Researchers in the Netherlands have developed a tiny wireless temperature sensor powered by radio waves. The technology, still in its infancy, could one day power smart homes.

The sensor can detect temperature, but could be designed to sense a range of external variables. For example, sensors employed in smart homes could detect the presence of a person in the room and automatically switch on or off air condition and heat.

Because the new sensor is wireless, powered by a radio waves, the technology is eco-friendly. No batteries or wires are required. The sensor -- which measures just 2 square millimeters and weights only 1.6 milligrams -- can be embedded in a layer of paint or cement, making it deal for use in smart homes.

The sensors are powered by a router, which directs a small beam of radio waves. The combination uses very little energy. Once the sensor has absorbed enough energy, it powers on and reads the temperature. The recorded temperature data is beamed back to the router at a slightly different frequency, before the sensor briefly powers off. The technology could be used to measure movement, light or humidity.

Currently, the sensor is limited to a working range of just an inch. But lead researcher Hao Gao -- who is preparing to receive his PhD from Eindhoven University of Technology for his work with sensors -- says he and his colleagues hope to expand its reach to 40 inches within the next year, and further still in the future.

Research partner Peter Baltus, a professor of wireless technology at Eindhoven, said the sensor could also be used to power wireless payment systems or identification technology.