Humidity sensor based on tapered no-core fiber coated with Ti3C2Tx MXene

An optical fiber relative humidity (RH) sensor based on tapered no-core fiber (TNCF) coated with Ti3C2Tx MXene (Ti3C2Tx) is proposed. The fluoride etching method is used to prepare Ti3C2Tx, which is used as the humidity sensitive material with a multi-layer structure, large specific surface area and rich hydrophilic groups, and optical deposition method is used to integrate Ti3C2Tx with TNCF. The diameter of TNCF between two sections of SMF is reduced to 11.6 μm to enhance RH sensitivity. The refractive index (RI) of Ti3C2Tx changes as a result of variations in RH, and this ultimately causes a shift in the transmission spectrum. The sensitivity of the device is -77 pm/%RH in the range of 33 %RH to 75 %RH. In the region of 75 %RH to 91 %RH, the sensitivity increases to 685 pm/%RH, the linear correlation coefficients of the two regions are 0.9521 and 0.9940, respectively. On average, the response time is approximately 3.5 seconds and the recovery time is about 12.7 seconds. The sensor may be utilized in possible domains, including biological, chemical, and food processing. Its benefits include a simple construction, cheap cost, high reversibility, and stability.