Soft Pressure Sensor Array Inspired by Human Skin for Detecting 3D Robotic Movement

3D soft pressure sensors play an important role in precise robotic operations. Multimodal soft pressure sensors that detect both static and dynamic pressure allow robots to respond accurately and in real time. Here, we present a sensor array with a size of 1.5 cm x 1.5 cm composed of capacitive and piezoelectric units, inspired by Merkel cells and Vater-Pacini corpuscles of human skin. The tangential force from 0.1 to 2 N at angles of 0 degrees, 45 degrees, 180 degrees, and 225 degrees can be resolved by analyzing the signals of the 16 piezoelectric sensors. The 4 capacitive sensors exhibit consistent and stable performance when sensing normal forces from 0.5 to 4 N. The weight and size of objects, as well as the direction of grasping, effectively distinguish the weight, size, and grasping direction of objects when integrated on a robotic gripper. Running and walking movements are recognized when attached to a robot's knee.