Investigation of Volatile Organic Compound Gas Sensor Based on Polydimethylsiloxane Self-Assembled Fabry-Perot Interferometer

A Fabry-Perot (F-P) interferometric fiber-optic sensor based on polydimethylsiloxane (PDMS) coated single-mode fiber (SMF) end is proposed, and the gas sensing characteristics of the sensor to volatile organic compound (VOC) gas are studied in detail. Due to the swelling effect of the PDMS, the cavity length and refractive index of the F-P cavity change with the concentration of VOC gas, which will then induce the wavelength shift of the F-P interferometer. It is proved that the wavelength shift is inversely proportional to the polarity of VOC gas. For weak-polar toluene gas with concentration changes from 0 to 560 ppm, the interference wavelength shifts 2.841 nm. Besides, the proposed sensor behaves fast response property, good time stability, and excellent repeatability.