A Future Without Batteries? Researchers Harvest Energy from WiFi

Unless a superior alternative to lithium batteries appears, device manufacturers have three general options: increase their size, make the hardware more efficient, or eliminate/replace components to reduce consumption. Now, what if it were possible to extract energy from another source? Say... the WiFi. A group of researchers at MIT has just announced their tests based on a flexible rectifying antenna (rectenna) made with a 2D semiconductor, obtaining energy from WiFi that could power sensors, medical devices, and a good part of the IoT world.

The laptop battery screams. The same happens with mobile batteries, tablets, wireless speakers, smart watches... the list goes on. Current technological development is tied to the whims of energy portability, and the truth is that the average user has no desire to micro-manage. No matter how much we adjust screen brightness or deactivate GPS, we are going to ask for more until the concept of battery is completely removed from the equation. So how do we achieve that? Energy must come from somewhere. This is where wireless transfer comes in. Perhaps we will never reach the level that Tesla imagined... but there are many WiFi networks out there. We only need a way to collect what they offer.

Obtaining Energy from WiFi

That is what a group of researchers at MIT is working on. Their latest efforts have led to the creation of the first flexible rectenna capable of taking high-frequency AC signals and transforming them into useful DC voltage to power low-consumption devices or recharge batteries. In other words, the flexible rectenna can generate electricity from WiFi networks. The design of rectennas is not exactly new. In fact, many contactless technologies (RFID) already use them, however, the novelty here is that the new rectenna breaks some limits. A normal rectenna leans toward silicon or gallium arsenide, suitable on a small scale, but heavy and very expensive beyond something mobile, while previous attempts at flexibility did not work at high frequencies. Instead, the researchers imagine this rectenna made with molybdenum disulfide (MoS2) covering walls, bridges, towers, and entire buildings, exposed to WiFi signals 24/7.

It is a very interesting vision... but how much energy can they extract? At classic power levels for a traditional WiFi network, the efficiency is 25-30 percent. Their most recent tests indicate about 40 microwatts on a general availability of 150 microwatts, enough to power an LED or a sensor. The best part is that this is not limited to WiFi. LTE, Bluetooth, and other similar bands could also act as energy sources. The next step? Improve efficiency.

Official announcement: Click here