Multifunctional thin film sensors based on amorphous diamond-like carbon for use in tribological applications

Amorphous diamond-like carbon films are well known for their excellent tribological properties. In this paper, we will discuss the sensoric properties of multifunctional a-C:H films with respect to force/load/pressure and temperature measurement. It turned out that nanostructured amorphous carbon films showed an impressive piezoresistive effect. Unlike well known strain gages and piezoresistive sensors, which detect a deformation of the base substrate, this novel sensor can be used in a complete stiff arrangement without any elastic joint. For film preparation, rf-plasma CVD processes were used. Besides gas pressure, a variation of the substrate power and bias potential was performed. It turned out that the tribological parameters varied slightly (hardness: 20-30 GPa, friction coefficient: 0.10 to 0.15),whereas the electrical parameters showed remarkable differences with respect to the electrical resistivity and piezoresistivity. This paper will also present different applications of amorphous carbon thin film sensors. (c) 2006 Elsevier B.V. All rights reserved.