Thin-film, flexible, surface-barrier-discharge, cold-plasma source for treatment of skin conditions

Abstract

Embodiments relate to apparatuses, methods, and systems configured to provide a plasma source for generating a cold atmospheric plasma. The plasma source includes a device in which electrodes are deposited on either side of a high dielectric film. The device may be used to treat a surface (e.g., skin, such as treating inflammatory skin disorders, skin wounds, skin infections, etc.) by positioning an active surface of the electrodes in proximity to the surface to be treated.

Description

THIN-FILM, FLEXIBLE, SURFACE-BARRIER-DISCHARGE, COLD-PLASMA SOURCE FOR TREATMENT OF SKIN CONDITIONSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application is related to and claims the benefit of priority of U.S. Provisional Application 63 / 564,642, filed on March 13, 2024, the entire contents of which is incorporated by reference.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH DEVELOPMENT

[0002] This invention was made with government support under Grant No.NI23HFPXXXXXG054 awarded by the United States Department of Agriculture / NIFA. The Government has certain rights in the inventionFIELD

[0003] Embodiments relate to apparatuses, methods, and systems configured to provide a plasma source for generating a cold atmospheric plasma. The plasma source may be a surface-barrier- discharge device in which electrodes are deposited on either side of a high dielectric constant film.BACKGROUND

[0004] Dermatological applications of cold atmospheric plasma (CAP) were among the first to be explored. CAP sources are capable of generating reactive oxygen and nitrogen species (RONS) within the medium that plasma ionizes. These RONS, which include hydrogen peroxide, hydroxyl radical, nitrites and nitrates, among many others, have significant roles in redox biology and cell physiology. CAP treatments have been shown to suppress inflammatory cytokines and modulators such as interleukin 1 (IL-1) and tumor necrosis factor alpha (TNF-a).Furthermore, CAP treatment both in vitro and in vivo has been demonstrated to reducelipogenesis and sebum production. An important factor in pathogenesis of acne is the overgrowth of bacteria, namely C. acnes. The antimicrobial properties of CAP are one of the better- established utilities of this technology in the realm of medicine.

[0005] Existing CAP sources include atmospheric pressure plasma jets (APPJs) and dielectric barrier discharge devices (DBDs). APPJs are comprised of a gas delivery apparatus where noble gases such as helium and argon are subject to strong electric fields and undergo ionization. DBDs are devices that consist of two dielectrically-coated electrodes separated by a distance. These devices either generate plasma in the air in between the electrodes or a noble gas is passed through this cavity facilitating CAP generation at lower voltages.

[0006] However, there are certain limitations that each of these classes of CAP sources have. APPJs require pressurized gas to pass through the gas delivery apparatus. Therefore, there is an inherent flow rate required to form the jet. This increases the infrastructure required and necessitates the use of a compressor or gas cylinder. The need for noble gases increases the cost to operate these plasma sources. Furthermore, the flow of gas can lead to agitation of lesions and excessive drying of skin. The plasma that APPJs generate exits the device in the shape of a plume and is focused into a very small area limiting the treatment and complicates normalization of CAP treatment.

[0007] Moreover, DBDs require relatively larger voltages to generate a small plasma. Coupled with the rigid form of the device and considering the non-flat topology of our body, normalization of the treatment across the entire target area is difficult. Some DBDs utilize the target (skin) as the ground electrode. In the case of dielectric failure, this could prove detrimental through electric shock.

[0008] Ultimately, a significant number of obstacles faced in the field of plasma medicine surround the question of safe and effective applicability. Reducing the voltage that plasma devices are operated at seems logical, but plasma ignition within air has proven difficult at low voltages. Due to the numerous inelastic electron collisions that are possible within air, plasma ignition requires a strong electric field.SUMMARY

[0009] We have designed a thin-film flexible surface barrier discharge (SBD) device designed for accessibility and cost-effectiveness. This device employs significantly less power than APPJs and DBDs. The device uses a very thin film dielectric material to separate two electrodes deposited on the surfaces of the film. The proximity of the two electrodes allows for generation of a strong electric field within the dielectric film. The plasma is then generated on the surface of the device and the presence of the patient-facing ground electrode reduces the risks associated with dielectric breakdown, due to the presence of a path of lower resistance for current to flow through instead of to the patient. Using a thin-film dielectric allows the device to be flexible and wrap around skin. Therefore, a normalized treatment can be applied across a large target.

[0010] Furthermore, a major safety concern with electrical devices is the concept of leakage current. This is often a problem with devices that are not adequately grounded. IEC60601 AAMI / NFPA 99 is the International Electrotechnical Commission’s guidelines on the safety of electrical biomedical devices approved by the FDA. However, while the device generates strong electric fields in close proximity of the skin, we utilized a circuit to model the impedance of the human body to measure leakage current out of the device to alleviate potential hazards.

[0011] In an exemplary embodiment, a device for generating a cold atmospheric plasma comprises a dielectric film having a first surface and a second surface opposite of the firstsurface, wherein the first surface is a treatment facing surface; a first electrode positioned on the first surface of the dielectric film; and a second electrode positioned on the second surface of the dielectric film, wherein the second electrode has a thickness of 0.05-10 pm.

[0012] In some embodiments, the plasma may be an ionized gas. For example, the ionized gas may include or consist of ionized air, include or consist of ionized nitrogen, include or consist of ionized oxygen, and / or mixtures thereof.

[0013] In some embodiments, the second electrode has a thickness of 0.05-1 pm.

[0014] In some embodiments, the first electrode has a thickness of 30-100 pm.

[0015] In some embodiments, the first electrode has a thickness of 35-100 pm.

