A humidity sensor is a simple humidity sensor. There are two main types of humidity sensors: resistive and capacitive.
The characteristic of the humidity sensitive resistor is that the substrate is covered with a film made of moisture-sensitive material. When the water vapor in the air is adsorbed on the moisture-sensitive film, the resistivity and resistance value of the element change. Humidity can be measured.
Humidity sensitive capacitors are generally made of polymer film capacitors. The commonly used polymer materials for humidity sensors are polystyrene, polyimide, butyric acetate, etc. When the ambient humidity changes, the dielectric constant of the humidity sensitive capacitor changes, and its capacitance also changes, and its capacitance change is proportional to the relative humidity.
The accuracy of the electronic humidity sensor can reach 2-3%RH, which is higher than the humidity measurement accuracy of the dry and wet bulb.
The linearity and pollution resistance of the humidity sensor are poor. When the humidity sensor detects the environmental humidity, the humidity sensor needs to be exposed to the environment to be measured for a long time, and it is easy to be polluted and affect its measurement accuracy and long-term stability. There is no wet and dry bulb method in this regard.