Low temperature fabric dielectric barrier discharge device

Abstract

A textile dielectric barrier discharge (DBD) device, which is a textile material comprising interconnected insulated conductive fibers, can be used to generate a cold uniform plasma by forming a discharge path from a conductive core of a first fiber, to a dielectric layer surrounding the conductive core, through an air gap, toward, for example, a second fiber or human skin. When the plasma emitting light in and around the air gap comes into contact with a contaminated surface (containing, for example, bacteria and / or viruses), the plasma induces reactive species to form on the contaminated surface and then allows the reactive species to kill the bacteria and / or viruses.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 033,457, filed on June 2, 2020, which is hereby incorporated by reference in its entirety.

[0003] STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0004] This invention was made with government support under Grant No. DE-AC02-09-CH11466 awarded by the Department of Energy. The government has certain rights in this invention. Background Art

[0005] There is an urgent need for widespread use of disinfectants and sterilization technologies. As the current COVID-19 pandemic has taken center stage, it is no longer limited to the medical, pharmaceutical or food industries, but extends to the decontamination of commonly used surfaces such as door handles and devices such as masks, mobile phones and pens.

[0006] A common problem involves fabrics becoming infected. To prevent this from happening, many approaches have been taken. Typically, current self-cleaning fabrics obtain their bioactive properties by adding chemical sterilants. Fabrics can be impregnated with chemical disinfectants, or the fabrics can be combined with other materials that are harmful to viruses and other microorganisms, such as heavy metals, copper, and various polymers that resist bacterial attachment and growth but do not kill microorganisms. Other materials being developed by others are based on combining nanoparticles or nanotubes that obtain biocidal properties when exposed to sunlight, for example, titanium nanoparticles. The main disadvantage of this type of material is that sunlight is required. Other nanoparticles with bactericidal properties (e.g., silver) can be incorporated into fibers, and various polymers can be activated by chemical treatments to create an acidic environment that acts against resistant bacteria and viruses. All of these methods require the addition of another substance, are temporarily effective, and none of them provides complete disinfection. Instead, all of these materials slow growth and / or reduce bacterial load. Therefore, a new method for providing disinfected fabrics is needed.

[0007] In the past two decades, cold atmospheric pressure plasma (CAP) has gained rapid development in the field of bacterial and viral inactivation and surface A poisoning. A recent review summarizes the achievements of a wide range of CAP plasma sources, including dielectric barrier discharge (DBD), which effectively inactivates bacteria, viruses, fungi and bacterial spores.

[0008] Despite these achievements, the only sterilization method involving plasma currently recommended by the Centers for Disease Control and widely accepted in the industry is a rigid device based on plasma activation of hydrogen peroxide vapor, one of the most effective and clean sterilization chemicals and a device that utilizes a vacuum chamber. See U.S. Patent No. 4,952,370. Hydrogen peroxide does not leave any hazardous residues because the decomposition products of hydrogen peroxide are water and oxygen.

[0009] The effectiveness of plasma disinfection and even sterilization is due to its biologically active properties, such as reactive oxygen species (ROS) and reactive nitrogen species (RNS), electrons, electrical currents, electric and electromagnetic fields, and UV rays. The mechanism of bacterial inactivation has been studied by many groups, but it is still unclear. The chemical and electrical properties of plasma can affect bacterial cells in stages. Electrons and electric fields affect cell membranes and facilitate cell penetration by RNS and some long-lived ROS. ROS participate in lipid peroxidation and other oxidative reactions that damage cell membranes and facilitate RNS / ROS transport into cells.

[0010] In cells, ROS / RNS damage proteins, lipids and DNA. The combined effect of these processes is bacterial cell inactivation. Most of the work on medical and biological applications of DBD has been conducted on one of three configurations: floating electrode configuration, plasma jet (floating electrode or dual electrode) and less common surface DBD. In the floating electrode device, the high voltage electrode is wrapped in a dielectric material and the treated surface acts as a ground electrode; the treated surface is exposed to a high electric field and a stream of charged particles. The most widely studied is the plasma jet, which uses power from pulsed dc to the microwave range, and in the plasma jet, the plasma effluent is carried by the gas flow to the treated surface. Plasma effluent is suitable for medical applications, but requires a compressed gas supply. Surface DBD is mainly studied as an actuator for flow control and large-area surface modification in aviation applications.

