NAME: Lilian Magermans
CONCENTRATION: Mechanical engineering
RESEARCH FOCUS: Surface engineering and hydrophobic materials
RESEARCH LAB: Joanna Aizenberg, Amy Smith Berylson Professor of Materials Science and Professor of Chemistry & Chemical Biology
ADVISOR: Solomon Adera, postdoctoral fellow in materials science and mechanical engineering
By: Mikayla Desmarattes, SEAS Correspondent
What have you been researching this summer?
I have been working in the Aizenberg Lab. A few years ago, the lab created a new type of surface inspired by the Nepenthes pitcher plant. These slippery liquid-infused porous surfaces (SLIPS) are micro/nanostructured superhydrophobic surfaces impregnated with lubrication oil. Water droplets are more mobile on these SLIPS than traditional superhydrophobic surfaces because the droplets are not in direct contact with the solid substrate (which could cause pinning), but rather are residing on an anatomically smooth oil layer. Since these surfaces are relatively new, there is still much we do not understand about the behavior of water droplets on SLIPS. My research this summer focuses on developing a better understanding of the coalescing mechanics of droplets on lubricant impregnated surfaces.
How do you conduct this research?
This summer I used high speed imaging to capture what happens when two water droplets start to interact. When droplets merge they are effectively pulling on each other until they make full contact and become one larger droplet. To analyze the high-speed videos that I took, I use software that tracks the edge of one of the droplets over time, which gives me valuable information such as the velocity and acceleration of the droplet. By varying the droplet size and the viscosity of the lubrication oil, I hope to be able to model the characteristic coalescing velocity and force.
Although this particular surface is very young, we look for analogies in literature to try to better understand the phenomena. So, for part of the research I used well-established equations such as the Young-Laplace equation (which describes the capillary pressure across the interface of two liquids. But I tried to create and validate a model, which was based on dimensional analysis and comparable phenomena described in literature. Right now, our understanding is that the speed of the droplets while they merge is dependent on the droplet’s diameter, lubrication thickness, viscosity, and the surface tension.
What are the applications of this research?
There is a high demand for superhydrophobic surfaces, basically in any application where you do not want water (or some other substances) to stick to the surface. One of the largest applications of SLIPS is in condensation, as they have shown to improve the heat transfer coefficient by shedding droplets faster. Since the majority of global energy is produced using steam cycles, improving the efficiency of those cycles could have a great impact on the world. Some other applications include anti-icing, anti-fouling, and drag reduction. Since this is still a new technology, I expect more applications to be discovered.
What obstacles have you faced while conducting this research?
The surfaces that I'm working on are very new; they were first demonstrated a few years ago. Although the surfaces are cheap and easy to make, making sure that they remain stable is more difficult. For example, one of the main issues that I had was the droplets displacing the oil and sticking directly to the solid substrate. I have had to learn about surface chemistry to solve these issues, but also needed some time to optimize my surfaces.
What are you plans for after graduation?
After graduation, I plan to get a master of science degree and then a Ph.D. in either material science or mechanical engineering. I really enjoy working in the academic field and could see myself becoming a professor somewhere down the road.