Self-powered flexible force-sensing sensor based on triboelectric nanogenerator: Practical applications in non-destructive harvesting of fresh fruits and vegetables

Abstract

Force sensing is a key capability for robots to achieve precise operations and interactions, especially in scenarios requiring soft sensing abilities for non-destructive grasping of irregular and fragile objects. With the development of triboelectric nanogenerator (TENG) theory, flexible self-powered sensing has emerged as a new approach for enabling self-driven perception in robots. However, the reported TENG electrodes are mostly made of rigid metal materials, facing challenges such as limited stretchability, low power outputs, and complicated fabrication processes. Herein, we report a ionogel-based triboelectric nanogenerator (IG-TENG), with good stretchability and precise force-sensing capabilities. A self-developed ionogel is applied as the conductive layer for the IG-TENG, which owns high stretchability (∼ 711 %) and great electrical conductivity (4.4 mS/cm). Then, we explored the application of IG-TENG in the non-destructive harvesting of fresh fruits and vegetables. It is then integrated with flexible end-effectors to sense their interaction forces during grasping. The results show that the force-sensing model based on IG-TENG exhibits high sensitivity (3.53 V/N), excellent linearity (R²= 0.989), and strong adaptability to varied postures, achieving an accuracy of up to 93.77 %. This study advances the implementation of non-destructive harvesting for fresh produce and offers an innovative solution for force sensing in robotic end-effectors.