Compact Michelson interferometer-based optical fiber sensor for reliable respiratory monitoring

Abstract In the field of respiratory monitoring, optical fiber sensors have shown great potential due to their high sensitivity, compact size, and immunity to electromagnetic interference. However, achieving a balance between sensitivity, curvature measurement range, and ease of manufacturing remains a challenge. In this study, we propose a novel Michelson interferometer-based optical fiber sensor designed to overcome these limitations. The sensor features an integrated design of single-mode fiber, multi-mode fiber, and seven-core fiber with a unique spherical fiber end. This innovative structure effectively increases the contact area with the human body and significantly increases the sensitivity of the sensor to small curvature changes. Experimental results demonstrate that the sensor achieves a linear curvature sensitivity of up to 2.33 dB m −1 over a curvature range of 0–3.96 m −1 , making it highly effective for capturing subtle respiratory-induced deformations. The compact and straightforward manufacturing process, combined with its high sensitivity and wide curvature range, positions this sensor as a promising candidate for wearable respiratory monitoring systems, with potential applications in continuous respiratory monitoring, sleep studies, and the early detection of respiratory disorders.