High sensitivity humidity sensor based on the U-shaped tapered no-core fiber coated with MXene

Ti₃C₂T_x MXene is an emerging two-dimensional material that has good potential in relative humidity (RH) measurement because of its unique layer structure, strong hydrophilic nature, and large specific surface area. Here, a high-performance RH sensor integrating Ti₃C₂T_X MXene nanosheets and U-shaped tapered no-core fiber (UTNCF) is proposed. The sensing principle is based on mode interference. The change of ambient RH leads to the change of the refractive index (RI) of Ti₃C₂T_x MXene, which eventually leads to the shift of the transmission spectrum of the sensing probe. The average sensitivity is 1.11 nm/%RH in the RH range of 45% to 80%, and the response time is 25 ms. The proposed micro-nano fiber RH sensor has the advantages of high sensitivity, fast response, good repeatability, and stability. In addition, the proposed sensor has a broad application prospect in human respiratory monitoring, industrial and agricultural production, and environmental monitoring.