size distribution of microdroplets created by the atomizer nozzles generating the microdroplets).

In some cases, such a process may include routing the microdroplets along a helical blade along the microdroplet chamber, particularly if either of the disinfection devices disclosed in Figs. 1A and IB are used. In addition or alternatively, the step of formulating the distribution of smaller size microdroplets may include colliding the microdroplets introduced into the microdroplet chamber with the opposing side of the microdroplet chamber, such as described in reference to the disinfection device in Figs. 6 A and 6B. In some cases, microdroplet size may be reduced by passing the microdroplets through a plasma generator and/or arranging the atomizers in tubing under the microdroplet introduction cavity as described in reference to Fig. IB. It is noted that depending on their design, any one or more of such configurations may yield a distribution of microdroplets having at least 10 times smaller average diameter at an end of the microdroplet introduction chamber than a distribution of microdroplets generated by the atomizer. In some cases, it may be one or more of the noted configurations of the microdroplet introduction chamber itself that yield a distribution of microdroplets having at least 10 times smaller average diameter at an end of the microdroplet introduction chamber than a distribution of microdroplets generated by atomizer. In any case, subsequent to mixing the microdroplets with the reactive oxygen and nitrogen species to form charged microdroplets, the charged microdroplets are discharged onto live plants. This method quickly and safely provides for sanitization, disinfection, and sterilization of the live plants with minimal fluid or fluid waste and without the need for or use of toxic chemicals, as the reactive species will degrade rapidly into nonreactive species which are innocuous after a short amount of time. However, these reactive species remain active to oxidize pathogens for at least 30 seconds, and most likely for several minutes at a minimum. Specifically, these devices and methods provide new mechanisms to reduce pathogen loads on growing plant materials grown in field, greenhouse, or container applications. In order to properly sanitize, disinfect, and/or sterilize the plants, the plants should be coating with microdroplets with a sufficient dwell time to destroy or inactivate pathogens. For example, a dwell time of at least thirty seconds on the surface of plants may be needed. However, additional time may be utilized without damage to the perishable items in most cases. Similar dwell times may be considered for other perishable items as well.

Because of their small size, the microdroplets expelled from the discharge outlets of the devices described herein are effective in fully and evenly coating plants on a field, in a enclosure, or in a container. Thus, where E. coli or other microorganisms are present on the surface of the plants, application of microdroplets destroys the microorganisms, even without the Fenton reaction. However, in the presence of iron, there will be even stronger oxidization and thus more effective killing of the various pathogens. Thus, by creating cleaner plant materials before harvest, once harvested, the risk of contamination and cross-contamination by the plants is reduced.

It will be appreciated to those skilled in the art having the benefit of this disclosure that this invention is believed to provide cold plasma disinfection devices that are environmentally safe and do not present a health hazard for disinfecting plants. Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. For example, although the emphasized use of the cold plasma disinfection devices disclosed herein is disinfect plants, the devices may be used to disinfect any item, including any perishable or non-perishable item. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention.

It is to be understood that the forms of the invention shown and described herein are to be taken as the presently preferred embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims. The term “approximately” as used herein refers to variations of up to +/- 5% of the stated number.

Claims

WHAT IS CLAIMED IS:

1. An agricultural treatment device, comprising: a sprayer bar; and a plurality of disinfection devices spaced along the sprayer bar; at least one air moving device for moving air into the plurality of disinfection devices; and at least one fluid reservoir and at least one pump for supplying fluid to the plurality of disinfection devices, wherein each of the plurality of disinfection devices comprise: a cold plasma generator; a microdroplet introduction chamber arranged upstream or downstream from the cold plasma generator; at least one atomizer for introducing microdroplets into at least one intake port of the microdroplet introduction chamber; and an outlet, wherein each of the plurality of disinfection devices is arranged on the sprayer bar such that plasma charged microdroplets are discharged from the outlet into an ambient of the agricultural treatment device.

2. The agricultural treatment device of claim 1 , wherein the agricultural treatment device is a tractor.

3. The agricultural treatment device of claim 1, wherein the agricultural treatment device is a spray boom.

4. The agricultural treatment device of claim 1 , wherein the agricultural treatment device is an irrigation system.

5. The agricultural treatment device of any of claims 1-4, wherein the at least one air moving device comprises a plurality of air moving devices respectively disposed within each of the plurality of disinfection devices.

