Abstract

Acoustical Microfluidics for Sorting and Control in Droplet Fluidics

Thomas Franke, Professor, University of Augsburg

The use of acoustics in microfluidics has become very popular for the past few years because it provides a versatile tool to manipulate small amounts of fluid on a chip in a highly controlled manner. Mixing, pumping, focusing and deflection has been successfully demonstrated and already included in commercial available products. In this presentation we show sorting of biological cells and drops at high speed in microfluidic channels. We apply a surface acoustic wave (SAW) generated on a piezo-electric substrate to actuate cells and drops and direct them into one or more collect channels. The sort is triggered by the fluorescence signal of the sample objects similar to detection in a fluorescence activated cell sorter (FACS). Every single cell is interrogated in a laser spot and a decision to select is made based on its fluorescence level. We can sort cells at rates as high as several 1000 cells/s. The sorting does not depend on cell size or another physical property such as charge, dielectric or compressibility contrast to the surrounding medium. Therefore, the sorting principle is very versatile and can be applied to large magnitude of different objects including particles and drops. Drops have been shown to be useful in many application for example to encapsulate cells and drugs and to serve as templates for microparticle formation in drug delivery. Using our acoustic technique we are able to robustly control drop size and volume.