Chemical microreactors are characterized by the extremely small dimensions of the reaction devices and related unit operation elements. In comparison to macroscale devices, large temperature and concentration gradients are feasible in microreactors, resulting in correspondingly high heat and mass transfer rates. Since the boundary conditions concerning flow, temperature, pressure, and other parameters can be precisely adjusted, and since the thermal mass of such microsystems is small, an exact setting of the residence time in the reaction volume is easily obtained. This leads to a novel approach for process control. Usually a number of microreactors are operated in parallel, with all devoted to either different or identical reactions. In the first case, microreactors may be regarded as devices generating information like miniaturized analytical laboratories; in the second case, they work as production units for chemical substances which achieve the required throughput by parallel operation.

The unique characteristics of microreactors open up novel approaches for utilizing a wide variety of reaction pathways, for improving safety aspects, for a faster transfer of laboratory results into production, and, evidently, for cost-saving innovations in many fields of modern chemistry and biotechnology.