This minuscule chip can measure the temperature wherever it's placed — and it never needs a battery, because it's powered by the radio waves from the same wireless network that it uses to communicate.
The sensor, which is a tiny 2mm square weighing just 1.6mg, communicates the temperature it records to a dedicated router nearby. Aboard the chip, a small antenna captures energy from the signals transmitted by the router. Once it's charged, the sensor quickly switches on, measures the temperature, and then transmits a small signal for the router to detect. The frequency of the transmitted signal relates to the measured temperature.
The chip is able to work beneath a layer of paint, plaster or concrete, which hints at its intended use: the researchers reckon that the tiny devices could be embedded within buildings to keep an eye on conditions. The same technology should, the researchers claim, also allow chips for the detection of movement, light and humidity to be built. And given the lofty ambitions, they're expected to be mercifully cheap — around $0.28 a pop.
There's just one sticking point. Right now, the chip can only transmit its signal a paltry 2.5cm. The researchers ultimately hope to bump that up to 5m. Until they do, though, you better have a pretty small house to monitor.