Biomedical Engineering Reference
In-Depth Information
If only small volumes of very expensive chemicals are needed, a micro-
reactor may be the thing to go for (Ehrfeld et al. 2000). In a microreactor,
very small channels of the order of magnitude of micrometers are used to
bring certain chemicals in contact with each other. Microfluidics, and with
increasing miniaturization often also nanofluidics, is the science that has
provided us with the understanding of the remarkable behavior of fluids
in small channels, and has allowed us to redesign processes to make use of
this behavior. One of the aspects of fluids in microchannels is that they flow
lamellar, which means that two fluids in one channel do not mix spontane-
ously. This means that it can be controlled when and where they mix, as well
as the exact conditions in which the chemical reaction takes place. Moreover,
in a thin channel, the interaction of the flowing component and the wall is
very intricate and since the wall often plays a role in the reactions that take
place, this means that this role is enhanced. It also means that the energy
exchange with the wall is much better, resulting in a high control of param-
eters such as the reaction temperature. This is extremely important since
temperature variations often give rise to other chemical reactions taking
place that produce unwanted side products. Small channels mean that very
little reagent is in play, which in turn means that reactions that previously
cannot be done safely on a large scale now become feasible.
Of course, one of the biggest drawbacks is that this way of doing chem-
istry only yields very small amounts of products. If these products have a
high value and/or only very little is needed for the application in mind, this
is not a problem. However, usually, more is needed. In traditional chemi-
cal process development, small-scale laboratory production is scaled up to
pilot plant production and next to industrial scale production. Usually these
scaling steps pose a very big risk for the company since laboratory produc-
tion in general is not a guarantee for good large-scale production. In fact, in
many cases, scaling has been the bottleneck that kills a new product. With
microreactor production, this need not be the case since the proof-of-concept
at the laboratory in a microreactor scales linearly toward larger production
volumes, simply by putting more microreactors in parallel. If the reaction
performs well in one microreactor, it will also do well in a thousand similar
microreactors, yielding a thousand times more products. Of course, if still
larger production volumes are required, a redesign of the microreactor for
mass parallelization would be wise from an economic point of view.
5.3 Opportunities for Food Product Development
The biggest opportunities that applications of nanotechnologies have to offer
to the food industry and to the consumers lie in the development of new
