Amorphous FeZr metal for multi-functional sensor in electronic skin

Abstract

The composition of an amorphous metal, which is well known for having no slip plane or slip direction, can be tailored for enhanced strength and a lower Young’s modulus under mechanical stress. Unlike crystalline metals, elastic amorphous metals can, in principle, be used as a flexible electrode in soft, wearable electronics. A metal with a lattice structure absorbs external energy, which causes structural deformations, while an amorphous metal does not absorb energy. Therefore, amorphous metals have excellent mechanical properties that can overcome the limitations of crystalline metals. However, voids inside such metals are easily formed according to Thornton’s model, which results in the formation of mesoporous (10–50 nm) rods due to the spatial separation of metal atoms. We eliminated the porosity in amorphous metals by controlling the kinetic energy of sputtered metal atoms and ions. Optimized Fe33Zr67 has an amorphous structure with a strength of 2.88 GPa and a Young’s modulus of 76.6 GPa. With this amorphous metal, we fabricated a stretchable and multi-functional sensor for electronic skin that enables the detection of pressure, temperature and light and also serves as a heater. In this work, we demonstrate the feasibility of the amorphous metal Fe33Zr67 in soft electronics for use in various industrial applications.