针对现有曲率传感器存在制造工艺繁琐、成本较高的问题，提出了一种基于光纤光栅的反射式拉锥光纤柔性曲率传感器，通过将单模拉锥光纤植入聚二甲基硅氧烷（polydimethylsiloxane，PDMS）材料中实现对曲率的柔性传感，同时，利用光纤布拉格光栅（fiber Bragg grating，FBG）的波分复用特性，将其与多个拉锥光纤曲率传感器级联，实现了多点拉锥光纤柔性曲率传感，可同时感知多点的曲率信息。实验结果表明，薄膜状的PDMS柔弹性良好，拉锥光纤与PDMS膜能同步弯曲，弯曲灵敏度约为0.593 48~0.606 96 dB/m-1。基于FBG的多点拉锥光纤柔性曲率传感还具有较好的抗串扰能力。进一步地，使用该柔性传感器对喉咙处及手腕处的人体活动监测进行了应用研究，结果表明该传感器不但能检测到人体微小的肌肉变化，也能检测到幅度较大的动作，在人体活动监测领域具有良好的发展前景。
Aiming at the shortcomings of the complicated manufacturing process and the high cost of the existing curvature sensors, a flexible curvature sensor based on fiber grating is proposed. Using the wavelength division multiplexing characteristics of fiber Bragg grating (FBG), it is cascaded with multiple taper fiber curvature sensors to realize the flexible curvature of multi-point taper fiber. This enables simultaneous sensing of the curvature information at multiple points. Experimental results show that the film-like PDMS has good flexibility, allowing synchronous bending of the tapered fiber and the PDMS film. The bending sensitivity is about 0.593 48~0.606 96 dB/m-1. The flexible curvature sensing of multi-point taper fiber based on FBG exhibits strong anti-crosstalk ability and can sense the curvature information of multiple points at the same time. Further, the flexible sensor is used to monitor human activity at the throat and wrist. Experimental results show that the sensor can not only detect small muscle changes in the human body but also capture larger movements, which suggests promising prospects for development.
[1] 曲道明, 孙广开, 孟凡勇, 等. 光纤植入聚酰亚胺薄膜柔性曲率传感器[J]. 仪器仪表学报, 2019, 40(1):109-116. Qu D M, Sun G K, Meng F Y, et al. Polyimide thin film flexible curvature sensor implanted with fiber grating [J]. Chinese Journal of Scientific Instrument, 2019, 40(1):109-116. (in Chinese)
[2] Zhao Y H, Wang C L, Yin G L, et al. Simultaneous directional curvature and temperature sensor based on a tilted few-mode fiber Bragg grating [J]. Applied Optics, 2018, 57(7):1671-1678.
[3] 付兴虎, 谢海洋, 朱洪彬, 等. 基于锥形光子晶体光纤马赫-曾德尔干涉的曲率传感器实验研究[J]. 光学学报, 2015, 35(5):0506002. Fu X H, Xie H Y, Zhu H B, et al. Experimental research of curvature sensor based on tapered photonic crystal fiber Mach-Zehnder interferometer [J]. Acta Optica Sinica, 2015, 35(5):0506002. (in Chinese)
[4] 冯爱明, 帅少杰, 孙志强, 等. 基于细芯光纤马赫-曾德干涉和曲率修正模型的高灵敏度光纤曲率传感器[J]. 光电子·激光, 2018, 29(7):691-697. Feng A M, Shuai S J, Sun Z Q, et al. High sensitivity curvature sensor based on thin core fiber Mach-Zehnder interferometer with a curvature corrected model [J]. Journal of Optoelectronics·Laser, 2018, 29(7):691-697. (in Chinese)
[5] 付广伟, 李颀峰, 李昀璞, 等. 温度不敏感的错位熔接-粗锥型光子晶体光纤曲率传感器[J]. 光学学报, 2016, 36(11):1106007. Fu G W, Li Q F, Li Y P, et al. Temperature insensitive curvature sensor of photonic crystal fiber based on core-offset splicing and waist-enlarged fiber taper [J]. Acta Optica Sinica, 2016, 36(11):1106007. (in Chinese)
[6] Tian Y, Chai Q, Tan T, et al. Directional bending sensor based on a dual side-hole fiber Mach-Zehnder interferometer [J]. IEEE Photonics Technology Letters, 2018, 30(4):375-378.
[7] Liu H, Yang H Z, Qiao X G, et al. Curvature and temperature measurement based on a few-mode PCF formed M-Z-I and an embedded FBG [J]. Sensors, 2017, 17(8):1725.
[8] 何彦霖, 张旭, 孙广开, 等. 复合基底柔性光纤曲率传感器[J]. 光学精密工程, 2019, 27(6):1263-1269. He Y L, Zhang X, Sun G K, et al. Flexible curvature sensor based on composite substrate [J]. Optics and Precision Engineering, 2019, 27(6):1263-1269. (in Chinese)
[9] Li P, Yan Z J, Zhou K M, et al. Monitoring static shape memory polymers using a fiber Bragg grating as a vector-bending sensor [J]. Optical Engineering, 2013, 52(1):014401.
[10] Tian K, Xin Y F, Yang W L, et al. A curvature sensor based on twisted single-mode-multimode-single-mode hybrid optical fiber structure [J]. Journal of Lightwave Technology, 2017, 35(9):1725-1731.
