Characterization of a Modified Surface Acoustic Wave Sensor Used in Electronic Nose for Potential Application in Breath Diagnosis

The common electronic nose (e-Nose) consists of an array of gas sensors with different sensitivity. Considering the particularity in the application of breath diagnosis, i.e., the great variety and the low concentration of the biomarkers (volatile organic compounds, VOCs) that exist in the breath sample, it is hard to find sensitive materials which are sensitive, selective and with low cross sensitivity to other gases to make appropriate gas sensors. In the article we published before, an e-Nose based on a polyisobutylene (RIB) film coated surface acoustic wave (SAW) delay line gas sensor (SAWDL) combined with GC is proposed. In this way the problem of finding different sensitive membranes was solved, but the working life and the coherence of the sensors are still not good enough. This article describes an uncoated surface acoustic wave resonator (SAWR) sensor, which has a higher sensitivity and stability, lower noise, longer lifetime and shows a great potential to use in an e-Nose for breath diagnosis.