MESA+ University of Twente
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Wojciech Bula (promotion date: 23 January 2009)

Microfluidic devices for kinetic studies of chemical reactions

Promotion date: 23. January 2009

Promotor: Prof. Dr. Han Gardeniers

This thesis describes the development of microfluidic platforms to perform on-chip kinetic studies of organic reactions.

To increase the number of kinetic points that are obtained for a single flow rate, the concept of multiplication of reaction lines was introduced. A 4-line quench flow parallel line microreactor, allows the diversification of reaction times by introduction of an inhibitor, into the reaction lines at different locations. Microreactors with 8, 16 and more parallel lines can easily be designed, fabricated and applied for kinetic studies.

A porous silicon layer is a functional and effective tool for studies on small molecules. Microreactors with integrated porous silicon spots are of great interest for biomolecular or metabolite analysis.

Could you describe the importance of these new kinds of fluidic systems?

This combination of microchannels in which the chemical reaction takes place and this special porous layer, is unique.

More or less, they form an interface between the micro and macro world. By using microreactors technology we benefit from the advantages of miniaturization. Reactions are performed safer with smaller environmental impact due to the reduced volume of reagents involved. Moreover, a lot of limitations of the batch-scale are absent in the micro world, therefore the reaction can be performed under conditions that are not achievable in conventional chemistry laboratory.

However, scaling-down the microreactors brings some disadvantages – the amount of sample available for analysis is very small. An efficient interface between the micro-scale and conventional analytical instrumentation, should be provided. We believe the integration of porous silicon spots with the microreactors is one example how to fill the gap between those worlds.

Moreover, the kinetic studies of chemical reactions can be performed more efficiently in microreactors with parallel reaction lines. For example, in case of 4-lines microreactor, instead of repeating an experiment four times, it is possible to perform four parallel reactions at one time.

How did you come into contact with MESA+?

During the Socrates/Erasmus student exchange program, I stayed in the TST and SC groups for four months. There I met Alexey Kovalgin and Remko Wiegerink.

I was attracted to MESA+, because it is an internationally recognized institute. I also learnt they have pretty good facilities, and the people working there are very keen on sharing knowledge.

Did these expectations become true?

Very much so. Everybody I asked for help, provided it. I also liked the way my supervisor supported me. He did give me complete freedom, calling himself more of an “advisor” than a supervisor.

In the Netherlands there is no huge gap between people at the top level and normal students. Despite differences in experience, the way people treat each other is on an equal basis.

What, in your opinion, is important for MESA+ in the future?

Investments should be maintained to keep the facilities at the top level. Instrumentation and hardware are really important in order to provide a modern environment for successful scientific research.

I think that variety of skills and backgrounds of collaborating participants of the research, is the key factor of efficient exchange and sharing of knowledge and ideas. Therefore, the multidisciplinary and international profile of the institute should be kept.

What are your future plans?

I am going to work as a post doc, on a European project. It focuses on the way moths use pheromones to attract and communicate. I am going to design and fabricate artificial gland that will mimic the release of the pheromone as the moths do.

The period of a post-doc is shorter than the PhD project. Therefore I expect a new challenge and valuable experience.