Dolbow Young Investigator Award
Critics are always looking for flaws and defects. Like critics, John Dolbow is also interested in defects, but not for their ability to detract from a finished product, but for the vast potential in better understanding and harnessing their potential. More specifically, he meticulously follows the process of materials as they change in response to mechanical loads, looking for that precise instant when they transform from one state into another.
As an example of these stress-response reactions, he cites those well-known frames for glasses that can be bent into any shape, yet snap back to their original shape, as if the material had a memory of its form.
“The act of twisting ‘breaks’ the symmetry of the material at the micro-scale, and in the process, the material transforms from one state (straight) to another (bent),” he said. “One phase likes to be ‘smaller’ than the other, causing the material to snap back after the twisting stops.”
One of the emerging materials Dolbow prefers to study is a substance known as a stimulus-responsive hydrogel. Hydrogels are fairly ubiquitous in every day life, appearing in everything from food products (like Jell-O) to shaving cream. Stimulus-responsive hydrogels have been specially designed to exhibit large volume changes in response to small changes in environmental stimuli, such as temperature, pH, and light. They do so as the gel undergoes a reversible phase transition from a swollen, water-filled state, to a collapsed one occupying a much smaller volume.
Stimulus-responsive hydrogels have become a hot research topic, as investigators submit them to different stimuli or stresses and study their responses. Increasingly, these materials are being examined for entirely new applications, such as artificial muscle and micro-scale pumps and actuators. Dolbow is interested in understanding how these relatively soft materials can sustain and transmit mechanical loads, what their limits are, and what can be done to improve their structural behavior.
While Dolbow is investigating the stress-response reactions in hydrogels, he’s also going one step farther. As a specialist in computational mechanics, he is applying what he learns from his experiments to create computer models that can predict how different hydrogels respond to different stimuli.
For his work to date in this burgeoning field of engineering, Dolbow received a Young Investigator Award from the International Association for Computational Mechanics. The award is given each year to recognize the achievements, especially in the form of papers published in scientific journals, of investigators under the age of 40.
Dolbow, who has been on the Duke faculty since 1999, serves as associate professor of both civil and environmental engineering, as well as mechanical engineering and material science.
He gives an example of how stimulus-responsive hydrogels are now being used to ensure the safety of jet fuels.
“If there is even the slightest bit of water in jet fuel, that would be catastrophic, as it could freeze in mid-flight,” Dolbow said, “If this particular device is placed in the fuel and there is any water present, the hydrogel swells and switches on a hologram that indicates the fuel is contaminated. So it acts as a sensor providing immediate information.”
His particular research is geared toward uncovering what happens to materials when they transition between different states. From that, Dolbow wants to develop computational methods to test in a ‘virtual’ manner how different materials react. With this knowledge, he hopes to discover how the macro-scale response of the materials can be influenced by phenomena at the micro-scale and below.
“We’re operating under the assumption that performing trial-and-error experiments can be a time-consuming and expensive proposition,” Dolbow said. “If we can figure out on the computer what works and what doesn’t work, we can more precisely design experiments or rule out fruitless experiments.”
This is not Dolbow’s first award. In 2005, he won the Gallagher Young Investigator Award from the U.S. Association for Computational Mechanics in 2005. A native of New Hampshire, received his undergraduate degree in mechanical engineering from the University of New Hampshire, as well as M.S. and Ph.D. degrees in theoretical and applied mechanics at Northwestern University. He then joined the Duke faculty in 1999.
This fall, Dolbow is headed to Harvard for a sabbatical, where he will continue his work in hydrogels with noted scientist Zhigang Suo.