US Patent 7068874 - Microfluidic Sorting Using Optical Switch

http://www.freepatentsonline.com/7068874.pdf

Microfluidics involves the manipulation of very small quantities of fluid and is useful for biological fluid processing and analysis. Often mixing or sorting of various biological fluids are performed for medical diagnostics using microfluidics and micromechanical switches or flow control using electrophoretic forces are involved in the sorting. However, more precise switching mechanisms are desirable. This patent provides for an optical switching mechanism to control the sorting of microfluidic particles. Claim 1 reads:

1. A microfluidic sorting device comprising: a substrate having a main microfluidic channel that branches into a plurality of microfluidic branch channels, the main microfluidic channel and the plurality of microfluidic branch channels adapted to contain a moving fluid having particles disposed therein; and a light source that produces at least one light beam directed at the main microfluidic channel, the light beam selectively switching the particles into the plurality of microfluidic branch channels without optically trapping the particles.