Graphene sensors: introduction and market status - Page 32

Iowa State University researchers have created a new, low-cost, easily produced, graphene-based sensors-on-tape that can be attached to plants to provide data that was previously very hard to collect. This can help farmers to breed plants that are more efficient in using water, for example, but also open new possibilities for creating new sensors for biomedical diagnostics, for checking the structural integrity of buildings, monitoring the environment and, after appropriate modifications, for testing crops for diseases or pesticides.

The tiny graphene sensors that can be taped to plants, and the researchers have dubbed it a plant tattoo sensor. The plant sensors have been successfully tested in lab and pilot field experiments. The graphene-on-tape technology in this study has also been used to produce wearable strain and pressure sensors, including sensors built into a smart glove that measures hand movements.

Researchers from Cornell have developed tiny graphene-enhanced robot exoskeletons that can rapidly change shape upon sensing chemical or thermal changes in its environment. And, they claim, these microscale machines equipped with electronic, photonic and chemical payloads could become a powerful platform for robotics at the size scale of biological microorganisms.

We are trying to build what you might call an ‘exoskeleton’ for electronics, said the team. Right now, you can make little computer chips that do a lot of information-processing … but they don’t know how to move or cause something to bend.

Graphene has been attracting attention due to its exciting properties and countless ideas for applications benefiting from those properties have been thought of; However, it is rightfully claimed that graphene has yet to transform an actual industry or become a household name.

With that said, graphene seems to be slowly but surely entering the market in all sorts of products. In this post, we list 10 products already commercially available that contain graphene - and these are not all of them. Hopefully this is just the beginning and many more applications will follow.

International wheel producer Vittoria sells a range of bicycle wheels that are built from graphene-enhanced composite materials. The wheels, called Quarno (Graphene Plus inside) are available in three different editions (46, 60 and 84 mm) and contain graphene nanoplatelets (GNPs) provided by Directa Plus. The company explains that the graphene grants the wheels advantages like heat dissipation (15-30°C lower) a crucial factor in the slopes, an increase in lateral stiffness (more than 50%) and puncture reduction, especially around the valve area.

Continuum Technologies, a UK-based company that develops graphene-based sensing nanotechnology embedded into fabrics, has one first prize in the 2017 Nokia Open innovation challenge.

Nokia will offer the startup the opportunity to explore joint business opportunities along with access to Nokia’s global resources.

Researchers from the University of Minnesota College of Science and Engineering have created graphene-based tiny electronic tweezers that can grab biomolecules floating in water with extraordinary efficiency. This, according to the team, could lead to a revolutionary handheld disease diagnostic system that could be run on a smartphone.

The graphene tweezers are said to be vastly more effective at trapping particles compared to other techniques used in the past due to graphene's extremely thin nature. The physical principle of tweezing or trapping nanometer-scale objects, known as dielectrophoresis, has been known for a long time and is typically practiced by using a pair of metal electrodes. From the viewpoint of grabbing molecules, however, metal electrodes are very blunt. They simply lack the sharpness to pick up and control nanometer-scale objects.

CVD processes are used to create high-quality single layer (also bi-layer and tri-layer) graphene sheets. These kinds of sheets exhibit exceptional properties and can be used in a variety of exciting applications, from touch layers to transistors and sensors. For many years, CVD has been a high cost production process and this graphene is still mostly used in research projects in academic and research institutes, but prices are gradually dropping, to the point where commercial applications are starting to appear on the market.

Recent years have, as we said, brought on a continuing price drop in CVD graphene prices. Spain-based Graphenea, a global CVD graphene leader, has an online shop in which it offers its high-end CVD graphene samples. We have been tracking the prices of Graphenea's CVD graphene since late 2015, and the graph above shows the price decrease.

Researchers at The University of Manchester have fabricated highly sensitive miniaturized pressure sensors using graphene membranes.

The team reported that the new sensor was made possible by developing a way to effectively float a graphene membrane mere nanometers above a silicon chip. When pressure moves this membrane closer to the surface of the chip, the resulting change in capacitance is measured to read out the pressure change. By fabricating thousands of such floating membranes next to each other, a device can be made of exceptionally high sensitivity to pressure changes.

Researchers at the University of Wisconsin-Milwaukee will be presenting a graphene-based sensing platform for real-time, low-cost detection of various water contaminants at the AVS's 64th International Symposium & Exhibition, being held Oct. 29-Nov. 3, 2017, in Tampa, Florida. The new sensor detects heavy metals, bacteria, nitrates and phosphates.

The sensor works by placing graphene-based nanosheets that are semiconducting between an electrode gap. The electrical conductivity of the graphene material changes with the binding of substances, called analytes, to its surface and their chemical constituents are identified and measured. "The magnitude of the conductivity change can be correlated to the concentration of analyte, and the technology also involves the functionalization of the graphene material surface with specific probes that can target a specific analyte," said the researchers.

Researchers at Chalmers University have developed a flexible detector for terahertz frequencies (1000 gigahertz) using graphene transistors on plastic substrates. It is said to be the first of its kind, and can extend the use of terahertz technology to applications that require flexible electronics, like wireless sensor networks and wearable technology.

At room temperature, the translucent and flexible device detects signals in the frequency range 330 to 500 gigahertz. The technique can be used for imaging in the terahertz area (THz camera), but also for identifying different substances (sensor). It may also be of potential benefit in health care, where terahertz waves can be used to detect cancer. Other areas where the detector could be used are imaging sensors for vehicles or for wireless communications.

Researchers in the UK (the University of Manchester) and Italy (the University of Pisa) have developed an inkjet-printed graphene strain gauge sensor on paper. The device is said to have a gauge factor of up to 125 even when very small strains are applied, and its overall sensitivity and performance can be tuned by different printing parameters, such as drop-spacing and number of printing passes. It might be used in applications like robot skin and health monitoring applications, and in smart packaging.

The team made their strain gauge by depositing conductive lines made from a network of graphene flakes (dispersed in water as the solvent) on a PEL P60 paper substrate using a simple Dimatix DMP-2850 inkjet printer. This printer can create and define patterns over an area of about 200 mm x 300 mm and handle substrates that are up to 25 mm thick. A waveform editor and a drop-watch camera system were used to manipulate electronic pulses to the jetting deice for optimizing the drops’ characteristics as they were ejected from the nozzle.