Multidirectional strain sensor using multimaterial 3D printing

This paper presents a fully 3D printed multidirectional strain sensor for robotic applications. The all-printed sensor constitutes a piezoresistive sensing layer of flexible carbon black engineered thermoplastic polyurethane (PI-ETPU), and a structurally engineered sensor frame printed using rigid polylactic acid (PLA). The sensor is printed using multi-material 3D printing and systematically positioned in the frame to uniquely detect multidirectional mechanical loading. The stress and strain distributions on the developed sensor structure, as well as the piezoresistive coupling of the active sensing layer are investigated using COMSOL Multiphysics. The results show discrete resistive responses over the three different displacements simulated. The unique motion and the response give the individual sensors the ability to infer new pieces of data such as angle and orientation from the piezoresistive behavior of each sensor. This makes the sensors promising for a wide range of applications, from artificially intelligent robots to rehabilitation and 3D texture mapping.