IdealPhotonics' fiber optic grating humidity sensor is a wavelength modulation device based on a moisture-sensitive material (such as polyimide) coated with FBG. It utilizes the grating wavelength drift caused by the hygroscopic expansion effect (sensitivity ~10pm/%RH) to achieve humidity monitoring over a wide range of 0-100%RH (accuracy ±1%RH) and resist electromagnetic interference. It is suitable for hazardous environments such as high-voltage substations and chemical storage tanks.The "All-Medium Humidity - Wavelength Direct Reading" sensor, through the synergistic design of moisture-sensitive materials (such as polyimide, response speed <5s) and FBG (sensitivity 15pm/%RH), achieves passive, explosion-proof monitoring across the entire 0-100%RH range (accuracy ±0.5%RH). It provides a calibration-free, long-term stable (drift <0.1%RH/year) humidity solution for hazardous scenarios such as oil storage tanks and underground cable tunnels.