Graphene sensors: introduction and market status - Page 31

Versarien has announced that the signing of an agreement to develop a range of graphene-based sensor technologies to enable the creation of digital bandages and wound dressings capable of various forms of physiological movement and excretion detection.

This project will utilize strain sensors printed with graphene ink using methods which have been developed by the Company’s subsidiary, Cambridge Graphene Limited. Trials will take place at the internationally renowned Addenbrooke’s Hospital in Cambridge. The team will work to optimize the usability of the data from the graphene dressings to ensure the optimal recovery of the patients post discharge. The agreement will also involve Dr. Chris Crockford, Managing Director of Digital and Future Technologies Limited, who will act as liaison between the hospital, Versarien and wider global providers in this field.

Scientists at Rice University have enhanced their formerly invented LIG technique to produce what may become a new class of edible electronics. The Rice lab of Prof. James Tour is investigating ways to write graphene patterns onto food and other materials to embed conductive identification tags and sensors into the products themselves.

"This is not ink," Tour said. "This is taking the material itself and converting it into graphene". The process is an extension of the Tour lab's perception that anything with adequate carbon content can be turned into graphene. In recent years, the lab has developed and expanded upon its method to make graphene foam by using a commercial laser to transform the top layer of an inexpensive polymer film.

Emberion developed graphene-based photodetectors that convert light to an electronic signal using graphene charge transducers combined with a nanocrystal light absorber. Potential applications include spectrometry, optical gas detection or optical power measurements.

The photodetectors provide responsivity and low noise over a broad spectral range from VIS to NIR/SWIR wavelengths without cooling below room temperature. The full dynamic range is 160 dB, owing to the low noise and an unsaturated response.

Researchers at Chalmers University of Technology and the Beijing University of Technology have exploited graphene's thermoelectric properties to create a new kind of radiation detector. Classified as a bolometer, the new device has a fast response time and, unlike most other bolometers, works over a wide range of temperatures. With a simple design and relatively low cost, this device could be scaled up, enabling a wide range of commercial applications.

In the new bolometer, radiation heats part of the device, inducing electrons to move. The displaced electrons generate an electric field, which creates a voltage difference across the device. The change in voltage thus provides an essentially direct measurement of the radiation.

Researchers from Cornell University and Honeywell Aerospace have designed a graphene-enhanced transient electronics technology in which the microchip self-destructs by vaporizing an action that can be remotely triggered without releasing harmful byproducts. In addition to transient electronics, the technology might find application in environmental sensors that can be remotely vaporized once they're no longer needed.

A silicon-dioxide microchip is attached to a polycarbonate shell. Microscopic cavities within the shell contain rubidium and sodium bifluoride. When triggered remotely by using radio waves, these chemicals thermally react and decompose the microchip. The radio waves open graphene-on-nitride valves that keep the chemicals sealed in the cavities, allowing the rubidium to oxidize, release heat and vaporize the polycarbonate shell. The sodium bifluoride releases hydrofluoric acid to etch away the electronics.

Researchers at The University of Manchester have found a new and exciting physical effect in graphene membranes that could be used in devices to artificially mimic photosynthesis.

The new findings demonstrated an increase in the rate at which the material conducts protons when it is simply illuminated with sunlight. The 'photo-proton' effect, as it has been named, could be utilized to design devices able to directly harvest solar energy to produce hydrogen gas, a promising green fuel. It might also be of interest for other applications, such as light-induced water splitting, photo-catalysis and for making new types of highly efficient photodetectors.

Researchers at Iowa State University, along with collaborators at Rice University, Ames Laboratory and Lehigh University, have designed a new graphene printing technology that can produce electronic circuits that are low-cost, flexible, highly conductive and water repellent. The scientists explain that this technology could enable self-cleaning wearable/washable electronics that are resistant to stains, or ice and biofilm formation.

We’re taking low-cost, inkjet-printed graphene and tuning it with a laser to make functional materials, said authors of the paper. The work describes how the team used inkjet printing technology to create electric circuits on flexible materials. In this case, the ink is flakes of graphene. The printed flakes, however, aren’t highly conductive and have to be processed to remove non-conductive binders and weld the flakes together, boosting conductivity and making them useful for electronics or sensors. Such post-print processes typically involve heat or chemicals, but the research group developed a rapid-pulse laser process that treats the graphene without damaging the printing surface even if it’s paper.

Researchers at The University of Central Florida have come up with a finding that enables graphene to better absorb light and showed more than 45% absorption of light in a single layer of graphene. This may open the door to graphene-enhanced applications that require the incident light to be fully utilized, like next-generation light detectors, touchscreens, and more.

This is the first published work on extremely high light absorption in graphene which is tunable dynamically, the researchers said. Theoretical studies show further design optimization can lead to further enhanced absorption close to 90%.

Researchers at the University of Sussex have developed a graphene-based sensor with the potential to prevent sudden infant death syndrome (SIDS) cases. The sensor is shaped like a flexible rubber tube filled with a solution of water, oil and particles graphene.

the sensors were said to be the most sensitive liquid-based devices to have ever been developed. Utilizing graphene's conductivity, the solution inside the tube conducts electricity. When the tube is stretched by even a tiny amount, the conductivity also changes and this change can be detected, indicating that movement (such as the rising and falling of a breathing person's chest) is occurring.

Researchers at The University of Manchester have developed graphene sensors embedded into RFIDs, which may have the potential to revolutionize the Internet of Things (IoT). The team layered graphene-oxide over graphene to create a flexible heterostructures that function as humidity sensors for remote sensing with the ability to connect to any wireless network.

The novel aspect of this development is that such sensors can be printed layer-by-layer for scalable mass production at very low costs. The device also requires no battery source as it harvests power from the receiver.