Flexible Self-Powered Tactile Sensors Based on Hydrothermally Grown ZnO Nanorods

Flexible tactile sensors with high sensitivity and good flexibility are urgently required in modern biomimetic robots' electronic skin, and artificial intelligence interaction. In this work, a flexible piezoelectric tactile sensor was fabricated using hydrothermally grown ZnO nanorods (ZnO NRs) on Cu-coated polyimide (PI) substrate. Structural and morphological properties of the ZnO NRs were investigated by SEM, XRD. The piezoelectric response properties of the sensors by using the pasted Cu/PI electrode and directly screen-printed Ag electrode were compared. The results show the sensor with the screen-printed Ag electrode exhibits a high sensitivity of 974 mV/N, which is higher than the pasted Cu/PI electrode, and the response of all sensors to the applied pressure is almost linear in the range of 0.1-1 N. Meanwhile, the sensor can be employed to detect human movements such as bending/stretching motion of fingers and the vibration of the vocal cords and pulse, and realize the conversion from mechanical energy to electrical energy. It is demonstrated that the sensor has great potential applications in wearable health monitoring systems and self-powered devices.