Wirelessly charging a battery is not exactly new. The market offers several solutions, but compatibility limits have kept demand very low. Add the fact that devices need to be nearly touching, when the idea is to “transmit” energy over wider distances. That is exactly what a team at the University of Washington achieved, using a WiFi router.
The concept of wireless transmission of electricity takes us into Nikola Tesla’s territory and his experiments at the dawn of the 20th century, but our goal here is not to recall the achievements and dreams of that fabulous inventor, but to explore modern solutions to a modern problem. What does that mean? Most people hate cables and do everything possible to hide them or reduce their dependence on them. That is one of the keys behind the success of WiFi. Until a few years ago, sitting in front of a desktop computer to surf the web was the rule rather than the exception, but today a WiFi router costs only a few euros. That leads many users to ask: why isn’t there a kind of “WiFi for electricity”? Well, experts are working on it, and the latest development brings us to the doors of the University of Washington.
How the WiFi router powers devices
There, a group used a WiFi router in such a way that it supplied power to small modified devices in six homes over a 24-hour period. In simple terms, the energy from the radio waves emitted by the router was converted to direct current with the help of a rectifier, and the remaining voltage was raised to the appropriate level with a DC-DC converter. The devices powered by the router are low-resolution cameras and temperature sensors, although it also recharged some batteries. It should be noted that all devices have very low energy consumption, but the distance covered by the router’s energy is between 3 and 8.5 meters (the final number depends on the accessory).
Challenges and limitations
According to Vamsi Talla, one of the team members, the most complicated part is getting the router to transmit energy constantly. When WiFi is used for communications, actual transmission occurs only when sending or receiving data, a behavior diametrically opposed to what is needed. The team’s solution was to create a piece of software that sends “noise” through multiple WiFi channels, which apparently guarantees the flow of electricity and the internet connection on the same router. The remaining problems for WiFi are regulatory. For example, the US FCC limits the power of WiFi signals to one watt, and many governments around the globe have adopted similar limits. Even so, the Internet of Things is crying out for something like this. With new designs and lower energy consumption, WiFi could become a viable source of electricity for those devices.
