Helical long period fiber grating sensor for non-invasive measurement of vital signs

Abstract

Long-term monitoring of the heartbeat and respiration of patients is critical for adjusting their care. However, current approaches are limited by skin contact, which may cause discomfort and restrict patients’ physical activities. In this study, we propose a new device for the non-invasive monitoring of vital signs based on a helical long-period grating (HLPG) sensor. The HLPG was fabricated with a single-mode fiber using a CO2 laser. The mode coupling in HLPG was analyzed and high curvature sensitivity (20.16 nm/m−1) was obtained, indicating its potential for monitoring vital signs. The experimental results of four healthy subjects indicated that the sensing system could simultaneously monitor vital signs. In conclusion, our sensing system is a promising candidate for long-term monitoring in hospital settings and healthcare.