Electronics - Page 7

Researchers from South Korea invented a simple way to achieve fine control over the integration of foreign atoms with graphene, developing composite graphene-based heterostructures that can be used to store energy at low cost and fabricate ultrathin, wearable electronics.

One way to specifically tailor graphene's properties is by integrating other materials into it, such as metals, insulators, and semiconductors, to form composite structures with desirable properties. For instance, researchers are adding metal oxides to graphene to create graphene monolayer/metal-oxide nanostructures (GML/MONSs) that have improved physical and chemical properties. However, depositing uniform layers of metal oxides over graphene without disturbing the characteristics of the graphene layer is extremely challenging.

A Penn State-led international research team (led by Professor Huanyu Larry Cheng at Penn State) recently published two studies that could boost research and development of future motion detection, tactile sensing and health monitoring devices.

There are various substances that can be converted into carbon to create graphene through laser radiation, in a process called laser-induced graphene (LIG). The resulting product can have specific properties determined by the original material. The team set out to test this process and has reached interesting conclusions.

Researchers from AMO, Oxford Instruments, Cambridge University, RWTH Aachen University and the University of Wuppertal have demonstrated a new method to use plasma enhanced atomic layer deposition (PEALD) on graphene without introducing defects into the graphene itself.

Currently, the most advanced technique for depositing dielectrics on graphene is atomic layer deposition (ALD), which allows to precisely control the uniformity, the composition and the thickness of the film. The process typically used on graphene and other 2D materials is thermal water-based ALD, as it does not damage the graphene sheet. However, the lack of nucleation sites on graphene limits the quality of the dielectric film, and requires the deposition of a seed layer prior to ALD to achieve good results. Another approach is plasma enhanced atomic layer deposition (PEALD), which, when applied to growth on graphene, can introduce surface damage. This is what to team addressed in this recent work.

Researchers from Kansas State University, led by Suprem Das, assistant professor of industrial and manufacturing systems engineering, in collaboration with Christopher Sorensen, university distinguished professor of physics, have shown potential ways to manufacture graphene-based nano-inks for additive manufacturing of supercapacitors in the form of flexible and printable electronics.

The team’s work could be adapted to integrate supercapacitors to overcome the slow-charging processes of batteries. Furthermore, Das has been developing additive manufacturing of small supercapacitors — called micro-supercapacitors — so that one day they could be used for wafer-scale integration in silicon processing.

A research team led by the University of Basel has found that the electronic properties of graphene can be specifically modified by stretching the material evenly.

The researchers, led by Professor Christian Schönenberger at the Swiss Nanoscience Institute and the Department of Physics at the University of Basel, have studied how the material’s electronic properties can be manipulated by mechanical stretching. In order to do this, they developed a kind of rack by which they stretch the atomically thin graphene layer in a controlled manner, while measuring its electronic properties.

Cardea Bio, a biotech company integrating molecular biology with semiconductor electronics, has signed a commercial partnership with Scentian Bio. Scentian is an expert in synthetic insect odorant receptors (iORs), one of nature’s ways of detecting and interpreting smells.

The partnership will enable Scentian to use a customized Cardean chipset, built with graphene-based biology-gated transistors, which will allow Scentian to manufacture a bio-electronic tongue/nose tech platform.

An international research team, led by the University of Cologne, has succeeded in connecting several atomically precise graphene nanoribbons to form complex structures. The scientists have synthesized and spectroscopically characterized nanoribbon heterojunctions, and were able to integrate the heterojunctions into an electronic component. In this way, they have created a novel sensor that is highly sensitive to atoms and molecules.

"The graphene nanoribbon heterojunctions used to make the sensor are each seven and fourteen carbon atoms wide and about 50 nanometres long. What makes them special is that their edges are free of defects. This is why they are called "atomically precise" nanoribbons," explained Dr. Boris Senkovskiy from the Institute for Experimental Physics. The researchers connected several of these nanoribbon heterojunctions at their short ends, thus creating more complex heterostructures that act as tunneling barriers.

A Rice University team has modified its laser-induced graphene technique to make high-resolution, micron-scale patterns of the conductive material for consumer electronics and other applications. Laser-induced graphene (LIG), introduced in 2014 by Rice chemist James Tour, involves burning away everything except carbon from polymers or other materials, leaving the carbon atoms to reconfigure themselves into films of characteristic hexagonal graphene. The process employs a commercial laser that writes graphene patterns into surfaces that to date have included wood, paper and even food.

The new version writes fine patterns of graphene into photoresist polymers, light-sensitive materials used in photolithography and photoengraving. Baking the film increases its carbon content, and subsequent lasing solidifies the robust graphene pattern, after which unlased photoresist is washed away.

Researchers at Duke University have created transistors with three carbon-based inks. The all-carbon thin-film transistors were made using crystalline nanocellulose as a dielectric, carbon nanotubes as a semiconductor, graphene as a conductor and paper as a substrate. This type of component could assist in addressing the environmental problem of accumulation of electronics that are non-recyclable.

Silicon-based computer components are probably never going away and we don’t expect easily recyclable electronics like ours to replace the technology and devices that are already widely used, said Professor Aaron Franklin, an electrical engineer at Duke University. But we hope that by creating new, fully recyclable, easily printed electronics and showing what they can do, that they might become widely used in future applications.

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