An integrated all-fiber-based sensing system for monitoring humidity physiological signals

With the advancement of wearable electronics, flexible sensors have attracted significant attention in health monitoring and personalized medical services. While these sensors exhibit excellent responsiveness for health tracking, they often overlook the importance of skin surface humidity. All-fiber-based sensors exhibit exceptional flexibility, breathability and lightweight nature. Given these advantages, all-fiber-based sensors are predisposed to be applied in skin humidity monitoring. However, their exploration in this field remains rarely reported. Therefore, developing an all-fiber-based sensor for real-time skin humidity monitoring is highly desirable. Herein, a highly stretchable, air permeable, moisture sensitive and antibacterial all-fiber strain and humidity sensor was fabricated by embedding lithium chloride (LiCl) into thermoplastic polyurethane (TPU) and polyethylene oxide (PEO) solutions. Benefiting from the uniform distribution and strong hygroscopicity of LiCl, the prepared nanofiber membrane exhibits rapid response, high sensitivity, and relative humidity sensing (from 30 % to 90 %). Additionally, the nanofiber membrane demonstrates excellent strain sensing performance stability and endures across 600 loading cycles in a large working range covering 0 to 450 %. Moreover, the resulting all-fiber-based sensor can be employed for monitoring human movements and detecting humidity bioelectrical signals. Therefore, the investigation is anticipated to provide novel strategies towards the advancement of next-generation multifunctional wearable electronic devices.