Detection of CO2 with (Hetero-) Polysiloxanes sensing layers by the change of work function at room temperature

Zhou et al. and Endres et al. reported on CO2-sensing using primary amino groups of Heteropolysiloxanes at higher temperatures (50-70°C) by means of a mass sensitive and a capacitive readout. Based on this work the read out of the change in the work function is investigated. The reversible interaction of CO2 with spin-coated Heteropolysiloxanes sensitive layers results in changes of the work function with typical signal heights of 15-20 mV (from 400 ppm up to 4000 ppm). Results are presented regarding variations in the chemical nature of the films. This opens up the possibility for a new ambient temperature CO2-sensor which shows fast response times as well as a high sensitivity for concentrations exceeding 400 ppm CO2 (background in atmosphere).