Maskless Formation of Conductive Carbon Layer on Leather for Highly Sensitive Flexible Strain Sensors

Development of strain sensors on flexible and breathable leather or textile has potential applications in Internet of Things, human–machine interfaces, and motion detection. Nevertheless, the fabrication of strain sensors with high performance on the above substrates in a maskless, scalable, and highly efficient manner is still a challenge. In this study, highly sensitive strain sensors are mask-freely fabricated on leather by a highly efficient and scalable laser direct writing (LDW) technique in open air without using any additional precursors. The strain sensors are constructed by the carbon flake synthesized by LDW carbonization of collagen fibers in the leather. The LDW carbonized leather-based device provides maximum sensitivities of ≈2009.5 and ≈50.9 for tension and compression strain detection, respectively. Additionally, the device has a minimum detection strain of 0.005% and a good mechanical stability over 10 000 bending cycles. The high performance of the flexible strain sensors as well as the developed maskless, scalable and highly efficient LDW technique endows the promising applications of the devices in human motion monitoring and external stimuli detection.