Researchers at TU/e have developed a very tiny wireless temperature sensor that is powered by radio waves that are part of the sensor’s wireless network. This means that the sensor needs not even a single wire, nor a battery that would have to be replaced. This breakthrough has a wide range of applications such as smart building and other Internet of Things applications. The smart buildings of the future will be full of sensors to regulate heating, cooling, lighting and a number of other actions. This new technology makes it possible to operate sensors without any batteries which makes installation and maintenance very easy.The current version of the sensor has a range of 2.5 cm. The researchers expect to extend this to a meter within a year, and ultimately to 5 meters. The sensor has a specially developed router, with an antenna that sends radio waves to the sensors to power them. Both the router and the sensor consume very little electricity. The sensor can also operate beneath a layer of paint, plaster or concrete, which makes it ideal for installation in to building.The sensor contains an antenna that captures the energy from the router. The sensor stores that energy and, once there is enough, the sensor switches on, measures the temperature and sends a signal to the router. This signal has a slightly distinctive frequency, depending on the temperature measured. The router can deduce the temperature from this distinctive frequency.The same technology enables other wireless sensors to be made, for example to measure movement, light and humidity. The researchers expect the cost of the sensors under mass production to be down to down to around 20 cents. The sensor is based on 65-nm CMOS technology.The project, called PREMISS, has received funding from the STW technology foundation. Hao Gao, the researcher behind this project will be awarded his PhD on Monday 7 December for his thesis in which he developed a sensor that measures just 2 square mm and weights a mere 1.6 milligrams, equivalent to a grain of sand. The title of Hao Gao’s thesis is ‘Fully Integrated Ultra-Low Power mm-Wave Wireless Sensor Design Methods’. The integrated circuits research was done in the Mixed-Signal Microelectronics group and also involved the TU/e groups Electromagnetics and Signal Processing Systems as well as the Center of Wireless Technology.