A Bilayer Thin-Film Strain Gauge With Temperature Self-Compensation

A Karma–CuNi bilayer strain gauge with a low-temperature coefficient of resistance (TCR) is designed for temperature self-compensation. The impact of heat treatment and structural parameters on its performance is investigated. The TCR of the bilayer thin-film strain gauge can be adjusted to near 0 ppm/°C by controlling the thickness ratio and the annealing temperature. Besides, the Karma–CuNi thin films had a gauge factor (GF) of 2.2. Finally, the Karma–CuNi bilayer thin-film strain gauge was fabricated on the metal substrates and bone-like metal elastomer. An experimental setup based on bending beam theory was developed to determine the GF of the strain gauges fabricated on metal substrate. It shows promising applications for in situ strain or torque measurement of some metal component when high sensitivity and high spatial resolution is required.