Fully 3D-Printed Soft Capacitive Sensor of High Toughness and Large Measurement Range

Soft capacitive sensors are widely utilized in wearable devices, flexible electronics, and soft robotics due to their high sensitivity. However, they may suffer delamination and/or debonding due to their low interfacial toughness. In addition, they usually exhibit a small measurement range resulting from their limited stiffness variation range. In this paper, soft silicone-based capacitive sensors are developed by using a customized multimaterial 3D printer. By curing silicone materials simultaneously, the continuous conductive and dielectric layers achieve a substantial interfacial toughness of 1036 J·m^-2. The sensor with tilted thin-plate dielectrics exhibits interfacial toughness of 645 J·m^-2 or 339 J·m^-2 in the transverse or longitudinal direction, respectively. Additionally, the sensors demonstrate a broad measurement range from 0.85 Pa to 5000 kPa. This extended range is facilitated by the significant stiffness variation of the separated tilted thin-plate dielectrics, ranging from 0.56 kPa to 19.76 MPa. Two applications of these fully printed soft sensors, including an intelligent sensorized insole and a robotic hand combining both soft actuators and soft sensors are showcased. It is believed that the strategy, employing 3D printing for soft microstructured sensors, is a general approach not only applicable for improving the performance of soft sensors, but also conducive to designing powerful soft functional devices.