Graphene sensors: introduction and market status - Page 53

A few days ago we reported on Bluestone Global Tech's new graphene based Field Effect Transistors. We have discussed it with BGT and have some more details on this exciting development. So first of all, we reported that the Gray-FETs are currently offered for research only, but BGT says that they are using a fab that can produce these in volume "to meet most demands". So this is suitable for commercial applications.

In fact BGT is already in talks with several academic and industrial customers. Having a standard GFET product can save a lot of time and will enable those customers to develop their own products based on these transistors faster then if they need to first develop the GFET themselves.

Researchers from the University of Manchester demonstrated how membranes can be "written" on to a graphene sheet surface using a technique known as Lipid Dip-Pen Nanolithography (L-DPN). The researchers have shown that graphene is a great surface for human-cell membrane research. Graphene combined with lipids may also enable new types of bio-sensors.

The researchers wanted to find a new way to study human cell phospholipid bi-layer membranes, which protect the cells.The membranes contain proteins, ion channels and other molecules, each performing vital functions. Researchers already developed model cell membranes on surfaces outside the body for research purposes. The new research have shown that graphene is a great surface to assemble said membranes and research them.

Researchers from Columbia University managed to p-dope (remove electrons) graphene with Boron. The same researchers already showed two years ago that it is possible to n-dope (add electrons) graphene with Nitrogen atoms.

The Boron doping does not significantly modify the basic graphene structure (this is also true for Nitrogen n-doping). The researchers report that one Boron atom bonds to 3 neighboring carbon atoms, and each dopant contributes roughly half a hole (a hole is the absence of an electron).

Last week we reported that Graphene Frontiers has been awarded a $744,600 grant from the NSF to develop and scale up their roll-to-roll graphene production. After discussing this with Graphene Frontier's CEO Michael D. Patterson, we have some more information about the company's technology and its business.

Graphene Frontier's technology was developed at the University of Pennsylvania. It is called Atmospheric Pressure CVD, or APCVD. This roll-to-roll process does not need a vacuum so it works in room pressure. The equipment required is smaller, faster and cheaper compared to CVD and this means that the manufacturing will be cost effective.

Researchers from Seoul National University developed a simple method to produce graphene nanonet (GNN) patterns on large areas. The patterns, which contain continuous networks of chemically functionalized graphene nanoribbons, could be used to make biosensor devices. These patterns behave better than GO or GNRs which are commonly used for biological sensing applications and are easy to make.

The GNN structures are made from continuous networks of GNRs with chemical functional groups on their edges. The chemical functional groups in the GNN can be functionalized with biological molecules such as DNA for biochip applications. The researchers successfully performed fluorescence imaging of DNA molecules on the GNN channels and has electrically detected the DNA at 1 nM concentrations using the GNN-based biochip devices.

Researchers from the US Naval Research Laboratory (NRL) have moved liquid droplets using long chemical gradients formed on graphene. The idea is that by changing the concentration of either fluorine or oxygen (formed using a simple plasma-based process) you can either push or pull droplets of water (also nerve agent simulant) across the surface of the graphene.

The researchers say that this could lead to applications relating to biological or chemical sensors, and also perhaps electronics and mechanical resonators. They say that in the future, such chemical gradients could be used to perhaps move single molecules.

Researchers from the Naval Research Laboratory at George Mason University report that graphene can replace Carbon Nanotubes (CNTs) in glucose sensors. The researchers use multilayered graphene petal nanosheets enhanced with platinum nanoparticles and enzyme glucose oxidase to monitor glucose concentrations found in saliva, tears, blood, and urine.

In past research, the researchers used CNTs with platinum nanoparticles to provide sensitive sensors. But these sensors were not stable as spacing of the nanoparticles on the CNTs significantly impacted the biosensor performance (as glucose diffusion is blocked when nanoparticles are too closely packed). In addition, they suffered from diffusion restrictions from neighboring nanoparticles.

Researchers from the University of Minnesota are developing a sensor platform that will help create an artificial pancreas. The wireless sensor that will continually monitor blood glucose will be based on graphene and it can be placed in blood vessels for accurate and continual monitoring.

This new project was funded by the 2013 Discovery Transformation Grant Program. This is one of four projects that received $2 million in total.

Researchers from the Universities of Bath and Exeter have developed and demonstrated an optical switch made from graphene. this switch has an incredibly short optical response - nearly a hundred times quicker than current materials.

This fast response is in the infrared part of the electromagnetic spectrum, which makes it useful for telecommunications, security and also medicine applications. Current optical switches have as response rate of a few picoseconds, and the few-layer-graphene switch's response rate is about one hundred femtoseconds.

Researchers from Sweden's KTH (Kungliga Tekniska Högskolan) Royal Institute developed piezoresistive sensors based on graphene membranes. They say that graphene increases the sensitivity of these MEMS sensors by up to 100 times while reducing the thickness.

The researchers used a graphene sheet over a cavity etched into a silicon dioxide (SiO2) film on a silicon substrate. The graphene acts as the membrane. They fabricated a prototype device, in this case a strain gauge, although this technology can be used to make other MEMS based sensors.