[0016] In some embodiments, the first electrode has a thickness of 0.1-1 pm.

[0017] In some embodiments, the first electrode has a thickness of 1- 30 pm.

[0018] In some embodiments, the device further comprises a voltage source electrically connected to the first electrode and the second electrode.

[0019] In some embodiments, the device further comprises a backing positioned over the second electrode such that the backing encapsulates the second electrode and forms a cavity.

[0020] In some embodiments, the device further comprises a voltage source positioned within the cavity, wherein the voltage source is electrically connected to the first electrode and the second electrode.

[0021] In some embodiments, the backing is formed from an electrically insulating material.

[0022] In some embodiments, the backing comprises at least one aperture configured to allow circulation of ambient air into and out of the cavity.

[0023] In some embodiments, the device further comprises a voltage source circuit comprising a voltage source, an inverter, a frequency multiplier, and an amplifier.

[0024] In some embodiments, the amplifier is a piezoelectric amplifier.

[0025] In some embodiments, the first electrode and the second electrode are electrically connected by the amplifier to the voltage source.

[0026] In some embodiments, the device is operated at an AC voltage of 400 V to 2.0 kV.

[0027] In some embodiments, the device is operated at an AC voltage of 800 V to 1.2 kV.

[0028] In some embodiments, the dielectric film comprises a material selected from the group consisting of polyimide, polytetrafluoroethylene, polyvinyl fluoride, polyethylene terephthalate, and combinations thereof.

[0029] In some embodiments, the first electrode comprises a conductive metal selected from the group consisting of copper, silver, gold, aluminum, platinum, and combinations thereof.

[0030] In some embodiments, the second electrode comprises a conductive metal selected from the group consisting of copper, silver, gold, aluminum, platinum, and combinations thereof.

[0031] In an exemplary embodiment, a method of making a device for generating a cold atmospheric plasma comprises providing a dielectric film having a first surface and a second surface opposite of the first surface; depositing a first electrode on the first surface of the dielectric film, wherein the first electrode is a is a treatment-facing electrode; and depositing a second electrode on the second surface of the dielectric film, wherein the second electrode has a thickness of 0.05-10 pm.

[0032] In some embodiments, the second electrode has a thickness of 0.05-1 pm.

[0033] In some embodiments, the first electrode has a thickness of 30-100 pm.

[0034] In some embodiments, the first electrode has a thickness of 35-100 pm.

[0035] In some embodiments, the first electrode has a thickness of 0.1-1 pm.

[0036] In some embodiments, the first electrode has a thickness of 1- 30 pm.

[0037] In some embodiments, depositing the first electrode includes screen printing at least one conductive metal on the first surface of the dielectric film.

[0038] In some embodiments, wherein the at least one conductive metal comprises a metal selected from the group consisting of copper, silver, gold, aluminum, platinum, and combinations thereof.

[0039] In some embodiments, depositing the second electrode includes depositing at least one conductive metal on the second surface of the dielectric film via a deposition method selected from the group consisting of sputtering, chemical vapor deposition, and atomic layer deposition.

[0040] In some embodiments, the at least one conductive metal comprises a metal selected from the group consisting of copper, silver, gold, aluminum, platinum, and combinations thereof.

[0041] In some embodiments, the dielectric film comprises a material selected from the group consisting of polyimide, polytetrafluoroethylene, polyvinyl fluoride, polyethylene terephthalate, and combinations thereof.

[0042] Other details, objects, and advantages of our apparatuses, methods, and systems for providing a plasma source for generating a cold atmospheric plasma will become apparent as the following description of certain exemplary embodiments thereof proceeds.BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The above and other objects, aspects, features, advantages, and possible applications of embodiments of the present innovation will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings. Like reference numbers used in the drawings may identify like components.

[0044] FIG. 1 shows a schematic representation of a cross-section view of an exemplary embodiment of a device with a voltage source positioned external to the device.

[0045] FIG. 2 shows a schematic representation of a cross-section view of an exemplary embodiment of a device with a voltage source positioned within the device.

[0046] FIGS. 3A and 3B show illustrations of top and bottom views of an exemplary embodiment of the device with an exemplary first electrode with a patterned structure.

[0047] FIGS. 4A and 4B show illustrations of top and bottom views of a device with an exemplary first electrode with another patterned structure.

[0048] FIG. 5 is a block diagram illustrating an exemplary voltage source circuit.

[0049] FIG. 6 shows photographs of an exemplary device, including a treatment-facing, ground electrode (left) and a backside high-voltage electrode (right).

[0050] FIG. 7 shows a schematic illustration of exemplary apparatuses used when treating targets inside petri dishes. These apparatuses were designed to account for the dimensions of petri dishes as well as the height of sample and agar where applicable.

[0051] FIG. 8 shows a diagram of an exemplary embodiment of a resistor-capacitor (RC) low- pass filter circuit used to measure leakage current.

[0052] FIG. 9 shows a graph of estimated plasma power, and particularly Lissajous curves of displacement current in a capacitor on the ground side of an exemplary embodiment of the device.

[0053] FIG. 10 shows a graph of estimated plasma power, and particularly calculated power based on the Lissajous curves shown in FIG. 9.

[0054] FIG. 11 shows a graph of leakage current of an exemplary embodiment of the device measured at a treatment distance of 2 mm across voltages. At maximum treatment voltage of 1.6 kV, patient leakage current is within the regulatory threshold of 100 pA.

[0055] FIG. 12 shows graphs of heat generation of an exemplary embodiment of the device measured using a thermocouple. The graphs show the surface temperature measured in continuous operation mode.

