wireless batterijloze thermometer van PhD Hao Gao, vakgroep Mixed Signal Microelectronics, EE TU/e

2 Millimeter Temperature Sensor Powered By Radio Waves

December 8, 2015 - Written By Daniel Fuller

The Internet of Things movement is chugging on at an unstoppable pace, but some of the hardware necessary for any real advancement isn’t quite there yet. Some particularly compelling pieces, such as Amazon’s Echo when paired with IFTTT, may give the illusion that we’re already living in the world of tomorrow, but a student at the University of Technology Eindhoven begs to differ. Hao Gao, a PhD holder as of yesterday, has designed a temperature sensor that’s roughly the size of a grain of sand and will never need an external power source. The same radio waves that it uses to communicate with itself are enough to give it the power it needs. In theory, this means the unit can continue functioning as long as the air is filled with such waves.

The prototype unit, brought to life with the help of a few other researchers at the university, is able to function even when placed under a layer of paint or concrete. It only has a range of 2.5 centimeters for now, but the team wants to increase that to 5 meters over time. The way it works is a specially made low-energy router picks up radio waves from the air, gathering energy from them. It then blasts this energy and the radio waves at the onboard sensor in a very precise manner. This allows for almost zero wasted energy. The sensor stores the energy until there is enough to send something back to the router. Thanks to very slight variations in frequency, the signal that the sensor sends at this point can be deciphered by the router to obtain temperature data.

This low power sensor is only the first of a new breed of tiny, practically self-powered tech that will start with small aspirations, but could perceivably evolve into all manner of small chips, from mobile routers to light sensors. The applications for this are incredibly far-reaching, as are the implications. Smart buildings, homes and manufacturing systems could make use of such sensors with very little fuss. On the mobile spectrum, this could mean your future smartphone can be designed with even more freedom than now and could use a much smaller measure of power. Taken to its logical extreme, it’s not a stretch to imagine near-microscopic processors and wireless chips sharing their self-gathered power pool, leaving your smartphone to not drain at all, or perhaps even charge, when left alone with the screen off.