Multi-frequency sound production and mixing in graphene

This is the final version of the article. Available from the publisher via the DOI in this record.The ability to generate, amplify, mix and modulate sound in one simple electronic device would open up a new world in acoustics. Here we show how to build such a device. It generates sound thermoacoustically by Joule heating in graphene. A rich sonic palette is created by controlling the composition and flow of the electric current through the graphene. This includes frequency mixing (heterodyning), which results exclusively from the Joule mechanism. It also includes shaping of the sound spectrum by a dc current and modulating its amplitude with a transistor gate. We show that particular sounds are indicators of nonlinearity and can be used to quantify nonlinear contributions to the conduction. From our work, we expect to see novel uses of acoustics in metrology, sensing and signal processing. Together with the optical qualities of graphene, its acoustic capabilities should inspire the development of the first combined audio-visual nanotechnologies.This work was funded by the EPSRC (EP/G036101/1

Electrochemical doping of graphene

The electrical properties of graphene are known to be modified by chemical species that interact with it. We investigate the effect of doping of graphene-based devices by toluene (C6H5CH3). We show that this effect has a complicated character. Toluene is seen to act as a donor, transferring electrons to the graphene. However, the degree of doping is seen to depend on the magnitude and polarity of an electric field applied between the graphene and a nearby electrode. This can be understood in terms of an electrochemical reaction mediated by the graphene crystal.The authors thank H. Pinto, R. Jones, A. S. Shytov, S. J. Green and D. W. Boukhvalov for useful discussions, P. R. Wilkins for technical support, and the EPSRC (grant numbers EP/G036101/1 and EP/G041482/1) for funding

A thermophone-based bridge circuit for the measurement of electrical and thermal properties of thin films

This is the final version. Available from the IOP Publishing via the DOI in this record. Data availability statement: The data that support the findings of this study are available upon reasonable request from the authors.Sound can be generated via modulated Joule heating of thin conductive films. Its amplitude and phase are sensitive to the electrical and thermal properties of the film. Here we show how such sound can be used to measure and quantify these properties. In particular, we experimentally determine the relative conductances of electrical paths in a multi-branched thin film, which can then be used to find the temperature dependence of the film conductance. This is achieved by nullifying the sound at a given point in the sound field using simple voltage control. This method, essentially an acoustic analogue of an electrical bridge circuit, is advantageous since it allows for electrical and thermal properties to be measured simultaneously. These attributes benefit the characterisation of complex circuit architectures, as well as thermal sensing.Engineering and Physical Sciences Research Council (EPSRC)Engineering and Physical Sciences Research Counci

Coupling and confinement of current in thermoacoustic phased arrays

This is the final version. Available on open access from the American Association for the Advancement of Science via the DOI in this recordData and materials availability: All data are available in the manuscript or the Supplementary Materials.When a medium is rapidly heated and cooled, heat transfers to its surroundings as sound. A controllable source of this sound is realized through joule heating of thin, conductive films by an alternating current. Here, we show that arrays of these sources generate sound unique to this mechanism. From the sound alone, we spatially resolve current flow by varying the film geometry and electrical phase. Confinement concentrates heat to such a degree that the film properties become largely irrelevant. Electrical coupling between sources creates its own distinctive sound that depends on the current flow direction, making it unusually sensitive to the interactions of multiple currents sharing the same space. By controlling the flow, a full phased array can be created from just a single film.Engineering and Physical Sciences Research Council (EPSRC)Royal Societ

Influence of luminescent graphene quantum dots on trypsin activity

Tanveer A Tabish,1,2 Md Zahidul I Pranjol,2 Ilayda Karadag,1 David W Horsell,1 Jacqueline L Whatmore,2 Shaowei Zhang1 1College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK; 2Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, UK Background: Protein–graphene interactions have the potential to play a pivotal role in the future directions of nanomedicine. These interactions lead to diverse processes such as generation of protein coronas, nano–bio interfaces, particle wrapping, and biocatalytic processes that could determine the ultimate fate of graphene nanocomposites in biologic systems. However, such interactions and their effects on the bioavailability of graphene have not yet been widely appreciated, despite the fact that this is the primary surface in contact with cells.Methods: This paper reports on the integrative physiochemical interaction between trypsin and graphene quantum dots (GQDs) to determine their potential biologic identity in enzyme engineering. This interaction was measured by a wide range of analytical methods.Results: Definitive binding and modulation of trypsin–GQDs was demonstrated for the first time by use of vibrational spectroscopy and wetting transparency, which revealed that trypsin was absorbed on GQDs’ surface through its cationic and hydrophilic residues. Our findings suggested that trypsin’s active sites were stabilized and protected by the GQDs, which were likely to be responsible for the high bioavailability of GQDs in enzymes.Conclusion: Our work demonstrates the efficacy of GQDs as an enzyme modulator with high specificity, and their great application potential in enzyme engineering as well as enzyme-based therapies. Keywords: graphene, enzyme, luminescence, bioavailability, surface energy&nbsp

Az ASS Berendezési Rendszerek Ipari Bt. vagyoni, pénzügyi és jövedelemi helyzetének elemzése

This is the final version. Available from Dove Medical Press via the DOI in this record.Background: Protein–graphene interactions have the potential to play a pivotal role in the future directions of nanomedicine. These interactions lead to diverse processes such as genera-tion of protein coronas, nano–bio interfaces, particle wrapping, and biocatalytic processes that could determine the ultimate fate of graphene nanocomposites in biologic systems. However, such interactions and their effects on the bioavailability of graphene have not yet been widely appreciated, despite the fact that this is the primary surface in contact with cells. Methods: This paper reports on the integrative physiochemical interaction between trypsin and graphene quantum dots (GQDs) to determine their potential biologic identity in enzyme engineering. This interaction was measured by a wide range of analytical methods. Results: Definitive binding and modulation of trypsin–GQDs was demonstrated for the first time by use of vibrational spectroscopy and wetting transparency, which revealed that trypsin was absorbed on GQDs’ surface through its cationic and hydrophilic residues. Our findings suggested that trypsin’s active sites were stabilized and protected by the GQDs, which were likely to be responsible for the high bioavailability of GQDs in enzymes. Conclusion: Our work demonstrates the efficacy of GQDs as an enzyme modulator with high specificity, and their great application potential in enzyme engineering as well as enzyme-based therapies.EPSRCFORCE Cancer Charit