[0011] Atmospheric pressure plasma has been shown to be effective for decontaminating surfaces from bacteria and viruses, but the level and rate of inactivation depends strongly on the biological species, experimental conditions, and plasma source. For example, for exposure to a gas produced by a known DBD, the D value (for 1 log 10The D value for the reduction of D = 15 sec is 225 sec; for another known DBD, the D value is 150 sec; for E. coli exposed to atmospheric pressure helium / atmosphere light discharge, the D value is 35 sec; and for the paper DBD, the D value is 15 sec. The rapid reduction of D = 15 sec is achieved by a disposable flexible DBD device using printed patterned electrodes on a paper substrate and operated at 2 kHz, 3.5 kV AC, 10 W. This is a disposable device.

[0012] Another variation of plasma sterilization is the use of hydrogen peroxide vapor activated by low-pressure plasma. Systems such as the Sterlis Healthcare Low Temperature Sterilization System are widely accepted methods for sterilizing materials that are sensitive to heat, moisture, and corrosion. In recent studies, the addition of hydrogen peroxide has been explored to enhance plasma sterilization at atmospheric pressure. Adding H2O2 droplets to the corona discharge produces 6log 10 and the addition of H2O2 vapor to the plasma effluent produced a bacterial load greater than 6 log 10 The main mechanism responsible for the enhancement depends on the type of plasma, the state of H2O2. H2O2 vapor is ionized in the plasma to form H2O2, while the droplets may be negatively charged, and the H2O2 aqueous solution is subjected to active species introduced into the solution by the plasma, similar to plasma activated water. Pure water is acidified by the plasma which enhances the bactericidal effect, while buffered solutions such as phosphate buffered saline (PBS) maintain the pH level but are affected by dissolved ozone, nitrates and peroxide radicals.

[0013] This diversity of results and conditions suggests a need for a self-disinfecting fabric that does not rely on other chemicals to provide biological activity. Summary of the invention

[0014] As detailed herein and in the accompanying drawings, a self-disinfecting plasma fabric is disclosed that can be used, among other things, for self-disinfecting personal protective equipment (PPE) (e.g., lab coats, aprons, face masks, protective sheets, gloves for individual consumers and medical use), for disinfecting existing PPE, for incorporation into the manufacture of self-disinfecting PPE, for self-disinfecting textiles for a wide range of medical uses (e.g., bandages, covers, pads for wound treatment (e.g., bedsores), treatment / prevention of skin infections, etc., and can be used alone or in combination with existing bandages and / or chemical wound treatments), for military applications as a defense against biological agents, and to help disinfect surfaces in professional settings or at home. As used herein, the term "fabric" is intended to encompass any arrangement of fibers interconnected in any suitable manner, such as by weaving, knitting, made on a loom, etc. Preferably, the fabric is a woven fabric made by hand or on a loom.

[0015] The disclosed method uses a dielectric barrier discharge source. The plasma source is generated by insulated conductive fibers. Preferably, a pocket-sized high voltage high frequency power source drives the plasma source. The plasma is generated in the natural spaces between the fibers. The plasma disinfects the fabric itself and can also disinfect other surfaces.

[0016] Compared to existing materials, the self-disinfecting plasma fabric disclosed herein can be self-disinfecting or even sterilizing by pressing a button when needed. The self-disinfecting plasma fabric does not require any complex equipment and is driven by a battery-operated pocket power supply. When turned on, the fabric will destroy any microorganisms that may have been exposed to either side of the material as needed. This fabric is a true self-disinfecting textile material.

[0017] One aspect of the present disclosure is a fabric dielectric barrier discharge (DBD) device. The device includes a plurality of fibers, each fiber including a conductive core, the conductive core surrounded by at least one dielectric layer, the one or more fibers forming an interconnected fiber network; and a power source (preferably a portable power source) operably connected to the one or more fibers. The power source should be configured so that when an electric current (preferably ≤2 mA) is applied, plasma can be formed in the air gap between the fibers to emit light, and preferably the temperature of the device is between about 22°C and about 40°C.

[0018] Optionally, the fabric dielectric barrier discharge (DBD) device consists essentially of: (i) the plurality of fibers; (ii) the power source; (iii) one or more switches; (iv) optionally, one or more processors; (v) optionally, one or more sensors; and (vi) optionally, one or more displays or visual indicators.

[0019] Optionally, within the textile arrangement, at least one dielectric layer of a first fiber (eg comprising a different material or having a different thickness) is different from at least one dielectric layer of a second fiber.The textile arrangement may comprise a plurality of interconnected fiber layers.

[0020] Optionally, the fabric dielectric barrier discharge (DBD) device further comprises at least one switch. A temperature sensor and / or a current sensor may also be optionally incorporated. At least one processor may also be utilized, for example, a processor configured to control the power supply based on feedback from a temperature sensor and a current sensor.