6. The agricultural treatment device of any of claims 1-5, wherein the at least one fluid reservoir comprises a plurality of fluid reservoirs respectively disposed within each of the plurality of disinfection devices, and wherein the at least one pump comprises a plurality of pumps respectively disposed within each of the plurality of disinfection devices.

7. The agricultural treatment device of any of claims 1-6, wherein the microdroplet introduction chamber comprises a helical blade for facilitating a spiral flow of microdroplets through the microdroplet introduction chamber.

8. The agricultural treatment device of claim 7, wherein the helical blade is configured to facilitate at least a 360° spiral flow of microdroplets through the microdroplet introduction chamber.

9. The agricultural treatment device of claim 7, wherein the helical blade is configured to facilitate at least a 720° spiral flow of microdroplets through the microdroplet introduction chamber.

10. The agricultural treatment device of any of claims 1-9, wherein a depth of the microdroplet introduction chamber at which the at least one intake port is arranged in less than 6 inches.

11. The agricultural treatment device of any of claims 1-10, wherein the outlet that is wider than the widest section of the microdroplet introduction chamber upstream of the outlet.

12. The agricultural treatment device of any of claims 1-11, wherein the microdroplet introduction chamber is configured to formulate a distribution of microdroplets having a smaller average diameter at an end of the microdroplet introduction chamber than a distribution of microdroplets introduced into the microdroplet introduction chamber at the least one intake port.

13. A disinfection device, comprising: an inlet comprising an air filter; an air moving device for drawing air from an ambient of the disinfection device through the air filter; a cold plasma generator arranged to receive filtered air from the inlet; a microdroplet introduction chamber arranged upstream or downstream from the cold plasma generator; at least one atomizer for introducing microdroplets into at least one intake port of the microdroplet introduction chamber, wherein the microdroplet introduction chamber is configured to formulate a distribution of microdroplets having a smaller average diameter at an end of the microdroplet introduction chamber than a distribution of microdroplets introduced into the microdroplet introduction chamber at the least one intake port; an outlet disposed downstream from the microdroplet introduction chamber and the cold plasma generator for discharging plasma charged microdroplets into an ambient of the disinfection device; a fluid reservoir and a pump for supplying fluid to the at least one atomizer; a power supply, wherein the power supply, the fluid reservoir, the pump, the at least one atomizer, the microdroplet introduction chamber, the cold plasma generator, the air moving device and the air filter comprise a portable cohesive unit; and one or more carrier features for facilitating manual portability of the cohesive unit, wherein the one or more carrier features comprise a handle and/or one or more shoulder straps.

14. The disinfection device of claim 13, wherein the microdroplet introduction chamber comprises a helical blade for facilitating a spiral flow of microdroplets through the microdroplet introduction chamber.

15. The disinfection device of claim 13, wherein a depth of the microdroplet introduction chamber at which the at least one intake port is arranged in less than 6 inches.

16. The disinfection device of any of claims 13-15, wherein the at least one atomizer is arranged at the at least one intake port, and wherein the microdroplet introduction chamber is configured to formulate a distribution of microdroplets having a smaller average diameter at an end of the microdroplet introduction chamber than a distribution of microdroplets generated by the at least one atomizer.

17. The disinfection device of any of claims 13-16, wherein the microdroplet introduction chamber is configured to formulate a distribution of microdroplets having at least 10 times smaller average diameter at an end of the microdroplet introduction chamber than a distribution of microdroplets generated by the at least one atomizer.

18. The disinfection device of any of claims 13-17, wherein the power supply, the fluid reservoir, the pump, the at least one atomizer, the microdroplet introduction chamber, the cold plasma generator, the air moving device and the air filter are contained in or attached to an exterior surface of a bag.

19. The disinfection device of any of claims 13-18, wherein the outlet is part of a handheld device.

20. An enclosure for growing plants, comprising: containers of plants; and a disinfection device attached to or arranged within the enclosure such that plasma charged microdroplets generated by the disinfection device are discharged onto the containers of plants, wherein the disinfection device comprises: an air moving device for drawing air from an ambient of the disinfection device into the disinfection device; a cold plasma generator; a microdroplet introduction chamber arranged upstream or downstream from the cold plasma generator; at least one atomizer for introducing microdroplets into at least one intake port of the microdroplet introduction chamber; and an outlet disposed downstream from the microdroplet introduction chamber and the cold plasma generator for discharging plasma charged microdroplets into an ambient of the disinfection device.

