Measuring Dynamic Shear Force and Vibration With a Bioinspired Tactile Sensor Skin

There is a need to measure dynamic tactile information to enhance robotic hand performance during haptic exploration and object manipulation. Here, we report on the dynamic characterization of a flexible, bioinspired, and resistive microfluidic shear force sensor skin. When the skin is subjected to shear force, one side of the skin experiences tension while the other side experiences compression, both of which are measured by liquid metal strain gauges embedded in polydimethylsiloxane. The sensor can measure dynamic shear forces during stepwise unloading, incipient slip, and controlled vibration tests. The sensor can quantify vibration up to 800 Hz with an average minimum displacement of $0.43~\mu \text{m}$ , which is equivalent to or better than human fingertips. We demonstrate the utility of the sensor skin by performing experiments with a robotic hand and arm. The shear sensing skin senses tactile events while a robotic arm performs several manipulation tasks including pick and place, drop, and handover. The skin is robust when used on a robot manipulator and shows promise in providing rich and dynamic tactile information that is beneficial to robotic and prosthetic applications.