Broadband mechanoresponsive liquid metal sensors

• Published in: Npj flexible electronics 2022-08, Vol.6 (1), p.1-8, Article 71
• Main Authors: Rahman, Md Saifur, Huddy, Julia E., Hamlin, Andrew B., Scheideler, William J.
• Format: Article
• Language: English
• Subjects: 639/166/987; 639/301/1005; 639/301/357/995; Biomechanics; Broadband; Casting; Chemistry and Materials Science; Circuits; Deformation; Electronics; Electronics and Microelectronics; Finite element method; Formability; Geometry; Instrumentation; Liquid metals; Liquid surfaces; Materials Science; Metals; Optical and Electronic Materials; Polymer Sciences; Sensors; Simulation; Skin; Skin effect; Strain gauges
• ISSN: 2397-4621; 2397-4621
• DOI: 10.1038/s41528-022-00206-3

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.