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Wireless Power for All May Become a Reality Thanks to Wi-Fi

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If any of you have ever heard of Tesla, the inventor not the car company, then you will probably know that he claimed to be able to power every hut in Africa wirelessly.  His claims were not believed by everybody unfortunately and the idea was never put into practice properly.

With the news this month though, it seems we may be a step closer to Tesla’s reality.

A team of scientists have used Wi-Fi signals to power a battery-free camera five metres away, an advance that brings the idea of the ‘Internet of things’ closer to reality.

The ‘Internet of things’ is the concept that almost every object could be fitted with a chip that broadcasts data such as its location or whether some other parameter such as temperature or pressure is dangerously high or low. However, for the ‘Internet of things’ to become a reality engineers have to solve one potential problem: how to power these numerous tiny machines.

Vamsi Talla and his colleagues at the University of Washington in Seattle could quite possibly have found a solution.

The researchers have demonstrated that Wi-Fi signals can be used to broadcast power to remote devices. They call their new approach power over Wi-Fi or PoWi-Fi. The science behind this is that Wi-Fi radio broadcasts are a form of energy an antenna can pick up. Wi-Fi receivers have been designed to harvest the information that these broadcasts carry.

Talla and his colleagues pointed out that there is no reason why the energy should not be harvested as well. The team’s approach is to simply connect an antenna to a temperature sensor, place it close to a Wi-Fi router and measure the resulting voltages in the device and for how long it can operate on this remote power source alone, seems simple right?.

The problem lies where Wi-Fi broadcasts are not continuous. Routers tend to broadcast on a single channel in bursts, and while this provides enough power for the sensor, as soon as the broadcast stops, the voltages drop.

The team involved programmed the router to broadcast noise when it is not broadcasting information and employ adjacent Wi-Fi channels to carry it so that it does not interfere with data rates, ‘MIT Technology Review’ reported.

Using three Atheros AR9580 chipsets; standard electronics for Wi-Fi routers they programmed these devices to broadcast in a way that can provide continuous power to an energy harvesting sensor.

They then measured the resulting voltages in the temperature sensor and determined how long it can work for at various distances from the modded router. They found that the temperature sensor can operate at distances of up around six metres from the router and by adding a rechargeable battery to the mix, it can be increased to about nine metres.

Now for the fun part. They also connected a camera to their antenna. To store energy, they attached a low leakage capacitor to the camera, and, in the subsequent tests, the camera performed remarkably well!

“The battery-free camera can operate up to approximately 5 metres from the router, with an image capture every 35
minutes,” the researchers said.

Unbelievably, the router could even power the camera through a brick wall, demonstrating that it would be possible to attach the device outside while keeping the power supply inside.

Source: Indian Express