Ion-plated discontinuous thin film strain gauges

Abstract

The major advantage of tunnelling thin film strain gauges over continuous thin films is high sensitivity. The main problem lies in instability with time, presumably due to island coalescence. In this study, the films were stabilized by the use of ion-plating deposition, which contributes to immobilize the grains. Discontinuous gold thin film strain gauges were prepared by deposition on Kapton substrates, which are resistant to plasma heating. Gauge factors measurement and resistance observations on hysteresis and stability were made for film sheet resistance in the range 10 2–10 7 Ω/sq. For a representative 7 nm thick strain gauge, a gauge factor of 38 was measured. Individual grains of 25-nm diameter with 6-nm separation distance were observed. The reduction of aging effects attainable by ion-plating deposition render discontinuous thin films applicable for high sensitivity strain gauges.