To create new and more efficient computers, medical devices and other advanced technologies, researchers turn to nanomaterials: materials manipulated on the scale of atoms or molecules that exhibit unique properties.
Graphene, a thin carbon flake like a single later than atoms, is a revolutionary nanomaterial due to its ability to easily conduct electricity, as well as its extraordinary mechanical strength and flexibility. However, a major obstacle in adopting it for everyday applications is producing graphene on a large scale, while maintaining its incredible properties.
In an article published in the journal ChemOpenAnne S. Meyer, associate professor of biology at the University of Rochester, and her colleagues at the Delft University of Technology in the Netherlands, describe a way to overcome this barrier. Researchers describe their method of producing graphene materials using a new technique: mixing of oxidized graphite with bacteria. Their method is a more efficient way in terms of costs, time savings and eco-compatibility for the production of graphene materials than those produced chemically and could lead to the creation of innovative information technologies and medical equipment.
Graphene is extracted from graphite, the material found in a common pencil. At exactly one thick atom, graphene is the thinnest, but strongest, two-dimensional material known to researchers. Scientists from the University of Manchester in the United Kingdom received the 2010 Nobel Prize in physics for their discovery of graphene; however, their method of using adhesive tape to produce graphene produced only small amounts of the material.
"For real applications you need large quantities," says Meyer. "Producing these large quantities is challenging and generally produces thicker and less pure graphene, and this is where our work was born."
To produce greater quantities of graphene materials, Meyer and his colleagues started with a graphite vial. They exfoliated the graphite, freeing the layers of material, to produce graphene oxide (GO), which they then mixed with the Shewanella bacterium. They allowed the beaker to sediment with bacteria and precursor materials during the night, during which the bacteria reduced the GO to a graphene material.
"The graphene oxide is easy to produce, but it is not very conductive due to all the oxygen groups in it," says Meyer. "The bacteria remove most of the oxygen groups, which turns it into a conductive material."
While the graphene material produced bacterially in Meyer's laboratory is conductive, it is also thinner and more stable than the chemically produced graphene. It can also be stored for longer periods of time, making it suitable for a variety of applications, including field-effect transistor biosensors (FETs) and ink conduction. FET biosensors are devices that detect biological molecules and could be used to perform, for example, real-time blood glucose monitoring for diabetics.
"When biological molecules bind to the device, they change the conductance of the surface, sending a signal that the molecule is present," says Meyer. "To create a good FET biosensor, a highly conductive material is desired, but it can also be modified to bind to specific molecules." The graphene oxide that has been reduced is an ideal material because it is light and very conductive, but generally retains a limited number of oxygen groups that can be used to bind to the molecules of interest.
The bacterially produced graphene material could also be the basis for conductive inks, which could in turn be used to make computer keyboards, printed circuit boards or small wires such as those used to defrost car windshields faster and more efficient. The use of conductive inks is a "simpler and cheaper way to produce electrical circuits, compared to traditional techniques," says Meyer. Conductive inks could also be used to produce electrical circuits on non-traditional materials such as fabric or paper.
"Our bacterially produced graphene material will lead to a much better suitability for product development," says Meyer. "We were also able to develop a" bacterial lithography "technique to create graphene materials that were only conductive on one side, which can lead to the development of new advanced materials on nanocomposites."
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Benjamin A. E. Lehner et al. Creation of graphene conductive materials by bacterial reduction by Shewanella Oneidensis, ChemistryOpen (2019). DOI: 10.1002 / open.201900186
Will your future computer be made using bacteria? (2019, 11 July)
recovered July 11, 2019
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