Soft Capacitive Pressure Sensors: Trends, Challenges, and Perspectives

Soft pressure sensors are critical components of e-skins, which are playing an increasingly significant role in two burgeoning fields: soft robotics and bioelectronics. Capacitive pressure sensors (CPS) are popular given their mechanical flexibility, high sensitivity, and signal stability. After two decades of rapid development, e-skins based on soft CPS are able to achieve human-skin-like softness and sensitivity. However, there remain two major roadblocks in the way for practical application of soft CPS: the decay of sensitivity with increased pressure and the coupled response between in-plane stretch and out-of-plane pressure. In addition to existing strategies of building porous and/or high dielectric constant soft dielectrics, are there any other promising methods to overcome those bottlenecks? Are there any further considerations for the widespread deployment of e-skins? This perspective aims to shed some light on those topics.