Galinstan Liquid Metal/Polyurethane Composite as a Multifunctional Stretchable Electrode and Piezoresistive Strain Sensor With Minimal Drift

ABSTRACT Soft wearable electronics leverage body‐conforming materials for remote health monitoring, human–machine interfaces, and adaptive robotics. As these systems evolve, there is a growing demand for multifunctional materials that serve as piezoresistive strain sensors and maintain electrical connections under high strains—necessitating materials that are highly conductive and stretchable. However, existing materials do not meet the conductivity requirements for multifunctional use as stretchable electrodes and when used as piezoresistive sensors suffer from high drift and low electromechanical stability, leading to calibration loss and unreliable performance. This work presents a multifunctional composite that enables both stable piezoresistive strain sensing with minimal drift and stretchable electricity transmission. Composed of eutectic gallium–indium–tin liquid metal (LM) and polyurethane (PU), the PU/LM film offers excellent stretchability (∼400%), high electrical conductivity (∼3.4 × 10 ³ S cm ⁻¹ ), low Young's modulus (∼16 MPa), minimal drift (∼−16%), and high cyclic stability at ∼350% strain. The applications of the PU/LM film as both a stretchable electrode for powering a mobile phone at up to 350% strain and a strain sensor for tracking dynamic finger bending angles (60–105°) are demonstrated. The PU/LM films offer a reliable soft multifunctional system for healthcare, assistive devices, and wearables.