Highly skin-conformal wearable tactile sensor based on piezoelectric-enhanced triboelectric nanogenerator

Highly skin-conformal wearable tactile sensors with high sensitivity and wide measurement range are promising for physiological signal monitoring, personalized recognition and human-machine interaction. In this paper, we report a hybrid piezoelectric-triboelectric sensor (HPTS) primarily composed of polarized micro-frustum-arrays structure lead-zirconate-titanate and polydimethylsiloxane (PZT&PDMS) composite film (m-PZT&PDMS) and mCu film, which can simultaneously generate the coupling of piezoelectric effect and triboelectrification by the contact-separation working mode. Combining the hybrid effect, micro-frustum-arrays structure and high piezoelectric constant material, the HPTS presents excellent sensitivity and wide measurement range. The HPTS can reach a sensitivity of 15.43 V/kPa when triboelectric effect performs in the pressure of 0 kPa-100 kPa, and 18.96 V/kPa when both the piezoelectric and triboelectric effects work in the pressure range of 100 kPa-800 kPa. In addition, the HPTS is largely based on the PZT&PDMS film being directly in contact with the skin, showing excellent skin-conformal characteristic. It also demonstrates good linearity, fast response time and high stability. These characteristics are attractive for sensing radial artery wave, monitoring the slide and touch of a finger, and detecting the strong pressure of limb movement. Hence, this work provides a new strategy by applying a highly skin-conformal piezoelectric-enhanced triboelectric nanogenerator with high sensitivity and wide measurement range as a wearable tactile sensor, exhibiting immense potential in medical research, personalized recognition and human-machine interaction.