Effect of Concentration on Surface Acoustic Wave Velocity in A Rayleigh-type Biosensor

Abstract

To predict the propagation velocity of different concentrations of bovine serum albumin (BSA) in a Rayleigh-type biosensor, we derived a new calculation method for a Rayleigh surface acoustic wave (SAW) device. The method can calculate propagation velocities of leaky Rayleigh waves and Rayleigh waves when liquid is placed in the groove of a Rayleigh-type SAW device. Different concentration of BSA proteins were used to evaluate the effect of these concentrations. In this study, we used different concentrations of BSA and a Rayleigh-type SAW device consisted of grooves of 0.25 mm width and 0.26 mm height and grooves of 0.40 mm width and 0.25 mm height, quartz as the substrate and interdigital transducers (IDT) with a 25.00 mm distance. The frequency of the Rayleigh-type SAW device was set to 157.6 MHz. Our data suggests that the propagation velocity of SAWs depends mainly upon BSA protein concentration and the size of groove. At the same concentration of BSA, the propagation acoustic wave velocity of BSA depends on the size of groove. The results showed the 0.40 mm width-0.25 mm height groove was more suitable than the 0.25 mm width-0.26 mm height groove for studying the propagation velocity of wave with liquid in a Rayleigh-type SAW device. With the same groove, the propagation velocity decreased when the concentration of BSA protein increased.