Analysis of humidity sensor products in the hottes

Several analysis of humidity sensor products in the market

there are many humidity sensor products at home and abroad in the domestic market, and capacitive humidity sensors are more common. Tata advanced materials humidity sensing materials gradually form industrial clusters such as automobile plates, frames, wheels, etc. the types of materials are mainly high molecular polymers, lithium chloride and metal oxides. The advantage of capacitive humidity sensor is that the response speed (the drying time of cement is generally more than 10 (1) 5 days). After the cement is completely dried, it is fast, small, linear and stable. Some foreign products also have high-temperature working performance. However, most of the products that achieve the above performance are foreign famous brands, and the prices are relatively expensive. Some low-cost capacitive humidity sensors sold on the market often fail to reach the above level, and the linearity, consistency and repeatability are not ideal. The deformation of the humidity sensing section below 30% RH and above 80% RH is serious. Some products are compensated and corrected by single-chip microcomputer, which makes the humidity jump "step by step", reduces the accuracy, and has the disadvantages of poor consistency and linearity. No matter high-grade or low-grade capacitive humidity sensors, their long-term stability is not ideal. Most of them drift seriously after long-term use. The capacitance value of humidity sensitive capacitance changes to PF level, and the change of 1% RH is less than 0.5pf. The drift change of capacitance value often causes dozens of RH% errors. Most capacitive humidity sensors do not have the performance of working at temperatures above 40 ℃, and often fail and damage

1 for a long time, many people have taken a fancy to the performance stability of imported machines

capacitive humidity sensors are also lack of corrosion resistance, and often have high requirements for the cleanliness of the environment. Some products also have light failure, electrostatic failure and other phenomena. Metal oxides are ceramic humidity sensitive resistors, which have the same advantages as humidity sensitive capacitors, but in a dusty environment, ceramic pores will be blocked, and the components will fail, The method of electrifying and dedusting is often used to deal with it, but the effect is not ideal, and it cannot be used in flammable and explosive environments. Alumina humidity sensing materials cannot overcome the weakness of "natural aging" of its surface structure, and the impedance is unstable. Metal oxide ceramic humidity sensing resistors also have the weakness of poor long-term stability. Lithium chloride humidity sensitive resistor has the most prominent advantage of strong long-term stability. Therefore, through strict process production, the instrument and sensor products can achieve high accuracy. Strong stability is that the products have good linearity, precision and consistency, and it is a reliable guarantee for long-term service life. The long-term stability of lithium chloride humidity sensor cannot be replaced by other humidity sensing materials