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Egbert van der Wouden (promotion date: 15 December 2006)

Field effect, flow control of electro osmotic flow

Promotion Date: 15 December 2006

Egbert van der Wouden

We have generated a flow using electric fields.
Electro osmotic flow only works in very small channels. When you apply an electric field you get a higher charge that pulls at the fluid in the channel, thus generating a flow. I applied an electrode to the wall with an insulated cover and by either removing or applying the cover I am able to control the flow.

What was your thesis about?

We have generated a flow using electric fields. Electro osmotic flow only works in very small channels. When you apply an electric field you get a higher charge that pulls at the fluid in the channel, thus generating a flow. I applied an electrode to the wall with an insulated cover and by either removing or applying the cover I am able to control the flow.

Why would you want to control the flow?

We are thinking of developing a system to carefully deliver a dose of medicine to the body by means of a chip. On the chip we put a strongly meandering channel.

In a meandering channel you get a high hydraulic resistance. The high hydraulic resistance sees to it that no leakage occurs, and the principle of electro osmotic flow allows us to carefully control the flow.

But how can you use it in a body when electricity is involved?

You can, because we are talking very low voltages. A pacemaker, for instance, has a very high pulse, but for a very short time.

Is this application ready to be used?

Not quite, there still are a few other problems left to be solved. But this device will eventually be used to carefully deliver doses of painkillers into the body in a specific area.

What is your specific contribution?

If you apply an ordinary voltage of 220 you would get electrolysis of water and the development of gas blocking the channel. So that is no option. I worked on the application of a strong alternating tension resulting in a zero charge but still resulting in a net flow.

Why did you choose this subject for your PhD?

I did my technical college (HBO) final thesis on a similar subject, had contacts in this university and was offered a PhD position.

Is that possible when you haven’t got a Master’s degree?

Yes, I don’t know when this possibility was introduced in the Netherlands, but I do know that it has been possible in other European countries. You do of course have to catch up on a few theoretical subjects, but it is quite doable.

What did you like best about your research?

The versatility of it. The combination of subjects: a bit of electro engineering, a bit of chemistry, a bit of physics. And the freedom you have to investigate anything you consider worthy of investigation.

Any frustrations or difficulties?

Well, towards the end you feel the pressure of getting your results ready for your thesis.

Have you been to conferences and such?

Yes, I have been to several conferences in the US. The very first conference I went to was in the US, to Pittsburgh. I gave my first presentation there. I remember how nervous I was that first time, but I still enjoyed it very much. And I got very positive reactions.

What are your future plans?

I don’t know yet. But I know that I like science. I like new things and the development of new things, finding my own way. I wouldn’t mind going abroad for a bit.