Biomimetic three-dimensional microchannel non-destructive self-healing flexible strain sensor based on liquid metal-polydimethylsiloxane elastomer

Flexible strain sensors (FSS) have garnered widespread attention due to their immense potential in wearable electronics, motion health monitoring, artificial electronic skin, and soft robotics. However, FSSs are susceptible to mechanical damage such as wear, cracks or breaks during long-term use, which diminish their reliability and service life. Inspired by the self-healing dual-phase structure of human skin and vascular networks, this study proposes a biomimetic three-dimensional microchannel non-destructive self-healing flexible strain sensor (B-TMN-SHFSS) based on the liquid metal-polydimethylsiloxane (LM-PDMS) elastomer. The B-TMN-SHFSS employs a layered design, layer-by-layer fabrication, and interlayer self-healing techniques to construct the microchannel within the self-healing PDMS elastomer (SPE), with the liquid metal (LM) being injected into the microchannel using a negative pressure injection method. Based on the modified protective layer design of the biomimetic three-dimensional microchannel, the high self-healing efficiency of the SPE and the fluidity of the LM, the B-TMN-SHFSS is able to restore the initial sensing performance after self-healing, while maintaining the integrity of the 3D microchannels with an electrical healing efficiency (EHE) of 100 %. Additionally, the B-TMN-SHFSS features high sensitivity (GF max  = 3.464) and a wide measurement range (0 to 216.68 %), making it suitable for human motion detection.