Opt Express. 2024 Sep 9;32(19):33208-33221. doi: 10.1364/OE.535272.
A flexible wearable sensor based on the Fabry-Perot (FP) structure for human breath monitoring is proposed and demonstrated. This sensor is constructed by fusing a single-mode optical fiber to a small section of capillary and coating the end with agar film. In high relative humidity (RH) environments, the agar film absorbs moisture from the air, which leads to a change in the length of the FP cavity to cause a shift in the interference spectrum. The sensor has a sensitivity of 0.95 nm/%RH for testing RH in the range of 60%RH to 85%RH. The temperature sensitivity of the sensor varies nonlinearly from 30°C to 90°C, averaging 0.34 nm/°C over the range of 30°C to 55°C and 0.06 nm/°C over the range of 60°C to 90°C. The temperature and RH crosstalk problems can be solved by using cascaded fiber Bragg grating followed by matrix operations to monitor temperature and RH parameters simultaneously. In addition, the sensor has a fast response time of 0.88 s and a recovery time of 1.17 s for human breathing. The normal and deep breathing of nine subjects are monitored using the sensor, demonstrating that the sensor is able to recognize normal and deep breathing accurately. The success of this sensor proves that it is feasible to develop sensors with good resistance to vibration interference, good repeatability and high stability for human breath monitoring, which is of great significance for research on human breath monitoring.
提出并演示了一种基于法布里-珀罗（FP）结构的用于人体呼吸监测的柔性可穿戴传感器。该传感器通过将单模光纤熔接到一小段毛细管上，并在其末端涂覆琼脂膜来构建。在高相对湿度（RH）环境中，琼脂膜从空气中吸收水分，导致 FP 腔的长度发生变化，从而引起干涉光谱的移动。该传感器在 60%RH 至 85%RH 的 RH 测试范围内的灵敏度为 0.95nm/%RH。传感器的温度灵敏度从 30°C 到 90°C 呈非线性变化，在 30°C 到 55°C 范围内平均为 0.34nm/°C，在 60°C 到 90°C 范围内平均为 0.06nm/°C。通过使用级联光纤布拉格光栅并进行矩阵运算，可以解决温度和 RH 的串扰问题，从而实现同时监测温度和 RH 参数。此外，该传感器具有 0.88s 的快速响应时间和 1.17s 的恢复时间，用于监测人体呼吸。使用该传感器监测了九名受试者的正常呼吸和深呼吸，结果表明该传感器能够准确识别正常呼吸和深呼吸。该传感器的成功证明了开发具有良好抗振动干扰、良好重复性和高稳定性的用于人体呼吸监测的传感器是可行的，这对于人体呼吸监测的研究具有重要意义。
