High Sensitivity and Large Strain Range Liquid Metal-Based Flexible Strain Sensors

Flexible strain sensors have gained significant attention in wearable electronics and biomedical applications due to their ability to accommodate large deformations while enabling real-time monitoring. However, achieving a balance between stretchability, conductivity, and temperature stability remains a challenge. This study presents a flexible strain sensor that integrates liquid metal (LM) within polydimethylsiloxane (PDMS) microchannels, leveraging the high conductivity of LM and the elasticity of PDMS to enhance sensitivity and mechanical stability under large strain conditions. Two sensor architectures were developed: a single-layer design and a double-layer structure that improves temperature stability by compensating for resistance changes. The sensor demonstrates excellent linearity (deviation <5%) and repeatability (error <1%), while optimizations of microchannel dimensions and chip thickness significantly improve sensitivity. Dynamic evaluation confirms rapid response (~0.3 s), exceptional fatigue resistance (3600 s), and reliable human motion monitoring under diverse conditions. The sensitivity of sensor increased by 10.8% between 20°C and 45°C, with a resistance-temperature coefficient of 0.433%°C⁻¹. This work contributes to the development of durable flexible strain sensors for wearable electronics and human-machine interaction.