When one recalls that graphene was first producedby placing scotch tape on top of the graphite found in pencils and then pulling the tape off, it may not sound so strange that the next breakthrough in nanofluidic devices may come from using paper and scissors.
Two researchers at Northwestern University have discovered that if you stack up layers of graphene on top of one another it creates a flexible paper-like material that forms tens of thousands of nanoscale channels between the layers. In keeping with the school supplies theme, the researchers further discovered that they could cut the paper-like material into any shape they wished with a pair of scissors.
“In a way, we were surprised that these nanochannels actually worked, because creating the device was so easy,” said Jiaxing Huang, quoted in a university press release. Huang, a Junior Professor in Materials and Manufacturing, who conducted the research with postdoctoral fellow Kalyan Raidongia, said, “No one had thought about the space between sheet-like materials before. Using the space as a flow channel was a wild idea. We ran our experiment at least 10 times to be sure we were right.”
The material could potentially have applications in batteries, water purification, harvesting energy and DNA sorting. While listing a range of applications for lab technologies is always a fairly easy matter, this material stands out in these application areas because of how cheaply and easily it is produced.
Typically nanofluidic devices require slow and expensive lithography techniques to carve out the channels. But this technique lends itself to the building of massive arrays of nanochannels simply by staking sheets of graphene oxide (GO) on top of one another. To create more nanochannels, simply stack more layers on top of each other.
The research, which was published in the Journal of the American Chemical Society (“Nanofluidic Ion Transport through Reconstructed Layered Materials’), demonstrated a working device using the material by cutting a piece of the GO paper into a centimeter-long rectangle. Huang and Raidongia covered the paper in a polymer. They then drilled either end of the rectangle to fashion holes in which an electrolyte solution was placed.
In tests, the researchers discovered that the rectangle conducted a higher than normal amount of current, whether it was laid out flat or bent.
The next step is to test the nanoscale properties of papier-mâché. Just kidding—but maybe someone should try it.
Dexter Johnson is a contributing editor at IEEE Spectrum, with a focus on nanotechnology.