How to Maintain Accuracy of Open Cavity Polymer Based Relative Humidity Sensors

Abstract

For relative humidity sensors the sensing element needs to be in direct contact with environmental moisture to allow transmission of moisture into the sensing material. Thus, an open cavity package is required for relative humidity sensors. As a result, the sensing material is always exposed to the external environment for the lifetime of the device. The sensing material may get exposed to environmental factors such as chemicals, dust, as well as extreme temperature and humidity conditions which may increase the error in accuracy beyond the datasheet specifications. This paper demonstrates a novel technique of offset error correction as well as different industrial packaging practices to mitigate the shift in accuracy of the device. This facilitates maintaining device accuracy for an extended lifetime which eliminates the need for system recalibration by end users saving cost and time.