1, the humidity sensor is the simplest humidity sensor. There are two kinds of humidity sensors: resistive and capacitive. Characterized in that the substrate is covered with a thin film made of moisture-sensitive materials. When the water vapor in the air is adsorbed on the humidity-sensitive film, the resistivity and resistance value of the element change, so this characteristic can be used to measure humidity.

2. Humidity-sensitive capacitors generally use polymer film capacitors, and commonly used polymer materials include polystyrene, polyimide, butyric acid acetate fiber, etc. When the environmental humidity changes, the dielectric constant of the humidity-sensitive capacitor changes, and so does its capacitance, which is proportional to the relative humidity.