Thermally stable metallic glass strain sensors with extended sensing range and sensitivity

Abstract

Metallic glasses (MGs) are metal alloys with attractive properties for use as electrodes in strain sensors, such as high conductivity, mechanical strength, and strong corrosion resistance owing to their unique amorphous atomic arrangements, which are critical criteria for highly reliable sensors. However, MG-based strain sensors that may detect strains of >1% with high gauge factors have not yet been reported. In this study, an AlY-MG thin film in an amorphous phase is successfully deposited on a target substrate via sputter deposition. Whereas layer-by-layer-assembled graphene nanoplatelets (GNP) enable stable strain sensing over an extended range, the amorphous atomic arrangement of the MG film resulted in more distinct changes in electron conducting path under strains from 2% to 10%, which is induced by cracks initiated on the surface of the AlY film. Furthermore, the chemical stability of the sputtered AlY thin film is examined via electrical and optical analyses, which prove the high chemical stability at the interface between AlY and the GNP layer. As a result, a strain sensor based on the AlY film, which may detect various human motions when adhered to the skin, is developed.