Miniature and high-performance optical fiber relative humidity sensor based on Fabry-Perot structure interacting with hydroxyethyl cellulose

A miniature Fabry-Perot fiber-optic sensor is demonstrated for high-performance relative humidity (RH) detection. This sensor is constructed by fusing a single-mode fiber to a small section of capillary coating the end with a hydroxyethyl cellulose film (HEC). The effects of capillary length and hydroxyethyl cellulose concentration on the RH response are investigated to obtain the preferential condition with capillary length of 102 & mu;m and HEC concentration of 0.03 g/ml. A testing RH sensitivity of 1.24 nm/%RH can be achieved in the range of 48%RH to 60%RH. Simultaneously, small hysteresis errors are demonstrated in the tests with increasing and decreasing RH values. The dynamic measurements reveal a response time of 1.61 s and a recovery time of 2.1 s. The high sensitivity, good stability and simple fabrication process of the sensor make it promising for practical applications of relative humidity sensors.

Automated summary

A miniature Fabry-Perot fiber-optic sensor with a hydroxyethyl cellulose film coating is developed for high-performance relative humidity detection. The sensor exhibits a testing RH sensitivity of 1.24 nm/%RH in the range of 48%RH to 60%RH, with small hysteresis errors and fast response/recovery times of 1.61 s and 2.1 s, respectively. The sensor's high sensitivity, stability, and simple fabrication process make it promising for practical applications.