Microfluidic centrifuge based on a counterflow configuration

Abstract

We present a microfluidic centrifuge with no moving parts, relying on a vortex formed between two counterflowing liquid streams. The centrifuge is driven by streams with a speed of 0.6–2.6 m/s, resulting in accelerations applied to samples between 50 and 2,000 g. The liquid flow in the centrifugation chamber and the transport of microparticles are visualized using epi-fluorescence microscopy and bright-field imaging with a high-speed camera. It is found that small particles follow the streamlines of the flow, whereas larger particles show a cross-stream migration. The size separation of different particles is demonstrated, and the experiments clearly indicate that as the flow speed increases, the particles in the vortex are increasingly driven outwards. Per construction, the centrifuge is ideally suited for handling small sample amounts and can be integrated with lab-on-a-chip systems.