Wireless chargers are already rapidly gaining popularity and are beginning to actively occupy their niche in the market. But such a technology is already actively stepping on the heels of the idea of how to charge the phone via Wi-Fi.
Chronology of development
The idea of transferring energy over long distances without the use of accompanying conductors has long excited the minds of the best thinkers on the planet. The first advances in this matter were outlined at the beginning of the 20th century.
The well-known Serbian scientist Nikola Tesla discovered, implemented and described the same technology. But society was not ready for such technologies, since the memories of the witch hunt and incidents in Salem were still alive in the memory of the people, and therefore the technology was consigned to oblivion and sunk into oblivion. But only up to a certain point.
A lot of time has passed since that moment, several world wars have happened, and now humanity has reached a level of development at which the ideas of almost a century ago become not so crazy and unacceptable.
In addition, technological progress and the evolution of microprocessor technology are a very decent help for converting electromagnetic waves into a directed flow of electrical energy.
There is no doubt that somewhere in closed facilities such a technology has long been developed and perfected. But for industrial purposes, these devices are unlikely to be used. Therefore, I propose to consider those options that were initially focused on entering the civilian market.
Modern level of development
The first time we heard that charging a phone over Wi-Fi was possible was about five years ago. This device was showcased at CES 2010 under the name RCA Airnergy Charger. According to the descriptions of the principle of operation, it was similar to the device proposed by Tesla.
Airnergy
The device was a small box of quite acceptable dimensions in order to constantly carry it in a jacket pocket; a cable for connecting to the phone came out of the box. Inside there was a small circuit with a Wi-Fi signal receiver and a small battery. Specific technical data has not been published, but a figurative model of the device's operation has been outlined.
The receiver intercepts radio waves through which information is transported, registers their oscillations, frequency and amplitude. After that, the circuit arranges them in such an order that they are no different from fluctuations in electricity. After completing the transformation, the newly formed electricity begins to fill the capacity of the battery. It remains only to connect the device and watch how the charging takes place.
But, alas, despite the genius of the idea, its implementation left much to be desired. The not very well polished general method of work, ergonomics and internal arrangement of the board did not even allow it to enter the market. What can we say about the ability to compete with traditional methods of supplying power.
The efficiency was monstrously low, despite the fact that at the presentation it was announced that the BlackBerry device was charged from 30% to full charge in just 90 minutes. But in fact, the technology was crude, and the device announced for the summer of the same year did not take place. Its cost was supposed to be about $ 40.
Product from Energous
Energous is currently selling such a device. Technological subtleties are not disclosed for reasons of intellectual property protection, since this technology is already more advanced than previously described.
Here you no longer need to connect to the gadget for charging. The device itself transforms the waves in such a way that they are focused not on data transmission, but on replenishing the charge level. The only significant drawback is work in only one mode: the device either charges the mobile device or provides access to the network.
Perhaps, if it were not for such a specific operating principle and the need to buy a new smartphone, the device would have found its audience.
Power over Wi-Fi
Finally, we got to the flagship of the implementation of such an idea. At the end of the first half of this year, it became known that the Washington Research University was actively testing a new power over Wi-Fi technology, which even then allowed charging not only the batteries of mobile devices. Satisfactory results were also obtained when recharging the watch's battery level.
Compared to the previous two charging methods, this method has several distinctive features.
First, there is no need to buy separate special devices or a new smartphone. All you need is to reflash your home router. This will not in any way affect its performance as an information relay. No hardware changes are required at all.
“Until now, a large number of works on the study of metamaterials have been purely theoretical. We have shown that a little practice will help these materials become useful for general use, ”the developers say modestly.
Metamaterials are essentially composite materials, the properties of which are determined not so much by the properties of the constituent elements as by an artificially created periodic structure.
Metamaterials are synthesized by introducing various periodic structures with a wide variety of geometric shapes into the original natural material, which modify the dielectric and magnetic susceptibility of the original material.
Mains or USB charging, traditional and portable batteries - all of this could soon be history. Two engineering students, Allen Hawkes and Alexander Katko, from Duke University School of Engineering, can help you forget these anachronisms, with the support of Professor Steven Cummer.
Using metamaterials, they developed a device that picks up a wireless internet signal and converts it into. According to the developers, the efficiency of this "energy collector" is higher than with wire charging, and the output parameters are very close to.
