Stretchable Strain Sensors Based on Liquid Metal Channels with Simultaneous Significant Improvements in Linearity and Sensitivity

Achieving high linearity, sensitivity, and stability simultaneously in stretchable strain sensors is critical for applications such as wearable electronics, human–machine interfaces, and structural safety monitoring. However, balancing these attributes remains a significant challenge. Here, a stretchable liquid metal (LM)-based strain sensor that combines exceptional linearity (R² ≈ 0.996 over 0% to 120% strain), sufficient sensitivity (≈8), and high stability (low drift error of ≈1.2% at 50% strain for 12 h, >10 000 stretching cycles) is presented. The sensor is constructed from an LM channel embedded with soft elastomeric foam infused with LM, all encapsulated in an elastomer. The embedded foam acts as a strain-responsive gate, controlling the connectivity pathways of the LM for electron flow. Under strain-free conditions, the LM exhibits high connectivity and low resistance, while under tensile deformation, it transitions to reduced connectivity and increased resistance, resulting in a highly linear resistance-strain response. Notably, the sensor's exceptional linearity simplifies calibration, reduces installation complexity, and ensures accurate measurements even under pre-strain or zero-clearing conditions. By integrating these key performance features, this sensor provides an effective solution for accurate strain sensing in wearable electronics, structural health monitoring, and human–machine interaction applications.