Capacitive-Triboelectric-Based Hybrid Sensor System for Human-Like Tactile Perception

Human skin contains slowly adapting (SA) and rapidly adapting mechanoreceptors (RA) through which it can discriminate between static and dynamic tactile stimuli. Biomimicking of such human tactile sensing systems using flexible and reliable sensors has recently gained importance for developing future robots and prosthetics with better sensory capabilities. In this work, a hybrid flexible sensor system consisting of a capacitive pressure sensor (CPS) (mimicking SA mechanoreceptors) firmly stacked over a triboelectric nanogenerator (TENG) (mimicking RA mechanoreceptors) was developed. CPS consisted of porous Ecoflex as the dielectric material, while the two layers used in TENG were made using copper-nickel conducting fabric and indium tin oxide-coated polyethylene terephthalate sheet. This hybrid sensor system was characterized and showed good sensitivity for CPS and voltage response for the TENG device. Later, three distinct scenarios for the hybrid system have been demonstrated, in which it was used for the qualitative hardness assessment, slip detection, and impact/vibration detection. In summary, the signals from both CPS and TENG complement each other, making this hybrid sensor system capable of simultaneously detecting both static and dynamic pressure signals.