One potential application for graphene (sheets of graphite only one or several layers thick) is as a resonator in nanoelectromechanical systems, in part because of the high ratio of stiffness to mass. However, the formation of large-area films of exfoliated graphene and manipulation of the graphene flakes are experimentally challenging. An alternative is to use a related material, graphene oxide, in which the graphene film is chemically modified with oxygenated substituents. Robinson et al. rapidly deposited graphene oxide platelets onto glass by spin casting along with rapid solvent evaporation, which formed ultrathin continuous films. These films could then be chemically reduced, and despite being as thin as 4 nm, could be released from the substrate by being dipped into basic solution. They could then be suspended onto substrates patterned with circular holes (between about 3 and 7 ?m in diameter) in order to form drum resonators. Laser interferometry revealed that these membranes resonate in the radiofrequency range and have quality factors up to 4000, which is comparable to those of diamond oscillators and exceeds typical values for graphene oscillators (10 to 200). This increase relative to graphene reflects the enhanced adhesion of graphene oxide to glass surfaces through surface oxygen groups. -- PDS
Nano Lett. 8, 3441 (2008).
