A Lightweight Skin-Adhesive Fiber Bragg Grating Sensor to Advance Minimally Invasive Healthcare Monitoring

Abstract

Wearable sensors that combine high precision with conformability and skin adhesion are crucial for reliable and highly unobtrusive physiological monitoring. In this context, increasing efforts are directed toward next-generation miniaturized self-adhesive sensors employing different sensing technologies. Herein, for the first time a self-adhesive sensor is developed for real-time detection of physiological and biomechanical strain signals, by embedding a fiber Bragg grating (FBG) sensor into a soft, biomimetic, flexible matrix. This hydrogel-based matrix, composed of gelatin methacrylate, xanthan gum, and glycerol, is engineered to balance fiber–matrix mechanical coupling and skin adhesion. The encapsulated FBG sensor exhibits stable optical response, reduced signal attenuation, and retains good sensitivity to both strain (0.07 nm mε⁻¹) and temperature (0.01 nm °C⁻¹). Preliminary on-skin tests on a healthy volunteer demonstrate the ability to capture subtle physiological signals such as breathing and heartbeats, as well as limb motion. Notably, the self-adhesive properties of the matrix enable firm skin contact without additional tapes, enhancing signal reliability, and reducing motion artifacts. This approach offers a robust, biocompatible, and scalable solution for wearable sensing, opening new opportunities in health monitoring, rehabilitation, and human–machine interfaces.