Surface acoustic wave biosensor based on a recombinant bovine odorant-binding protein

Abstract

In this work we present a Surface Acoustic Wave (SAW) biosensor system based on a recombinant bovine odorant-binding protein (bOBP) suitable to detect boletus odorant. To optimize the bOBP's deposition method on the interdigital transducers (IDTs), the protein was deposited by means of droplet method on the surface of a 155 MHz 2-port SAW resonator on ST-cut quartz. In order to promote the protein adhesion, IDTs were made of thin gold film. The frequency shift of the resonator, after deposition, shows the presence of the protein on the IDT's surface. By using two identical 2-ports SAW resonators, operating at 392 MHz and exploiting gold/aluminum multilayered interdigital electrodes, a differential configuration was implemented. In this way, common mode parasitic effects, such as temperature variations have been reduced. The SAW resonators were used as frequency control element in a Pierce oscillator. The differential frequency shift, due to the SAW velocity changes as consequence of odorant concentration, was measured, showing a resolution of 44 ppb and a sensitivity of 314 Hz/ppm. © 2010 Springer Science+Business Media B.V.