Scientists at the University of Illinois at Urbana-Champaign have built a "smart brick" that could keep tabs on a building's condition and help ensure the safety of occupants.

"This innovation could change the face of the construction industry," says Chang Liu, a professor of electrical and computer engineering at Illinois. "We are living with more and more smart electronics all around us, but we still live and work in fairly dumb buildings. By making our buildings smarter, we can improve both our comfort and safety."

Liu and graduate student Jon Engel have developed a multi-modal sensor package that can convey building data to a remote operator. To create this extraordinary brick, the scientists combined sensor fusion, signal processing and wireless technology with basic construction material.

Concealed inside the smart brick are a thermistor, a two-axis accelerometer, a multiplexer, a transmitter, an antenna and a battery. These components allow it to track a building's temperature, vibration and movement when the brick is built into a wall.

Such information could be critical to firefighters confronting a skyscraper engulfed by flames or to rescue workers trying to determine the integrity of a facility rocked by an earthquake.

"Our proof-of-concept brick is just one example of where you can have the sensor, signal processor, wireless communication link and battery packaged in one compact unit," says Liu. "You also could embed the sensor circuitry in concrete blocks, laminated beams, structural steel and many other building materials."

To prolong battery life, the brick could send information about the building at regular intervals, instead of constantly transmitting data, says Liu. An inductive coil—like those found in electric toothbrushes and some artificial heart pumps—could be used to charge the battery through the brick.

Currently, the researchers are utilizing off-the-shelf parts in their prototypes, leaving "lots of room for making the sensor package smaller," says Engel. "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."

Stiff and brittle, silicon can crack or break easily. "Sensor packages built on flexible substrates would not only be more resilient," says Engel. "They would offer additional versatility. For example, you could wrap a flexible sensor around the iron reinforcing bars that strengthen concrete and then monitor the strain."

In fact, Liu and Engel have already created such sensors by placing metal films on flexible polymer substrates. Calling their invention "smart skin," the researchers say the sensor material could be applied to any surface, such as a robotic finger.

"While a typical tactile sensor can only measure surface roughness, our sensor material can determine roughness, hardness, temperature and conductivity," says Liu. "The combined input gives you a much better idea of the type of material being touched."

The researchers manufactured the smart skin at the university's Micro and Nanotechnology Laboratory. Although the skin is not yet wireless, Engel is finetuning the analog-to-digital conversion process to employ current wireless technology.

In contrast, the smart bricks are already totally wireless. And their potential applications extend beyond monitoring a building's condition to keeping tabs on nurseries, daycares and senior homes. They could also be used to make interactive "smart toys" that react to a child's actions.

"In a smart doll, for example, sensor capability would distinguish between caressing and slapping, allowing the doll to react accordingly," says Liu. "In the gaming industry, wireless sensors attached to a person's arms and legs could replace the conventional joystick and allow a 'couch potato' to get some physical exercise while playing video games such as basketball or tennis. The opportunities seem endless."

The work was conducted through the university's Center for Nanoscale Science and Technology and funded by the National Science Foundation.

Source: Smart Bricks Could Monitor Buildings, Save Lives
Jim Kloeppel
University of Illinois at Urbana-Champaign News Bureau, June 12, 2003
http://www.news.uiuc.edu/scitips/03/0612smartbricks.html