A new sensor system for SO2 with IDC and SAW elements

Applying new transducer principles on well known indicator materials improves the performance of the whole system, especially the humidity interference. A well known SO2-sensitive material (heteropolysiloxane, NND)/PTMS) was tested with a SAW (Surface Acoustic Wave, STW Surface Transverse Wave Mode) transducer and an IDC (Interdigital Capacitor) device. Due to a different relative sensitivity of the coated IDC and SAW device to SO2 and humidity, we were able to reduce the overall cross-sensitivity of the system to humidity significantly. The combination of these two different types of transducers, in case of need extended with other transducers, increases the performance of the sensor system.