Graphene & New Materials Tech Digest - May 2017

Super-conduction inducing sandwich

MIT researchers have shown graphene’s ability to inherit some superconducting qualities when sandwiched between two superconducting materials. The graphene sandwich alters the behaviour of its electrons enabling them to pair up into Andreev states – an electronic configuration that allows a non-superconducting material to carry a current that flows without dissipating energy. The scientists see this as having potential to conduct research into exotic particles such as Majorana fermions that have implications for quantum computing. 

Aerogel helps with desalination

A team of scientists at Hubei University, Wuhan, China, have demonstrated graphene being used to cause water to turn into steam without boiling. This technique has implications for desalination, conventionally an energy-hungry process that requires boiling of the saltwater and capture of the desalinated steam. The team created a graphene aerogel film that floats on the surface of the liquid where it heats water to a shallow depth after exposure to sunlight. The aerogel heated 100ml of water to 45C which is an increase of 13C compared to water without the aerogel. The gel’s structure causes steam to be siphoned off the water surface at a rate 13 times that of untreated water. The team says that it will work on making the material tougher, which would make it suitable for use in manufacturing techniques. 

Asthma attack warning device

Scientists at Rutgers University – New Brunswick have developed a graphene-based sensor that promises to help monitor and alert asthma sufferers when they are at risk of an attack. The device measures nitrite in exhaled breath condensate using reduced graphene oxide. Nitrite levels can indicate inflammation levels in the lungs. The device would work like a breathalyser with the user blowing into the device periodically to monitor their condition and see the effect of air pollutants and other factors on the condition. The team see this as being used like a Fitbit with the user wearing it on the body. 

Graphene paint

Graphenstone, a paint manufacturer, has released a series of paints that include graphene. The company says that the inclusion of graphene provides the paints with high adhesion, condensation resistance, washability, flexibility (reduced cracking), water repulsion, and increased strength and durability as well as thermal conductivity. 

Anti-bacterial properties of graphene

Rice University researchers have discovered that laser-induced graphene (LIG – a type of spongy graphene) can be used to kill bacteria and prevent fouling (the build-up of biological material on a wet surface). The latter property gives the material potential uses in water treatment plants, oil-drilling operations, hospitals and ocean applications. The former property comes to light when the LIG is used as electrodes with a small applied voltage. In a test the LIG electrodes were charged with 1.1 volts - a process which caused bacteria to be pulled to the anode. When the voltage was increased to 1.5V the cells vanished within 30 seconds. At 2.5V the bacteria disappeared from the surface almost immediately. It is thought that the effect is produced due to contact with the LIG’s rough edges, the electrical charge and toxicity from hydrogen peroxide. Furthermore, the LIG did not foul up (become covered in the dead bacteria), overcoming a problem common in many industrial cases. There is no indication of further research being planned. 

3D printed metamaterial

Duke University researchers have 3D printed electromagnetic metamaterials using an electrically conductive material compatible with a standard 3D printer. The metamaterial being used (named Electrifi) can manipulate electromagnetic waves in a specific way to determine how the wave works. The ability to use a standard 3D printer to print these materials enables developers to experiment with the novel potential of the materials. By printing cubes of the metamaterial and combining them in particular ways researchers can build new devices. For the device to work the electromagnetic waves must the about the same size as the blocks, which limits the blocks to handling only radio waves and microwaves. It is believed that the material could be used for rapid design and prototyping of Bluetooth, wireless sensing, Wifi and communication device components. 

Graphene for better anodes

Zenyatta, a Canadian graphite producer, has had its graphene oxide material tested by a US advanced materials company that included it in its lithium ion battery silicon-graphene anodes. The inclusion of graphene with silicon in battery anodes helps prevent the natural degradation that inhibits silicon’s suitability as an anode material. Further testing of the composite will include: its aqueous dispersion quality, compatibility with processing method and yield, electrochemical performance and characterisation of the composite material. 

Using corn to manufacture graphene

Scientists at Heilongjiang University in Northeast China have begun manufacturing graphene from corn. They believe their method enables cheaper, cleaner manufacturing of graphene than traditional methods. The process involves extracting furfural, an oily aldehyde, and other substances from the corn kernel. The remaining cellulose can then be used as the base chemical to manufacture the graphene. The university cooperated with Shengquan Group, a chemical company, that set up the first manufacturing line dedicated to producing graphene from sources other than graphite in 2014. In its first year, it produced 20 tons of graphene from corn fibres, and 100 tons in 2016. The process can use corn that might otherwise go to waste. 

Graphene-quantum dot CMOS camera

The ICFO (Institute of Photonics Sciences) has developed a graphene-quantum dot based CMOS (complementary metal-oxide-semiconductor) integrated camera that can create images of visible and infrared light simultaneously. The work overcomes a long-term problem in the subject, namely how to integrate CMOS and non-silicon semiconductors. The researchers built a monolithic CMOS integrated circuit with graphene, resulting in a high-resolution image sensor composed of hundreds of thousands of graphene-quantum dot photodetectors. When they tested its potential as a camera it exhibited high sensitivity to UV, visible and infrared light simultaneously. The scientists see the device being used in low-power optical data communication and small, ultra-sensitive sensing systems. 

 

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