Faces of innovation: Pieter Verding

How do you explain your PhD defense to an outsider?

"My PhD is essentially about understanding and controlling what happens to very small droplets during ultrasonic spray coating. We use ultrasonic vibrations to break a liquid into tiny droplets, which are then transported towards a surface to form a thin coating. I investigated the complete process, from how these droplets are created, how they travel through the air, and how they interact with the surface, to how they eventually form a coating. By understanding these individual steps and how they are connected, we can make the coating process more predictable and reduce the amount of trial and error needed to obtain a good coating."

IUMAT takes a highly interdisciplinary approach. How has this changed your perspective on materials technology?

"It has taught me that materials technology is rarely just about the material itself. A good example from my PhD is diamond coating. Diamond has exceptional material properties, but having the right diamond nanoparticles is only the starting point. To successfully deposit them and obtain a homogeneous diamond layer, you also need to understand the ink formulation, its rheology, how it atomizes into droplets, how these droplets are transported, how they interact with the substrate, and ultimately, how to grow them to a suitable coating. This required me to combine knowledge from materials science, fluid dynamics, rheology, surface science, heat and mass transfer, data analysis, and physics. IUMAT's interdisciplinary environment has therefore changed the way I approach materials technology: rather than looking at the material or an individual process parameter in isolation, I now try to understand the complete process and how the different disciplines interact."

EUREKA moment: what was the absolute highlight of the past few years?

"For me, the real Eureka moment was the cooled-substrate experiment. Conventionally, we often think about heating a substrate to accelerate solvent evaporation during coating. My colleague decided to explore the opposite direction and cool the substrate instead. Seeing that this could strongly change the droplet behavior and suppress the characteristic coffee-ring-like deposition was a very exciting moment. It was unexpected and opened up a completely different processing regime. We do not yet fully understand all the underlying mechanisms, which actually makes the result even more interesting to me and something I would really like to investigate further."

Where do you hope your research will be in 7 years? What impact will this have on everyday life?

"In seven years, I hope we will have moved from largely trial-and-error optimization of ultrasonic spray coating towards a much more predictive and physically informed process. Ideally, you would define the ink properties, substrate, equipment and desired coating properties, and use our understanding of the complete droplet-to-film process to determine a suitable processing window much more efficiently.

The impact on everyday life may not always be directly visible, because these coatings can be extremely thin, but they can be used in technologies such as sensors, electronics, energy devices, etc. Better control of the coating process means using less material, producing less waste, and making advanced functional coatings easier to manufacture on a larger scale. Ultimately, I hope the research contributes to making these functional coatings more efficient, sustainable, and economically viable."