Additively Manufactured Capacitive Proximity and Tactile Sensors for Soft Robotic Systems

Soft robotics are considered one of the most promising approaches towards fully collaborative robotic devices. Soft robotic systems are intrinsically safe due to their compliant nature. Using additive fabrication for the development of soft capacitive sensors, enables high flexibility and individualization capabilities in terms of design and material properties. In this work, we outline the sensorization of stretchable capacitive sensors for proximity and tactile detection. This sensor will represent an essential component of a soft robotic finger in future work. While the functional principle has already been shown previously, here we explore the design space further and perform more in depth test of the influences of the stretch on both proximity and tactile measurements. The capacitive pad's sensitivity is evaluated by applying normal force on each sensor, where the applied force is ranged between 2 N and 16 N, with resultant capacitive change of the four tactile sensors between 3 pF and 7 pF. The pad's deformation is tested by stretching the pad up to 5 cm. This results in increasing the capacitance of the tactile sensing elements between 0.6 pF and 1.5 pF, and decreasing of the capacitance in the proximity sensing elements between 1.4 pF and 1.5 pF.