Scientists deployed Wi-Fi signals to power a battery-free camera placed at a distance of five meters, a step that brings a more powerful Internet of Things (IoT) a step closer to reality. According to the researchers, a Wi-Fi signal can be used to broadcast power to distant devices, which is called Power over Wi-Fi or PoWo-Fi.
Wi-Fi to facilitate IoT
the Internet of Things is the concept that every device could be equipped with a chip that broadcasts data such as its location or other parameters such as temperature or pressure. However, one challenge that engineers need to be figure out is how to connect the array of tiny machines without batteries in all of them. Vamsi Talla and colleagues at the University of Washington in Seattle might have a solution to this.
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Wi-Fi radio broadcasts are basically a type of power signal picked up by the antenna. Wi-Fi receivers are made to collect the information that is carried by these broadcasts. Talla and his colleagues stated that this energy could be made use of many ways.
More on the the study
The researchers connected an antenna to a temperature sensor, placed it close to the Wi-Fi routers, and noted the resulting voltages in the device and for the length it can operate on this remote power source alone. Since Wi-Fi broadcasts are not consistent, variation in the signal varied the power for the sensor.
According to the MIT Technology Review, the scientists programmed the router to broadcast noise when it is not broadcasting information, and employed adjacent Wi-Fi channels to transmit, in order to prevent interference in data rates.
For the experiment, researchers used three AR9580 chipsets, standard electronics for Wi-Fi routers. The devices were programmed to broadcast to provide continuous power to an energy-harvesting sensor. After the experiments, the scientists measured the resulting voltages in their temperature sensor, and analyzed how long it can work at various distances from the modified router. The scientists noted that the temperature sensor could operate as far as six meters from the router, and by adding a rechargeable battery to the mix, the working range can be increased to about nine meters.
The researchers also attached a camera to the antenna that performed well in the tests. “The battery-free camera can operate up to [about five meters] from the router, with an image capture every 35 minutes,” researchers said.