Wireless sensors are being used to help create building designs that can stiffen themselves against the stress of earthquakes or even detect damage and repair it, according to two research projects underway in the U.S. and Europe.

In the U.S., wireless sensors have been successfully tested as part of a mechanism that strengthens the structural integrity of large buildings exposed to earthquakes.

And an ambitious project is underway in Europe to build a "self-healing" house that can detect damage and repair it.

Wireless sensors are commonly associated with radio frequency identification — or RFID — tags used to track inventory and send simple signals short distances. But advances in technology are making sensors smaller and more powerful.

Earthquake engineer Shirley Dyke at Washington University in St. Louis tested wireless sensors about 2.5 square centimetres in size in a lab simulation as part of a response mechanism to earthquakes.

The wireless sensors are attached to the sides of buildings to monitor the force of sway when an earthquake or similar shaking occurs.

The sensors then send messages to controls called magneto-rheological (or MR) dampers within the building's structure that can stiffen and lend added support when a quake is detected.

The MR dampers are filled with a fluid that includes suspended iron particles. When an electric current is sent through the fluid the iron particles align in response, adding structural support.

Dyke said that while a few structures in Asia are using MR-dampers, none control them wirelessly.

She said in a release Tuesday that the use of wireless sensors will make systems designed to limit structural damage more affordable.

"This [wireless] is where structural control technology is going," said Dyke. "It will be much easier putting wireless sensors into a building compared with taking walls out and installing wires and cables."

A building that repairs itself

Researchers at the University of Leeds are also attempting to earthquake-proof a building using wireless technology, but in a decidedly different way.

The $21.4 million European Union-funded project announced earlier this month aims to design a "self-healing" villa on a Greek mountainside that will fill its own cracks after receiving signals from wireless sensors.

The self-healing walls will contain a special nano-polymer particle that turns into liquid when squeezed under pressure, flow to the weakened areas and harden to form a solid structure. The polymer will be released in response to RFID tags and other wireless sensors designed to monitor everything from vibrations, temperature, humidity and gas levels.

The project is expected to be completed by December 2010.