Micro force sensor with piezoresistive amorphous carbon strain gauge

In this contribution, we report for the first time on a piezoresistive amorphous carbon (a-C) strain gauge successfully integrated into a silicon micro cantilever force sensor. Amorphous carbon was sputter deposited on a silicon membrane and structured by the lift-off technique using photo resist. Cantilevers comprising a-C strain gauges were etched out of this membrane using TMAH and KOH in a bulk silicon micromachining process. Realized prototypes were tested by applying a variable load to the cantilever free end. We found linear characteristics of the strain gauge resistance vs. the applied force in the range of 0 to /spl plusmn/600 /spl mu/N revealing a piezoresistive gauge factor of a-C of nearly 70.