[0021] Optionally, the fabric dielectric barrier discharge (DBD) device can be controlled by a timer. For example, the device can be set to start when a button is pressed and automatically shut off after a predetermined time period (e.g., 2 minutes), which has been shown to be sufficient to kill bacteria and reduce the viability of viruses.

[0022] A second aspect of the present disclosure is a method for sterilizing a surface. The method includes first providing a fabric dielectric barrier discharge (DBD) device as previously described. Then, a cold uniform plasma can be generated by forming a discharge path from the conductive core of a first fiber of the plurality of fibers to the at least one dielectric layer surrounding the first fiber, to the at least one dielectric layer surrounding the second fiber of the plurality of fibers, to the conductive core of the second fiber. When the plasma contacts a contaminated surface (containing, for example, bacteria and / or viruses), the plasma induces reactive species to form on the contaminated surface, and then allows the reactive species to kill the bacteria and / or viruses. In some cases, the method includes ensuring that the plasma remains in contact with the surface for at least a predetermined period of time. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is a depiction of one embodiment of a fabric dielectric barrier discharge device.

[0024] Figure 2 is a cross-sectional view of one embodiment of a fiber having multiple layers.

[0025] Figure 3 is a simplified illustration of one embodiment of a fabric dielectric barrier discharge device in operation.

[0026] Figure 4 is a simplified cross-sectional view of an embodiment of a fabric dielectric barrier discharge device including a plurality of fiber layers.

[0027] Figure 5 is a simplified cross-sectional view of one embodiment of a fabric dielectric barrier discharge device including a plurality of fiber layers and two semi-permeable outer layers.

[0028] Figure 6 is a graph showing that the average power increases linearly as a function of the applied voltage amplitude when the duty cycle and frequency are held constant at 20% and 40 kHz, respectively.

[0029] Figure 7 is a flow chart of one embodiment of the disclosed method.

[0030] Figure 8 is a graphical representation of bacterial disinfection in an area larger than the size of a braided DBD after 120 seconds of exposure.

[0031] Fig. 9 is a graph showing current and voltage traces recorded during operation of one embodiment of a fabric DBD, wherein the operating parameters are as follows: V max =3.8kV, 40.7kHz, 25% duty cycle, 0.1mJ / cycle

[0032] Fig.10 is corresponding to Fig. 9 Lissajous figure of the current and voltage traces.

[0033] Fig.11 is a graph showing the reduction in viral load in dry and liquid suspensions of Herpes Simplex Virus (HSV) after exposure to an embodiment of a fabric DBD. Error bars are based on three replicates for each condition.

[0034] Fig.12 is a diagrammatic representation of an alternative embodiment of a fabric DBD. DETAILED DESCRIPTION

[0035] The disclosed fabrics are based on low temperature plasma sterilization by dielectric barrier discharge (DBD) at atmospheric pressure. DBD can be generally understood as a capacitively coupled plasma source having one or two electrodes, which are covered with a dielectric material and are generally driven in the kHz frequency range. The dielectric barrier and high frequency of the electrical power make DBD safe for human contact. DBD has entered the medical field for wound treatment and other disinfection and treatment applications. DBD produces a gas plasma with biologically active properties, which are mainly attributed to the production of reactive oxygen species (ROS: O2-, OH, etc.) and reactive nitrogen species (RNS: NO, N2O, NO3-). The effectiveness of low temperature plasmas such as those produced in DBD against bacterial and viral contamination has been previously demonstrated.

[0036] See also Figure 1Embodiments of the disclosed fabric dielectric barrier device (100) can generally be considered to require two basic components: (i) a plurality of fibers (110) interconnected to form a fiber web (e.g., a substrate layer); and (ii) a power source (140). Each fiber in the plurality of fibers (110) comprises, consists essentially of, or consists of two components: (i) an inner conductive layer or core (120); and (ii) one or more outer dielectric layers (130) surrounding the inner conductive layer.

[0037] The cross-section of each fiber may be of any suitable cross-sectional shape, such as circular, oval or rectangular.

[0038] The inner conductive layer or core of each fiber can independently comprise any suitable conductive material, including metals, alloys, conductive compounds or combinations thereof. The inner conductive layer or core can be a single layer of conductive material. Specific examples of such suitable conductive materials include copper, sodium, sodium-potassium alloys, magnesium, lithium, magnesium / copper mixtures, magnesium / silver mixtures, magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al2O3) mixtures, indium, lithium / aluminum mixtures, rare earth metals, etc. In some embodiments, the inner conductive layer or core is a carbon fiber or a carbon-coated polymer fiber. Preferably, the inner conductive layer or core is configured to have a certain degree of flexibility / non-rigidity.

