In this paper, number 17 of the thematic tutorial series “Acoustofluidics – exploiting ultrasonic standing waves, forces and acoustic streaming in microfluidic systems for cell and particle manipulation” – we present the theory of surface acoustic waves (SAWs) and some related microfluidic applications. The equations describing SAWs are derived for a solid-vacuum interface before generalisations are made about solid-solid and solid-fluid interfaces. Techniques for SAW generation are discussed before an overview of applications is presented
