Last year I jokingly wrote that graphene would be a dead cert if there were an awards ceremony for material of the year. It turns out the hits keep on coming in 2012: researchers at Berkeley believe graphene could make it easier to study liquids with a microscope.
Graphene is made up of a single layer of carbon atoms, arranged in a hexagonal chain like chicken wire. This makes it particularly strong despite being so thin that three million layers would only be one millimeter thick. The result can roughly be compared to having a material with the flexibility of a sheet of paper but ten times the strength of steel.
Initial ideas had graphene as a possible material for building part of airplanes or even spacecraft. It later emerged it conducted electricity more quickly than silicon, meaning it could be used for computer chips, and that passing water over it generated electricity, making it suitable for powering underground oil and gas sensors. Another potential use was to hold lithium ions in place, making for quicker and longer-lasting recharging cycles for cellphone batteries.
Now the University of California team, lead by Jong Min Yuk, reports another benefit from the properties of graphene: the chain structure means that to some practical purposes it is as good as transparent. As with chicken wire, you don’t get an unobstructed view, but you can certainly see enough to tell what’s going on on the other side.
This characteristic can be exploited with transmission electron microscopes. Rather than using light, these pass a beam of electrons through the specimen and then create an image from the resulting interactions, offering far greater detail than is possible with a light-based microscope.
One major barrier with electron microscopes is that they don’t work well with liquid specimens. The microscope needs to hold the specimen in a vacuum to avoid air molecules interfering with the beam, but liquids normally vaporize in a vacuum. To date, freezing the specimen has been the main workaround.
Yuk’s solution is to put the liquid specimen inside a capsule made of graphene. The graphene casing is tight enough to hold the liquid in place and prevent vaporization, but with wide enough gaps between the chains of atoms to allow the imaging.
The main potential limitation is that it’s not yet clear if radiation damage could occur on biological specimens when using this new technique.