Biocompatible liquid metal coated stretchable electrospinning film for strain sensors monitoring system

Liquid metals (LMs) are potential inorganic materials which could be applied in flexible and deformable electronics owing to their fluidity, low viscosity, high metallic conductivity, and low toxicity. However, recently reported sensing devices based on LMs required complex processes with high cost. Herein, a flexible three-dimensional (3D) conductive network was prepared by coating LM droplets onto an electrospun thermoplastic polyurethane (TPU) fiber film. The LM is suspended between the TPU fibers and self-coalesces into a vertically buckled and laterally mesh-like structure, which provides good biocompatibility, conductivity, and stretchability simultaneously. The LM-TPU composite-film-based flexible device demonstrates a multitude of desired features, such as a widely workable stretching range (0%-200%), sufficient sensitivity under stretching strain (gauge factor (GF) of 0.2 at 200% strain), and outstanding stability and durability (9000 cycles). In vitro biocompatibility experiments show that the LM-TPU composite film directly attached to the skin has excellent biocompatibility. Such strain sensor-based integrated monitoring systems could monitor human body motions in real time, such as muscle movement and joint motion, revealing application prospects in healthcare and human-machine interfacing.

Automated summary

Liquid metals have great potential in flexible and deformable electronics due to their fluidity, low viscosity, high conductivity, and low toxicity. However, existing sensors based on liquid metals are complex and costly. In this study, a flexible three-dimensional conductive network was created by coating liquid metal droplets onto a thermoplastic polyurethane fiber film. This network exhibited excellent biocompatibility, conductivity, and stretchability, making it suitable for monitoring human body movements and healthcare applications.