Shape-Programmable Liquid Metal Fibers

Abstract

Conductive and stretchable fibers are the cornerstone of intelligent textiles and imperceptible electronics. Among existing fiber conductors, gallium-based liquid metals (LMs) featuring high conductivity, fluidity, and self-healing are excellent candidates for highly stretchable fibers with sensing, actuation, power generation, and interconnection functionalities. However, current LM fibers fabricated by direct injection or surface coating have a limitation in shape programmability. This hinders their applications in functional fibers with tunable electromechanical response and miniaturization. Here, we reported a simple and efficient method to create shape-programmable LM fibers using the phase transition of gallium. Gallium metal wires in the solid state can be easily shaped into a 3D helical structure, and the structure can be preserved after coating the wire with polyurethane and liquifying the metal. The 3D helical LM fiber offered enhanced stretchability with a high breaking strain of 1273% and showed invariable conductance over 283% strain. Moreover, we can reduce the fiber diameter by stretching the fiber during the solidification of polyurethane. We also demonstrated applications of the programmed fibers in self-powered strain sensing, heart rate monitoring, airflow, and humidity sensing. This work provided simple and facile ways toward functional LM fibers, which may facilitate the broad applications of LM fibers in e-skins, wearable computation, soft robots, and smart fabrics.

Supercooled Liquid Ga Stretchable Electronics

“…Normally, liquid N 2 or dry ice are required to overcome the supercooling effect. [ 73 ] By using appropriate nucleating agents, we can easily manipulate the freezing process at any time and accelerate it using a thinner layer or lower temperature.…”

Recent progress in fiber-based soft electronics enabled by liquid metal

“…The study shows that such conductors have a 1,273% breaking strain. The fiber diameter can be reduced by applying strain to the fibers during polyurethane curing (MA et al, 2022). The abrasion resistance and stability of LMcoated fibers during practical applications should be considered.…”

A dual-mode wearable sensor with coupled ion and pressure sensing

“…Wearable sensors can be classified into physical and biochemical types based on target physiological signals. Specifically, wearable physical sensors are designed to monitor biophysical signals such as body motions, blood pressure, heart rate, or body temperature [9][10][11][12][13] , while biochemical sensors focus on the analysis of biomarkers in body fluids to indicate the health state at the molecule level [14][15][16][17] . The comprehensive evaluation of the body state for precious health management and diagnosis calls for nextgeneration hybrid wearables capable of physical and biochemical sensing concurrently [18,19] .…”