Surface acoustic waves in biosensing applications

In this paper, we review the utilization of surface acoustic waves in biosensing applications. A brief background on the theoretical aspects and on the modeling principles for acoustic wave propagation in a liquid medium is provided first. Subsequently, different types of surface acoustic waves (SAWs) generated on piezoelectric substrates are discussed, with the basics of wave formation, operation principles, and material considerations. Several advancements in SAW biosensor design that have been developed to achieve enhanced sensor functionality are also presented. We have overviewed different sensing capabilities of SAW devices in different biosensing applications, such as the detection and manipulation of cells, and the quantification on proteins, vapor molecules and DNA hybridizations. The challenge of biofouling, which can affect the sensitivity and specificity of bioassays, is addressed in detail. Several techniques used to reduce biofouling are discussed including one based on acoustic streaming using Rayleigh SAWs. With their ability to mitigate sensor signal interference due to biofouling, and reduce incubation times using acoustic streaming, and combined with their high sensitivity, SAWs can be used as cost-effective platforms for various point of need (PON) based biosensing applications.