Infrared light for charging: “This technology could make charging cables superfluous”

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“This technology could make charging cables redundant”

Inductive smartphone charging Inductive smartphone charging

Inductive smartphone charging

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It’s a dream for technicians and smartphone users to be able to charge their mobile devices anywhere in the room without using a cable. However, inductive charging technologies have their limitations. Korean scientists now use infrared light to transmit electricity – more than 30 meters.

S.smartphones that can be charged wirelessly have been around for many years. Just place it on the charging station and electricity is transmitted inductively. However, the charging station must be connected to the mains to be able to supply an AC coil. This current generates an alternating magnetic field that penetrates the mobile phone and induces an electrical voltage in the receiving coil. Generates the charging current of the built-in battery.

This can be a little more convenient than plugging the charging cable into your device. But the dependence on the nest remains. Charging only works in the immediate vicinity of the charging station – and is stationary because it is connected to the mains via cable.

Many dream that innovative technology will enable wireless charging of smartphones and other mobile devices anywhere in the room. In principle, the principle of power transmission by induction also works over longer distances.

Performance is an issue

The problem, however, is performance. The greater the distance between the transmitting and receiving coils, the less energy from the originally introduced electrical energy reaches the device to be charged.

In September 2021, scientists from the University of Tokyo reported in the journal Nature Electronics about an innovation that enables the inductive transmission of electricity with at least 50% efficiency in a three by three by two meter test room.

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Whether 50 percent is a lot or a little is up to the observer. But the effort to get there was tremendous. In the center of the room stood an electrically conductive rod through which the current passed through the floor, walls and ceiling back to the rod.

These are huge design measures to be able to wirelessly charge smartphones in a tiny room, where in case of doubt the nearest outlet could be very close.

Energy transfer with light

And then half of the electricity is “thrown away” unused. No wonder that in the meantime we have not heard anything about the practical implementation of this research success.

Now it is Korean scientists from Sejong University that are giving us new hope for indoor wireless charging. Jinyong Ha’s research team takes a completely different approach. The system developed by them is not based on electromagnetic induction, but on the transfer of energy by means of light.

In the journal Optical Express, scientists report that they can deliver electricity from a distance of 30 meters using invisible infrared light (wavelength 1.55 micrometers). There is still an optical power of 400 milliwatts.

You can barely charge your smartphones

A photovoltaic cell (one centimeter per centimeter) converts light into electricity: 85 milliwatts are then available. It’s still not enough to charge smartphones in a reasonable amount of time, but scientists are optimistic that they can further optimize the technology and achieve better performance.

There is a good chance that scientists will be able to work on the further development of the technology. Since the achieved transmission values ​​are already sufficient to wirelessly power smaller sensors, such as those provided for in the so-called “Internet of Things”.

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“This is especially true of the many sensors that monitor the production process in factories,” says Jinyong Ha, and also has a long-term goal in mind: “This technology could make it unnecessary to constantly carry cables to charge our smartphones and tablets with us. us “.

But let’s wait and see if we shouldn’t make better use of every energy-saving opportunity in the future. Because one thing is for sure: no matter how advanced the technology of wireless charging devices is, it uses more energy than direct connection to a socket. Convenience comes at a price.

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