Application of atmospheric plasma could be used for wound healing, skin rejuvenation, and wrinkle treatment. The authors explored the feasibility of atmospheric microplasma irradiation (AMI) for enhancement of percutaneous absorption of drugs as an alternative to hypodermic needles. Pig skin was used as a biological sample exposed to AMI and analyzed by attenuated total reflection-Fourier transform infrared spectroscopy. A tape-stripping test (an evaluation method for skin-barrier performance) was also conducted to compare with AMI. Transepidermal water loss was also measured and compared with and without AMI. Results showed that surface modification of the stratum corneum (outermost skin layer) was observed upon AMI. Small pores on sample skin were observed with plasma jet irradiation due to the collision of charged particles. Percutaneous absorption was confirmed without damage upon microplasma irradiation. Our data suggested that dye pathways through skin samples could be related to the dynamic behavior of intercellular lipid bilayers, suggesting that AMI could enhance percutaneous absorption.

Decomposition of formaldehyde (HCHO) by a microplasma reactor in order to improve Indoor Air Quality (IAQ) was achieved. HCHO was removed from air using one pass through reactor treatment (5 L/min). From an initial concentration of HCHO of 0.7 ppm about 96% was removed in one pass treatment using a discharge power of 0.3 W provided by a high voltage amplifier and a Marx Generator with MOSFET switches as pulsed power supplies. Moreover microplasma driven by the Marx Generator did not generate NOx as detected by a chemiluminescence NOx analyzer. In the case of large volume treatment the removal ratio of HCHO (initial concentration: 0.5 ppm) after 60 minutes was 51% at 1.2 kV when using HV amplifier considering also a 41% natural decay ratio of HCHO. The removal ratio was 54% at 1.2 kV when a Marx Generator energized the electrodes with a 44% natural decay ratio after 60 minutes of treatment.

A study of the transdermal delivery of Cyclosporine A by atmospheric plasma irradiation was realized on the epidermal layer of the Hairless Yucatan micropig. Drug flux and the amount of drug penetrated through the skin were determined by a Franz cell diffusion experiment. After treatment of the skin by atmospheric plasma jet or microplasma dielectric barrier discharge, an increase in the permeability of the skin was observed. The authors did not observe drug penetration for samples that were not treated with plasma. There was no significant difference between treatments of skin by plasma jet or microplasma dielectric barrier discharge. Drug flux increased to its maximal value up to 3 h after the drug application, and then it decreased. This phenomenon could indicate a temporal effect of plasma on skin. A pharmacokinetic two-compartment model was developed to estimate the possibility of using plasma drug delivery of Cyclosporine A in medical praxis. Our model showed that it is possible to use this technique if a suitable treatment area and concentration of applied drug are chosen.

Multiple vapor inlet systems have been developed to enhance the homogeneity of deposited polyacrylic acid films via medium and atmospheric pressure plasma technology. Different inlet systems were experimentally tested and optical reflectance spectrometry (OPS) was used to measure the differences in thickness of the films along the exposed surface. Standard deviations of more than 65% were reduced to less than 10%. COMSOL models point to the gas flow as the main contributor to the film homogeneity. OPS analysis of the best set‐up shows a linear relationship between thickness and exposure time (100–200 nm/min). XPS C1s deconvolution indicates a preservation of +50% of the –COOH groups and a significant incorporation of other oxygen containing groups.

Pollution of the atmosphere from various sources, including factories and automobiles, is a serious problem worldwide and should be controlled and reduced. Nonthermal plasma is studied by various groups and has been applied for exhaust gas treatment and indoor air purification. Microplasma, which is atmospheric pressure nothermal plasma, has recently been studied by many researchers. Although nonthermal-plasma diagnosis by emission spectroscopy has been applied by many authors, the mechanisms are not sufficiently understood. In this paper, the diagnosis of the microplasma discharge in N 2 gas and N 2 /NO gas mixture are presented. An experimental Marx generator with MOSFET switches was used to generate pulsed output voltages of up to −1.8 kV. Emission spectra were observed by a spectrometer with intensified charge-coupled device camera and a photomultiplier tube. The formation of radicals was confirmed by NO-γ band, N 2 second positive band, and N + 2 first negative system. Time evolution of light emission that is measured by the photomultiplier tube showed differences between the NO-γ band and the N 2 second positive band. This condition is suggested to be the result of different light emission mechanisms; the N 2 second positive band is excited by direct electron impact, and the NO-γ band is excited by collisions of N 2 metastables.

Inactivation of microorganisms, such as Escherichia coli, by exposure to a microplasma is experimentally investigated. A microplasma is an atmospheric-pressure nonthermal plasma. Microplasmas, which generate high-intensity electric fields, can be formed using relatively low discharge voltages (0.7-1.1 kV) across small discharge gaps (0-100 μm). The key benefits of the practical application of exposure to a microplasma are as follows: 1) the low discharge voltage and 2) the simple apparatus because a vacuum enclosure is not required. Hence, the apparatus for generating a microplasma could be relatively small and inexpensive and could be integrated into a portable device. The ozone generated by a microplasma at a low power level was measured, although the specific power density of the microplasma was larger than that of large-scale conventional plasmas. The emission spectra of the microplasma discharge in N 2 was measured: 1) to confirm the UV light emission and 2) to identify the active chemical species generated by the microplasma discharge. The emission spectra was also measured with the presence of water droplets. The UV light from the microplasma discharge showed excited nitrogen molecules and OH radicals. In this paper, two cultures of bacteria, i.e., gram-negative Escherichia coli HB101 and gram-positive Bacillus subtilis JCB 20036 were the target microorganisms to be inactivated. In the experiments reported here, the number of bacteria decreased after microplasma treatment. The inactivation rate increases as the discharge voltage increases. Escherichia coli is completely inactivated when air is used as carrier gas at a plasma discharge voltage of 1.05 kV. Using nitrogen as carrier gas, the highest inactivation rate is 77% at a discharge voltage of 1.15 kV. In addition, Bacillus subtilis is inactivated with a rate of 97% at 1.07 kV with air as carrier gas. Using nitrogen as carrier gas and a discharge voltage of 1 kV results in an inactivation rate of 70% of bacteria. The inactivation of microorganisms by microplasma may be due to several factors either individually or in combination of the following: 1) the excited molecules and ions; 2) ozone; 3) high electrical fields; and 4) UV light. The effect of active species such as OH radicals may also be important since all the bacteria were carried within a small water droplet in between the electrodes.

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