A self-protective piezoelectric-piezoresistive dual-mode device with superior dynamic-static mechanoresponse and energy harvesting performance enabled by flextensional transduction

Dual-mode pressure sensors capable to perceive various external dynamic and static mechanical stimulus are constantly required to develop wearable electronics and smart subhuman robots. However, most sensors can hardly exhibit robust and reliable highly sensitive response to dynamic and static mechanical stimulus coming from rough or cuspidal surfaces. Here, we report a self-protective piezoelectric-piezoresistive dual-mode pressure sensor based on elastic cylinder induced flextensional transduction due to the positive Poisson effect. The cylindric design allows the transition from normal force to lateral expansion force, avoiding direct contact with rough or cuspidal surfaces and endowing the sensor with self-protective characteristic. Surprisingly, the flextensional transduction can give rise to more than 10 times amplification of the normal force to lateral expansion force, contributing to significantly enhanced sensitivity of the piezoresistive and piezoelectric response. Meanwhile, the open circuit voltage, short circuit current and power density of the device can reach up to 200 V, 8 μA and ~82 μW/cm2, enlightening people to design high-performance piezoelectric energy harvesting devices. In addition, the dual-mode device exhibits great potentials for dynamic-static pressure detection and sports evaluation. The proposed flextensional transduction strategy provides people great inspirations to design self-protective sensing devices with dynamic-static mechanoresponse for more complex application scenarios.