Ultrasensitive and Robust Flexible Sensors Based on Bacterial Cellulose/ZnO Nanorods for Next-Generation Electronic Skin and Human–Machine Interaction

Abstract

The rapid development of wearable electronics has driven extensive interest in flexible pressure sensors for applications such as human-machine interaction, electronic skin, and health monitoring. Nevertheless, the attainment of elevated sensitivity, minimal detection limits, and expeditious responses continues to represent a formidable challenge. In this study, we present a piezoresistive pressure sensor that exhibits flexibility, based on bacterial cellulose (BC) nanofibers that have been modified with zinc oxide (ZnO) nanorods. The optimized BC/ZnO-0.3 sensor exhibits a high sensitivity of 23.14 kPa^–1 in the low-pressure region, a wide sensing range (0–2.5 kPa), fast response/recovery (74/109 ms), no lag during pressure relief, and excellent durability over 2500 cycles. This is due to the synergistic coupling between the elastic BC scaffold and the conductive pathways formed by ZnO nanorods. In comparison with previously reported BC-based sensors, the present BC/ZnO film demonstrates significantly enhanced sensitivity and faster response, owing to the optimized conductive percolation network. The sensor facilitates the real-time detection of various human joint movements, in addition to subtle biomechanical signals. It demonstrates efficacy in speech signal monitoring and handwriting trajectory identification. Of particular significance is the integration of the sensor onto a robotic finger, which has been demonstrated to successfully detect pressure magnitude during grasping operations. This represents a significant step towards the realization of human-machine interaction. The BC/ZnO film sensor demonstrates high sensitivity, rapid response, and robust cyclability, suggesting significant potential for applications in human behaviors monitoring and electronic skin.