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Surface acoustic wave (SAW) devices have been widely used for various chemical sensing applications because the
sensor signal can be detected by simple and inexpensive electronics. The interactions between target analyte and the
sensor surface cause changes in the mechanical, electrical, dielectric properties of the sensing coating deposited onto
acoustic transducer. The changes in these properties will lead to changes in the velocity and amplitude of wave modes,
which can be measured by frequency and insertion loss (IL) changes when the acoustic element is realized as a delay line
or resonator. Among the different sensing coatings, the supermolecules are of considerable interest because the host
molecules can be thought as original receptors allowing a specific recognition of guest molecules based on "key-lock"
system. In this paper, SAW ethanol gas sensors that utilize the supermolecule of cryptophane-A as sensitive layer have
been studied. We synthesized cryptophane-A from vanillyl alcohol using a double trimerisation method and deposited it
on the SAW devices to fabricate cryptophane-A based SAW gas sensors. The SAW frequency and insertion loss (IL)
were measured using a network analyzer. The frequency shift as the response of the cryptophane-A based SAW sensors
to different concentration ethanol was measured at room temperature. It is found that the cryptophane-A based SAW
sensor has high sensitivity and good reproductivity to ethanol. The frequency response increased linearly with the
concentration of the ethanol.
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