[0056] FIG. 13 shows graphs of heat generation of an exemplary embodiment of the device measured using a thermocouple. The graphs show the surface temperature measured in pulsed operation mode (15 seconds on / 15 seconds off).

[0057] FIG. 14 shows a graph demonstrating the efficacy of an exemplary embodiment of the device in treatment of gram-negative bacteria strain E. coli. in pulsed operation (p « 0.05, N = 5).

[0058] FIG. 15 shows a graph demonstrating the efficacy of an exemplary embodiment of the device in treatment of gram-positive bacteria strain S. aureus, in pulsed operation (p « 0.05, N - 5).

[0059] FIG. 16 shows a graph demonstrating the efficacy of an exemplary embodiment of the device in treatment of gram-positive bacteria strain C. acnes. in pulsed operation (p « 0.05, N = 5).

[0060] FIG. 17 shows images demonstrating the safety of keratinocyte after exposure to an exemplary embodiment of the device. Western blotting data using caspase 3 markers and PARP markers show no significant apoptosis of cells at lower exposures. Brightfield microscopy images showing morphology and viability of plasma-exposed keratinocytes are included.

[0061] FIG. 18 shows ROS distribution on the surface of an exemplary embodiment of the device, which was developed using a Kl-Starch model. The left image shows the lowest dose of treatment, and the right image shows the highest dose of treatment.DETAILED DESCRIPTION

[0062] The following description is of exemplary embodiments and methods of use that are presently contemplated for carrying out the present invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing the general principles and features of various aspects of the present invention. The scope of the present invention is not limited by this description.

[0063] Embodiments generally relate to apparatuses, methods, and systems configured to provide a plasma source for generating a cold atmospheric plasma. The plasma source may be a surface-barrier-discharge (SBD) device in which electrodes are deposited on either side of a high dielectric strength film. In practice, when a voltage is applied to the electrodes, an electric field may be created along the surface of the dielectric film, causing air or gas molecules near the surface of the dielectric film to ionize, which may lead to a plasma discharge. This discharge may be used to treat a surface (e.g., skin, such as treating inflammatory skin disorders, skin wounds, skin infections, etc.) by positioning an active surface of the electrodes in proximity to the surface to be treated.

[0064] The terms “plasma” and “cold atmospheric plasma” may be used interchangeably herein.

[0065] FIGS. 1 and 2 show a schematic representation of an exemplary embodiment of a device 100 configured to generate a cold atmospheric plasma. The device 100 has a voltage source 200 that is electrically connected to at least one electrode.

[0066] The device 100 includes a dielectric film 106 having a first, treatment-facing surface 106a and an opposite second surface 106b. A first electrode 102 is positioned on the first surface 106a of the dielectric film 106, and a second electrode 104 is positioned on the second surface of the 106b of the dielectric film 106. The dielectric film 106 therefore spatially separates and spaces apart the first electrode 102 from the second electrode 104.

[0067] The dielectric film 106 may extend laterally at least as far as the lateral extensions of the first electrode 102 and the second electrode 104. In some embodiments, the dielectric film may extend laterally beyond the lateral extensions of the first electrode 102 and / or the second electrode 104.

[0068] The first electrode 102 and the second electrode 104 may work together to generate plasma. As will be described in further detail, the voltage source 200 may be electrically connected to the first electrode 102 and the second electrode 104. In particular, the voltage source 200 may be electrically connected to the second electrode 104 such that an AC voltage can be applied to the electrode. As the dielectric film 106 is configured to generate an electric field, the dielectric film 106 serves to insulate the first electrode 102 and the second electrode 104 from one another.

[0069] The dielectric film 106 may include any one or combination of dielectric materials (e.g., materials design to be nonconductive, in particular to be insulating). In some embodiments, the dielectric film 106 includes polyimide (PI), polytetrafluoroethylene (PTFE), polyvinyl fluoride (PVF), polyethylene terephthalate (PET), or any other suitable material and / or combinations thereof. The dielectric film 106 is thin, and may have a thickness of 1-100 pm, such as 1-50 pm or 1-25 pm.

[0070] As described above, the first electrode 102 is positioned on a first, treatment-facing surface 106a of the dielectric film 106. The first electrode 102 is therefore positioned to face the surface to be treated. The device 100 is configured such that the plasma is preferably generated on the side of the first electrode 102 (e.g., on the surface of the first electrode 102). The first electrode 102 is a grounded electrode such that it may serve as a return path for an electrical current, completing the circuit and establishing a reference point for the high-voltage secondelectrode 104. The grounded first electrode 102 may therefore reduce the risks associated with dielectric breakdown by providing a path of lower resistance for the electrical current to flow through.

[0071] The first electrode 102 includes at least one conductive metal, such as copper, silver, gold, aluminum, platinum, or any other conductive metal and / or combinations thereof.

[0072] As described above, the second electrode 104 is positioned on a second surface 106b of the dielectric film 106, which is opposite the treatment-facing surface. The second electrode 104 is a high-voltage electrode configured to generate an electric field.

[0073] The second electrode 104 includes at least one conductive metal, such as copper, silver, gold, aluminum, platinum, or any other conductive metal and / or combinations thereof.

[0074] In some embodiments, the first electrode 102 and the second electrode 104 include the same conductive metal(s). In other embodiments, the first electrode 102 and the second electrode 104 include different conductive metal(s).