[0039] The diameter or thickness of each inner conductive layer or core is not particularly limited. Preferably, the diameter or thickness is ≤10mm, ≤6mm, ≤3mm, ≤2mm, ≤1mm or ≤0.5mm. In a preferred embodiment, the wire is a 30 or 32AWG gauge wire.

[0040] The one or more dielectric layers may comprise any suitable dielectric material, but preferably the layer comprises a flexible / non-rigid material. For example, the dielectric layer may comprise, for example, polyimide, polyamide, polytetrafluoroethylene (PTFE), polyethylene (PE), polypropylene (PP), silicon-based materials, quartz, glass, or other dielectric materials known to those skilled in the art, but quartz and glass are not preferred.

[0041] The diameter or thickness of each inner conductive layer or core is preferably ≤10 mm, ≤6 mm, ≤3 mm, ≤2 mm, ≤1 mm, ≤0.5 mm, ≤0.4 mm, ≤0.3 mm, ≤0.25 mm or ≤0.2 mm.

[0042] refer to Figure 2Each fiber may include multiple layers, including multiple dielectric layers. For example, in some embodiments, the fiber (111) may include an inner conductive core (121), a first dielectric layer (131), and a second dielectric layer (132), wherein the first dielectric layer includes a first dielectric material, the first dielectric material surrounds the inner conductive core (121) and contacts it, and the second dielectric layer includes a second different dielectric material, the second different dielectric material surrounds the first dielectric layer (131) and contacts it.

[0043] In some embodiments, one or more of the fibers include other coatings or materials. Multiple coatings may be appropriately utilized to provide specific desired properties. Non-limiting examples include polytetrafluoroethylene (PTFE) and expanded polytetrafluoroethylene (ePTFE) and related materials, and polysiloxanes or other silicon-based polymer materials. Preferably, the additional coating is an insulating material that is a flexible, ductile, low conductivity polymer.

[0044] In some embodiments, the total number of warp fibers (e.g., fibers or fiber portions oriented in the length direction of the disclosed plasma fabric) per square inch of fabric is equal to the total number of weft fibers (e.g., fibers or fiber portions oriented in the width direction of the disclosed plasma fabric). In some embodiments, the total number of warp fibers is not equal to the total number of weft fibers per square inch of fabric. The number of fibers per square inch can be varied to optimize energy consumption for the same biological or disinfection outcome. For example, a mask can be manufactured that utilizes a fabric with fewer fibers per square inch and larger openings than a glove.

[0045] In a particularly preferred embodiment, two fibers are used per fabric DBD, such as Fig.12 Arrangement as shown. Specifically, the plurality of fibers (900) is composed of two single fibers (901, 902). The first single fiber (901) passes back and forth through the fabric, wherein most of the fibers are configured to form, for example, the equivalent of a plurality of weft fibers. The second single fiber (902) passes back and forth through the fabric in a direction perpendicular to the first single fiber, wherein most of the fibers are configured to form, for example, the equivalent of a plurality of warp fibers. Then, a power source can be connected to the two fibers, and the free end of each fiber is insulated.

[0046] refer to Figure 3, showing an embodiment of the disclosed fabric dielectric barrier device (200) in operation. Here, due to the arrangement of the power source and the fibers, when the inner conductive layer (220, 221) of the fibers (210, 211) is connected to the power source (240) and a current is applied, a plasma (260) will form (e.g., "light") in and around the air gap (250) between the fibers (210, 211), thereby filling the spatial volume covering a portion of two or more fibers. That is, a cold uniform plasma can be generated by, for example, forming a discharge path from the conductive core (220) of a first fiber (210) of the plurality of fibers to the at least one dielectric layer (230) surrounding the first fiber, through the air gap (250), to the at least one dielectric layer (231) surrounding the second fiber (211) of the plurality of fibers, to the conductive core (221) of the second fiber.

[0047] The air gap (250) between the outer surface of one fiber and the outer surface of a second fiber is typically asymmetric around the fibers; that is, typically one portion of the fibers may contact another fiber, while another portion of the fibers will have a small gap, and yet another portion will have an even larger gap.

[0048] In some embodiments, the air gap will be ≤ 10 μm, ≤ 5 μm, ≤ 4 μm, or ≤ 3 μm.

