Highly sensitive printed crack-enhanced strain sensor as dual-directional bending detector

Strain sensors with good flexibility and high sensitivity attracted a lot of interest because of their potential applications in wearable electronics. In this paper, we demonstrate a high-performance crack-based strain sensor based on printable polyvinyl chloride/carbon black (PVC/CB) composite material. Flexible conductive circuit and PVC/CB composite were screen-printed to a desirable geometry on a polyimide (PI) substrate. After 5000 bends, a stable cracked morphology formed on the PVC/CB surface, which greatly enhanced the sensitivity of our strain sensor: corresponding gauge factors were equal to 741 and 1563 gauge under the tensile and compressive strains, respectively. Our crack-based strain sensor also demonstrated high stability. Additionally, this work shows the application of this crack-based sensor for human activity detection to demonstrate their application prospects for flexible and wearable electronic devices.