Smart bombs. Smart drugs. Smart cards. And now ... smart bricks. Equipped with electronic sensors, these clay-fired building blocks could make homes and office towers far more "intelligent" than today's versions - and, quite possibly, safer.
For example, smart-brick technology might have helped firefighters change their rescue tactics as the World Trade Center teetered toward collapse on 9/11. The technology also could provide early warnings for hidden stresses, such as those that caused a Paris airport terminal to fall down in May. It might broadcast hidden damage in the aftermath of an earthquake or from floods from a storm such as hurricane Charley.
"We are living with more and more smart electronics all around us, but we still live and work in fairly dumb buildings," says Chang Liu, who invented the smart brick with his colleagues at the University of Illinois Center for Nanoscale Science and Technology. "By making our buildings smarter, we can improve both our comfort and safety."
The difference between a regular brick and a smart brick is a compartment on one side of the smart brick. Inside, researchers have stuffed advanced wireless electronics - sensors, signal processors, a wireless communication link, and a battery, all packaged in one compact unit.
"A construction worker can handle this just like a regular brick," Dr. Liu says. The sensors also have been embedded in construction materials such as plastic, wood, and steel-reinforced concrete.
The sensors are designed to monitor a building's temperature, vibration, and movement. They send the information wirelessly to a remote computer.
Several of the bricks embedded at different locations in a building could act as a kind of network, working together to provide a picture of the overall stability of the structure. This information would be vital to firefighters battling a blaze or to rescue workers determining the soundness of an earthquake-damaged structure.
Even in the absence of a disaster, building managers and even homeowners could use the data to manage and repair buildings. For example, the data could pinpoint for managers where foundations need to be reinforced or walls replaced. Homeowners could tailor heating and air conditioning throughout a house for maximum energy efficiency.
Liu and graduate student Jon Engel make the sensors by depositing metal film on flexible liquid crystal polymers. Then, using conductive epoxy glue, they bond the film to copper leads on silicon materials. Although this system is workable, the researchers say they're working to refine it.
"The sensor package itself is getting smaller since we are applying our own in-house microelectromechanical sensors, which are extremely small," Mr. Engel says. The entire package is as small as several hundred microns (only as wide as roughly seven human hairs laid side by side).
There are still challenges to be overcome before smart bricks, concrete blocks, and structural steel start showing up in homes and workplaces. One is size, surprisingly.
The researchers used off-the-shelf components in their first-generation smart bricks, so there is "lots of room for making the sensor package smaller," Engel says. "Ultimately, we would like to fit everything onto one chip, and then put that chip on a piece of plastic, instead of silicon, to make it more robust."
Another challenge is flexibility. Silicon is brittle and easily cracks or breaks. So researchers want to replace it with a flexible plastic. That would make the bricks more resilient - and more versatile.
"You could wrap a flexible sensor around the iron-reinforcing bars that strengthen concrete and then monitor the strain," Engel says.
The University of Illinois has applied for patents on the smart brick. Meanwhile, the university's Office of Technology Management is trying to license the technology to companies. "This innovation could change the face of the construction industry," Liu says.