Iontronic Capacitance-Enhanced Flexible Three-Dimensional Force Sensor With Ultrahigh Sensitivity for Machine-Sensing Interface

Flexible three-dimensional (3D) force sensors have been extensively investigated in the field of robotics due to their ability to provide feedback information from multiple directions. However, the development of flexible 3D force sensors with high sensitivity and decoupling capabilities remains a significant challenge, hindering the ability of robots to perceive their external environment. In this letter, we present a novel flexible 3D force iontronic sensor (FTIS) that utilizes ionic materials with micro-pyramidal structures and a backpropagation (BP) neural network method based on deep learning. The FTIS exhibits outstanding sensitivity, with over 8000 $\text{N}^{-{1}}$ in the normal direction and over 4000 $\text{N}^{-{1}}$ in the shear direction, and has a rapid response time of 27-ms. Additionally, it demonstrated stable working durability, with over 8000 cycles without signal delay. To validate the utility of the sensor, we integrated it as a machine-sensing interface on a mechanical claw to measure changes in forces in the triaxial direction. Our design concept has the potential to advance the development of multidimensional force sensors in the future.