[0075] In some embodiments, the first electrode 102 may have a thickness of greater than 30 pm to 100 pm or less, such as from 35-100 pm, 50-100 pm, or 75-100 pm. In some embodiments, the first electrode 102 may be an electrode deposited via known deposition techniques, such as physical vapor deposition (e.g., sputtering, evaporation), chemical vapor deposition, or atomic layer deposition. In such embodiments, the first electrode 102 may have a thickness of 0.1 pm or greater to less than 1 pm, such as from 0.1-0.9 pm, 0.1-0.75 pm, 0.1-0.5 pm, or 0.1-0.25 pm. While lower thicknesses may enable the first electrode 102 to have increased flexibility, lower thicknesses may also make the first electrode 102 more prone to damage, such as scratching.

[0076] The second electrode 104 may have a thickness of from 0.05 pm or greater to 10 pm or less, such as from 0.1 pm or greater to 1 pm or less, 0.5 pm or greater to 1 pm or less . In someembodiments, the second electrode 104 may be an electrode deposited via known deposition techniques, such as physical vapor deposition (e.g., sputtering, evaporation), chemical vapor deposition, or atomic layer deposition. While lower thicknesses may enable the second electrode 104 to have increased flexibility, lower thicknesses may also make the second electrode 104 more prone to damage.

[0077] Accordingly, the first electrode 102, the second electrode 104, and the dielectric film 106 together provide the device 100 with a small overall thickness. The thickness of device 100 enables it to be flexible, making the device particularly well-suited for skin-treatment applications. The device 100 may be configured to accommodate any region of skin (e.g., any body part) and / or topology, and to properly function while undergoing stresses and / or deformations related to flexing the device 100.

[0078] In some embodiments, the device 100 may be configured as a patch configured to be worn by a user and / or applied to a user’s skin.

[0079] The first electrode 102 may be designed to be flat or substantially flat such that the overall low thickness of the device 100 may be maintained. In some embodiments, the first electrode 102 may be structured or patterned. In one embodiment, the first electrode 102 may be designed as a wheel-and-spoke pattern (see FIGS. 3 A and 3B). In another embodiment, the first electrode 102 may be designed as a structure with a plurality of linear elements spaced apart from one another (see FIGS. 4A and 4B). It is contemplated that the structure or pattern of the first electrode 102 is not particularly limited and may be designed according to a particular use of the device 100. It is contemplated that the structure or pattern of the first electrode 102 may be required to generate plasma in adjacent air, specifically uniform plasma generation.

[0080] In some embodiments, the structure or pattern of the first electrode 102 may be configured to accommodate incorporation of a complementary device, such as an optical sensor. For example, the first electrode 102 may be designed as a wheel -and-spoke pattern in which the “hub” (e.g., central portion) of the pattern is hollow to accommodate incorporation of a complementary device. In some embodiments, the structure or pattern of the first electrode 102 may be configured to accommodate incorporation of a plurality of complementary devices, such as a plurality of optical sensors. For example, the first electrode 102 may be designed as a plurality of wheel-and-spoke patterns (e.g., in square or linear pattern) in which the hub of each pattern is hollow to accommodate incorporation of a complementary device.

[0081] The second electrode 104 may be designed to be flat or substantially flat such that the overall low thickness of the device 100 may be maintained.

[0082] In some embodiments, the first electrode 102 and the second electrode 104 are of the same size (e.g., diameter, width, lateral extension) and / or shape. In other embodiments, the first electrode 102 and the second electrode 104 are of different sizes (e.g., diameters, widths, lateral extensions) and / or shapes.

[0083] The device 100 may further include a backing 108. The backing 108 may be positioned over the second electrode 104 such that the backing 108 encapsulates the second electrode 104. The backing 108 may therefore extend laterally at least as far as the second electrode 104. The backing 108 may further extend laterally at least as far as the dielectric film 106.

[0084] In some embodiments, the backing 108 is configured to create a cavity 110 between the second electrode 104 / di electric film 108 and the backing 108 such that the second electrode 104 is not in contact with the backing 108.

[0085] In some embodiments, the backing 108 may be configured to be handled, physically manipulated, or contacted by an operator during use of the device 100. In some embodiments, the backing 108 may form an ergonomic shape designed to fit comfortably within an operator’s hands or fingers.

[0086] In some embodiments, the backing 108 is a low thickness coating.

[0087] In exemplary embodiments, the backing 108 is an insulating material. In some embodiments, the backing 108 may be a gel backing, such as an electrically-insulting gel backing.

[0088] In exemplary embodiments, the device 100 is open to the environment, such that ambient air may circulate around the electrodes. For example, the backing 108 may include at least one aperture (not shown) such that ambient air may circulate in and out of the cavity 110.Alternatively, the device 100 may include a spacer 112 configured to enable ambient to circulate in and out of the cavity 110.

[0089] In some embodiments, the generated plasma may be an ionized gas. For example, the ionized gas may include or consist of ionized air, include or consist of ionized nitrogen, include or consist of ionized oxygen, and / or mixtures thereof.

[0090] The first electrode 102 and the second electrode 104 may be operated within a low AC voltage range (peak-to-peak voltage range), such as from 400 V to 2.0 kV, or from 800 V to 1.2 kV.

[0091] The voltage source 200 may be a battery. In one embodiment, the battery is positioned within the device 100, such as within the cavity 110. In another embodiment, the battery is positioned outside of (e.g., external to) the device 100.

[0092] The voltage source 200 may be electrically connected to the first electrode 102 and the second electrode 104. In practice, the voltage source 200 may apply a voltage to the second electrode 104, thus creating an electric field, causing surrounding gas (e.g., air) molecules near the surface of the dielectric film 106 to ionize. This may lead to a plasma discharge.

[0093] The device 100 may include a voltage source circuit (see FIG. 5). The circuit may include the voltage source 200, an inverter 202, a frequency amplifier / multiplier 204, and an amplifier / transformer 206. The amplifier / transformer 206 may be configured to deliver the voltage to the electrodes. In some embodiments, the amplifier / transformer 206 is a piezoelectric amplifier or piezoelectric transformer.

