Broadband mechanoresponsive liquid metal sensors

Abstract

Stretchable electronics have the fundamental advantage of matching the complex geometries of the human body, providing opportunities for real-time biomechanical sensing. We report a method for high-frequency AC-enhanced resistive sensing that leverages deformable liquid metals to improve low-power detection of mechanical stimuli in wearable electronics. The fundamental mechanism of this enhancement is geometrical modulation of the skin effect, which induces current crowding at the surface of a liquid metal trace. In combination with DC sensing, this method quantitatively pinpoints mechanical modes of deformation such as stretching in-plane and compression out-of-plane that are traditionally impossible to distinguish. Here we explore this method by finite element simulations then employ it in a glove to detect hand gestures and tactile forces as well as a respiratory sensor to measure breathing. Moreover, this AC sensor uses lower power (100X) than DC sensors, enabling a new generation of energy-efficient wearables for haptics and biomedical sensing.