Refractive Index Sensors Based on Ti₃C₂T_x MXene Fibers

The sensitivity of fiber optic biosensors to detect trace biochemical molecules is highly challenging. Two-dimensional (2D) MXene is recently found to have strong sensitivity enhancement on biosensing, gas sensing, and humidity sensing because of its characteristics of metallic conductivity, hydrophilic surface, large specific surface, and wide band optical absorption. Here, for the first time, the experimental evidence supports the mechanism that the characteristics of 2D MXene Ti3C2Tx can enhance sensitivities of fiber optic biosensors and two kinds of fiber optic biosensors are demonstrated to compare the sensitivity enhancement between those with and without MXene decoration. Refractive index (RI) detection can be used to quantitatively reflect the detection ability of biosensors. In this paper, we use RI detection to quantify the performance improvement of our sensors. A high-performance fiber optic surface plasmon resonance sensor with a ∼30% sensitivity boost is demonstrated, and a fiber optic RI sensor exhibits an outstanding sensitivity enhancement of more than 8 times, which can be applied to the detection of most trace biochemical molecules. Additionally, the former can also tune its operation window to adapt to different detection conditions, while the latter can work in a wide spectrum with the same high quality performance. Our findings may advance the future development of MXene-based optical sensing technology.