Use of the dynamic response of QCM sensors to detect CO in presence of interferents

In this paper an innovative electronic nose, based on Quartz Crystal Microbalances (QCMs), is presented. The system comprises a dedicated fully digital front-end hardware that measures the QCM resonance frequency shift using a technique proposed by Cantoni [1]. This technique allows reducing the measurement time while maintaining a high frequency resolution. The developed system allows measuring variations of the sensor resonance frequency shifts during chemical transients obtained with abrupt changes in gas concentrations. Hence the reaction kinetics can be exploited to differentiate among different compounds. In this paper the application of the developed electronic nose to the detection of CO in presence of ethanol is presented. The results obtained by an array of 4 sensors with different sensitive layers are presented. An exponential fitting of the transient responses is used for feature extraction.