Investigation of the piezoresistive properties of nano structured amorphous carbon for force sensor applications

This paper deals with the preparation and investigation of nano structured diamond-like-carbon films with respect to the piezo resistive, electrical and mechanical properties. Therefore a-C, a-C:H and doped a-C:H:W films were prepared at different plasma conditions.The films were mechanically characterized by AFM and Hysitron, which was also used for nano topographic investigations. Selected films were investigated by Raman spectroscopy for revealing the sp2 /sp3 bonding ratio.For investigations of the electrical transport mechanism and the piezoresistive properties the films were deposited on Si-wafer and on steel substrates. The measurements included resistivity vs load, strain and temperature plots. This piezoresistive carbon coating can be used for force/pressure transducer and tribological coating as well. This allows direct measurements at mechanically treated surfaces.