Scanning kelvin probe systems are non-contact, non-destructive instrument. It is designed to measure the surface work function difference between conducting, coated, or semi-conducting materials and a metallic probe. It operates using a vibrating capacitance probe, and through a swept backing potential, the work function difference is measured between the scanning probe reference tip and sample surface. The work function can be directly correlated to the surface condition. It has ability to make measurements in a humid or gaseous environment.