Rich Pell, EETimes
6/11/2015 00:00 AM EDT
An article in the MIT Technology Review presents a power-over-Wi-Fi system that uses existing Wi-Fi chipsets in wireless routers to deliver far-field wireless power to various sensors as well as to recharge coin cell batteries at distances up to 28 feet.
The power-over-Wi-Fi system — or "PoWiFi" for short — is a University of Washington (Seattle, WA) research project aimed at powering the Internet of Things (IoT) using Wi-Fi signals. Its concept is that Wi-Fi receivers could, in addition to retrieving the information being transmitted over Wi-Fi, be designed to harvest the energy in these signals as well.
The biggest hurdle in achieving this is the discontinuous nature of normal Wi-Fi signals — data is often broadcast in bursts, on a single channel. Initial testing with a temperature sensor that had been fitted with a Wi-Fi antenna showed that while voltage across the sensor often came close to the 300 mV needed for the sensor to operate it was not enough.
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