UV-Curable Polymer-Based Optical Fiber Microbubble FP Humidity Sensor

To achieve low-humidity detection of gas, an optical fiber Fabry–Pérot (FP) humidity sensor based on an ultraviolet (UV)-curable polymer-coated microbubble is proposed in this study. Experimental results show that the sensor demonstrates a sensitivity of 21 pm/% RH within 3% RH–30% RH, with a maximum nonlinearity error of 1.16% RH, excellent linearity, and high reversibility. Moreover, it maintains consistent performance in 30% RH–90% RH. The sensor exhibits low-temperature cross-sensitivity, which can be further mitigated via temperature compensation. Notably, it features a wide dynamic range, high stability, low cost, high spectral contrast, and rapid response/recovery times of approximately 60/36 s, while remaining unaffected by high-pressure environments. These attributes make it promising for humidity monitoring in gas-insulated switchgear (GIS) electrical equipment.