A team of researchers from Dioxide Materials and the University of Illinois at Urbana-Champaign has shown that an efficient chemical sensor can be made by stacking graphene flakes randomly.
The research team produced the carbon lattice flakes having one-atom-thickness by bombarding bulk graphite placed in a solution with ultrasonic waves, causing the material to break into thin sheets. The team then produced a graphene film with randomly aligned stacked flakes by filtering the solution. It used the resultant graphene film for making the topmost layer of a chemical sensor.
The chemical sensor’s exposure to test chemicals modifies the surface chemistry of its graphene film, causing the generation of an electrical signal by the subsequent electron movement through the film. This signal marks the existence of the chemical. During the experiment, the research team produced thinner and thicker films by varying the quantity of the filtered solution. The team discovered that thin films composed of haphazardly stacked graphene are capable of detecting microscopic quantities of test chemicals more reliably when compared to earlier sensors made of graphene crystals or carbon nanotubes.
The research team predicted that the optimized sensitivity is caused by the fact that flaws in the carbon-lattice structure in the vicinity of the boundary of the graphene flakes make the electrons to ‘hop’ easily through the graphene film. Applied Physics Letters, a journal of the American Institute of Physics, has accepted to publish the team’s article titled ‘Chemical Sensors Based on Randomly Stacked Graphene Flakes.’
Source: http://www.aip.org