[0049] In some embodiments, for any given fiber layer, every warp fiber will be in contact with every weft fiber, and / or every weft fiber will be in contact with every warp fiber. Even if the wires are in contact, there will be at least a small air gap.

[0050] The plasma generated by these devices allows the devices to act as a self-sterilizing plasma cloth. The flexible cloth can be used, for example, to repeatedly sterilize various tools, surfaces, etc. and / or itself (for example, if the fabric DBD is used as PPE, such as a mask).

[0051] In addition, although Figure 1 The fabric dielectric barrier device is shown as a single layer, but the device may include a discharge cell having multiple layers of first and second electrodes, where the first electrode may be passed through only one, two, or three or more layers of fabric as desired. Figure 4In the , a fabric dielectric barrier (400) is shown as including two layers (410, 420), where each layer can be the same or different. In some embodiments, each layer is oriented so that the two-dimensional orientation of the fibers in one layer matches the two-dimensional orientation of the fibers in the other layer. That is, if one layer has fibers that are generally oriented from left to right and from top to bottom, the next layer has fibers that are also oriented in those directions. In some embodiments, each layer is oriented differently so that the two-dimensional orientation of the fibers from one layer does not match the two-dimensional orientation of the fibers in the other layer. That is, if one layer has fibers that are generally oriented from left to right and from top to bottom, the next layer can have fibers that are rotated 45 degrees so that the fibers are oriented from bottom left to top right and from bottom right to top left. Alternatively, the fibers can be twisted first and then used to make the fabric device.

[0052] An optional semi-permeable layer may also be utilized, such as Figure 5 As shown. Figure 5 As shown, the fabric dielectric barrier device (500) can include a semi-permeable layer (540, 541) and one or more fabric layers (510, 520) and a power source (530). The semi-permeable layer can take any suitable form, including, for example, a dielectric fabric or mesh, and can include any suitable material, including a dielectric material or an insulating material. In some embodiments, the semi-permeable layer is a disposable cover surrounding the disclosed fabric layer, and can include, for example, a polymer such as polyethylene or polypropylene.

[0053] refer to Figure 1 The fabric dielectric barrier device (100) is powered by a power source (140), which may optionally be a portable power source and may optionally include, for example, one or more batteries or supercapacitors. Any suitable power source is contemplated. The power source may be configured to provide AC or DC power.

[0054] The required output of the power supply is determined in part based on the size of the fabric DBD.Preferably, the power supply is configured to provide power at a frequency between 1 kHz and 1 GHz.Preferably, the power supply is configured to provide power at a voltage preferably between 100 V and 10 kV.

[0055] In some embodiments, the power supply is relatively small (eg, within a housing of 4 cubic inches or less).

[0056] Because all conductive wires are insulated, they do not need to be grounded and the user is therefore protected by the insulation.

[0057] In some embodiments, the power source is configured to provide a current less than or equal to 2 mA. The power source is connected to the electrodes using any suitable means, including by, for example, a wire, a conductive wire, or a conductive tape. The opposing electrodes are connected in groups by any suitable means, including by, for example, a wire, a conductive wire, a conductive tape, or a fabric strip at the end of the fiber.

[0058] These devices preferably do not contain any additional gas supply or complex advanced power supply, and are preferably configured to enable long-term stable operation (ie, at least one month, preferably at least 2 months, and more preferably at least 3 months).

[0059] In some embodiments, the power supply is controlled or configured to provide current so that the temperature of the device is maintained at ≤50°C or ≤40°C and ≥15°C or ≥22°C. In some embodiments, the power supply is controlled or configured to provide current so that the temperature of the device is maintained between about 15°C and about 50°C, and more preferably between about 22°C and about 40°C. As used herein, the term "about" a certain temperature indicates a value generally within ±5% (e.g., the lower limit of the range is -5%, and the upper limit of the range is +5%) as appropriate. For example, "between about 10°C and about 100°C" will be intended to cover between 9.5°C and 105°C.

[0060] The fabric dielectric barrier device (100) may optionally contain additional components, including one or more switches or other electronic components (145) for controlling the current to the fibers, one or more sensors (146), one or more displays or visual indicators (147), and one or more processors (148). The one or more processors (148) will be configured to operably communicate with one or more of the various components in the system, such as the power source (140), the sensor (146), and / or the display or visual indicator (147).

[0061] In a preferred embodiment, the device will include at least one switch (145) configured as an on / off switch.

