On-chip centrifuge using spiral surface acoustic waves on a ZnO/glass substrate

Abstract

On-chip centrifuges based on acoustic methods have promising applications in biomedicine, environmental protection, and food testing. Glass materials are ideal for microfluidics because of their low cost, chemical inertness, thermal stability, and excellent optical transmission. This paper demonstrates a glass-based, efficient, and controllable particle centrifuge. A circular interdigital transducer with spiral electrodes was fabricated on a composite substrate of ZnO film and quartz glass (QG), generating an omnidirectional spiral surface acoustic wave field. A vorticity field was generated in a sessile droplet, and controlled concentrations of polystyrene particles with different diameters and Hela cells in the droplet were achieved. A linear relationship was observed between the driving voltage and the field amplitude, and in turn, between the voltage and the streaming velocity. The performance of the device can be improved by tuning the driving voltage or the recipe of the solvent. The ZnO/QG-based centrifuge shows good performance in enriching micron/submicron particles and cells and is compatible with optical tools, offering good promise in enriching low abundance micro- and nanoparticles, especially in rare samples.