Machine Embroidery Enclosure for Stretchable Fiber Optic Respiration Sensor

Abstract

Abstract Developing an unobtrusive respiration sensor is a key task for daily health and safety monitoring, especially for individuals with potential breathing abnormalities or those performing in physically challenging conditions. This study introduces a machine‐embroidered enclosure that guides a soft and extensible lightguide to react to the strains on a compression shirt caused by the respiration of the wearer. The shape of the stretchable optical fiber changes from serpentine in rest (exhalation) to straight under strain (inhalation), which affects the light transmittance. In tests with 13 healthy adults, the respiratory volume prediction through a deep learning model trained by the light intensity and truth from a commercial spirometer shows a high correlation in both static (r2 > 0.880) and dynamic postures (r2 > 0.690). This system also accurately measures the respiratory rate under sitting and walking conditions (absolute error 7.122 dB). The strain‐sensing capability of this sensor depends on the parameters of the embroidery, including the stitch density, stitch tightness, and embroidery shape. Durability tests confirm that the system still functions after 100 000 abrasions and 10 cold washes.

Keywords

• optical sensing
• respiration
• textile strain gauges