Capacitive RH sensors consist of a ceramic substrate on which a thin film of polymer is deposited between two conductive electrodes. The sensing surface is coated with a microporous metal electrode, allowing the polymer to absorb moisture while protecting it from contamination and exposure to condensation. As the polymer absorbs water, the dielectric constant changes incrementally and is nearly directly proportional to the relative humidity of the surrounding environment. Thus, by monitoring the change in capacitance, relative humidity can be derived.

Innovative Sensor Technology IST AG humidity sensors are capable of measuring 0 % RH to 100 % RH and operating at temperature ranges of -80 °C to +190 °C. The humidity product line features sensors with excellent linearity, low hysteresis, fast response times, and high chemical resistance.