[0062] If one or more sensors (146) are included, such sensors may be in operable communication with the one or more processors (148) or the one or more displays or visual indicators (147). For example, a temperature sensor may be connected to a warning light via some basic circuitry (well known in the art) such that when the temperature exceeds a threshold, the warning light turns on. In some embodiments, the sensor may send feedback about the temperature and current to the processor, which then uses the feedback to determine whether the current needs to be adjusted, and if so, how much, or whether a fault has occurred. Based on the determination, the processor may then cause the power supply (140) to shut down or adjust the current, and / or generate an indication on the display or indicator light (147) that a problem has occurred.

[0063] Additionally, one or more surfaces or portions of the device may also have its temperature or other parameter periodically or continuously measured or monitored by a temperature sensor (146). In some embodiments, the surface of the dielectric layer of one or more fibers may be monitored by a sensor. Any suitable sensor may be utilized, such as a thermocouple.

[0064] The display or visual indicator (147) may comprise any known display or visual indicator, including color or monochrome LED / OLED displays and / or LED lights. To maximize battery life, the display or visual indicator is preferably small, low-power, or intended to be "on" only for a short period of time (e.g., 1 minute or less).

[0065] The one or more processors or control circuit systems (148) may be present for controlling the generation of plasma and / or other components of the device. The processor or control circuit system may be operably connected to the temperature sensor (146) and the power supply (140). The processor or control circuit system may be configured to maintain an appropriate operating temperature, as previously discussed. The processor or control circuit system may be configured to automatically shut down safely if the temperature is detected to be outside a target range or exceeding a threshold. The safety shutoff may also be configured to occur if the voltage or current exceeds a specific threshold.

[0066] As an example of a discharge device in operation, a typical current trace contains a displacement current sinusoidal component of, for example, (42±2) kHz and a superimposed spike corresponding to the discharge, for example, of 10-50 nanoseconds duration. The displacement current can be subtracted from the total measured current to obtain the discharge current. The number of discharges, the overall duration of the discharges, and the amplitude of the discharges can increase with increasing voltage.

[0067] The number of individual discharges or current peaks varies depending on the maximum applied voltage (overvoltage). For example, in some embodiments, the number of current peaks (over 10 mA) is 15±8 at 2 kV and increases to 45±8 for 3 kV.

[0068] As is apparent from the Lissajous figure, the greater the number of current spikes, the greater the amount of charge transferred in the circuit. The Lissajous figure has a slightly asymmetric dual slope shape due to the greater number of more intense discharges for negative voltages (positive patterned electrodes). The energy dissipated per cycle in the circuit can be calculated as the area of ​​the Lissajous figure, and then the power P is determined using the frequency f, duty cycle v: P = fv∫QdV, where Q is the charge measured by the capacitor probe, and dV is the voltage obtained by the high voltage probe.

[0069] For example, for a peak voltage of 1.9 kV, the energy per cycle is 0.04 mJ / cycle. For a frequency of 41 kHz and a duty cycle of 20%, this results in a power of 0.3 W. For a maximum voltage of 2.9 kV, the energy per cycle is 0.14 mJ / cycle and the power is 1.1 W. Approx. 2 cm 2 The corresponding power density of the device is 0.15-0.5W / cm 2 The maximum applied AC voltage was varied from 1.6 kV to about 3 kV while keeping the frequency and duty cycle constant. The resulting power varied linearly with the applied voltage (see Figure 8 ), which can be used as a calibration curve to set the desired power for a given device. Increasing the operating voltage increases the discharge power and corresponds to an increase in the number of individual discharges and plasma production. Increasing the duty cycle increases the overall power consumption of the device but does not change the number of individual discharges per cycle.

[0070] In some embodiments, any gap between the outermost dielectric layer and the target surface to be disinfected is ≤ 2 cm, and preferably ≤ 1 cm, and more preferably ≤ 5 mm, and most preferably ≤ 2 mm. In some embodiments, the gap is ≤ 1 mm. In some embodiments, the gap is between 1 μm and 2 mm, and preferably between 1 mm and 2 mm.

[0071] Examples

[0072] Several examples were woven on a hand loom. The fibers used consisted of 32 American Wire Gauge (AWG) copper wires as a conductive core, each surrounded by flexible silicone. In some examples, the braid was tight, with the fibers in contact with each other. In other samples, the spacing between each weft fiber and the spacing between each warp fiber was between 1 mm and 2 mm. These examples are suitable for making sterilization bags for personal items and / or for incorporation in wound dressings.

[0073] Also disclosed is a method for sterilizing a surface, the method comprising: Fig. 9 As shown, one embodiment of a method (600) begins by providing (610) a disclosed fabric dielectric barrier discharge (DBD) device.

