Development of a high-sensitivity and fast-response fiber temperature sensor utilizing Ti₃C₂T_X MXene/PDMS composites and Vernier effect

Precisely measuring temperature holds great significance for human daily life and industrial production. A high-sensitivity and fast-response optical fiber temperature sensor based on the vernier effect is proposed. A Fabry-Perot interferometer (FPI) filled with Ti₃C₂T_X MXene and polydimethylsiloxane (PDMS) composites is employed as a sensing probe for the first time, and a cascaded Mach-Zender interferometer (MZI) as a reference unit due to its insensitivity to temperature. The temperature sensitivity of the FPI filled with Ti₃C₂T_X MXene/PDMS composites is 1.63 nm/°C owing to the excellent thermal expansion characteristics of PDMS, and the response time is shortened from 3.021 s to 719 ms compared to that of the FPI filled with pure PDMS attributed to the high thermal conductivity of MXene. The cascading of FPI and MZI with similar free spectral ranges generates the vernier effect. The sensitivity is magnified by 19.44 times, reaching up to 31.62 nm/°C in the range of 36.5 - 37.2 °C, and the response time is 721 ms. Furthermore, experimental results demonstrate the sensor's good stability, implying its potential applications of the sensor in medical diagnosis, environmental monitoring and biosensing.