Flexible micro-strain graphene sensors enhanced by laser-induced cracks for health monitoring

In-situ fabrication of patterned laser-induced graphene (LIG) has unique advantages, holding broad application prospects in the preparation of flexible electronic devices. However, a facile strategy is still demanded to improve the sensitivity of LIG-based sensors in detecting micro-strains. Herein, we propose a flexible graphene strain sensor enhanced by laser-induced cracks, which is capable of detecting small deformations. When the scanning spacing was expanded from 100 mu m to 140 mu m, abundant micro-cracks formed between adjacent LIG stripes, providing more sensing units. The open and close of cracks lead to significant change of resistance, enhancing the sensitivity of LIG-based sensors. The average gauge factors of sensors were improved to 98 (0-2 % strain), increasing nearly 20 times. The strain sensors exhibit high performance response to subtle signals of the human body. High-quality seismocardiography (SCG), pulse wave and respiration curves were achieved by our sensors, providing a lot of useful information for screening chronic diseases. Overall, this research highlights an effective method for fabricating high performance flexible strain sensors for long-term health monitoring.