[0094] In some embodiments, the first electrode and the second electrode are electrically connected by the amplifier / transformer 206 to the voltage source 200.

[0095] In some embodiments, the first electrode 102 and the second electrode 104 may be powered by an alternating current with a frequency of 5 kHz. Other embodiments may utilize another frequency for an alternating current.

[0096] Embodiments further relate to methods of using the device 100. In one exemplary use, the device 100 is configured for dermatology applications. The device 100 may be used to treat or heal wounds, such as superficial (e.g., epidermal) wounds, partial thickness (e.g., dermal) wounds, and full-thickness wounds. The device 100 may also be used to treat skin infections, such as bacterial infections, viral infections, fungal infections, and parasitic infections. The device 100 may also be used to treat inflammatory skin disorders, such as skin disorders with a microbial component (e.g., bacterial, fungal, viral, etc.). Exemplary skin disorders / infections include, but are not limited to, atopic dermatitis (S. aureus), acne (C. acnes), rosacea (Demodex mites), scabies, impetigo (S. aureus, Sir. pyogenes), folliculitis (Pseudomonas), diabetic ulcers(fungal), seborrheic dermatitis (Malassezia), hidradenitis suppurativa (Prevotella,Prophormonas, Peptoniphils, S. aureus, etc.), herpes zoster (shingles), and HSV-1.

[0097] In particular, the device 100 may be configured to combat acne through inhibition of C. acnes, inhibition of sebum production, and / or anti-inflammatory effects.

[0098] In exemplary embodiments, the device 100 may be configured to inhibit bacteria such as E.faecium, S. aureus, K. pneumoniae, A. baumannii, P. aeruginosa, E. spp, and / or E coli. It is contemplated that the device 100 and its operation parameters (e.g., voltage, frequency) may be tuned to target particular bacteria. The device 100 may particularly be configured to inhibit bacteria while also causing no or substantially no damage to keratinocytes.

[0099] In practice, the active surface of the device 100 (e.g., the surface of the first electrode 102) may be positioned on the body of an animal and / or in proximity (e.g., 2-5 mm) to the skin to be treated. The device 100 may be configured to deliver a continuous treatment. The device 100 may alternatively be configured to deliver a pulsed treatment, wherein treatment is applied for a first predetermined time, followed for a wait period of a second predetermined time, and then repeated. The first predetermined time may be between 1-60 seconds, between 5-45 seconds, between 10-30 seconds, or between 15-20 seconds. The second predetermined time for the wait period may be between 1-60 seconds, between 5-45 seconds, between 10-30 seconds, or between 15-20 seconds. In some embodiments, the device 100 may include a timer circuit to effectuate the pulsed treatment.

[0100] The device 100 can include a power switch or power button (not shown) defined on the backing 108 or have another mechanism for being activated (e.g., detection sensor of being in contact or in close proximity to skin to automatically turn on the ring device 100, etc.).,

[0101] In practice, an operator may hold the device 100 in a stationary or substantially stationary manner, thus applying targeted treatment to a surface to be treated. Additionally, or alternatively, an operator may move or sweep the device 100 across the surface to be treated. In some embodiments, the device 100 can be positioned on a holder that can direct the targeted treatment to the body or surface to be treated.

[0102] Embodiments further relate to methods of making a device 100. The method may include providing a dielectric film 106, and depositing electrodes on either side of the film. For example, the first electrode 102 can be printed (e.g., screen printing or any other suitable printing technique) on a surface of the dielectric film, and the second electrode 104 can be sputtered on the opposite surface of the dielectric film (e.g., via sputter deposition methods).EXAMPLES

[0103] An exemplary embodiment of the device was constructed according to the disclosure provided herein. The embodiment of the device included a thin-film dielectric material with two electrodes on either side of the material to form the first electrode 102, second electrode 104, and dielectric film 106. Polyimide film (commercial name: Kapton) of 50-micron thickness was used. Kapton films were cleaned with 75% isopropyl solution and dried with microfiber cloth. These films then underwent UV-ozone treatment for 10 minutes to improve silver ink adhesion. Wheel-and-spoke pattern silver electrodes were screen printed on one side of the Kapton film that was utilized as the dielectric material (e.g. dielectric film 106). The silver ink used was Creative Materials 118-09A / B119-44. The print was then cured in an oven at a temperature of 125°C for 30 minutes. The wheel-and-spoke pattern design had a diameter of 25 mm. A circular silver electrode of matching diameter was deposited on the other side of the film using Quorum sputter coater (Model ql50r). The thickness of the sputtered layer was 1000Angstrom. Wires were attached to both sides (e.g., both electrodes) using a two-part conductive silver epoxy (MG chemicals 8330S). The silver epoxy was thoroughly mixed inside a syringe, applied to the leads, and cured at 65°C for 2 hours. Top and bottom images of the exemplary embodiment of the device that was formed via this methodology is shown in FIG. 6. As discussed below, this embodiment was subjected to different experimental evaluations and analyses.

