Technical / Research

Earlier this year, Tohoku University researchers created a technique that could micro/nanofabricate silicon nitride thin devices with thicknesses ranging from 5 to 50 nanometers. The method employed a femtosecond laser, which emitted extremely short, rapid pulses of light. It turned out to be capable of quickly and conveniently processing thin materials without a vacuum environment.

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By applying this method to an ultra-thin atomic layer of graphene, the same group has now succeeded in performing a multi-point hole drilling without damaging the graphene film. 

Researchers from Gwangju Institute of Science and Technology (GIST) and Chonnam National University Medical School have developed graphene-based conductive hydrogel electrodes that offer convenience of use, controllable degradation, and excellent signal transmission. 

Implantable bioelectrodes are electronic devices that can monitor or stimulate biological activity by transmitting signals to and from living biological systems. Such devices can be fabricated using various materials and techniques. But, because of their intimate contact and interactions with living tissues, selection of the right material for performance and biocompatibility is crucial. Conductible hydrogels are attracting great attention as bioelectrode materials owing to their flexibility, compatibility, and excellent interaction ability. However, the absence of injectability and degradability in conventional conductive hydrogels limits their convenience of use and performance in biological systems. The researchers' new graphene-based conductive hydrogels possess injectability and tunable degradability, furthering the design and development of advanced bioelectrodes. 

Graphene-Info is happy to give the stage to talented young graphene researchers, especially with such commitment and passion as Roberto Pezone from TU Delft, who has agreed to chat with us and answer a few questions about his background, work and collaboration with the Graphene Flagship.

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Roberto Pezone checking a wafer at its initial fabrication stages

Q: Thank you for this interview Roberto! Very nice to e-meet you. We know you have been involved with graphene research for some time, can you give us a quick overview of your graphene research interests and projects?

Thank you for the opportunity to discuss my research. Within the Graphene Flagship's Work Package 6 (core 3), my primary focus lies in integrating graphene into sensors, particularly microphones. My main objective is to develop methods that enable the seamless integration of graphene on a wafer-scale while thoroughly exploring the advantages and disadvantages associated with such approaches.

In addition to developing fabrication techniques, I am also highly interested in characterizing the potential of graphene for acoustic devices. This type of research plays a crucial role in bridging the gap between graphene's exceptional properties and its practical utilization in the industry, unlocking higher performance and new sensor concepts.

Researchers from Germany's RWTH Aachen University, Forschungszentrum Jülich and Japan's National Institute for Materials Science (NIMS) have found that bilayer graphene allows the realization of electron–hole double quantum dots that exhibit near-perfect particle–hole symmetry. Moreover, They showed that particle–hole symmetric spin and valley textures lead to a protected single-particle spin-valley blockade that will allow robust spin-to-charge and valley-to-charge conversion, which are essential for the operation of spin and valley qubits.

Quantum dots in semiconductors such as silicon or gallium arsenide are considered great candidates for hosting quantum bits in future quantum processors. The recent study essentially shows that bilayer graphene has even more to offer than other materials. The double quantum dots the researchers have created are characterized by a nearly perfect electron-hole-symmetry that allows a robust read-out mechanism – one of the necessary criteria for quantum computing. 

Researchers from Japan's RIKEN Center for Emergent Matter Science, National Institute for Materials Science (NIMS) and Nagoya University have developed a material, based on graphene oxide nanofillers embedded in a hydrogel, that can channel mechanical energy in one direction but not the other, acting in a “nonreciprocal” way. Using the composite material - which can be constructed at various sizes - the team was able to use vibrational, up-and-down movements, to make liquid droplets rise within a material. Using the material could make it possible to use random vibration usefully to move matter in a preferred direction.

To create the unique material, the group used a hydrogel - a soft material made mainly of water - made of a polyacrylamide network and embedded graphene oxide nanofillers into it, at an angle. The hydrogel is fixed to the floor, so that the top part can move when subjected to a shear force but not the bottom. The fillers are set at an angle, so that they were angled clockwise from top to bottom. When a shear force is applied toward the left, from the direction the nanofillers are leaning, they tend to buckle and hence lose their resistance. But in the other direction, where they are facing away from the force, the applied shear merely makes them stretch even longer, and they maintain their strength. This allows the sheet to deform in one direction but not the other, and in fact the group measured this difference, finding that the material was approximately 60 times as resistant in one direction than the other.

Researchers at North Carolina State University (NC State), National Science and Technology Development Agency and NSTDA Characterization and Testing Service Center in Thailand have created a graphene-based cathode in the shape of a thread-like fiber. The researchers were then able to use the fiber to create a zinc-ion battery prototype that could power a wrist watch.

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Battery prototype with thread-like cathode. Image from NCSU website

The proof-of-concept study is a step forward in the development of a fiber-shaped battery that could ultimately be integrated into garments.

Scientists from CiQUS, ICN2, University of Cantabria, Donostia International Physics Center (DIPC), and Technical University of Denmark (DTU) have joined forces to develop a versatile method for building brick by brick carbon nanocircuits with tunable properties. The team sees this as a significant breakthrough in the precise engineering of 2D materials. The proposed fabrication technique opens exciting new possibilities for materials science, and, in particular, for application in advanced electronics and future solutions for sustainable energy.

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The team synthesized a new nanoporous graphene structure by connecting ultra-narrow graphene strips, known as “nanoribbons”, by means of flexible “bridges” made of phenylene moieties (which are portions of larger molecules). By modifying in a continuous way the architecture and angle of these bridges, the scientists can control the quantum connectivity between the nanoribbon channels and, ultimately, fine-tune the electronic properties of the graphene nanoarchitecture. The tunability could also be controlled by external stimuli, such as strain or electric fields, providing opportunities for different applications.

A team of researchers, led by Northwestern University and the University of Texas at Austin (UT), has developed a graphene-based cardiac implant. Similar in appearance to a temporary tattoo, the new graphene “tattoo” implant is thinner than a single strand of hair yet still functions like a classical pacemaker. But unlike current pacemakers and implanted defibrillators, which require hard, rigid materials that are mechanically incompatible with the body, the new device softly melds to the heart to simultaneously sense and treat irregular heartbeats. The implant is thin and flexible enough to conform to the heart’s delicate contours as well as stretchy and strong enough to withstand the dynamic motions of a beating heart.

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After implanting the device into a rat model, the researchers demonstrated that the graphene tattoo could successfully sense irregular heart rhythms and then deliver electrical stimulation through a series of pulses without constraining or altering the heart’s natural motions. The technology also is optically transparent, allowing the researchers to use an external source of optical light to record and stimulate the heart through the device.

A Penn State-led international collaboration has developed a self-powered, standalone sensor system capable of monitoring gas molecules in the environment or in human breath. The system combines nanogenerators with micro-supercapacitors to harvest and story energy generated by human movement. 

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The researchers' tech should cost up to just a few dollars for materials and uses widely available equipment. The development is the culmination of years of work led by corresponding author Huanyu “Larry” Cheng, James L. Henderson Jr. Memorial Associate Professor of Engineering Science and Mechanics at Penn State.

Researchers from the SUNY Polytechnic Institute, Stony Brook University and the Brookhaven National Laboratory in the US, along with Aalto University in Finland, have demonstrated a new electronic device that employs the unique ways in which electrons behave in graphene and high-temperature superconductors.

The experiment, led by Sharadh Jois and Ji Ung Lee from SUNY with the support of theoretical work done by Jose Lado, assistant professor at Aalto, demonstrated a new quantum device that combines both graphene and an unconventional high-temperature superconductor.