High throughput microfluidic system for heterogeneous assays

High throughput screening is central to drug discovery. A category of assays known as heterogeneous assays have desirable properties for high throughput screening. However, their use has been somewhat limited, partly because of the complicated robotics required to automate them in microtitre plate format. In particular, some of the assays require washing steps that demand dedicated robotics. Another category of assays termed homogenous assays has been more popular as such assays take less steps to perform, require less complicated robotics, and are often easier to scale down. We demonstrate the execution of a heterogeneous assay that involves washing steps employing only liquid handling functionality used for homogenous assays, thus combining the qualities of both categories of assays. The washing does not require dedicated robotics, but is achieved through a passive surface tension based pumping scheme, that drives liquid through a microchannel.