Remember reading in the paper about “smart homes”-houses that signal coffee makers to turn on when you wake up and lock the door when you leave? That was only the tip of the iceberg. These days, researchers are busy making everything smarter-and smaller.
At a recent talk on applications of nanotechnology in space, Dr. Robert Gorbet discussed the potential of “smart materials.” These are materials with properties that we can take advantage of, such as shape changes in response to changes in temperature.
“They’re a novel class of materials,” says the assistant professor of electrical and computer engineering at the University of Waterloo. “I use the word ‘novel’ because a lot of materials change behaviour under changing environments-for example, steel expands, but it doesn’t expand in a way that we can take advantage of.” Smart materials, on the other hand, react to changes in the environment in ways that we can use.
So what are these smart materials and what are they good for? Gorbet cited shape memory alloys (SMAs) as an example. SMAs are metals that can be severely deformed, and then heated up to return to their original shape-or “remembered length,” as Gorbet puts it while demonstrating with a metal string. SMAs rely on temperature changes to generate motion and perform work.
Clementine, the lunar spacecraft launched in 1994 to map the lunar surface, used the properties of SMAs to separate its solar panels. Electrical signals activated the resistance heater, raising the temperature of the SMA, which expanded and generated a very large force to rupture the screw that connected the panels. As a non-explosive way of deploying objects in space, SMAs have since been used in 26 other spacecrafts.
Dr. Glenn Hibbard, an assistant professor in materials science and engineering science at U of T, was also present. He is interested in manipulating metals at the atomic level to make them stronger.
Materials like brass can bend because of “loopholes” in their atomic structure. Working with metals like iron-nickel and cobalt, Hibbard creates uniform metal solids by assembling building blocks of crystal lattices. By controlling the structure of metals at this scale, you can make very hard yet very small solids that can be used in tiny devices like gears that are as thin as a strand of hair.
Working on the scale of one billionth, or 0.000000001 of a metre, nano is really becoming big. Being able to control the structure of material means we can build tools as puny as we need them to be, like cameras shaped like pills that we can swallow to take pictures of the gut, or ultra-small pumps that deliver doses of insulin to patients with diabetes.
There is great potential for mini high-precision devices in the future, Gorbet remarks. He spoke about “smart wings” on airplanes that self-diagnose with “little sensors.”
“The U.S. military has a big push to build ‘smart skins’ with sensor grids that are able to tell where on the plane it’s been hit and to what extent the damage is,” he says. Commercial airplanes would be able to detect the kinds of turbulent forces it is up against and make adjustments to optimize the flight path.
However, Gorbet admits that these intelligent structures can only come about at very high costs, and institutions are not going to pour big bucks into researching devices like smart wings if they do not know for certain the money will pay off.
“In this new world of budget cutbacks,” Gorbet continues, “people like NASA and the American military are no longer doing things just because they’re cool, or just because they can. They need a justified performance benefit that is measurable.”