21. The enclosure of claim 20, wherein the enclosure is a greenhouse.

22. The enclosure of claim 20, wherein the enclosure is a vertical farming warehouse.

23. The enclosure of any of claims 20-22, wherein the microdroplet introduction chamber comprises a helical blade for facilitating a spiral flow of microdroplets through the microdroplet introduction chamber.

24. The enclosure of any of claims 20-23, wherein a depth of the microdroplet introduction chamber at which the at least one intake port is arranged in less than 6 inches.

25. The enclosure of any of claims 20-24, wherein the microdroplet introduction chamber is configured to formulate a distribution of microdroplets having a smaller average diameter at an end of the microdroplet introduction chamber than a distribution of microdroplets introduced into the microdroplet introduction chamber at the least one intake port.

26. The enclosure of any of claims 20-25, wherein the disinfection device comprises a fluid reservoir and a pump for supplying fluid to the at least one atomizer.

27. The enclosure of any of claims 20-25, wherein the enclosure comprises a fluid supply line, and wherein the disinfection device comprises a fluid line coupled to the fluid supply line for supplying fluid to the at least one atomizer.

28. A container for growing plants, comprising a cold plasma disinfection device attached to the container such that plasma charged microdroplets generated by the cold plasma disinfection device are discharged into an ambient of the container, wherein the cold plasma disinfection device comprises: an air moving device for drawing air from an ambient of the container into the disinfection device; a cold plasma generator; a microdroplet introduction chamber arranged upstream or downstream from the cold plasma generator; at least one atomizer for introducing microdroplets into at least one intake port of the microdroplet introduction chamber; and an outlet disposed downstream from the microdroplet introduction chamber and the cold plasma generator for discharging plasma charged microdroplets into an ambient of the disinfection device.

29. The container of claim 28, wherein the container is a plant pot.

30. The container of claim 28, wherein the container is a vertical farming structure.

31. The container of any of claims 28-30, wherein the microdroplet introduction chamber comprises a helical blade for facilitating a spiral flow of microdroplets through the microdroplet introduction chamber.

32. The container of any of claims 28-30, wherein a depth of the microdroplet introduction chamber at which the at least one intake port is arranged in less than 6 inches.

33. The container of any of claims 28-32, wherein the microdroplet introduction chamber is configured to formulate a distribution of microdroplets having a smaller average diameter at an end of the microdroplet introduction chamber than a distribution of microdroplets introduced into the microdroplet introduction chamber at the least one intake port.

34. The container of any of claims 28-33, wherein the disinfection device comprises a fluid reservoir and a pump for supplying fluid to the at least one atomizer.

35. A method to reduce pathogenic loads on live plants, comprising: introducing air into a plasma generator to generate reactive oxygen and nitrogen species; introducing microdroplets into a microdroplet chamber; formulating a distribution of microdroplets having a smaller average diameter at a discharge end of the microdroplet chamber than a distribution of microdroplets introduced into the microdroplet chamber; mixing the microdroplets with the reactive oxygen and nitrogen species to form charged microdroplets; and discharging the charged microdroplets onto live plants.

36. The method of claim 35, wherein the step of formulating the distribution of microdroplets comprises routing the microdroplets along a helical blade along the microdroplet chamber.

37. The method of claim 35, wherein the step of formulating the distribution of microdroplets comprises colliding the microdroplets introduced into the microdroplet chamber with the opposing side of the microdroplet chamber.

38. The method of any of claims 35-38, wherein the step of mixing the microdroplets with the reactive oxygen and nitrogen species is conducted in the microdroplet chamber.

39. The method of any of claims 35-38, wherein the step of mixing the microdroplets with the reactive oxygen and nitrogen species is conducted in the plasma generator.

40. The method of any of claims 35-38, wherein the step of mixing the microdroplets with the reactive oxygen and nitrogen species is conducted downstream of the microdroplet chamber and the plasma generator.