Flexible self-powered multifunctional sensor for stiffness-tunable soft robotic gripper by multimaterial 3D printing

Proprioceptive sensation via embedded flexible sensors is essential for soft robotic grippers to realize safe and dexterous grasping. We demonstrate a self-powered, flexible multifunctional sensor by combining a polyvinylidene difluoride film with a microstructured jamming layer. The jamming layers and the finger body are fabricated by a multimaterial 3D printing technology. The sensor built into the soft finger can provide passive proprioceptive sensations of curvature and stiffness, with maximum sensitivity of 0.55 mV m and 0.09 Vm/N respectively. It also acted as an active jamming element to tune finger stiffness (15–44 N/m) while not affecting the dynamics of the robotic movement. We demonstrate the multifunctional sensor with a three-fingered robotic gripper to successfully record finger bending and stiffening in the ‘pick and place’ process. This work shows potential of greatly enhancing the way in which a gripper interacts with objects that are manipulated and provide a route to achieve anthropomorphic grippers.