Non-invasive human vital signs monitoring based on twin-core optical fiber sensors

Abstract

Twin-core fiber (TCF)-based sensor was proposed for non-invasive vital sign monitoring, including respiration and heartbeat. The TCF was homemade and the corresponding sensor was fabricated by sandwiching single-mode fiber (SMF) on both ends. The offset distance between SMF and TCF was optimized while the length of TCF was identified from preliminary vital sign measurement results. Then, the TCF-based sensor was attached under a mattress to realize non-invasive vital sign monitoring. Both respiration and heartbeat signal can be obtained simultaneously, which is consistent with the reference signals. For further application, post-exercise physiological activitity characterization were realized based on this vital sign monitoring system. In discussion, mode coupling in TCF was analyzed and utilized for curvature sensing with achieved sensitivity as high as 18 nm/m −1 , which supported its excellent performance for vital signs monitoring. In conclusion, the TCF-based vital signs monitors can be a promising candidate for healthcare and biomedical applications.

Fiber Optic Sensors for Vital Signs Monitoring. A Review of Its Practicality in the Health Field

“…For the sensors for blood pressure monitoring presented in Table 5 , we conclude: the best results [ 88 , 89 , 90 , 91 ] are for those that show greater test data due to the different zones of the body where the sensor was placed. This is because a change in blood pressure can be seen in these areas, where it can be said that the best area is the wrist, due to the ease of placement of the sensor and the results shown.…”

“…They obtained detection ranges of 1550 ± 0.5 and 1525–1570 nm ± 0.1, or the wavelength at which it operated. In another work, we can observe in Figure 14 how through the characterization of an SMF they created a twin core that operated from 1551.85 nm to 1552.15 nm, where they used a dopant agent of pulverized gold [ 88 ]. The result was a noninvasive sensor to measure respiration and HR with readings in the human chest, obtaining a sensitivity of 18 nm/m −1 .…”

“… (Adapted) Design of the twin core fiber and its operation. In ( a ) you can also observe the operating wavelength of the SMF once it is characterized as a twin core, where it is also doped with sprayed gold to increase sensitivity and in ( b ) the schematic design and representation of the characterized fiber—a great job with a lot of creativity to create single mode fiber—two core fiber—single mode fiber (SMF-TCF-SMF) array [ 88 ]. …”

“…In Table 3, we present data from work done with respiration but which involved a modification in the nanostructure of the OF by using chemical doping agents, which is why we differentiate them from the studies in Table 2-apart from the fact that it can be observed they are the most investigated fiber optic sensors, with the highest number of studies that are talking about vital signs. In (a) you can also observe the operating wavelength of the SMF once it is characterized as a twin core, where it is also doped with sprayed gold to increase sensitivity and in (b) the schematic design and representation of the characterized fiber-a great job with a lot of creativity to create single mode fiber-two core fiber-single mode fiber (SMF-TCF-SMF) array [88].…”

Wearable Optical Fiber Sensor Based on a Bend Singlemode-Multimode-Singlemode Fiber Structure for Respiration Monitoring

“…In 2014, W. Zheng et al designed an intensity-based notched polymer optical fiber fabric strain sensor for monitoring respiration [9]. In 2019, F. Z. Tan et al proposed to use twin-core fiber based sensor to detect the human respiration and heartbeat signals [10]. In 2020, an in-line few-mode fiber Mach-Zehnder interferometer structure sensor is proposed by R. H. Wang et al and applied to the respiration monitoring [11].…”