M/spl times/N micro flow switches using electrokinetic forces

This paper presents experimental and numerical investigation on electrokinetic-focusing 1/spl times/N (1 sample inlet-port and N outlet-ports) and M/spl times/N (M sample inlet-ports and N outlet-ports) flow switches for bio-analytical applications. The microfluidic device integrates two important microfluidic phenomena, including electrokinetic-focusing and valveless flow switching inside multi-ported microchannels. A voltage control model is proposed, which achieves electrokinetic focusing/switching in a pre-focusing flow switch system. Using the developed methods, the sample can be electrokinetically pre-focused to a narrow stream and can be continuously injected into desired outlet ports. The microfluidic chip presented here is promising for high-throughput chemical analysis, cell fusion, fraction collection, fast sample mixing and many other applications in the field of micro-total-analysis systems.