▎ 摘　　要

NOVELTY - A method of producing reduced graphene oxide film involves providing a mixture of graphene oxide platelets, water, and an organic solvent; spin coating the mixture by placing a drop of the mixture on a spinning substrate while blowing a drying gas onto the substrate and allowing the water and the organic solvent on the substrate to evaporate; and repeating the spin coating at least one time to form a graphene oxide film in contact with the substrate. USE - For producing reduced graphene oxide (GO) film useful in sensors, in optical modulator and switch (claimed). Also useful as a transparent electrode or thin-film transistor; and as the active material for the direct electronic detection of chemical/biological analytes and as an electronic material for flexible large-area displays; and to form suspended membranes with potential application in nanomechanical devices, electromechanical optical modulators, permeable membranes, filters for organic and biomolecular species, and nanofluidics. ADVANTAGE - The method provides low-cost production. The deposition and transferring of large-area reduced GO thin-films is possible using simple bench-top chemistry. Because GO films can be deposited via spin-casting or air-brushing, they can be fabricated on a variety of substrates, as well as transferred to any substrate. The chemistry of the release step for reduced GO thin-films is selective such that the film is only released from regions of the substrate that were in direct contact with the basic KOH or NaOH solution. The reduced GO thin-film chemical sensors provide increased signal. For a range of chemical analytes the conductance response of the graphene oxide sensor may be greater than pure carbon nanotube films. The two-dimensional natural of the reduced GO thin-film may allow for fewer charge fluctuations, resulting in a decrease in low-frequency noise of one- to two- orders of magnitude. Reduced GO thin-films may be deposited at room temperature by spin-coating or air-brushing allowing the use of inexpensive flexible substrates. Graphene oxide can have considerably more oxygen functional groups than carbon nanotubes. Thus the GO thin-films may be more readily functionalized, leading to chemical detection specificity. The GO thin-film may be almost completely transparent, as observed by a very slight color contrast between the film and substrate. After reduction, GO increases in conductivity by four- to five-orders of magnitude and can be modulated by 200-300%. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) film (F1) comprising overlapping platelets of reduced graphene oxide, where the film is 1-100 nm thick and is in electrical contact with two electrodes; (2) sensor comprising the film (F1) and the electrodes; an intake that contacts a fluid sample to the film; and an electrical meter in contact with the electrodes, where the film is in contact with a contoured substrate such that portions of the film are suspended above the substrate; (3) mass sensor comprising the film (F1) and contoured substrate; and a device that measures vibrations of the suspended film; (4) device comprising the film (F1) and contoured substrate, where the space between the suspended film and the contoured substrate is a microfluidic channel; (5) optical modulator comprising the film (F1) and contoured substrate, two electrodes in electrical contact with the film; a voltage source attached to the electrodes that applies a voltage that causes a portion of the suspended film to contact the substrate; (6) switch comprising the film (F1) and contoured substrate; two electrodes in electrical contact with the film; a third electrode on the substrate below the suspended portion of the film; a voltage source attached to the electrodes in electrical contact with the film that applies a voltage that causes a portion of the suspended film to contact the third electrode.