A microreactor or microstructured reactor or microchannel reactor is a device in which chemical reactions take place in a confinement with typical lateral dimensions below 1 mm;the most typical form of such confinement are microchannels. Microreactors are studied in the field of micro process engineering, together with other devices (such as micro heat exchangers) in which physical processes occur. The microreactor is usually a continuous flow reactor (contrast with/to a batch reactor). Microreactors offer many advantages over conventional scale reactors, including vast improvements in energy efficiency, reaction speed and yield, safety, reliability, scalability, on-site/on-demand production, and a much finer degree of process control. A microreactor or microstructured reactor or microchannel reactor is a device in which chemical reactions take place in a confinement with typical lateral dimensions below 1 mm;the most typical form of such confinement are microchannels. Microreactors are studied in the field of micro process engineering, together with other devices (such as micro heat exchangers) in which physical processes occur. The microreactor is usually a continuous flow reactor (contrast with/to a batch reactor). Microreactors offer many advantages over conventional scale reactors, including vast improvements in energy efficiency, reaction speed and yield, safety, reliability, scalability, on-site/on-demand production, and a much finer degree of process control. Gas-phase microreactors have a long history but those involving liquids started to appear in the late 1990s. One of the first microreactors with embedded high performance heat exchangers were made in the early 1990s by the Central Experimentation Department (Hauptabteilung Versuchstechnik, HVT) of Forschungszentrum Karlsruhein Germany, using mechanical micromachining techniques that were a spinoff from the manufacture of separation nozzles for uranium enrichment. As research on nuclear technology was drastically reduced in Germany, microstructured heat exchangers were investigated for their application in handling highly exothermic and dangerous chemical reactions. This new concept, known by names as microreaction technology or micro process engineering, was further developed by various research institutions. An early example from 1997 involved that of azo couplings in a pyrex reactor with channel dimensions 90 micrometres deep and 190 micrometres wide.