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Researchers at the Federal Polytechnic School of Lausanne (EPFL) in Switzerland have developed an adjustable graphene capacitor that could significantly increase the speed and efficiency of wireless communication systems. The system, which operates at very high frequencies, with unprecedented results, could reach revolutionize the internet of things.
There are many types of wireless communications: mobile phones with 4G or 5G connectivity, GPS devices and computers connected via Bluetooth, portable sensors, etc .; and they all work in different frequency bands. To work with multiple platforms, connected devices have to support a wide range of frequencies without gaining excessive volume due to hardware.
Today, most portable wireless systems are equipped with reconfigurable circuitry that can adjust its antenna to transmit and receive data in different frequency bands. The problem is that the technologies available today, such as MEMS and MOS, which use silicone or metals, they don't work well at high frequencies. And that's precisely where data can travel much faster.
Therefore the discovery of the EPFL researchers it's so interesting, because allows circuits to operate at both low and high frequencies; and with unprecedented efficiency.
The new graphene solution, developed in the Nanoelectronic Devices Laboratory, is designed to replace the adjustable capacitors, present in all wireless devices. The device "reconfigures" the circuits to different frequencies so that they can operate in a wide range of frequency bands. In addition, it meets other needs that are not covered by MEMS capacitors and MOS:
- Good performance at high frequencies
- A tiny size (about 0.05 cm).
- And the ability to adjust it with low power levels.
Furthermore, the graphene capacitor developed by the EPFL researchers:
- It is compatible with traditional circuits
- Consumes very little energy
- And above 2.1 Ghz it easily surpasses its competitors.
"The surface area of a conventional MEMS system would have to be a thousand times greater to reach its capacitance value," said Clara Moldovan, lead author of the study.
How the graphene condenser works
The discovery of the EPFL researchers is based on a smart sandwich structure.
"When graphene was discovered, more than 10 years ago, it caused quite a stir," Moldovan noted. “It was considered a miraculous material, because it is a very good electrical and thermal conductor, as well as being flexible, light, transparent and resistant. However, the researchers discovered that it was difficult to integrate into electronic systems, because its atomic thickness gives it a high effective resistance ”.
The sandwich-like structure takes advantage of the fact that a two-dimensional gas of electrons in a quantum well can behave like a quantum capacitance. This is because it follows the Pauli exclusion principle, according to which it takes a certain amount of energy to fill a quantum well with electrons. Quantum capacitance can be easily measured in single-atom graphene layers and its main advantage is that it is adjustable by varying the charge density in graphene with a very low voltage.
"By applying a voltage, we can adjust our capacitors to a certain frequency, in the same way that a radio is adjusted to tune in to different stations," Moldovan said.
Main advantages and applications of the new graphene condenser
In addition to the advantages already mentioned, the new condenser can be rigid or flexible, which considerably increases its possible applications.
- By operating at high frequencies, it will improve the data flow between connected devices
- It could extend the life of batteries
- It will lead to increasingly compact devices
- In its flexible state, it could easily be used on sensors placed on clothing or directly on the human body.
Despite all this, According to EPFL researchers, graphene will not replace silicon as has been said over and over over the years, but the ultimate technology will be a hybrid that combines graphene with advanced silicon technologies.
The reason is that, in electronics, graphene is most effective when combined with silicon functional blocks.
What does not seem to be any doubt, according to the results of the investigation, is that the incorporation of graphene It could revolutionize wireless communications and, with it, the Internet of Things and smart cities.
The research has been published in the specialized journal Nanoletters.
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