Nanocrack-based strain sensors

Cracks are always associated with defects or damage. However, recently cracks have attracted great research interest in many fields. One of the most successful applications of cracks is nanocrack-based strain sensors (nCBSSs). The first nCBSS prototype developed in 2014 was bioinspired by the crack-shaped sensory organs of a spider, and it exhibited an incredible sensitivity to strain and vibration. From then on, a lot of effort has been devoted to studying nCBSSs, and nCBSSs have demonstrated their great potential for applications in just a few years. Herein, aiming to provide a valuable reference to researchers from different fields, a comprehensive review of nCBSSs is provided, including their typical fabrication processes, sensing mechanism, performance and applications particularly for personal healthcare, sport performance monitoring and human-machine interfaces. Finally, a brief conclusion and several current challenges were discussed.