A High-Sensitivity Flexible Stretchable Fiber-Optic Sensor Based on the Waveguide Loss Principle

This article introduces a flexible, stretchable fiber-optic sensor optimized for continuous health monitoring. The sensing system consists of a single-mode optical fiber with a serpentine configuration design, a laser diode, and an optoelectronic conversion module. We developed a waveguide loss model to elucidate the sensor’s operating principles and guide its fabrication. A series of performance experiments have been conducted to characterize that the sensor provides the ability to measure large strains (50%) and has a low detection limit (1%), high repeatability, and excellent resistance to external factors (temperature, humidity, folding, and tactile pressure). Additionally, the sensor is interfaced with a human-machine interaction (HMI) system to translate joint movements such as those of wrists, arms, and fingers into control signals for interactive applications. This sensor also effectively captures weak physiological signals from the human carotid artery, enabling the recognition of different movement states. This research demonstrates the sensor’s potential in smart wearable devices, offering a low-cost, highly sensitive solution for advanced health monitoring applications.