[0074] The device is then activated and a cold uniform plasma is generated (620). This generation occurs by forming a discharge path from the conductive core of a first fiber of the plurality of fibers to the at least one dielectric layer surrounding the first fiber, and through an air gap in and around which the plasma will emit light. The discharge path preferably continues to the at least one dielectric layer surrounding a second fiber of the plurality of fibers, to the conductive core of the second fiber. In some embodiments, the discharge path may not continue to the second fiber, but rather toward and through a human being. The air gap between the fibers and the human being (or clothing, etc.) may allow the plasma to form.

[0075] Once the plasma is formed in the volume of space surrounding the air gap, reactive species (630) may be induced to form on the contaminated surface by contacting the contaminated surface with the generated cold uniform plasma. The contaminated surface typically contains bacteria, viruses, or a combination thereof. The contaminated surface may also contain other biological species, such as fungi. The contaminated surface may be the outer surface of a fiber within the disclosed fabric DBD, or the contaminated surface may be an external surface, such as human skin, a work surface, etc.

[0076] Optionally, the method can include maintaining or sustaining (640) the plasma in contact with the contaminated surface for at least a predetermined period of time, such as at least 1 second, at least 5 seconds, or at least 10 seconds.

[0077] The reactive species are then allowed (650) to kill bacteria, viruses, or a combination thereof on the contaminated surface.

[0078] Example 2

[0079] The antibacterial effect of the plasma fabric device was tested using E. coli as a model bacterium. For this example, the E. coli OP-50-GFP strain was used because this strain expresses green fluorescent protein and forms a dense bacterial lawn (1 awn) when spread on LB agar plates. Bacteria that have been killed cannot express this protein and therefore will not emit green.

[0080] At time = 0, the entire agar plate fluoresced green. After 30 seconds, bacteria were removed from approximately 97% of the plate area beneath the fabric device, and from approximately 70% of the total plate area. After 60 seconds, bacteria were removed from over 99% of the plate area beneath the fabric device, and from approximately 85% of the total plate area. Figure 8 The results after 120 seconds of exposure are shown graphically. Specifically, on an agar plate (701), an outline (702) of where the fabric device is placed is shown. As shown, there are only a small amount of bacteria (705) in the agar plate, which are located at the edge of the plate away from the fabric device. There is a large area of ​​space (707) that is free of bacteria around where the fabric device is placed. Indeed, bacteria were removed from 100% of the plate area below the fabric device, and roughly speaking, bacteria were completely eliminated on 97% of the total plate area.

[0081] The fabric device used in this example is about 2.5 cm with about 10 fibers per cm. 2 The braid is made of two continuous silicon insulated 30 gauge wires. One end of each wire / fiber is connected to the output of a kHz range AC power source. Fig. 9 The voltage and current traces are shown. The transferred charge was also measured using a 10nF measuring capacitor in series with the device. Using a Lissajous plot ( Fig.10 ) to obtain the energy per cycle E. The average power of the device is calculated as P = v·f·E, v-duty cycle as a fraction of the on time, f-frequency (Hz), E-energy per cycle (J). Fig.10 The graph shown corresponds to Vmax = 3.8 kV, 40.7 kHz, 25% duty cycle, 0.1 mJ / cycle, about 1 W, 0.4 W / cm for braid area 2 .

[0082] After successfully decontaminating bacteria, the fabric device was then tested against viruses in additional experiments.

[0083] Virus disinfection experiments were performed using herpes simplex virus (HSV). A drop of the virus suspension was placed in a 30 mm diameter petri dish and dried for approximately 20 minutes until visually dry. The petri dish with the dried suspension was inverted on top of a support with a fabric DBD ("braid") so that the braid was in contact with the dried suspension. Immediately after each treatment, 1 mL of buffer solution was added to the petri dish to immediately terminate the reaction. The resulting virus suspension was used to determine the concentration of plaque forming units and compared with an untreated suspension. After a 4-minute treatment, the braid showed a 99.3% reduction in live virus (see Fig.11 ).

[0084] Additionally, because sterilization and other biological outcomes depend on the gas output of the device, experiments were performed using Fourier Transform Infrared Absorption Spectroscopy to confirm the output of biologically active species.

