D3.2 - CO2 Sensors Based on Workfunction Readout Using Floating Gate FET Devices with Polysiloxanes Sensing Layers

SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
Proceedings SENSOR 2011
D3 - Gas Sensors I
R. Pohle, O. von Sicard, M. Fleischer - Siemens AG, München (Germany), H. Frerichs, C. Wilbertz, I. Freund - Micronas GmbH, Freiburg (Germany)
557 - 561


The reliable detection of CO2 is key for demand controlled ventilation (DCV) in buildings, which allows for energy savings up to 30%. Presently, optical detection methods are only in use for a small percentage of building ventilation systems due to the relatively high cost of these sensing systems. A reliable low cost CO2 sensor would allow for widespread use of DCV.
Siloxanes are particularly suitable for the detection of CO2 due to their ability to form an acid base reaction with the molecule CO2. CO2 detection at room temperature with siloxanes was already demonstrated using a lab-scale Kelvin Probe setup. The readout of gas-induced workfunction changes via hybrid suspended gate field effect devices (HSGFET) has been accepted as a promising technique for the realization of a versatile, low-cost sensor platform for several years. Micronas GmbH is already in the process of industrializing the advanced floating gate FET (FGFET) device.
In this work we describe the transfer of heteropolysiloxanes sensing layers into the floating gate FET (FGFET) sensor platform in order to enable reliable low-cost CO2 detection.
The promising CO2 sensing characteristics of the heteropolysiloxane sensing layers have been successfully transferred to the FGFET platform. The reported results illustrate the capability of the FGFET platform for room air monitoring applications. Further investigations will focus on the influence of temperature and humidity on the CO2 response as well as on cross interference of other gases present in ambient air.