High-throughput Interfacing of Microfluidic Chips

Advantages associated with the miniaturization of chemical processes, include improved efficiency with respect to sample size, cost, response times, analytical performance, and system integration. However, to seamlessly integrate these chip-based operations within the robotized environment of drug discovery labs and screening factories, interfacing chips with lab robotics is an enabling factor.

To address this obstacle, a number of interfacing techniques have been developed at Coventor Inc. around a single innovative concept: the so-called "virtual wall". A virtual wall is an opening in the wall of a liquid carrying microchannel, small enough to keep flowing liquids inside the channel by capillary pressure. Typically the wall opening is in the order of 50-100 micrometer. The resulting meniscus forms a access port to the liquid inside the channel.

Various examples of bi-directional liquid interfacing using virtual walls will be shown. In one application, picoliter amounts of liquid are injected into the channel by using a droplet generator to shoot 50 micrometer drops into the channel meniscus. In another example, drops are ejected from the channel by using the virtual wall as a nozzle and generating pressure pulses in the channel to shoot droplets out. Also, results will be shown on a capillary electrophoresis (CE) chip in which sample is injected directly into the separation channel, eliminating the need for on-chip sample reservoirs and voltage switching thereby allowing a high level of integration.