Graphene based materials: Past, present and future

We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field.

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Science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems

An introduction to heat transfer

Graphene-based nanomaterials for drug delivery and tissue engineering.

https://cyberleninka.org/article/n/323323.pdf

Production and processing of graphene and 2d crystals

This paper introduces an electrical four-point measurement method enabling thermal and electrical conductivity measurements of nanoscale materials. The method was applied to determine the thermal and electrical conductivity of reduced graphene oxide flakes. The dielectrophoretically deposited samples exhibited thermal conductivities in the range of 0.14–2.87 W m−1 K−1 and electrical conductivities in the range of 6.2 × 102–6.2 × 103 Ω−1 m−1. The measured properties of each flake were found to be dependent on the duration of the thermal reduction and are in this sense controllable.

https://iopscience.iop.org/article/10.1088/0957-4484/20/40/405704/pdf

An electrical method for the measurement of the thermal and electrical conductivity of reduced graphene oxide nanostructures

S1-S11 Further characterization of the structures 10 μm 10 μm a) b) 10 μm 10 μm 10 μm 10 μm a) b) Figure S1. Scanning electron microscopy (SEM) images of the resulting materials formed at flow-rate ratio of 1 and at concentration of: a) 0.0024M (TTF), 0.0006M (hydrogen tetrachloroaurate) and b) 0.0072M (TTF), 0.0018M (hydrogen tetrachloroaurate). Figure S2. Graph showing the correlation between average widths of the structures with their standard deviation and the flow-rate ratio of the synthesis. The averages are calculated from approximately 100 different wires chosen randomly and from different areas for each sample.

A microfluidic approach for the formation of conductive nanowires and hollow hybrid structures.

Numerical modeling and experiments are performed investigating the properties of a dielectrophoresis-based deposition device, in order to establish the electrokinetic framework required to understand the effects of applied inhomogeneous electric fields while moving particles to desired locations. By capacitively coupling electrodes to a conductive substrate, the controlled large-scale parallel dielectrophoretic assembly of nanostructures in individually accessible devices at a high integration density is accomplished. Thermal gradients in the solution, which give rise to local permittivity and conductivity changes, and velocity fields are solved by coupling electric, thermal, and fluid-mechanical equations. The induced electrothermal flow (ETF) causes vortices above the electrode gap, attracting particles, such as single-walled carbon nanotubes (SWNTs), before they are trapped by the dielectrophoretic force and deposit across the electrodes. Long-range carbon nanotube transport is governed by hydrodynamic...

Electrokinetic framework of dielectrophoretic deposition devices

A major obstacle in the realization of commercially viable single-walled carbon nanotube (SWNT) devices, hindering the functionality of this uniquely interesting type of material, is their type and site selective integration. Specifically, SWNT based piezoresistive pressure sensors require the incorporation of individual small bandgap semiconducting (SGS-)SWNTs at the positions of highest membrane strain. In this paper, the purely parallel fabrication of ultrasmall piezoresistive pressure sensors (membrane diameter 100–120 μm) with SGS-SWNTs as active transducer elements is demonstrated, using dielectrophoresis. Good alignment avoids strain components other than from the principal axis and superior strain sensitivity to state-of-the-art silicon based piezoresistive pressure sensors is achieved through the highly selective integration of SGS-SWNTs at high dielectrophoretic deposition frequencies. The long-term stable devices have sensitivities as high as S0 ∼0.25 ΔR R−1 bar−1, at a resolution better than 50 mbar, and a power consumption of less than 40 nW. The scale-up of the introduced robust and reliable fabrication process is straight-forward and provides very promising avenues toward successful realization of functional, commercially viable SWNT sensors.

Piezoresistive pressure sensors with parallel integration of individual single-walled carbon nanotubes

Graphene handling is still dominated by serial mechanical exfoliation, which may well facilitate measurements in a laboratory environment but does not allow reliable larger-scale integration. Herein we demonstrate the controlled, high-yield (>90%), site-selective deposition of ultrathin few-layer (three to ten) graphene oxide by dielectrophoresis between prefabricated electrodes. Individual layers are found near the edges. Initially insulating, thermal reduction at 450 °C thins out the two-dimensional few-atom thick films and dramatically reduces electrical resistances down to 40 kΩ. Conductivities between 15 and 36 S/cm are obtained. The introduced method permits the nonintrusive, parallel, large-scale assembly of soluble two-dimensional nanostructures and sheets.

Brian R. Burg

Papers

An electrical method for the measurement of the thermal and electrical conductivity of reduced graphene oxide nanostructures

A microfluidic approach for the formation of conductive nanowires and hollow hybrid structures.

Electrokinetic framework of dielectrophoretic deposition devices

Piezoresistive pressure sensors with parallel integration of individual single-walled carbon nanotubes

High-yield dielectrophoretic assembly of two-dimensional graphene nanostructures