Non-leakage and High Stretchable Sheath–Core Structure Liquid Metal-Based Strain-Sensing Fiber for Smart Wearable

Abstract

Recently, the ever-increasing demand for wearable electronics has significantly accelerated the development of flexible strain sensors. Liquid metal exhibits potential applications in smart wearable devices because of its high electrical conductivity and room temperature fluidity. However, its applications are limited by challenges in terms of issues in achieving liquid metal (LM) non-leakage, wide detection range, and high conductivity simultaneously. Herein, we developed a non-leakage and high stretchable sheath–core structure liquid metal-based strain-sensing fiber and, in particular, unique conductive pathways were constructed within core fibers featuring a microporous structure, where gallium-based liquid metals (LM) formed islands, and carboxyl carbon nanotubes (CNTs) served as bridges under large strains. This structure ensures the stable containment of liquid metal (LM) without any leakage. Through the cooperative interaction between carboxyl carbon nanotubes (CNTs) and liquid metal (LM), the composite fiber SA@LM-CNT achieves an impressive detection range of up to 190%, high conductivity of 3333.3 S/m, and a Young’s modulus of 0.94 MPa. Moreover, it demonstrates stable performance over more than 10,000 cycles. Lastly, leveraging semi-automated loom, this fiber strain sensor can be seamlessly integrated into textiles to conformally track various human body movements. This work presents a novel strategy for fabricating LM-based strain-sensing fibers without leakage, aiming to achieve both liquid metal leakage prevention and high stretchability simultaneously.