In its current form, wireless charging technology is not much different from the usual one in terms of efficiency: the charged gadget must be in contact with the charger. At the same time, the space around us is literally overflowing with "ownerless" radiation, which is a source of energy.
A team of researchers at the Massachusetts Institute of Technology (MIT) presented blueprints and diagrams of a system that can capture energy from various electronic devices, including Wi-Fi signals, and use it to charge other devices.
We are talking about terahertz radiation, which is in the range of the electromagnetic spectrum between infrared and microwave radiation. At first glance, it may seem that this is a real energy "gold mine" - however, as practice shows, it is not so easy to "develop" it.
A device developed at MIT — a terahertz rectifier — provides this capability. It consists of a small square of graphene with a boron nitride (BN) layer underneath and antennas on either side. The antenna picks up terahertz radiation, detecting signals passing through the graphene, which in turn causes the electrons in the graphene to move in one direction, creating a direct current.
According to the researchers, graphene in this case should be as pure as possible, since any impurities "scatter" the flow of electrons. The boron nitride layer prevents this. Usually, electrons in graphene uniformly "scatter" in all directions, but boron and nitrogen atoms in the blocking layer accumulate them in one direction.
It is likely that the performance of a terahertz rectifier will be small, capable of satisfying the energy demand of only small devices - at first, these may be electronic implants (for example, pacemakers).
The ultimate goal of the development of the MIT team is to create a technology that will provide passive recharging of mobile devices during their operation.