Lab-on-fiber: Highly sensitive methane sensor based on ZIF-8/PDMS functionalized Fabry‐Perot interferometer

Methane, as the second most significant greenhouse gas globally, necessitates highly sensitive and rapid detection technologies for environmental protection. To take full advantage of lab-on-fiber gas sensing technology, this paper presents an optical fiber CH 4 sensor based on a functionalized Fabry-Perot interferometer (FPI). The sensor consists of a single-mode fiber (SMF), a hollow-core capillary (HCC), and a ZIF-8/Polydimethylsiloxane (PDMS) composite sensing membrane. Among them, ZIF-8 is synthesized via a room-temperature solvothermal method, with characterization data confirming its successful preparation. And the composite film is formed by uniformly mixing ZIF-8 with PDMS prepolymer and a crosslinking agent, followed by dip-coating onto HCC end face. The high specific surface area of ZIF-8 allows CH 4 molecules to be adsorbed onto its internal surface through van der Waals forces, leading to a change in the refractive index of the composite membrane and enabling highly sensitive CH 4 detection. The influence of ZIF-8 content on sensor performance is systematically investigated. Experimental results indicate that at a ZIF-8 content of 3 wt%, the sensor sensitivity is 12.95 pm/ppm within the methane concentration range of 0–400 ppm. Furthermore, the sensor exhibits response and recovery times of 1 min and 4 min, respectively, along with excellent reproducibility and stability. These results demonstrate that the proposed sensor achieves comprehensive sensing performance, featuring high sensitivity, rapid response/recovery, and excellent repeatability. It provides an effective solution for high-performance methane sensing and offers a new strategy for gas-oriented lab-on-fiber technology.