[0104] In one experiment, the device was powered by an alternating current with a frequency of 5 kHz. Voltages above 800 V were used to generate plasma. FIG. 7 displays apparatuses used to hold the device and / or maintain a uniform distance of 2 mm when treating targets in petri dishes. As can be seen from FIG. 7, the device was encased inside a shell with extending arms. These arms sat flush atop the treatment petri dish. The vertical placement of the arms account for the height of the plate. Variations were printed for agar containing plates.Methods

[0105] Electrical Measurements: A capacitor was attached to the ground side of the device. Two different capacitance values of 22 nF and 10 nF were used for different experiments. Voltage was measured across the capacitors using a 10* probe (Tektronix TPP0101) that was connected to an oscilloscope (Tektronix DPO2014B). The charge (Q) in the capacitor (C) for a given voltage (V) was calculated using the following equation:Q = CV

[0106] The charge in the capacitor plotted against the input voltage yielded Lissajous curves. The area inside of the Lissajous curve was calculated using Euler’s method and multiplied by the frequency to estimate the power into the plasma.

[0107] Leakage Current Testing: The leakage current was evaluated using the low-passRC -filter displayed in FIG. 8 with the impedance of the circuit matching that of the human body.The filter utilized resistors Rl, R2, and a source of voltage V as shown in FIG. 8. The use of the low-pass filter allowed for removal of noise and accuracy of the data by matching the measurement frequency to that of the device. A square copper sheet of 5 cm width was placed 2 mm (treatment distance) away from the surface of the device 100. The sheet was attached to the circuit and voltage was measured across the capacitor. The probe was connected to an oscilloscope (Tektronix DPO2014B) and the voltage was recorded. The leakage current was then calculated using Ohm’s law.

[0108] Temperature Measurements: Heat generation on the surface of the device was evaluated using a thermocouple (EXTECH Easy View 15). To measure the temperature, the device was operated at various voltages for a predetermined amount of time. The thermocouple probe was then placed against the surface of the device and temperature was measured within 1 second of shut-off. The device was allowed to cool to room-temperature before moving onto the next set of voltage and time test parameters.

[0109] Bacteria Culture and Treatment: E. coli (MG 1665) and S. aureus (USA300 FE2) were grown in LB broth (Difco Lot # 0365816). The culture was diluted with media to achieve a bacteria density of 3xl08CFU / mL for both E. coli and S. aureus. 100 mL of the resulting suspension was plated in 90-mm LB agar (Sigma Lot# SLCF3576) plates. The final population seeded on the plates were 3x 107CFU (colony-forming unit).

[0110] C. acnes (6919) was grown in a pre-reduced Modified Reinforce Clostridial media in-house. Anaerobic conditions were achieved using an Oxoid AnaeroJar 2.5 L coupled with Thermo AnaeroGen 2.5 L oxygen scavenger packets. The culture was diluted with media toachieve a bacteria density of 3 x 108CFU / mL seeding 3 * 107CFU per plate. The resulting suspension was plated in Tryptic Soy Agar with 5% defibrinated sheep blood 90-mm plates.

[0111] All treatments were done inside laminar hoods. The discharge surface of the device was placed 2 mm away from the agar surface and treatment took place with various input voltages and exposure times using both continuous and pulsed treatments. Pulsed treatment was achieved by turning the device on and off in intervals of 15 seconds until the total desired on- time was achieved. After treatment, the plates were incubated for 24 hours for E. coll and 5. aureus. The incubation time for C. acne was 72 hours. The plates were imaged post incubation and area of inhibition was measured using ImageJ (N1H software).

[0112] Cell Culture and Treatment: Normal human epidermal keratinocytes (NHEKs) were acquired from a commercial source of pooled donor neonatal human epidermal keratinocytes (Lonza). The NHEKs were cultured in KGM™ GOLD culture medium supplemented with SingleQuots™ Supplements and Growth Factors (Lonza). For the individual experiments, NHEKs were plated on 3.5-cm cell culture dishes (Falcon) and allowed to grow to confluence prior to the experiment. Media were refreshed every 2-3 days.

[0113] For plasma exposure, cells were washed twice with PBS, then in a minimal volume of PBS (just enough to submerge the cell monolayer), the monolayer was exposed to the device at various doses. After exposure, PBS was removed and conditioned medium was added back. Plates were then put back into the incubator for 48 hours prior to harvest. Representative brightfield images (20 - objective; 200* total magnification) of the cultured cells were taken prior to plasma exposure and at 24 and 48 hours post-exposure. During harvest of total cell lysates, cells were washed twice with ice-cold PBS, harvested directly in IX SDS sample buffer + BME, and boiled for 10 min. Whole cell extracts were stored at -20°C until use.

[0114] For Western blotting, equal amounts of protein were loaded on polyacrylamide gel (10-15%). Proteins were transferred to a nitrocellulose membrane and probed using antibodies against Caspase-3 (CS #9662), PARP (CS #9542) (Both 1 : 1000 - Cell Signaling, Beverly MA), and GAPDH (#10494-l-AP) (1 :3000 - Proteintech, Rosemont, IL).

[0115] Kl-Starch Model for ROS Detection: Potassium iodide starch mixture was used as an indicator of Reactive Oxygen Species (ROS). Kl-Starch was suspended inside agar and treated with the device. 1 g of potassium iodide and 1 g of starch were added to a solution of 8-g agar with 200-mL DI water at 50°C and poured inside 35-mm petri dish. In the presence of ROS, the iodide was oxidized and turns into iodine. Iodine, in turn, reacted with starch and turned blue in color. These experiments enabled the visualization of ROS concentrations across the embodiment of the device 100 and qualitatively measure ROS formation on the surface of the device.

[0116] Statistical Analysis: Statistical significance evaluation was performed using Microsoft Excel. One-way ANOVA, two-way ANOVA, or t-test were performed where applicable and probability of null hypothesis were reported. Condition of p < 0.05 (5%) was set for statistical significance. Error bars correspond to ± standard deviation and are displayed where applicable.Results

[0117] Electrical Power Measurements: A common approach to measuring CAP treatment dosage is plasma power. Although differences in design and geometry of CAP sources can affect the plasma and the underlying chemistry, this method can serve as an initial step for comparing and correlating the plasma generated in different devices. Hence, a reasonable comparison can be made for treatment results across experiments involving differing devices.

