Effect of Different Inorganics on Polyimide-Based Bragg Grating Humidity Sensor

摘要

Effect of activated carbon and lithium chloride on polyimide-based fiber Bragg grating relative humidity sensor has been experimentally investigated. Through dip coating process, organic-inorganic hybrid coatings were deposited on fiber Bragg grating to form different relative humidity sensors. Experimental results show that the addition of activated carbon or lithium chloride alone could increase the humidity sensitivity (1.67 times and 1.61 times, respectively), but the structure which contains both lithium chloride and activated carbon increases the sensitivity most (3.9 times). In the 14-day stability test, the fluctuation of pure polyimide sensor is +/- 6.5%, while the ones of activated carbon sensor, lithium chloride sensor, activated carbon, and lithium chloride sensor are +/- 3%, +/- 8%, and +/- 1.6%.