TU/e develops wireless temperature sensor that extracts energy from radio waves

The Eindhoven University of Technology has succeeded in developing a wireless temperature sensor whose battery never needs to be charged. That’s because the tiny device can get its energy from wireless signals.

According to the scientists, the chip gets its energy from the wireless network to which it is connected, although it does require a special router. This is because it has to send special radio waves that the temperature sensor uses for the energy supply. The signals are sent in a targeted manner, so that little electricity is required for the transmission, according to the makers.

The chip itself is about 2 square millimeters in size and weighs 1.6 milligrams. That makes it the smallest temperature sensor in the world and about as heavy as a grain of sand, according to the TU/e ​​scientists. Temperature readings are read by the radio waves that the sensor sends back to the router; depending on the temperature, the signals deviate slightly in frequency, so that the temperature can be derived.

Because the temperature sensor can be incorporated in concrete and also works if it is covered by a layer of paint, all kinds of applications are conceivable in large buildings. The processing of the sensors throughout the building can be done, for example, by sticking them to the wall with a layer of latex, explains TU/e. As a result, builders spend little extra time installing the chips. Furthermore, the costs should not be high: in mass production, the cost per chip is about 20 cents, according to the researchers.

A disadvantage of the temperature sensor is that it only has a range of 2.5 centimeters. However, the makers are hopeful that this will have been stretched to one meter in a year. After that, they want to make a version that has a range of five meters.