Sometimes simplicity is best. Two Northwestern University researchers have discovered a remarkably easy way to make nanofluidic devices: using paper and scissors. And they can cut a device into any shape and size they want, adding to the method's versatility.
Nanofluidic devices are attractive because their thin channels can transport ions -- and with them a higher than normal electric current -- making the devices promising for use in batteries and new systems for water purification, harvesting energy and DNA sorting.
The "paper-and-scissors" method one day could be used to manufacture large-scale nanofluidic devices without relying on expensive lithography techniques.
The Northwestern duo found that simply stacking up sheets of the inexpensive material graphene oxide creates flexible "paper" with tens of thousands of very useful channels. A tiny gap forms naturally between neighboring sheets, and each gap is a channel through which ions can flow.
Using a pair of regular scissors, the researchers simply cut the paper into a desired shape, which, in the case of their experiments, was a rectangle.
"In a way, we were surprised that these nanochannels actually worked, because creating the device was so easy," said Jiaxing Huang, who conducted the research with postdoctoral fellow Kalyan Raidongia. "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."
Huang is an assistant professor of materials science and engineering and the Morris E. Fine Junior Professor in Materials and Manufacturing in the McCormick School of Engineering and Applied Science.
"Many people have studied graphene oxide papers but mainly for their mechanical properties or for making graphene," Huang said. "Here we show that graphene oxide paper naturally generates numerous nanofluidic ion channels when layered."
The findings are published in the Journal of the American Chemical Society.
To create a working device, the researchers took a pair of scissors and cut a piece of their graphene oxide paper into a centimeter-long rectangle. They then encased the paper in a polymer, drilled holes to expose the ends of the rectangular piece and filled up the holes with an electrolyte solution (a liquid containing ions) to complete the device.
Next they put electrodes at both ends and tested the electrical conductivity of the device. Huang and Raidongia observed higher than normal current, and the device worked whether flat or bent.
The nanochannels have significantly different -- and desirable -- properties from their bulk channel counterparts, Huang said. The nanochannels have a concentrating effect, resulting in an electric current much higher than those in bulk solutions.
Graphene oxide is basically graphene sheets decorated with oxygen-containing groups. It is made from inexpensive graphite powders by chemical reactions known for more than a century.
Scaling up the size of the device is simple. Tens of thousands of sheets or layers create tens of thousands of nanochannels, each channel approximately one nanometer high. There is no limit to the number of layers -- and thus channels -- one can have in a piece of paper.
To manufacture very massive arrays of channels, one only needs to put more graphene oxide sheets in the paper or to stack up many pieces of paper. A larger device, of course, can handle larger quantities of electrolyte.
The paper is titled "Nanofluidic Ion Transport through Reconstructed Layered Materials."
Megan Fellman | EurekAlert!
At last, butterflies get a bigger, better evolutionary tree
16.02.2018 | Florida Museum of Natural History
New treatment strategies for chronic kidney disease from the animal kingdom
16.02.2018 | Veterinärmedizinische Universität Wien
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.
But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...
Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.
The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...
Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters
Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...
Let’s say the armrest is broken in your vintage car. As things stand, you would need a lot of luck and persistence to find the right spare part. But in the world of Industrie 4.0 and production with batch sizes of one, you can simply scan the armrest and print it out. This is made possible by the first ever 3D scanner capable of working autonomously and in real time. The autonomous scanning system will be on display at the Hannover Messe Preview on February 6 and at the Hannover Messe proper from April 23 to 27, 2018 (Hall 6, Booth A30).
Part of the charm of vintage cars is that they stopped making them long ago, so it is special when you do see one out on the roads. If something breaks or...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
16.02.2018 | Information Technology
16.02.2018 | Health and Medicine
16.02.2018 | Physics and Astronomy