Materials Science Meets Nanoscale Heat Transfer
Scientists estimate that more than 60% of energy consumed in the United States is wasted. “The question is, ‘How do we make materials that can be more energy efficient, that can conform to any geometry and be integrated into things?’” said professor Patrick Hopkins, who holds joint appointments in the University of Virginia departments of Mechanical and Aerospace Engineering, Materials Science and Engineering and Physics. Hopkins is also the graduate director for Mechanical and Aerospace Engineering.
Hopkins leads the Experiments and Simulations in Thermal Engineering (ExSiTE) research group. His ambitious team has published more than 200 papers, including recent papers in Nature Nanotechnology, Advanced Materials, Advanced Functional Materials and Nano Letters, to name a few. They have also combined to earn more than $10 million in funding from organizations such as the National Science Foundation, U.S. Office of Naval Research, U.S. Army Research Office and the U.S. Air Force Office of Scientific Research.
Their pioneering work has led to major advancements in understanding how heat moves across materials and in developing novel ways of integrating materials science and nanoscale heat transfer.
One recent discovery came from studying the unique thermal properties of a protein found in squid ring teeth—the fingernail-like claws on squid tentacles. When these properties are replicated in a biopolymer, researchers are able to program the material to make smart fabrics that can dynamically change their insulating behavior based on the presence of water.
“This is the perfect material, because when you hydrate it, it increases the thermal conductivity and increases heat dissipation,” said Ph.D. student John Tomko. “And then when you cool off, and you're not sweating anymore, it goes back to an insulative state to retain heat.”
Hopkins, who is Tomko’s Ph.D. adviser, said, “The thermal conductivity of materials is typically assumed to be a static, intrinsic property of a material. What we have shown is that you can `switch‘ the thermal conductivity of a material like you would turn a light bulb on and off via a switch on the wall. Only, instead of using electricity, we can use water to create this switch. This creates a dynamic and controllable way to regulate the temperature and/or heat flow of materials and devices.”