A hybrid porous carbon-decorated multi-layered graphene-based breathable and ultra-sensitive piezoresistive strain sensor for wearable physiological signal monitoring

The development of stretchable strain sensors incorporating electrodes enhanced with nanomaterials holds promise for revolutionizing wearable healthcare systems and human-machine interfaces, marking a significant shift in the landscape of sensing technologies for the next generation. Following this feat, a novel flexible and stretchable electrode material comprising hybridized metal-organic framework (MOF)-derived porous carbon (HPC) deposited on laser-engraved graphene (LEG) for piezoresistive wearable strain sensors is introduced. HPC provides compensation for microcrack formation on LEG through a slippage mechanism, mitigating the breakage that occurs during intense stretching actions. Furthermore, the flexible electrode was transferred to the breathable porous styrene-ethylene-butylene-styrene (PSEBS) substrate. PSEBS provides heat dissipation and sweat evaporation from the skin-sensor interface, which makes them an impregnable substrate to counteract local heating, thereby, improving the sensor's reliability. The synergistic interplay between HPC and LEG fosters the formation of an enhanced conductive pathway, resulting in heightened sensitivity, with a maximum gauge factor of 575,542 and a lower limit of detection of 0.04%, surpassing its non-porous counterparts in terms of sensitivity, reliability, and comfort. To validate its efficacy, various demonstrations are presented, showcasing its ability to accurately capture full-range human body motions, monitor vital signs, and facilitate seamless human-machine interactions.