Contact electrification studies using atomic force microscope techniques

Contact electrification measurements using atomic force microscopy techniques were performed using micrometer-sized spheres made of polystyrene and flat substrates of either freshly cleaved, highly oriented pyrolytic graphite (HOPG) or a 0.2-μm-thick Au[111] film grown on mica. The polystyrene/HOPG interaction exhibited significant electrostatic charging when compared to the polystyrene/Au system. This result is consistent with qualitative expectations of contact charging based on a triboelectric series of common materials. The observed contact electrification is also consistent with electronic charge transfer between materials, rather than an ionic or material transfer mechanism.