The device converts the microwave Wi-Fi signal into DC power, suitable for directly charging the battery of a mobile phone or any other portable device. The key to this technology is a metamaterial with specific properties, selected in such a way as to capture various forms of wave radiation and transform them into a usable form. After successful tests, the developers assure that the source of energy can be signals from satellites, sound or WiFi networks.
“This design can be adapted to convert radiation of different frequencies and natures, including vibration and sound,” says Katko.
In our age, when we are constantly surrounded by various kinds of radiation - television and radio broadcasting, mobile networks, etc. - this technology will allow us to charge our phones wherever we are.
Hawkes and Katko connected 5 metamaterial fiberglass plates with braided copper conductor in series. The resulting device converts the WiFi signal to 7.3 V, while the USB standard is limited to 5 V. The energy conversion efficiency is 36.8%, which is comparable to a solar panel.
The metamaterial was obtained by combining fiberglass, copper and gold and has such an unusual combination of properties of the starting materials that it can easily be called a "supermaterial".
"Imagine . In this fabric, light can only pass through the threads. If you make a hole in it with a needle, the light will go around it, keeping the original path of movement, since it can only move along the thread. The light will continue to move and the hole remains essentially invisible, ”explains David Smith of Duke University.
Metamaterial acts in a similar way, controlling how waves move through its structure, making it possible to capture those waves and transform their energy.
Researchers report that this metamaterial can be used to improve the energy efficiency of our homes and apartments. For example, a ceiling can be covered with such a material and will pick up the signal of the wireless Internet, as if reusing energy that is usually lost.
As we continue to plug our mobile devices into power outlets, technology improvements are in full swing. Hawkes and Katko are working on efficiency gains and miniaturization to make it possible to integrate such a device into a mobile phone. And we will finally stop worrying about the forgotten charger at home.
Based on materials: dailymail.co.uk
Radio waves from WiFi networks completely fill the indoor space. In fact, this radiation carries a lot of energy, which is wasted, wasting heating the walls and furniture of the apartment. It can be used profitably - to charge batteries and operate miniature electronics.
For example, here are prototypes of four gadgets that were powered by WiFi as part of the Seattle experiment (see below).
Camera without battery (the maximum distance from the router can be 5.8m)
Temperature sensor (max.distance 6 m) 
Battery charger for lithium-ion batteries (max.distance 8.5 m) 
Charger for NiMH batteries (max.distance 8.5 m) 
In Seattle, six homes took part in the experiment. They were given WiFi routers and a collection of electrical gadgets with an energy harvester that converts 2.4GHz radio waves to DC.
A real-world experiment showed that for 24 hours all distributed devices were powered exclusively by WiFi radio waves, while the router continued to successfully perform its main function, distributing Internet traffic to computers and other home devices.
The authors say that the key problem in the transmission of energy over WiFi is the uneven transmission pattern, which makes it difficult to achieve the voltage required for the operation of mobile devices (0.3V).
Therefore, the developers introduced PoWiFi - according to them, the world's first real-life system that uses existing commercially available WiFi chipsets to collect energy and power. The key elements of this system are the WiFi transmitter and the energy harvesting module.
In particular, the Atheros WiFi transmitter chipset has been modified to inject a small amount of traffic into empty gaps.
The energy harvesting module was made to work simultaneously on multiple 2.4 GHz WiFi channels.
Module design: matching circuit, an electric current rectifier converts the wave energy into direct current, and then the voltage is increased to a useful level by a DC-DC converter. The module exhibits less than -10 dB return loss over a 72 MHz WiFi operating range.
The researchers were able to successfully power the Omnivision OV7670 VGA video camera and temperature sensor via WiFi, as well as recharge the Li-Ion and NiMH batteries (standard penlight batteries).
All the details of the described design are explained in the scientific work, and the efficiency of the system is assessed there according to the results of the experiment.
P.S. Interestingly, in one of the additional experiments, the researchers built a structure of two antennas, their own energy assembly module with a USB connection.
Such a system allows you to charge any USB gadgets at a good speed. For example, they brought the Jawbone UP24 fitness bracelet to 41% in just 2.5 hours.
It would be nice to put more such energy collectors in the apartment. Or all over the entrance.
In our world, when we are in the office, at home, with friends, everywhere the same wires are surrounded, wireless charging is salvation. With several devices at your disposal, I can argue that you have at least two charges by your bed. I'm right? It is because of this that many smartphones on the market have the ability to charge wirelessly, according to the Qi standard. Today, Ossia Inc ...
