Flexible Pressure Sensor Based on Tetrapod-Shaped ZnO-PDMS Piezoelectric Nanocomposites

Abstract

A flexible pressure sensor with co-planar electrodes was fabricated based on piezoelectric nanocomposites by the combination of polydimethylsiloxane (PDMS) base polymer with zinc oxide (ZnO) nanotetrapods (ZNTs) fillers. ZNTs were synthesized by an oxidation process of Zn powder at different temperatures over 900 °C in air, and its crystallinity and structural morphology could be controlled effectively by the growth temperature based on scanning electron microscopy, X-ray diffraction, and photoluminescence spectroscopy analyses. The effects of the growth temperature and filler concentration of ZNTs on the piezoelectric properties of the nanocomposite sensors were investigated. The sensors exhibit a good linear response to external pressure less than 14 N, and the sensitivity increases with the increase of the growth temperature and ZNTs filler concentration due to the improvement in the crystallinity, the aspect ratio of T-arms, and the interconnectivity between ZNTs/ZNTs interfaces in the nanocomposite film. The sensor can be employed to detect human movements such as bending/stretching motions of fingers and the vibration of vocal cords. It is demonstrated that the sensor has potential applications in hand gesture and speech recognition.