With few exceptions, virtually every solid material expands when it is heated up. However, a new research project from researchers at the Massachusetts Institute of Technology and the University of Southern California want to buck the trend.
“What we tried to achieve was to build a material structure that would shrink when you heat it and expand when you cool it down,” Nicholas Fang, an associate professor of mechanical engineering at MIT, told Digital Trends.
To achieve this, Fang and his colleagues created tiny, 3D-printed star-shaped structures — around the size of a single sugar cube — which rapidly shrink when subjected to extreme temperatures of 540-degrees Fahrenheit. These metamaterials were fabricated using interconnecting beams of a slow-to-expand material containing copper, and more elasticized, rapid-expanding polymer substance.
While the crazy, natural world-inverting properties of the structure are interesting from a research perspective, what Fang and others are most interested in is possible heat-proofing abilities of the strucutre, which can withstand notable shifts in temperature without expanding.
“One possible application is precision optics,” Fang said. “If you have a camera that is operating over a very wide range of temperatures, you want to make sure the lens will stay focused at a variety of temperatures. Overcoming thermal expansion is very important. Another application would be in dental fillings. If you fill a dental cavity then you absolutely don’t want the filling to pop out as a result of temperature change. The same could be true of solar cells.”
The structure could also be useful when it comes to printed circuit boards, since the sudden heating when a CPU is running can have a negative effect on their performance.
“In short, any material that has to undergo a wide range of temperature changes could benefit from this technology,” Fang said.