In our world, when we are in the office, at home, with friends, everywhere the same wires are surrounded, wireless charging is salvation. With several devices at your disposal, I can argue that you have at least two charges by your bed. I'm right?
It is because of this that many smartphones on the market have the ability to charge wirelessly, according to the Qi standard. Today, Ossia Inc has made another breakthrough, according to the assurances of company representatives, all devices that have Bluetooth or Wi-Fi can be charged without wires at all.
Unlike existing wireless charging standards, which operate at very short distances, a development by Ossi Inc, called Cota, can charge devices up to 30 meters away. This technology uses Wi-Fi signals and Bluetooth waves as "wires" through which the charge is transmitted. In addition, Cota Ossia uses the existing antennas that are installed in the devices for this. On this basis, manufacturers will not need to change anything. All that is required is the installation of a special chip that converts the signal.
As you would expect, with the advent of new wireless charging technology, there are also new chargers and so-called “receivers”. Tiny IC receivers can be installed either on the board of a smartphone or tablet itself, or in the battery itself. After the Cota Ossia charger detects this chip within its range, it will “send” thousands of signals to the receiver, which the chip will convert and thus, the device's battery will receive the charge it needs. If you are afraid of any radiation, then according to the assurances of representatives of Ossia Inc., their charger emits a signal no more than a mobile phone during a call.
Next-generation wireless charging: Ossia Cota
Based on this, such chargers can be installed anywhere: in the house, office, cafe and even outdoors. So, with this wireless charging technology, you can charge your devices without even knowing it. It should be noted that not only smartphones and tablets, but also other household appliances can replenish the charge using this technology. At least that's what the manufacturer's representatives said.
At the moment, Ossia Inc. intends to enter into contracts with various manufacturers of both mobile devices and household appliances. Considering the fact that smartphones nowadays live more and more often “at the outlet”, this technology can really become a breakthrough in this area.
Although modern technology for wireless charging of mobile gadgets simplifies the process of replenishing the battery charge, it still has a number of limitations. The QI standard really relieves users of smartphones and wearable electronics from the need to connect a cable to the connector of their devices, but "ties" this process to a certain place - a surface with a charging pad. A solution that would not require performing any additional manipulations with the same smartphone will make a real breakthrough, a revolution in the industry. The first steps in this direction, as, for example, the Cota startup, are being taken now. However, the effectiveness of the described system casts doubt on the technology of not only experts, but also ordinary people. Nevertheless, it is the Wi-Fi signal that is considered as an alternative and conditionally promising method of transferring charge over a distance, which was demonstrated by researchers at the Laboratory of Sensor Systems at the University of Washington using their own Power over WiFi system as an example.
Scientists were able, taking the Wi-Fi signal as a basis, to ensure the autonomous operation of the CCTV camera and the sensor that determined the temperature. Thus, the specialists of the University of Washington confirmed in practice that the discussed technology has the right to life in certain situations.
It should be noted that the standard signal in the wireless coverage area seemed to American scientists to be insufficiently reliable, since the packet data transmission format at those moments when a device connected to a public network required it did not allow the router to be used as an uninterrupted power source. Therefore, the engineering team slightly modified the access point based on the serial Atheros AR9580 chipset, which in no way affected the quality of the service provided - providing Internet access. As a result, the improved model of the router continuously filled the coverage area with so-called "noise" in the form of a radio signal, which was only responsible for recharging the electronics with a homemade Wi-Fi module on board. The latter, in turn, acted not only as a receiver, but was also responsible for collecting the energy received wirelessly.
Commercially available TP-Link TL-WDR4300 router equipped with an AR9580 radio module for operation in the 5 GHz band
The result of the experiment, in which the OV7670 video camera and a simple temperature sensor were used, was the following result: the developers of the Power over WiFi system were able to provide wireless power to the sensor for its continuous operation at a distance of six meters from the signal source. As for the camera, here the achievements turned out to be much more modest: in the photography mode, the charge accumulated in 35 minutes using Wi-Fi was only enough to take one black and white picture with a resolution of 174 x 144 pixels (this required 10.4 mJ). Scientists have resorted to two different layouts of the receiver module, as a result of which the working distance from the router to the camera ranged within 5-8 meters, including the wall separating the source and the signal receiver.
According to the authors of the Power over WiFi project, wireless networks can become a perfectly acceptable way of recharging for devices with minimal power consumption, which would be activated for a short period of time - sensors for monitoring sudden changes in the environment.
