On the basis of composite materials, novel capacitive humidity sensors are developed and manufactured in collaboration with the Fraunhofer Institute for Applied Polymer Research (IAP) and the companies Chemnitzer Werkstoffmechanik GmbH (CWM) and Gesellschaft für Mikroelektronikanwendung Chemnitz mbH (GEMAC). Sensors have been realized with different layouts on printed circuit boards and glass substrates. The nominal capacity is in the range of 200 to 500 pF, depending on the layout.
The humidity-sensitive dielectric of the sensor consists of ceramic particles embedded in a polymer matrix. Because of special preparation techniques, the particles are in good contact to the environment, despite the matrix.
The composite humidity sensors reveal a very high sensitivity of up to 4.5 pF / % r. h. and response times of less than 20 seconds.
With the humidity-sensitive composites, almost any sensor design is creatable - flexible substrates and curved and uneven surfaces are not an obstacle. With different coating technologies, e.g. screen printing, we are able to produce scalable large-area sensor arrays to determine humidity distributions quickly and reliably.