Multi-unit Integration in Microfluidic Processes: Current Status and Future Horizons

Microfluidic processes, mainly for biological and chemical applications, have expanded rapidly in recent years. While the initial focus was on single units, principally microreactors, technological and economic considerations have caused a shift to integrated microchips in which a number of microdevices function coherently. These integrated devices have many advantages over conventional macro-scale processes. However, the small scale of operation, complexities in the underlying physics and chemistry, and differences in the time constants of the participating units, in the interactions among them and in the outputs of interest make it difficult to design and optimize integrated microprocesses. These aspects are discussed here, current research and applications are reviewed, and possible future directions are considered.