[0118] In the case of the device, only 15-28% (depending on the voltage) of the applied power is delivered to the plasma. The input parameters are displayed in Table 1.Table 1 : Calculation of power input into the device as a wholeRMS Input Current (mA) RMS Input Voltage (kV) Input Power (W)2.9 0.57 1.653.7 0.71 2.635.3 0.85 4.516.5 0.99 6.448.4 1.1 9.248.8 1.3 11.4

[0119] There are various methods that can be used to estimate the power of a nonequilibrium plasma. Given the nature of such discharge regimes, the bulk of the power can be estimated by the density, excitations, and kinetics of electrons. However, other methods such as a Lissajous curve can be used to develop a more holistic picture. This technique utilizes the capacitive nature of the plasma and the trapezoid shape that results from it on charge-vs. -voltage plot to calculate the energy of a single period and convert it to power. The trapezoid shape stems from the fact that when plasma is ignited it absorbs the power applied to the device much like a capacitor possessing an inherent capacitance. However, when the plasma is off the only capacitance in the system is that of the dielectric barrier. Lissajous curves and their calculated plasma power are displayed in FIGS. 9 and 10.

[0120] Leakage Current Measurements: The device was designed for application to inflammatory skin conditions. However, prior to direct application to skin, the safety of thedevice was studied. Beyond temperature measurements, two experimental efforts were conducted as a small-scale safety analysis of the device.

[0121] The first set of experiments involved a concept called leakage current. This is a standard test for electrical devices that are intended for biomedical applications involving patients and operators. Leakage current evaluation is referenced as a requirement by a variety of regulatory organization guidelines such as United States Food and Drug Administration (FDA) and International Electrotechnical Commission (IEC). These guidelines are available in IEC60601 AAMI / NFPA 99 and summarized in Table 2.Table 2: FDA approved IEC regulations regarding the safety of electrical medical devices and the hazards of electric shock: IEC60601 AAMI / NFPA 99[00122J Leakage current is described as any unintended current that is deposited to the patient by the device. It is measured using an RC circuit that resembles the impedance of the human body. A low-pass filter is added to the circuit to reduce noise. Voltage in the circuit was measured and converted to leakage current. The calculated current for various voltages isdisplayed in FIG. 11. This device falls under type BF (body floating) and the displayed experimental data represents a normal operating condition (NC). At a maximum test voltage of 1.6 kV the leakage current measured for the device was 79 pA. This is well within the regulatory threshold of 100 pA as specified in IEC60601 AAMI / NFPA 99.

[0123] Surface Temperature of the Device: Thermal generation on the surface of the device was evaluated and presented in FIG. 12. Although the highest temperature of 44°C does not pose any damage to cells, an attempt to reduce these temperatures was undertaken. The device was operated in a pulse regime during which 15 seconds of discharge was followed by 15 seconds of no power to the device, repeated until the desired total on-time was achieved.Thermal generation on the surface of the device under pulsed operation is presented in FIG. 13. At the highest exposure rate and intensity, the surface temperature of the device was reduced by 5°C. Extending the off-time between 15-second pulses did not have significant further reduction in temperature. The trend presented within the data takes the shape of an inverse exponential, suggesting that the temperature is approaching a plateau. This also suggests that the majority of heat generation occurs in the first few seconds of operation. Furthermore, looking at the change in temperature on the surface of the device it is apparent that pulsed treatment is much more effective at reducing heat at lower voltages of operation.

[0124] In vitro Testing of Effects on Bacteria: The device may be used for the treatment of inflammatory skin conditions. These conditions can often involve infections; hence, understanding the effects of the device on pathogens is an important step in the evolution of this device. One target of the device and the condition discussed in the context of this Example is acne vulgaris.

[0125] The device may combat acne lesion formation through inhibition of C. acnes, inhibition of sebum production, and / or anti-inflammatory effects. This example focuses on the antimicrobial properties of plasma and its effects on C. acnes. Treatment of bacteria was undertaken on freshly-plated cultures with populations large enough to form a bacterial lawn. After treatment and incubation large areas of discontinuity in the bacterial lawn, referred to as zones of inhibition, signal inactivation of the underlying bacteria. Along with C. acnes, grampositive 5. aureus was treated as an initial probe into other dermatologically-relevant bacteria. E. col was also evaluated to distinguish the effects of the device on Gram-positive and Gramnegative bacteria. The device was effective against all three strains; however, Gram-positive strains showed increased susceptibility (FIGS. 14-16).

[0126] In vitro Testing of Effects on Keratinocytes: Considering that the device is configured to be applied to skin, keratinocytes were cultured and treated to determine appropriate operation voltage at which C. acnes is inactivated but keratinocytes remain healthy. Microscopy and Western blot were used to evaluate apoptosis (programmed cell death) of treated keratinocytes. Apoptosis was observed at higher voltages in select regions of the cell culture plates, no significant cell damage was observed at lower exposures (FIG. 17). It is clear that treatments exhibiting voltages of 1.2 kV and above begin to show signs of apoptosis. However, this effect did not appear to affect the entire plate; rather, it is localized. We suspect locally high concentrations of RONS are responsible. An experiment involving the Kl-Starch model as an indicator of RONS concentration was devised to test this hypothesis.

