Batteries Not Included
Wi-fi is already a remarkable technology which allows computers, smartphones, or other gadgets to connect to the internet or communicate with other similarly minded devices within a particular area without the need for wires. Now researchers in the US are looking into using wi-fi as a source of energy which can beam power to any device that is looking for it. Batteries beware. The boffins have come up with a battery free camera which searches for power from ambient wi-fi signals, stores it in a capacitor and then uses it when called upon to take pictures. The team from the University of Washington in Seattle recognised that the energy contained in ambient wi-fi signals was similar to the voltages required to operate a wide range of low power devices.
One big problem needed overcoming though. As wi-fi signals only come in bursts across a variety of different frequencies, the required level of energy is only available intermittently. So the team came up with a solution. They modified the standard wi-fi hotspots and routers to broadcast noise when a channel was not transmitting data. This allowed the power of the wi-fi signals to remain constant at a low but sufficiently high enough level to power a small camera and temperature sensor positioned several metres away from the hotspot. Encouragingly, generating the noise did not result in any meaningful slowdown in data transmission rates across hotspots, while the camera was able to gather enough energy to take a picture every 35 minutes.
The reseachers believe that the system, known as power-over-wi-fi, could power small sensors and actuators to provide information, as well as carry out tasks as part of the so-called ‘Internet of Things’ that are expected to become common place in buildings. It’s got the renowned MIT excited. An article in the college’s Technology Review says “The ability to deliver power wirelessly to a wide range of autonomous devices and sensors is hugely significant. Powi-fi could be the enabling technology that finally brings the internet of things to life.” Power up.