Serpentine-Inspired Strain Sensor with Predictable Cracks for Remote Bio-Mechanical Signal Monitoring.

Flexible strain sensors have attracted intense interest due to their application as intelligent wearable electronic devices. However, it is still a huge challenge to achieve a flexible sensor with simultaneous high sensitivity, excellent durability, and a wide sensing region. In this work, a crack-based strain sensor with a paired-serpentine conductive network is fabricated onto flexible film by screen printing. The innovative conductive network exhibits a controlled crack morphology during stretching, which endows the prepared sensor with outstanding sensing characteristics, including high sensitivity (gauge factor up to 2391.5), wide detection (rang up to 132%), low strain detection limit, a fast response time (about 40 ms), as well as excellent durability (more than 2000 stretching/releasing cycles). Benefiting from these excellent performances, full-range human body motions including subtle physiological signals and large motions are accurately detected by the prepared sensor. Furthermore, wearable electronic equipment integrated with a wireless transmitter and the prepared strain sensor shows great potential for remote motion monitoring and intelligent mobile diagnosis for humans. This work provides an effective strategy for the fabrication of novel strain sensors with highly comprehensive performance.