Particles and molecules handling in micro channels

High performance flow monitoring systems are needed to monitor the particles and biomolecules flow in micro channels. For the design of microfluidic devices and systems, the finite element analysis tools play an important role. These systems are useful to evaluate the correspondence between the computational fluid dynamics (CFD) simulation and the actual flow in micro channels. The micro flow cell realizing 3D sheath flow was designed and the prototype was fabricated and evaluated. Since the flow distribution of the sample is critically changed with the pressure and the flow rate of the carrier, the 3D CFD analysis is indispensable to design the micro flow cell. The principle of 3D sheath flow is applicable to realize particles and biomolecules observation and handling systems. Novel micro flow switches using thermal gelation of methylcellulose (MC) have been developed. Since the local plug is formed illuminating the laser beam, the flow can be stopped at any point in the microchannels. The switching time of about 1 sec both open-to-close and close-to-open was achieved. By using the MC as a carrier flow, DNA, protein and biological cell sorting micro flow systems can be realized in the simple 2D microchannel structures.