SnO2 nanomaterial coating micro-fiber interferometer for ammonia concentration measurement

This paper provides a quick and simple method for detecting ammonia gas concentration by coating microfiber interferometer (MFI) with SnO2 sensitive material. The MFI sensor is fabricated by the method of fiber fusion and taper. Then the nanomaterial sensitive to ammonia is prepared by hydrothermal method and coated in the sensing area. When the sensor is in contact with ammonia the SnO2 nanomaterial can adsorb ammonia molecules, which changes the refractive index of the MFI surface and causes the sensor transmission spectrum to shift. The real-time sensing of ammonia concentration can be realized by judging the magnitude of spectral shift. The sensor unit has only optical signal, simple structure, low cost and high sensitivity. The sensor can effectively detect the concentration of ammonia within the range of 0 ppm-10,476 ppm, and the sensor has a sensitivity of 0.58 pm/ppm. The experiment show that SnO2 nanomaterial have high sensitivity to ammonia gas, and the interference sensor coated with SnO2 nanomaterial has good repeatability and selectivity, so it has a broad application prospect in gas sensing in the future.