Pospori Andreas, Ioannou Andreas, Kalli Kyriacos
Photonics and Optical Sensors Research Laboratory, Cyprus University of Technology, Saripolou 33, 3036 Limassol, Cyprus.
Sensors (Basel). 2022 Sep 23;22(19):7233. doi: 10.3390/s22197233.
Polymer optical fibre Bragg grating (POFBG) sensors are of high interest due to their enhanced fracture toughness, flexibility in bending, and sensitivity in stress and pressure monitoring applications compared to silica-based sensors. The POFBG sensors can also detect humidity due to the hydrophilic nature of some polymers. However, multi-parameter sensing can cause cross-sensitivity issues in certain applications if the temperature and humidity measurements are not adequately compensated. In this work, we demonstrate the possibility of selectively tuning sensors' temperature and humidity sensitivities to the desired level by applying a certain amount of fibre pre-strain. The temperature sensitivity of POFBG sensors fabricated in perfluoropolymers (CYTOP) can be selectively tuned from positive to negative values, having the option for insensitivity in specific temperature ranges depending on the amount of the applied pre-strain. The humidity sensitivity of sensors can also be changed from positive values to insensitivity. The importance of thermal annealing treatment of POFBG sensors for improved repeatability in temperature measurements is also reported. An array of 4 multiplexed POFBGs was fabricated, and each sensor was pre-strained accordingly to demonstrate the possibility of having targeted temperature and humidity sensitivities along the same fibre.
与基于二氧化硅的传感器相比，聚合物光纤布拉格光栅（POFBG）传感器因其增强的断裂韧性、弯曲灵活性以及在应力和压力监测应用中的灵敏度而备受关注。由于某些聚合物的亲水性，POFBG传感器还可以检测湿度。然而，在某些应用中，如果温度和湿度测量没有得到充分补偿，多参数传感可能会导致交叉敏感问题。在这项工作中，我们展示了通过施加一定量的光纤预应变将传感器的温度和湿度灵敏度选择性地调整到所需水平的可能性。在全氟聚合物（CYTOP）中制造的POFBG传感器的温度灵敏度可以根据施加的预应变量从正值选择性地调整为负值，在特定温度范围内具有不敏感的选项。传感器的湿度灵敏度也可以从正值变为不敏感。还报道了POFBG传感器的热退火处理对于提高温度测量重复性的重要性。制造了一个由4个复用POFBG组成的阵列，并且每个传感器都相应地进行了预应变，以证明在同一根光纤上具有目标温度和湿度灵敏度的可能性。
