Low-Profile Shear Force Tactile Sensor Based on Optical Methods

An electrically driven shear stress tactile sensor is experimentally demonstrated. The device design incorporates an ultrathin platinum Ohmic contact conformally coated around the elastic nanopillar structures by atomic layer deposition. The nanopillar, comprising of a series of InGaN/GaN multiple quantum wells, is optically active when biased with an electric current. Upon the application of an external shear force, the deformation of the nanopillar structures causes the intensity of the emitted light from InGaN to reduce. Using symmetry breaking via an elliptical cross Section of the nanopillar, both the force’s magnitude and direction can be directly measured. The functionality of the proposed tactile sensor was verified both numerically and experimentally.