A new SO2 sensor system with SAW and IDC elements

Applying new transducer principles on well known indicator materials improves the performance of the whole system, especially the humidity interference. A well known S02-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 ]DC and SAW devices to S02 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.