A multi-purpose microfluidic perfusion system with combinatorial choice of inputs, mixtures, gradient patterns, and flow rates

Microfluidic perfusion systems, characterized by deterministic flow, low reagent consumption, small dead volumes, large integration in small footprints, high-throughput operation, and low-cost fabrication, are being increasingly used for cell culture studies in applications such as basic cell biology, molecular biological assays, tissue engineering, and systems biology. We report a multipurpose, pressure-driven and computer-controlled microfluidic perfusion device containing sixteen inlets and a large cell culture chamber. The user can choose, with sub-second temporal resolution, (a) to feed the chamber with one of 16 inlets, all 16 inlets, or one of 64 combinations of 2, 4, or 8 inlets using a binary multiplexer; (b) to introduce into the chamber a heterogeneous laminar flow of the inlets, a smoothened gradient, or a fully homogenized mixture; (c) to bypass the chamber in order to purge the inlet lines so as to minimize the dead volume; (d) to generate asymmetrical and curvilinear flow patterns within the chamber by opening side outlets; and (e) to slow down the flow by combinatorially adding segments of high fluid resistance (sixteen different levels of flow rates are possible using only four valves). All functionalities are combined to create complex gradient patterns and sequential perfusions within the central chamber.