[0127] ROS Distribution Methods: We hypothesize that the localized nature of the apoptosis observed is due to higher accumulation of RONS in that region. In an attempt to test this hypothesis, the Kl-starch model was used to qualitatively measure RONS concentrationacross the plasma region. Kl-starch plates were treated similarly to cell culture plates and the areas of oxidation were measured. Images of oxidation were correlated to the surface of the electrode and the results are displayed in FIG. 18. This figure presents two extreme cases of exposure. The left side of the figure displays treatment results at 1 kV for 90 s whereas the right side of the figure represents treatment at 1.6 kV for 300 s. Initial data suggest non-uniform distribution of ROS across the surface of the device. This could explain the localized cell death observed with higher doses of keratinocyte treatment.

[0128] It should be understood that modifications to the embodiments disclosed herein can be made to meet a particular set of design criteria. For instance, the number of or configuration of components or parameters may be used to meet a particular objective.

[0129] It will be apparent to those skilled in the art that numerous modifications and variations of the described examples and embodiments are possible in light of the above teachings of the disclosure. The disclosed examples and embodiments are presented for purposes of illustration only. Other alternative embodiments may include some or all of the features of the various embodiments disclosed herein. For instance, it is contemplated that a particular feature described, either individually or as part of an embodiment, can be combined with other individually described features, or parts of other embodiments. The elements and acts of the various embodiments described herein can therefore be combined to provide further embodiments.

[0130] It is the intent to cover all such modifications and alternative embodiments as may come within the true scope of this invention, which is to be given the full breadth thereof. Additionally, the disclosure of a range of values is a disclosure of every numerical value within that range, including the end points. Thus, while certain exemplary embodiments of theapparatus and process and / or utilization and methods of making and using the same have been discussed and illustrated herein, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.

Claims

What is claimed is:

1. A device for generating a cold atmospheric plasma, the device comprising: a dielectric film having a first surface and a second surface opposite of the first surface, wherein the first surface is a treatment facing surface; a first electrode positioned on the first surface of the dielectric film; and a second electrode positioned on the second surface of the dielectric film, wherein the second electrode has a thickness of 0.05-10 pm.

2. The device of claim 1, wherein the second electrode has a thickness of 0.05-1 pm.

3. The device of claim 1, wherein the first electrode has a thickness of 30-100 pm.

4. The device of claim 1, wherein the first electrode has a thickness of 35-100 pm.

5. The device of claim 1, wherein the first electrode has a thickness of 0.1-1 pm.

6. The device of claim 1, wherein the first electrode has a thickness of 1-30 pm.

7. The device of claim 1, further comprising: a voltage source electrically connected to the first electrode and the second electrode.

8. The device of claim 1, further comprising:a backing positioned over the second electrode such that the backing encapsulates the second electrode and forms a cavity.

9. The device of claim 8, further comprising: a voltage source positioned within the cavity, wherein the voltage source is electrically connected to the first electrode and the second electrode.

10. The device of claim 8, wherein the backing is formed from an electrically insulating material.

11. The device of claim 8, wherein the backing comprises at least one aperture configured to allow circulation of ambient air into and out of the cavity.

12. The device of claim 1, wherein the device further comprises: a voltage source circuit comprising a voltage source, an inverter, a frequency multiplier, and an amplifier.

13. The device of claim 12, wherein the amplifier is a piezoelectric amplifier.

14. The device of claim 12, wherein the first electrode and the second electrode are electrically connected by the amplifier to the voltage source.

15. The device of claim 1, wherein the device is operated at an AC voltage of 400 V to 2.0 kV.

16. The device of claim 1, wherein the device is operated at an AC voltage of 800 V to 1.2 kV.

17. The device of claim 1, wherein the dielectric film comprises a material selected from the group consisting of polyimide, polytetrafluoroethylene, polyvinyl fluoride, polyethylene terephthalate, and combinations thereof.

18. The device of claim 1, wherein the first electrode comprises a conductive metal selected from the group consisting of copper, silver, gold, aluminum, platinum, and combinations thereof.

19. The device of claim 1, wherein the second electrode comprises a conductive metal selected from the group consisting of copper, silver, gold, aluminum, platinum, and combinations thereof.

20. A method of making a device for generating a cold atmospheric plasma, the method comprising: providing a dielectric film having a first surface and a second surface opposite of the first surface; depositing a first electrode on the first surface of the dielectric film, wherein the first electrode is a is a treatment facing electrode; and depositing a second electrode on the second surface of the dielectric film, wherein the second electrode has a thickness of 0.05-10 pm.

21. The method of claim 20, wherein the second electrode has a thickness of 0.05-1 pm.

22. The method of claim 20, wherein the first electrode has a thickness of 30-100 pm.

23. The method of claim 20, wherein the first electrode has a thickness of 35-100 pm.

24. The method of claim 20, wherein the first electrode has a thickness of 0.1-1 pm.

25. The method of claim 20, wherein the first electrode has a thickness of 1-30 pm.

26. The method of claim 20, wherein depositing the first electrode includes screen printing at least one conductive metal on the first surface of the dielectric film.

27. The method of claim 26, wherein the at least one conductive metal comprises a metal selected from the group consisting of copper, silver, gold, aluminum, platinum, and combinations thereof.

28. The method of claim 20, wherein depositing the second electrode includes depositing at least one conductive metal on the second surface of the dielectric film via a deposition method selected from the group consisting of sputtering, chemical vapor deposition, and atomic layer deposition.

29. The method of claim 28, wherein the at least one conductive metal comprises a metal selected from the group consisting of copper, silver, gold, aluminum, platinum, and combinations thereof.

30. The method of claim 20, wherein the dielectric fdm comprises a material selected from the group consisting of polyimide, polytetrafluoroethylene, polyvinyl fluoride, polyethylene terephthalate, and combinations thereof.

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