A tilted fiber Bragg grating pH sensor coated with polyaniline

A functionalized tilted fiber grating (TFBG) sensor based on polyaniline (PANI) was proposed for the detection of environmental pH. The pH sensor is fabricated by coating PANI to the surface of optical fiber. The transmission spectrum of the sensor changes significantly with the change of external pH value. Moreover, the sensitivity is directly related to the thickness of the polyaniline film. The test results show that the pH detection range is 2-11.2, and the maximum sensitivity is up to 1.82 dB/pH. Furthermore, the proposed pH sensor exhibits good biochemical compatibility, which exhibits great application prospects in biomedicine field.