Acousto-microfluidics: Trapping and transporting microbubbles using surface acoustic waves

The spatial control of micro-particles is crucial to the development of microfluidic, on-chip platforms for characterisation, modification and sensing applications. We demonstrate the use of surface acoustic waves (SAWs) to generate ordered arrays of microbubbles, and transport these arrays by controlled modulation of the SAW frequency. Micro-particle and microbubble arrays are repeatedly captured at a series of spatial positions in a microfluidic channel. Periodic cycling of the applied SAW frequency across the transducer bandwidth is shown to produce long-range transportation of micro-particle and microbubble arrays. The exquisite control over particle position and transport in microfluidic devices that our technique allows could find wide applications for non-invasive and programmable ordering and transport of biological materials in microfluidic systems.