MESA+ University of Twente
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Volume 2, 2013

From coffee stain to filled nano-football

The interview with PhD student Hanneke Gelderblom takes place in the group’s coffee corner. Usually not the best place for an interview. However, it’s a befitting place to talk about her research as it so happens that Gelderblom is studying how fluids such as coffee and wine dry up. Moreover, she is also able to check whether the printer (unfortunately for this article not an inkjet printer that produces droplets but a laser printer) is printing her draft thesis properly. She hopes to obtain her doctorate from Detlef Lohse, head of the physics of fluids group.

Why did you come to Twente?
“I was studying biomedical technology at Eindhoven and had finished my final assignment on the hydrodynamics of blood flow through blood vessels. For my PhD research I was searching for something in the physics of fluids, preferable a combination of theory and experiment. Lohse’s group is one of the best in this field. World wide.”

And, were you successful, finding a combination of theory and experiment?
“Yes, although I must say that I haven’t conducted many experiments myself. I’m better at making models, with pen and paper that is. But I have worked closely together with Álvaro Gomez Marin. He was a postgraduate in our group. He is an expert in the evaporation of fluids in a controlled fashion. After carrying out an experiment he always asked me whether I could explain the results. That was the starting point for me to make calculations and create a model that not only explained the results but also predicted what would happen if he made adjustments to certain conditions in his experiment.

Isn’t that a bit dull just sitting at your desk with paper in front of you and pen in hand?
“No, on the contrary. It’s always puzzles that you are trying to solve. Besides, you work together on something, and my models give rise to new ideas for experiments. And it always gives you a good feeling to understand what the world’s all about. Plus the fact that it proves to be useful. Take our coffee stain research for example. That started purely out of curiosity. But industry apparently has a problem with evaporating fluids and the circles they subsequently leave behind.”

What is the goal of your research?
“First and foremost to satisfy our curiosity, explain why things happen in nature the way they do. Having said that, we also want to be able to design things ourselves. For instance, you can fill a droplet of fluid with microscopic polystyrene balls. That’s the plastic used to make plastic beakers and chip boxes. If you then let the droplet evaporate in a controlled fashion, then you automatically get a good stacked structure. A sort of ‘filled nano-football’. This self-assembly of orderly structures could possibly mean something in terms of new fabrication techniques for computer chips.

How do you look back on your doctoral research, and what will the future hold in store for you?
“Well, when I first started here four years ago I had to acclimatise. Ours is a big group, almost sixty people. I really had to find my way around. After six months I had found my feet and that’s when everything started to go smoothly. By the way, a large group also has an advantage. There’s always someone around to help you if there’s something you don’t know. For instance, I have learnt a great deal from Leen van Wijngaarden. That’s an eighty year-old professor emeritus. He still comes here and is a sort of walking encyclopedia. Right now I can’t say anything about the future. I’m working on something very exciting and it just isn’t finished yet.”

NAME : Hanneke Gelderblom (1985)
POSITION : PhD student in Detlef Lohse’s Physics of Fluids group. Hopes to obtain her doctorate in April 2013 on research into how fluids evaporate
PREVIOUSLY: Studied biomedical technology at Eindhoven from 2003 to 2009 with a final assignment on the hydrodynamics of blood flow through vessels
MESA+...“offers me the facilities to carry out my research properly”