Triboelectric proximity and contact detection using soft planar spiral electrodes

Abstract

In this study, planar spiral electrodes for triboelectric contact and proximity detection are investigated. The spiral electrodes are created using liquid metal in a soft elastomer in order to make the sensor flexible and stretchable. When the metallic object to be detected comes in contact with the silicon elastomer surrounding the electrodes, charge transfer occurs, and this can be utilized for contact and noncontact sensing of the metallic object in flat or curved geometries. An equivalent electrical circuit model for the noncontact system is proposed and found to be in good agreement with the experimental data. A comparison between triboelectric proximity detection and eddy current resonance frequency proximity detection, using the same electrode geometry, shows that the two methods have comparable sensitivity. An added advantage of the triboelectric system is that it transforms mechanical into electrical energy and thereby allows one to monitor the triboelectrical signal upon impact of a metal object, and the experimental data show that the generated current scales with the impact force.