Classification and evaluation of sensing films for QCM odor sensors by steady-state sensor response measurement

When we discriminate gases using quartz crystal microbalances (QCMs) odor sensors, it is important to understand gas sorption characteristics of sensing film materials coated on their electrodes and to select them according to target gases. Although we have so far studied the properties of various kinds of sensing film materials by a flow-type odor sensing system to measure transient responses, the steady-state responses are measured in the present study to evaluate partition coefficient precisely. Twenty-four sensing film materials were chosen from gas chromatography (GC) stationary phases and lipids, 41 sample gases from volatile organic compounds (VOCs) and odorants as sample gases. Then, we tried to classify the sensing films using principal component analysis (PCA). As the result of analysis, it was found that sorption characteristics of GC materials mainly depend on their polarity. The properties of lipid films do not depend on the number of carbon atoms (C16, 18, 20) in the tails but depend on the kind of head group and the number of double bond in the tail. Moreover, we tried to classify the odorants using those 24 kinds of sensors and PCA.