New materials for sputtered strain gauges

Commercial strain gauges obtain a gauge factor of approximately 2 with a compensated temperature coefficient of resistivity (TCR). Therefore, material development for sputtered thin films with a high gauge factor and negligible TCR was conducted. The object for self compensated sensor materials is the combination of a semiconducting material (negative TCR) with high gauge factor and a metal (positive TCR) leading to a TCR close to zero. With nickel containing diamond-like carbon films (Ni-DLC or a-C:H:Ni) and Ag-ITO compounds zero crossing in TCR and gauge factors higher than 10 were achieved.