Fully Elastic and Metal-Free Tactile Sensors for Detecting both Normal and Tangential Forces Based on Triboelectric Nanogenerators

A tactile sensor should be able to detect both normal and tangential forces, which is mandatory for simulating human hands, but this fundamental function has been overlooked by most of the previous studies. Here, based on a triboelectric nanogenerator (TENG) with single-electrode mode, the fully elastic and metal-free tactile sensor that can detect both normal and tangential forces is proposed. With tiny burr arrays on the contact interface to facilitate the elastic deformation, the detected normal pressure by the device can reach to 1.5 MPa with a sensitivity of about 51.43 kPa V-1, and a large range of tangential forces can be detected ranging from 0.5 to 40 N with rough sensitivity of 0.83 N V-1 (0.5-3 N) and 2.50 N V-1 (3-40 N). Meanwhile, the applied tangential forces from different directions can also be clearly distinguished by the four-partitioned electrode structure. Moreover, a shield film is coated on the top surface of the device, which can screen the electrostatic interference and enhance the repeatability of the device. The demonstrated concept of this self-powered tactile sensor has excellent applicability for industrial robotics, human-machine interactions, artificial intelligence, etc.