Abstract

Acoustic Holograms to Shape Microfluidic Flows: Applications in Medical Diagnostics

Jonathan Cooper, Wolfson Professor and University Vice Principal, Glasgow University

Microfluidics and Lab-Chip technologies are synonymous with the movement of fluids on or around microstructured surfaces, including channels. Flow is often driven by peristaltic pumps or through electrokinetic flows (including electro-osmosis, for example). Recently, the use of pressure driven flow through the use of surface acoustic waves (SAWs) has attracted much attention.  To better control the nature of the acoustic field when using SAWs, we have introduced the idea of using frequency dependent periodic arrays known as phononic crystals within microfludics. In doing so, we have enabled new "acoustic holograms" that result in waveguiding, reflectors, bandgaps and lenses, shaping the ultrasonic field and creating new microfludic flows.  We are able to demonstrate how we can create interesting new liquid manipulations, including on-chip centrigugation, cell lysis through shear, cell separation, liquid heating and atomization. The applications of this technology are demonstrated through three examples, namely (i) sample preparation and identification of malarial parasites in whole blood; (ii) the measurement of visco-elastic properties of blood; and (iii) the control of the size distribution of droplets during nebulization (a requirement in pulmonary drug delivery, for example).