A capacitive CO2 sensor system with suppression of the humidity interference

This paper presents a capacitive CO2 sensor system with an effective numerical suppression of the humidity interference. The system consists of an heatable Interdigital transducer with a CO2 indicator (heteropolysiloxane coating), a capacitive humidity sensor and (op-tional) a temperature sensor. The CO2 measurement range has a high resolution between from 100 - 3000 ppm CO2 and covers with a lower resolution 100 - 10000 ppm CO2 (twice TLV). These specifications follow the needs of ventilation systems (indoor air quality monitoring). The software algorithm for the humidity interference rejection can be scaled down to a microcontroller (i.e. 0851 family). The oral presentation was awarded with the conference's silver medal.