This interview focuses on fundamental and applied research in the Soft Matter and Biological Physics group (Professor Kees Storm), the Fluids and Flows group (Assistant Professor Hanneke Gelderblom) and the Transport in Permeable Media group (Associate Professor Henk Huinink).
Why does TU/e have such an outstanding reputation in Applied Physics?
Kees: “Our department and TU/e’s strength in general lies in a balanced mix between fundamental research and applied science, and high synergy effects across the different departments. As a theoretical physicist, my time is devoted to creating models that describe, and ideally predict, the behaviour of known and new living and non-living materials. Fascinating stuff and as fundamental as you can get! The applied physicists and chemical engineers who embrace those models, experiment with them and create new technologies for application in the real world are the second key element in TU/e’s total added-value package. The way we have structured the department and our strong links to industry are crucial to our success.”
Hanneke: “I studied biomedical engineering originally and wrote my master’s thesis on the subject of cardiovascular fluid dynamics, which is blood flow of course. During my PhD I moved to fundamental fluid physics. In my current research, I combine these interests and work on the fundamental physics of biological fluids, such as bacterial suspensions. TU/e is an ideal environment for interdisciplinary work like this. Kees has hit the nail on the head: the strong interaction between fundamental research, applied science and industry sets TU/e apart. The other point I would make is that everybody here is collaborative, inquiring and passionate about making a difference.”
Henk: “My focus is on materials that can be used to store heat and then release it again. The applied science implications are obvious in a world that is desperately looking for clean and sustainable heating systems that do not contribute to climate change. But this is still basic, fundamental science: we are working on modifying a crystalline structure, which is hard by definition, to create a new material that is capable of movement. I would also say that Eindhoven has the perfect ecosystem for meaningful fundamental research.”
What have you focused on during the past 12 months?
Kees: “Our work focuses on replicating the properties of the biological materials that make up our cells. Put simply, we want to synthesise sustainable and recyclable self-repairing materials that are capable of assembling themselves like cellular matter. During the past 12 months, my collaboration with Rint Sijbesma in the department of Chemical Engineering at TU/e has resulted in a bio-inspired synthetic material that is, indeed, capable of organising and structuring itself. This all started about 10 years ago when I showed Rint some of our models for biopolymer materials. He saw that these models could be used to produce a synthetic material. The first result was a basic material that captured some of the properties of the living material but which, unlike a cell, was basically passive and inert. Rint’s next stroke of genius involved adding small amounts of a different polymer to create an intelligent material which can autonomously contract like a tiny muscle. The theoretical underpinnings are there, so our focus has now switched to investigating the mechanical responses of this new composite material.”
Hanneke: “I built an experimental set-up that allows you to see bacteria suspended in liquid droplets and track how the bacteria move over time. Basically we make the bacteria fluorescent and can then visualize their movements by illuminating them at a specific wavelength. Why is this important? Well, surface contamination by bacteria is a general problem, but particularly relevant in respect of medical instruments. And a good knowledge of how bacteria behave in droplets can also tell us how contamination spreads when you sneeze or flush the toilet. In hospitals, for example, a good understanding of how droplets that contain bacteria or viruses can be controlled is extremely important. I also started to teach during the past 12 months. The opportunity to teach was one of my reasons for joining the Applied Physics Department.”
Henk: “Our understanding of the processes for storing heat by embedding water and salt in a crystalline matrix has developed significantly. The fact that crystal is a hard material perplexed us initially: you need to change the whole structure to get water into the matrix. We didn’t really understand the mechanisms, but knew that there would be several intermediate stages. We have now identified those intermediate stages and found proof that thin liquid films, highly concentrated ions in water, can exist within a crystalline structure. This means that movement is possible and that new crystal can be fed by old crystal. We have also discovered ways of increasing the crystal’s storage capacity so that more heat can be released.”
New territories to explore, very exciting stuff! Where do you hope to be in three years?
Kees: “Rint and I are working on some new ideas to investigate the biomedical potential of our materials. The basic idea is that we will synthesise programmable materials with predetermined properties (stiffness, surface roughness, etc.) and use them to make biological cells respond the way we want. For example, we’d like to see whether we can force stem cells to develop into a specific type of cell, such as liver cells, and then bring those cells to maturity outside the body. Ultimately, we’d love to be able to grow cells for every organ in the body, programmed to be accepted by our bodies like their own cells.”
Hanneke: “I hope to form a group that focuses specifically on the interface between fluid physics and biological matter. A promising theme I am currently working on is the assembly of biological matter by exploiting fluid flows. Ideally, I would focus on the fundamental research and build strong collaborations to explore applications of my work in tissue engineering, printing biological materials or medicine.”
Henk: “Now that we have proof of concept, three areas require further research and experimentation. We need to determine how to increase mobility in the crystal to increase its capacity; two PhD students are working on this. We also need to control expansion and shrinkage to keep the material stable – a PhD student and a post- doctoral researcher are investigating this aspect. And, finally, we need to understand the total process better to ensure the desired level of activity throughout the material. A PhD student will start working on this aspect soon.”
TU/e is obviously recognised as a leading university in Applied Physics. Would you recommend TU/e to other academics looking for research opportunities?
Kees: “I graduated from Leiden originally and then worked as a postdoc in Philadelphia, Paris and Amsterdam before coming to Eindhoven. I started on a tenure track here in 2007 and was ultimately appointed full professor in 2017. TU/e embraces Applied Physics in all its aspects and highlights its societal value as well as the fundamental research aspects. Eindhoven is unique in terms of its scale and short lines of communication within a highly connected knowledge ecosystem that includes industry. The department’s highly organised chain of knowledge ensures maximum benefit for everybody. We have a world-leading profile in these areas. I would definitely recommend Eindhoven and TU/e to colleagues looking for research positions.”
Hanneke: “I graduated from Twente and then got involved with a project for ASML here in Eindhoven before joining TU/e. Eindhoven is absolutely the right environment for me, as it allows me to combine my interests in biomedical engineering and fluid physics, and provides ample opportunities in my area of focus. Furthermore I find teaching enormously rewarding. TU/e has given me the chance to spread my wings and develop in the direction I want. It’s a great place for fundamental research, multidisciplinary collaboration and has a strong link to applications.”
Henk: “TU/e and Eindhoven are a hive of activity when it comes to energy technology. We have DIFFER, a strong Energy Technology group in the department of Mechanical Engineering, the Building Performance Group in the department of the Built Environment is looking closely at heat management and there is a strong link with solar cell technology. These separate tracks are now coming together much more. So it’s an exciting time, particularly in my area, and that obviously means opportunities for colleagues looking for research positions. And the people here really want to have an impact on the future.”
What unresolved question or dream inspires you?
Kees: “The transition to sustainable materials is the major challenge in my area. We must find solutions for our depleting fossil fuel problem and decide how to support a growing global population in a way that does not put our planet and future at risk. At some stage, in the not too distant future, we will have exhausted the planet’s conventional resources and it’s up to science to have a package of solutions ready and waiting. My dream is that we will succeed.”
Hanneke: “I dream of using fundamental fluid physics
to make a real contribution to medical science or biology. Specifically in the area of cells, organ on a chip technology and tissue engineering. Fluid dynamics plays a role in all these areas.”
Henk: “I hope that my work will result in a material that can be used in commercial products within the next 10 years. A heating system for people’s homes for example. Developments in this area are moving at lightning speed at the moment, a bit like the electronics revolution of the 1950s and 1960s.