Humidity is measured by a capacitive sensor made of a hygroscopic polymer. The sensor works by detecting changes in the dielectric constant, which is directly proportional to the relative humidity of the surrounding environment. The advantages of this type of sensor include insensitivity to temperature changes, quick response time and durability.
The temperature sensor is a platinum resistance thermometer (100Ω at 0°C). The Pt100 resistance variation is transformed into a current or voltage signal linear to temperature.