Contactless vital signs monitoring based on few-mode and multi-core fibers

Abstract

Few-mode and multi-core fibers are proposed and demonstrated for contactless vital signs monitoring in this paper. In-line optical fiber interferometers using few-mode and multi-core fibers are designed and offset splicing is utilized for mode excitation. Extinction ratio and insertion loss are analyzed experimentally under different offset distances. The fabricated in-line interferometers are packaged under the mattress to realize contactless vital signs signals collection. By using filtering techniques, both respiration and heartbeat signals can be recovered successfully, and respiration as well as heartbeat ratio are obtained. Mode excitation and interference are theoretically analyzed in few-mode fiber while curvature sensing experiments using multi-core fiber interferometer are performed to verify its excellent performance on vital signs monitoring. The successful demonstration on contactless vital signs monitoring makes few-mode and multi-core fibers promising candidates for healthcare applications.

Advances in Multicore Fiber Interferometric Sensors

“…In addition, due to the outstanding advantages of the MMZI, i.e., compact size, simple configuration, easy fabrication, long-term stability, high sensitivity, etc., MMZIs have been widely used for sensing applications of various parameters, which can be classified into bending-related parameters and environmental parameters. In recent years, some novel sensor applications based on the MMZI have been proposed, such as vital signs monitoring [ 43 ], microsurgery [ 44 ], and distributed vibration sensing [ 45 ], showing the prospects of the MMZI in practical application scenarios. Moreover, multicore photonic crystal fibers have also been widely used for MMZIs, and have been developed for measuring temperature [ 46 ], strain [ 47 ], hydraulic pressure [ 48 ], refractive index [ 49 ], gas [ 50 ], bending [ 51 ], etc.…”

Vital Signs Monitoring Based on Interferometric Fiber Optic Sensors

“…In addition to the traditional MZI, F. Tan et al proposed in-line interferometers based on few-mode fiber (FMF) and multi-core fiber (MCF) for vital signs monitoring [15]. The structure of the FMF interferometer is to use two sections of SMF spliced at both ends of the FMF, as shown in Figure 2a.…”

“…Due to the high cost of the FBG sensors and the limited sensitivity of the intensity-based sensors, researchers chose the interferometric FOS for vital signs monitoring. Researchers have dedicated much time and effort to the design of sensor structures [12][13][14][15][16][17][18][19][20][21][22][23], demodulation methods [12,[24][25][26][27][28][29][30][31][32][33][34][35][36] and the application of vital signs monitoring [12][13][14]16,[18][19][20][21][22][23][35][36][37][38][39][40][41][42][43][44][45].…”

All fiber human heart-rate sensor based on the evanescent field disturbance in no-core fiber

“…This sensor shows the advantages of simple structure and low error reporting rate, but the micro-bending fiber optic sensor still has the disadvantage of easy fracture. Fengze Tan et al designed a straight-way fiber interferometer using few-mode multicore fibers with bias splicing for mode excitation in 2020 [15]. The excellent performance in vital sign monitoring was verified experimentally.…”