[0085] To determine the output of biologically active species, the fabric DBD in this example was placed in a gas cell (10 cm optical path) and turned on. FTIR absorption spectra were obtained during operation under different conditions including lower and higher voltages and powers. The spectra were used to identify the molecular species present in the gas flowing out of the device and to calculate the absolute concentrations of ozone and nitrogen oxides, which are important for disinfection and other biomedical applications. For example, at 0.175 mJ / cycle, the following concentrations were determined: O3 -8.2x10 15 em -3 (0.09%), and N2O-6.75x10 13 cm -3 (0.003%). As the power increases, the concentration of O3 decreases and the concentration of N2O increases. Therefore, the composition of the device output depends on the input power.

[0086] By adjusting the power for a given desired result, this means that the user can "dialin" the device to provide a desired composition of the gas output. For example, to kill species that are more affected by ozone than nitrogen oxides, it will be more effective to use a lower power input. In some embodiments, one or more processors on the device can access various databases or tables containing, for example, curves that relate input power to gas output and other databases or tables that relate biological species to the time it takes to kill a certain percentage (e.g., 99%) of a given bacterial species when exposed to various output gases (ozone, nitrogen oxides, etc.). Based on those databases, the device can calculate or otherwise determine the optimal input power for killing bacteria by identifying the input power that produces a gas composition that kills one or more target bacteria in an effective manner.

[0087] Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.

Claims

1. A fabric dielectric barrier discharge device, comprising: a plurality of fibers, each fiber comprising a conductive core surrounded by at least one dielectric layer, the one or more fibers forming a woven interconnected fiber web; as well as A power source is operably connected to the one or more fibers, the power source being configured such that when an electric current is applied, a plasma is enabled to emit light in air gaps formed between the fibers.

2. The fabric dielectric barrier discharge device according to claim 1, wherein the device consists of: the plurality of fibers; the power supply; one or more switches; one or more processors; one or more sensors; as well as One or more displays or visual indicators.

3. The fabric dielectric barrier discharge device of claim 1, wherein at least one dielectric layer of a first fiber of the plurality of fibers is different from at least one dielectric layer of a second fiber of the plurality of fibers.

4. The textile dielectric barrier discharge device of claim 1, wherein the at least one dielectric layer of each fiber of the plurality of fibers is identical. The fabric dielectric barrier discharge device according to claim 1 , wherein the power supply provides an AC voltage. The fabric dielectric barrier discharge device according to claim 1 , wherein the power supply provides a DC voltage.

7. The textile dielectric barrier discharge device according to claim 1, wherein the power supply provides a voltage with a pulse frequency between 1 kHz and 1 GHz.

8. The fabric dielectric barrier discharge device of claim 1, wherein the device comprises a plurality of interconnected fiber layers.

9. The fabric dielectric barrier discharge device according to claim 1, wherein the fabric dielectric barrier discharge device is powered by a portable power source.

10. The fabric dielectric barrier discharge device of claim 1, wherein the current is less than or equal to 2 mA.

11. The fabric dielectric barrier discharge device of claim 1, wherein the temperature of the device is between 22°C and 40°C.

12. The fabric dielectric barrier discharge device of claim 1, further comprising at least one switch.

13. The fabric dielectric barrier discharge device according to claim 8, further comprising a temperature sensor and a current sensor.

14. The fabric dielectric barrier discharge device of claim 9, further comprising at least one processor configured to control the power supply based on feedback from a temperature sensor and a current sensor.

15. A method for sterilizing a surface, the method comprising: A fabric dielectric barrier discharge device is provided, the fabric dielectric barrier discharge device comprising: a plurality of fibers, each fiber comprising a conductive core, the conductive core surrounded by at least one dielectric layer, the one or more fibers forming a woven interconnected fiber web; and a power source operably connected to the one or more fibers, the power source being configured such that when an electric current is applied, plasma can emit light in air gaps formed between the one or more fibers; generating a cold uniform plasma by forming a discharge path from a conductive core of a first fiber of the plurality of fibers, to at least one dielectric layer surrounding the conductive core of the first fiber, through an air gap, toward a second fiber of the plurality of fibers or a human; inducing formation of reactive species on a contaminated surface containing bacteria, viruses, or a combination thereof by contacting the contaminated surface with the generated cold uniform plasma; and The reactive species is allowed to kill the bacteria, virus, or combination thereof.

16. The method of claim 15, wherein the discharge path is formed from the conductive core of the first fiber of the plurality of fibers, to the at least one dielectric layer surrounding the conductive core of the first fiber, through an air gap, to the at least one dielectric layer surrounding the conductive core of the second fiber of the plurality of fibers, to the conductive core of the second fiber.

17. The method of claim 15, further comprising maintaining the plasma in contact with the contaminated surface for at least a predetermined period of time.

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