Scientists convert WiFi signals into electricity
MIT has developed 'Rectenna' to convert received WiFi signals into wireless energy.
(Web Desk) – Scientists have invented a device that can transform Wi-Fi signals into a form of energy that could be used to power electronics – without a battery.
According to researchers, Wi-Fi could become a widespread source of power by using a two dimensional semi-conductor to transfer it.
In this regard, a new type of rectenna – a rectifying antenna which can be used for converting electromagnetic energy into direct current (DC) electricity – can be used to capture waves of Wi-Fi and converts them into a wireless energy using the semiconductor.
The device could power large-area electronics, wearables and even medical devices.
The rectennas can convert alternating current (AC) waves into direct current voltage, which is more useful for electronics. 
However, a new type of rectenna captures Wi-Fi waves and transforms them to wireless energy using the semiconductor.
We have come up with a new way to power the electronics systems of the future - by harvesting Wi-Fi energy in a way that s easily integrated in large areas - to bring intelligence to every object around us, said Professor Tomas Palacios, who co-authored the study in the Massachusetts institute of Technology (MIT).
The conversion process also requires a piece of equipment known as a rectifier. Most traditional rectifiers are thick and inflexible.
Hence, the team of researchers used a super thin and malleable material known as molybdenum disulfide (MoS2), one of the thinnest semiconductors in the world to avoid the problem.
Such a design has allowed a fully flexible device that is fast enough to cover most of the radio-frequency bands used by our daily electronics, including Wi-Fi, Bluetooth, cellular LTE, and many others, postdoctoral fellow and first author of the study, Xu Zhang, said.
Dr Zhang managed to find a way to streamline this process and make the transition from AC to DC more efficient by decreasing capacitance in the system.
The researchers have also claimed that the semiconductor is flexible and can be made in a roll-to-roll process to cover very large areas, potentially walls or ceilings.
During experiments, the researchers device has produced about 40 microwatts of power when exposed to the typical power levels of Wi-Fi signals of about 150 microwatts.
And that is sufficient power to charge a mobile.
