A test specimen for investigation of plasma modification of interior surfaces in polymeric three-dimensional microstructures

A special test specimen was designed to facilitate surface analysis inside of trench and gap structures in polymeric microstructures after plasma treatment. Using advanced micro moulding technology a cost effective, disposable, well-defined polymeric microstructure with plane side wall surfaces in the depth and high aspect ratios could be manufactured. Very thin structures with characteristic dimensions much less than 100 μm are reproducible. This was utilized to design a specific trench structure with a variable aspect ratio of 2–10, which can be broken off after plasma treatment. The necessity to use such special test specimen was demonstrated by high resolution scanning XPS measurements on cutted edges of polystyrene samples. Long range disturbances of the chemical surface composition of up to 0.5 mm from the edge were detected. Two examples for the usefulness of the described device are given. They demonstrate differences in trench modification effects of plasma polymerization and vapor phase grafting after plasma activation.