Transistors

Researchers from Portugal's International Iberian Nanotechnology Laboratory and Italy's Istituto Italiano di Tecnologia have addressed the need for noninvasive, ultrasensitive alternatives to currently available glucose monitoring sensors used for continuous monitoring of diseases like Diabetes Mellitus and presented electrolyte-gated graphene field-effect transistors functionalized with glucose oxidase. The scientists developed an optimized fabrication process that integrates a 32-transistor matrix within a miniaturized 1000 μm² footprint, ensuring high device uniformity while enabling detection in 40 μL analyte volume. 

A comprehensive suite of techniques (including Raman spectroscopy, X-ray photoelectron spectroscopy, and water contact angle measurements) reveals the stepwise evolution of graphene chemistry and surface properties leading to the controlled immobilization of glucose oxidase. The team's findings demonstrate p-type doping and tensile strain in the graphene channel across the nanomolar–millimolar glucose concentration range. The enzyme-catalyzed oxidation of glucose produces hydrogen peroxide in close proximity to the graphene channel, inducing a systematic shift in the Dirac point voltage toward more positive values. Under these conditions, the biosensor achieved an attomolar limit of detection and a sensitivity of 10.6 mV/decade, outperforming previously reported glucose sensors. 

Paragraf, the UK-based company pioneering the mass production of graphene-based electronics with standard semiconductor processes, has been awarded a grant of £419,419 (around USD$520,000) from Innovate UK for the purpose of producing a proof-of-concept prototype of a novel semiconductor memory technology using a new class of ferroelectric materials complemented with graphene on a silicon platform.

The joint grant will also see Prof. Judith Driscoll’s research group at the University of Cambridge’s Department of Materials Science and Metallurgy receive £299,198 to develop processes for depositing ferroelectric materials on top of Paragraf’s transfer-free graphene in order to produce novel memory devices, including a graphene-ferroelectric field effect transistor (G-FeFET). This is expected to lead to power savings of an order of magnitude relative to existing memory device technology, which is key to saving power in data centres and consumer devices to support the AI revolution.

Researchers from Penn State recently developed a portable and wireless device to simultaneously detect SARS-CoV-2, the virus that causes COVID-19, and vitamin C, a critical nutrient that helps bolster infection resistance, by integrating commercial transistors with printed laser-induced graphene.  

By simultaneously detecting the virus and vitamin C levels, the test could help individuals and their health care providers decide on more effective treatment options, the researchers said. For example, someone with low vitamin C levels may benefit from a supplemental boost, while someone with normal or high vitamin C levels may need to consider other options.  

Versarien has launched a new biosensor chip utilizing novel graphene barristor sensor platform technology. These graphene barristor devices, developed in South Korea by A Barristor Company (ABC), will utilize chemical vapor deposition (CVD) grown graphene, that is produced under a Versarien license. Versarien has signed a distribution agreement with ABC to distribute the products in the UK and Europe.

A barristor (triode device) is a new type of graphene‐based transistor with a Schottky barrier between graphene and silicon. The current modulation is amplified more than 10,000 times compared to graphene field‐effect transistors (GFET), enabling the barristor transistors to overcome many GFET limitations.

Researchers from Friedrich Schiller University Jena, CNM Technologies, NOXXON Pharma, APTARION Biotech and Radboud University Medical Center have developed graphene field effect transistor (GFET) sensors based on van der Waals (vdW) heterostructures of single-layer graphene layered with a molecular ≈1 nm thick carbon nanomembrane (CNM).

1 / 1Schematic illustration of the fabrication steps of the l-AP/PEG-CNM GFET sensors. Credit: Advanced Materials 

The CNM acts as an ultrathin molecular interposer between the graphene channel and the analyte and allows bio-functionalization without impairing the graphene properties including its charge carrier mobility. 

Archer Materials has announced that successfully miniaturized its Biochip graphene field effect transistor (gFET) design, reducing its size by 97% and significantly lowering fabrication costs. The development marks a significant step in Archer’s efforts to strengthen its semiconductor capabilities and expand its role in medical diagnostics.

This advancement, achieved in collaboration with Applied Nanolayers and AOI Electronics, enhances the chip’s readiness for integration in home testing devices for chronic kidney disease. 

Researchers from Penn State University and NASA Goddard Space Flight Center recently developed an 'electronic tongue' based on a graphene-based ion-sensitive field-effect transistor, capable of identifying differences in similar liquids, such as milk with varying water content; diverse products, including soda types and coffee blends; signs of spoilage in fruit juices; and instances of food safety concerns. The team also found that results were even more accurate when artificial intelligence (AI) used its own assessment parameters to interpret the data generated by the electronic tongue.

Graphene ISFET chip mounted on a printed circuit board (PCB). Image from: Nature

The sensor and AI can broadly detect and classify various substances while collectively assessing their respective quality, authenticity and freshness. This assessment has also provided the researchers with a view into how AI makes decisions, which could lead to better AI development and applications, they said.

An international group of scientists, including ones from the UK's University of Bath, Friedrich Schiller University Jena in Germany and the University of Pisa in Italy, recently set out to investigate the ultrafast opto-electronic and thermal tuning of nonlinear optics in graphene.

Opto-electronic modulation of third harmonic generation in a graphene field-effect transistor. The illustration includes a sketch and a microscopic optical image of the device. Image credit: University of Bath

Nonlinear optics explores how powerful light (e.g. lasers) interacts with materials, resulting in the output light changing color (i.e. frequency) or behaving differently based on the intensity of the incoming light. This field is important for developing advanced technologies such as high-speed communication systems and laser-based applications. Nonlinear optical phenomena enable the manipulation of light in novel ways, leading to breakthroughs in fields like telecommunications, medical imaging, and quantum computing. Graphene's exceptional electronic properties, related to relativistic-like Dirac electrons and strong light-matter interactions, make it promising for nonlinear optical applications, including ultrafast photonics, optical modulators, saturable absorbers in ultrafast lasers, and quantum optics.

While silk protein has been used in designer electronics, its use is currently limited in part because silk fibers are a messy tangle of spaghetti-like strands. To address this, researchers from Pacific Northwest National Laboratory, University of Washington, Lawrence Berkeley National Laboratory, North Carolina State University and Xiamen University have developed a uniform two-dimensional (2D) layer of silk protein fragments, or "fibroins," on graphene. 

Scheme of silk fibroin assembly on highly oriented pyrolytic graphite (HOPG) characterized by in situ AFM. Image from Science Advances

The scientists explained that their work provides a reproducible method for silk protein self-assembly that is essential for designing and fabricating silk-based electronics. They said that the system is nontoxic and water-based, which is vital for biocompatibility.

Archer Materials has started experiments to detect and monitor chronic kidney disease on its Biochip graphene field effect transistor (“gFET”) sensors.

Archer, through one of its foundry partners, has reportedly verified a process that directly grows graphene surfaces to produce enhanced devices, rather than transferring the graphene to a device from a wafer, as previously done. The team has tested the devices by storing them in normal air conditions over a two-month period, finding no significant degradation in performance.