As the digital age advances and grows, the number of sources with wireless connectivity for the transmission of information without cables between different devices has grown incredibly in recent years. Something that results in the widespread use of the 2.4GHz radio frequency used by the WiFi connection. In this way, there would be an excess of available signals that could be useful for alternative uses.
A team of researchers from the University of Tohoku, in Japan, and the University of Singapore, has developed a technology that uses torque oscillators (STO), small intelligent devices, in order to collect and convert the frequencies of wireless radio in energy with which to power various small electronic devices.
In their study, published in Nature Communications , the researchers were able to successfully harvest energy using signals from the WiFi band with which they were able to power a light-emitting diode (LED) completely wirelessly and without using any type of battery .
As experts say, we are continually surrounded by WiFi signals, which we can use to connect to the Internet and access our favorite web pages. However, when we do not, it is a type of connectivity that, in the end, becomes inactive, becoming a huge waste.
The results obtained in the research would be a step towards converting the easily available 2.4GHz radio waves into a green source of energy , which would help reduce the need for batteries to power some of the electronic devices we use daily.
In this way, electrical sensors and small devices could be fully and completely wirelessly powered by radio frequency waves as one more part of what is known as the “Internet of Things”.
Converting WiFi signals into usable green energy
The so-called torque oscillators are a class of emerging devices that generate a series of microwaves and have applications in wireless communication systems. However, there are two factors that can hamper your application: low power output and wide line width.
While the mutual synchronization of multiple torque oscillators would be one way to overcome this problem , current schemes, such as short-range magnetic coupling between multiple STOs, have spatial restrictions.
On the other hand, the long-range electrical timing using vortex oscillators is limited in frequency responses of only a few hundred MHz. Furthermore, it also requires dedicated current sources for the individual torque oscillators, which can end up hampering and preventing its general implementation on the chip.
In order to overcome low-frequency and spatial limitations, the team of scientists has devised a matrix in which eight STOs are connected in series. Using this matrix, the different 2.4 GHz electromagnetic radio waves (which WiFi uses) were converted into a direct voltage signal , which was then transmitted to a capacitor with which to illuminate a 1.6 volt LED. When the capacitor was charged for just 5 seconds, it was able to illuminate the same LED for a minute after the wireless power was disconnected.
In their study, the researchers also found that the parallel configuration is more useful for wireless transmission , thanks to its much more stable control over impedance mismatch and better stability in spectral noise behavior and in the domain of time.
What can be the next steps?
To improve the energy harvesting capacity of this technology, scientists are now looking to increase the number of torque oscillators in the array that they have designed. They also plan to test their energy harvesters for wireless charging of other useful sensors and electronic devices.
To achieve this, the research team also hopes to work with various industry partners to explore the development of on-chip torque oscillators for self-sustaining intelligent systems. This could open up a lot of possibilities for wireless charging .
