Abstract: In this paper, we study polymer humidity polyimide （PI） thin film for humidity sensor fiber Bragg grating principle and applications, and sensing characteristics of the analysis and measurement. Experiments show that plating has polyimide （PI） thin film of fiber Bragg grating reflection peak position drift volume and the humidity is a linear relationship, easy calibration, realize a high-precision measurement of humidity. Materials produced by this than other types of humidity sensors humidity sensor superior performance.

Key words: polyimide film, moisture sensitive polymer, fiber Bragg grating, fiber grating sensor, humidity sensor