Ultralarge Elastic Deformation (180° Fold) of Cubic-^natBP Microwires for Wearable Flexible Strain Sensors

Abstract

Flexible strain sensors that can convert mechanical irritation from an external environment into electrical signals are key components in wearable devices. Here, using the principle of a B–Ni phase diagram, a pure-phase cubic natural boron phosphide (c-natBP) single-crystal microwire is obtained, which possesses ultralarge elastic deformation realized with the bending degree up to 180°. Based on the natBP microwire, a flexible strain sensor is prepared with an obvious quasi-linear response to external strain exhibited, which can be attributed to the Schottky barrier height (SBH) formed at the metal–crystal contact changing with the strain. Such strain-induced change results from lattice deformation, reconstructing the electronic structure and electron affinity. Furthermore, the effective and fast response of this flexible strain sensor in the practical applications of bicycle speed detection as well as finger and wrist bending detection demonstrates the potential of c-natBP microwire flexible strain sensors in wearable electronics, man–machine systems, and soft robotics.