Hydrogen sulfide gas sensor based on TiO2–ZnO composite sensing membrane-coated no-core fiber

Abstract

Abstract A novel hydrogen sulfide (H2S) gas sensor based on multimode interference is proposed and presented. The sensor is constructed by a 30 mm no-core fiber (NCF) and two 30 mm thin-core fibers (TCFs). The first part of the TCF is excited by the high-order modes, in the second part of TCF, the basic core and high-order modes are coupled to the last single-mode fiber, which can induce inter-mode interference. Titanium dioxide–zinc oxide (TiO2–ZnO) composite film is coated on the outside surface of the NCF by the dip-coating method. The experimental results indicate that there is a good linear relationship between the wavelength shift and the different H2S gas concentrations. The sensor has a sensitivity of 21.26 pm ppm−1 in the gas range of 0–50 ppm H2S. In addition, the TiO2–ZnO composite sensing membrane has good selectivity for H2S gas. The response and recovery times are about 90 s and 115 s, respectively. The sensor has the advantages of simple structure, high sensitivity, easy manufacture and could be used in toxic H2S gas monitoring.