Odor sensing system using ball SAW devices

In this study, we have developed an odor sensing system using an array of ball SAW devices and pattern recognition technique. High sensitivity can be expected since SAW propagation length utilized for sensing is long due to multiple round trips in spite of its small size. An atomizer was used to realize uniform coating over a ball SAW device. The experiment on discrimination among apple, pineapple and orange flavors was successfully performed using four ball SAW devices coated with different films even if the sensor array was exposed to odors with different concentrations. Moreover, the change of the attenuation loss due to odor adsorption was measured together with its phase change. The change of the attenuation loss enhanced the pattern separation in some cases.