Researchers show that the terahertz nonlinearity of graphene can be efficiently controlled using minimal electrical gating

A team of researchers from Bielefeld and Berlin, together with researchers from other research institutes in Germany and Spain, recently demonstrated that graphene's nonlinearity can be efficiently controlled by applying comparatively modest electrical voltages to the material.

The gated graphene sample device in which the graphene film acts as a channel between source and drain electrodes  imageThe gated graphene sample device in which the graphene film acts as a channel between source and drain electrodes subjected to a constant potential difference of 0.2 mV. Image from Science Advances

It was recently discovered that the high electronic conductivity and "massless" behavior of graphene's electrons allows it to alter the frequency components of electric currents that pass through it. This property is highly dependent on how strong this current is. In modern electronics, such a nonlinearity comprises one of the most basic functionalities for switching and processing of electrical signals. What makes graphene unique is that its nonlinearity is by far the strongest of all electronic materials. Moreover, it works very well for exceptionally high electronic frequencies, extending into the technologically important terahertz (THz) range where most conventional electronic materials fail.

Cardea Bio and the Georgia Tech Research Institute enter DARPA agreement to develop airborne SARS-CoV-2 sensors

The Defense Advanced Research Projects Agency (DARPA) recently awarded the Georgia Tech Research Institute (GTRI) an agreement, as part of their SenSARS program, to develop a sensing platform to detect airborne SARS-CoV-2 particles. Cardea Bio is a sub-contractor to this agreement.

This agreement will enable the two institutions to develop a real-time pathogen identification technology that can be applied to many different defense and civilian environmental monitoring applications.

Graphene ‘nano-origami’ could enable tiny microchips

Scientists at the University of Sussex have developed a technique for making tiny microchips from graphene and other 2D materials, using a form of ‘nano-origami’.

By creating distortions in the structure of the graphene, the researchers were able to make the nanomaterial behave like a transistor. “We’re mechanically creating kinks in a layer of graphene,” says Professor Alan Dalton of the School of Mathematical and Physics Sciences at the University of Sussex. “It’s a bit like nano-origami. Using these nanomaterials will make our computer chips smaller and faster. It is absolutely critical that this happens as computer manufacturers are now at the limit of what they can do with traditional semiconducting technology. Ultimately, this will make our computers and phones thousands of times faster in the future.”

Researchers design an accurate, high-speed, portable bifunctional electrical detector for COVID-19

A research team at South China University of Technology, Peking University and other China-based universities have developed an accurate, rapid, and portable electrical detector based on the use of graphene field-effect transistors (G-FETs) for detection of RNA from COVID-19 patients.

Schematic diagram of the operation procedure of our G-FET-based biosensing system for COVID-19 image

The detection system consists of two main parts: a plug-and-play packaged biosensor chip and an electrical measurement machine. The unique feature of this method is that the extent of hybridization between the ss-DNA probe and viral RNA can be directly converted to the current change of graphene channels without repetition of the PCR process. Furthermore, this method was validated using clinical samples collected from many patients with COVID-19 infection and healthy individuals as well, and the testing results were in full agreement with those of PCR-based optical methods.

Researchers design method that makes graphene nanoribbons easier to produce

Russian researchers have proposed a new method for synthesizing high-quality graphene nanoribbons. The team's approach to chemical vapor deposition offers a higher yield at a lower cost, compared with the currently used nanoribbon self-assembly on noble metal substrates.

Two nanoribbon edge configurations imageTwo nanoribbon edge configurations. The pink network of carbon atoms is a ribbon with zigzag (Z) edges, and the yellow one has so-called armchair (A) edges. Image credit MIPT

Unlike silicon, graphene does not have the ability to switch between a conductive and a nonconductive state. This defining characteristic of semiconductors is crucial for creating transistors, which are the basis for all of electronics. However, once you cut graphene into narrow ribbons, they gain semiconducting properties, provided that the edges have the right geometry and there are no structural defects. Such nanoribbons have already been used in experimental transistors with reasonably good characteristics, and the material’s elasticity means the devices can be made flexible. While it is technologically challenging to integrate 2D materials with 3D electronics, there are no fundamental reasons why nanoribbons could not replace silicon.