‘A glass plate makes a excellent microreactor test setup’

The microreactor is not always easier to use than a large reactor vessel. But in many cases it is an excellent test reactor that can save time and money. This was shown by Dr Jan Swarts of Wageningen University, who compared enzyme reactions at the microscale and macroscale. He also foresees applications of the microreactor in small-scale production, for example of medicines.

A glass plate measuring 1.5 by 4.5 cm, containing 15 tubes the diameter of a human hair (100 µm): this is a microreactor, which you can use to test chemical reactions. ‘If you fill a standard reactor vessel with multiple liquids or gases, then the components become turbulent and mix together. At the microscale, however, components can continue to flow beside each other.’ This property can be useful.

Swarts studied the progression of two enzyme reactions in the microreactor: a slow reaction, where an enzyme makes fats, and a fast reaction, where an enzyme breaks down sugars. ‘For the slow reaction, we thought that this would probably take place more quickly in the micro-reactor, because then you have an extremely rapid input of raw materials that come very close together. But the enzyme turned out to be the limiting factor, it simply could not go any faster.’ With the fast enzyme reaction as well, it turned out that the micro-reactor did not work faster than the reactor vessel with a mixing system.

‘At the same time, at the micro-scale we could successfully calculate the best reaction conditions for enzyme reactions. This makes the microreactor into a very good test facility. At the microscale, I needed 500 times less material to obtain the same information. This leads to savings of time and money, because enzymes can be very expensive.’

For example, the microreactor is very suitable for developing medicines, as an interim step for upscaling the production. ‘They are useful systems for small-scale production, and you can always have many small units operating in parallel.’

With colleagues in Wageningen, Nijmegen and Duisburg, Swarts is working on a prototype of a micro-reactor system. He foresees beautiful applications in the distant future. ‘Perhaps in 30 years we will no longer have a pharmacy where thousands of pills are stored, but only a small number of raw materials from which the pharmacist manufactures medicines at a microscale, customised to the patient. Chronic patients could make their own medicine at home with a microreactor. These are images of the future and options that we should start thinking about now.’ / Albert Sikkema