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Dunn wins CAREER award to improve mechanics of hydrogels

7/10/2018

Taylor Tucker, MechSE Communications

Alison Dunn
Alison Dunn
Assistant Professor Alison Dunn has won the National Science Foundation’s prestigious Faculty Early Career Development Program (CAREER) award for her research on hydrogel interfacial slip. CAREER grants are awarded to junior faculty whose research shows great potential early in their careers.

The award will provide Dunn with a five-year grant dedicated to research in the pursuit of new knowledge for designing hydrogels that will perform in a sliding interface—specifically, gels that would interface with biological tissues. The energy dissipated in slip at the hydrogel’s surface is characterized by unique mechanisms, such as viscoelasticity, that Dunn’s research will help identify in more detail. Her project is titled, "Mechanics-Driven Energy Dissipation in Soft Matter Lubrication."

Her work also has the potential to further develop general rules for designing hydrogels with specified lubrication requirements.

“One of the overarching goals of my work is to provide design rules for surface performance of soft materials,” said Dunn. “This work will significantly contribute to that because it will build understanding of how the surfaces respond to shear.”

Using the inspiration of articular cartilage and its ability to lubricate while providing damping, Dunn will study the fundamental energy dissipation mechanisms in slip of hydrogels.
Using the inspiration of articular cartilage and its ability to lubricate while providing damping, Dunn will study the fundamental energy dissipation mechanisms in slip of hydrogels.
Hydrogels, which contain water and polymer as integral parts of their structure, experience friction when acting in a sliding interface. The friction dissipates energy, but how it is dissipated between the water and polymer is not yet known. When it is more fully understood, hydrogel surfaces can be designed for long-term, robust surface performance, minimizing the probability of damage or wear.

Human cartilage, for example, needs to be robust and have a long lifespan while taking loads in shear and providing mechanical damping. For this reason, it has very complex lubrication properties. Hydrated soft materials have the potential for replacing worn-out or damaged cartilage in the body, but designing them for such a purpose is not possible until the mechanics of energy dissipation under fluid load support and fluid shear have been determined.

Dunn is able to test hydrogels by pushing them in a sliding interface while observing under a microscope in real time.

Chris Johnson, a PhD student in MechSE, uses his background on this project to explain tribology concepts, such as how a record player works, to high school students at an outreach event at a recent conference.
Chris Johnson, a PhD student in MechSE, uses his background on this project to explain tribology concepts, such as how a record player works, to high school students at an outreach event at a recent conference.
“We change the sliding conditions like load and speed, which are known to drive lubrication,” said Dunn. “The response of the interface under these changing conditions can give us an idea of how the material itself is dissipating energy.”

Both undergraduate and graduate students will work on this project with Dunn in her lab, the Materials Tribology Laboratory. Thanks to the grant, students will also have the opportunity to present results at the annual meetings of the Society for Tribologists and Lubrication Engineers (STLE) and others.

Dunn is grateful for receiving such support at this time in her career. 

“I hope to accomplish some very exciting experimental work with my students, and to contribute to the larger scientific community,” she said.