Capacitive Tactile Sensor with Stacked Structure and Hybrid Fabrication for Multiaxial Force Decoupling

Abstract

This study shows the development of a capacitive tactile sensor (CTS) which can not only sense multiaxial forces but also decouple the applied normal and shear force due to its innovative structure and fabrication. The design contains five capacitors arranged in a specific pattern as a sensing unit with a stacking structure. Three polyethylene terephthalate substrates with two polydimethylsiloxane dielectrics and silver electrodes were used in one capacitor, and one and four capacitors were put to the top and bottom, respectively, which were able to detect normal and shear forces respectively. In addition to conventional photolithography, inkjet printing was introduced for laminating the structures. Under the normal force, the top layer capacitor showed a higher sensitivity of 0.5008 pF/N, while the bottom layer capacitors showed a much lower sensitivity of 5.2667fF/N on average. In case of the horizontal load bottom layer capacitor showed higher sensitivity. This sensitivity difference in the two modes allows users to decouple the applied force type and direction for the first time.