Surface technology with cold microplasmas

Various new plasma-based surface technological processes are made feasible by localizing atmospheric-pressure discharges to predefined volumes with sub-millimeter linear dimensions. So-called Plasma Printing processes use cold discharges in microcavities formed temporarily by contacting a substrate with a suitably designed kind of plasma stamp. Aside from dielectric barrier discharges driven by mid-frequency (MF) AC voltages, cold microplasmas can also be sustained in arrangements without a dielectric barrier, if RF excitation is used. The modification or coating of internal surfaces in already sealed microfluidic systems promises the achievement of a wide range of physico-chemical surface properties which are difficult to attain by wet-chemical or low-pressure plasma processes. Using a proper electrode arrangement, the coating or modification can be localized to a selected segment of a microfluidic system.