Spindle-knot reinforced liquid metal-based strain sensor with excellent stretchability and stability

Gallium-based liquid metals, with their excellent conductivity, natural deformability, and biocompatibility, are regarded as promising candidates for future wearable devices. Drawing inspiration from the Plateau-Rayleigh instability, a novel method for fabricating a high-performance spindle-knot fiber structured strain sensor is proposed. Periodic spindle-knot structure on the fiber within a flexible substrate can induce strain redistribution. Liquid metal is encapsulated on the flexible substrate by a simple method. Under mechanical strain, the liquid metal layer autonomously regulates via its native oxide, exhibiting a distinct sensing mechanism. The resulting spindle-knot fiber strain sensor offers an ideal integration of sensing performance, including high sensitivity (gauge factor = 4.59), a wide working range (>180 %), fast response speed (response/relaxation time of 180/ 145 ms), and reliable fatigue life (over 15,000 cycles). Due to its excellent sensing performance, the strain sensor is well-suited for detecting monitor subtle signals and vigorous movements. Finally, the intelligent glove prototype system constructed using a multiple sensor array offers a feasible strategy for operating smart robotic hands by accurately capturing human motion.