Epitaxial Liftoff of Wafer‐Scale VO 2 Nanomembranes for Flexible, Ultrasensitive Tactile Sensors

Highly sensitive tactile sensors with long-term stability and low power consumption are one of the key components for flexible electronics. Here, for the first time, the fabrication of VO2 nanomembrane tactile sensors by epitaxial liftoff from ZnO sacrificial layer is reported. The wafer-scale nanomembranes inherit the structural and electrical properties of the as-grown films, and the wet transfer generates negligible influence on the quality of VO2. Most importantly, giant electrical responses to external strains are found due to the release of substrate clamping, and a high gauge factor up to approximate to 1100 is derived. Furthermore, the electrical properties show no deterioration after repeatedly bending the nanomembranes for 10 000 times at a radius of 1 cm. The VO2 nanomembrane sensors are utilized to monitor the radial artery pulse, and totally reproducible waveforms with ultrahigh sensitivity to the tactile stimuli are observed. Moreover, the power dissipation of the VO2 tactile sensors can be lowered down to the picowatt level, allowing for the future construction of self-powered sensing systems together with nanogenerators. This study provides a substantial step toward large-scale preparation of oxide nanomembranes and therefore paves a promising way for flexible oxide electronics.