Optical emission spectroscopy, ranging from visible to near infrared, is used to determine densities and rotational temperatures of N 2 (B 3 g ) and N 2 (C 3 u ) states in a nitrogen-argon (0-95% Ar) discharge, under moderate pressures . The plasma is sustained by a helical cavity with an excitation frequency of 27 MHz and power fixed to 28 W. Firstly, in the case of a pure N 2 discharge, the two states turn out to have a similar rotational temperature, which approximates the gas temperature reasonably well. With a gradual increase in the Ar concentration up to 95%, the rotational temperature of N 2 (C 3 u ) roughly doubles while that of N 2 (B 3 g ) stays unchanged at 430 ± 50 K regardless of the gas composition. Secondly, as observed, the densities of the N 2 (B 3 g ) and N 2 (C 3 u ) states increase with increasing Ar percentage in the gas mixture. The increase in the emission intensity values is less marked for positions corresponding to both ends of the cavity. In fact, the difference in the emission level between the power input and helix middle positions is reduced, revealing that the total discharge is more uniform along the cavity for large argon concentrations. The experimental results show a strong dependence of temperatures and densities on the Ar amount in the gas mixture. A kinetic model is developed to explain this phenomenon, which is then used in modelling density evolutions versus relative abundance of Ar and versus the position along the cavity axis. The model indicates the importance of the role of electron and metastable species in the above-described discharge.

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.

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Optical emission spectroscopy in vacuum ultraviolet and UV spectral ranges is applied to study densities, and vibrational and rotational temperatures of the N 2 molecule in a nitrogen-argon (0-95% Ar) plasma sustained at a pressure of 400 Pa by a helical cavity supplied with a power of 28 W and an excitation frequency of 27 MHz. The spatial investigation of all emission systems from UV to NIR shows a minimum situated in the middle of the helical structure and two maxima located at the positions where the RF power is transmitted to the gas and at the end of the helix. The minimum was deepest for emission of the first positive (1 + ) nitrogen system. This hollow shaped density profile due to the presence of a non-linear phenomenon in the discharge is constant whatever the gas composition. The emissions related to Lyman-Birge-Hopfield and the second positive (2 + ) systems of molecular nitrogen, and N( 2 P) atoms, are analyzed versus the Ar percentage. Additionally, the NO(A 2 + → X 2 ) and OH(A 2 + → X 2 ) emission systems coming from impurities are investigated. All the densities of the considered species increase with Ar amount. The rotational and vibrational temperatures of the emitter species are determined through the comparison between experimental and simulated spectra. In the case of a N 2 discharge, all the rotational temperatures deduced through the nitrogen emission systems are equal and can be assimilated to the gas temperature. With the increase in the Ar amount, only the rotational temperature obtained from the 1 + system is close to the gas temperature. The rotational and vibrational temperatures related to the NO(A 2 + ) species are constant whatever the gas composition. The vibrational distribution function of N 2 (a 1 g ) state presents a Boltzmann law with a vibrational temperature in the range 5600-8000 K (±1000 K) for the N 2 -x% Ar mixture with x < 75%. When the Ar percentage increases above this limit, we observe strong deviations from the Boltzmann law and no temperature can be deduced. Some kinetic considerations, where the nitrogen and argon metastables play an important role, are discussed to explain the strong dependence of the temperatures and density species toward the Ar amount in the gas mixture.

Human skin is the largest organ and also the main barrier that prevents foreign substances from entering the body. The surface properties of the skin are relevant for transdermal drug delivery and cosmetics. Yucatan micropig skin is used as a substitute for human skin. A microplasma electrode is used for surface modification of the skin epidermal layer of the Yucatan micropig. Microplasma dielectric barrier discharge has a thin dielectric as a barrier (∼50 μm) and a frequency of 25 kHz. The surface properties of the epidermal layer were characterized by the measurement of the contact angle of the water droplet. The effects of different gases such as air, nitrogen, oxygen, helium or argon were compared. The change of the contact angle is temporal and it is returned to its initial state after several hours. Among the gases used for plasma ignition, oxygen and argon were the most effective for skin treatment. The distance of the skin from the electrode and the treatment time played a crucial roles in the increasing water contact angle. Changes of surface atomic concentration were determined by x-ray photoelectron spectroscopy. After microplasma treatment, the oxygen and nitrogen concentration increased at the skin surface.