Atmospheric-pressure piezo-driven microplasma source for bio-medical applications

Abstract: The microplasma source using a piezo-electric transformer is investigated for bio-medical applications. It comprises of a rod-shaped piezo transformer with a rectangular cross-section. The piezo element is housed in the front end of a metal tube; the power and gas supply enter the tube through its rear end. A quartz tube is coaxially fitted to the metal tube for experimental purpose and to protect the active plasma from perturbation by ambient air. Helium is generally used as the working gas. Nitrogen is used as admixture for diagnostics. Plasma conditions are characterized by determining gas temperature and plasma parameters namely electron density and electron distribution function. Gas temperature in the plasma volume is determined using optical emission spectroscopy and numerical simulation. The excitation emission of N2(C-B, 0-0) at 337 nm is fitted with rotational distributions simulated for different gas temperatures. Electron velocity distribution function (EVDF in eV-3/2) is determined by comparing the ratio of excitation emission of N2(C-B, 0-0) to tha