Design of a recursively-structured valveless device for microfluidic manipulation.

A recursively-structured apparatus based on a pneumatic pumping structure has been investigated numerically and experimentally in the present study. For the T-connected channels, this apparatus demonstrated the ability to manipulate the liquid drop from a first channel to a second channel, while simultaneously preventing flow into the third channel. The microTAS research aimed at biochemical analysis miniaturization and integration has recently made explosive progress. However, there is still a considerable technical challenge in integrating these procedures into a multiple-step system. An important issue for this integration is microfluid management techniques. The microTAS method must be designed considering special transport mechanisms to move samples and reagents through the microchannels. The structure of this apparatus was simple and easily fabricated. Moreover, because there is a continuous airflow at the "outlet" during fluid manipulation, it is possible to avoid contamination of the air source similar to the "laminar flow hook" in biological experiments. Utilizing the concept of a recursive structure, one can easily design a device wherein more than three channels are included in the flow network, either intersecting in a single junction or in multiple junctions.