Graphene has attracted a great deal of attention because of its unique electronic properties that were praised by the Nobel Prize in 2010. Graphene holds promise to become a material of choice for the next generation of photovoltaic cells, field-effect devices (FED), flexible electronics, advanced composite materials, biosensors and advanced membranes. Raman spectroscopy is an easy and non-destructive method that played a critical role in characterization of graphene materials.
Researchers at the Max Planck Institute of Colloids and Interfaces and collaborators at the University of California at Santa Barbara and the University of Chicago believe they have uncovered the basis how marine mussels use the byssus, a bundle of tough and extensible fibres, to fasten securely to wave-swept rocky coastlines.
(I) Mussels attach to hard surfaces in the marine intertidal zone with the byssus. (II) Byssal threads are extensible fibers with a hard and rough-textured protective cuticle (scanning electron microscopy). The knobby morphology of the cuticle originates from granular inclusions embedded in a continuous matrix. (III) The amount of dopa-iron complexes was found to be much higher in the granules than the matrix, which likely leads to their differences in mechanical performance during stretching. (Image: Matt Harrington, Max Planck Institute of Colloids and Interfaces)
An educational webinar from Materials Today is coming soon:
- Topic: Introduction to Raman Spectroscopy as a Characterization Tool for Graphene and Carbon Nanostructures
- When: Tuesday March 9th, 2010
- Time: 16h00 GMT, 11h00 EST
- Duration: 1 hour
Registration is free. Simply, follow this link to reserve your place.
Nanotechnology and nanoscience have certainly been one of the most popular fields of research in the last decade. Manufacturing processes are now able to carry out the deterministic synthesis of nanostructures with properties radically different from their macroscopic forms, enabling the realization of previously unthinkable devices. Despite these advances, few nanofabrication techniques feature the required characteristics for the commercial manufacturing of these new products in an effective fashion since they are either too slow, or too expensive and complex.
This page is a summary of my doctoral thesis project, accomplished at the Laboratory for multiscale mechanics at the École Polytechnique de Montréal (LM2, mechanical engineering). The main objective of this project was to develop a new manufacturing technique allowing the local synthesis of nanostructures on a surface for their eventual integration into nanodevices. The desired process has to be selective, reproducible, versatile, simple, fast and inexpensive for potential industrial utilization. Moreover, the manufacturing process must have a minimal environmental impact for sustainable development.
To implement the required specifications, a laser process combining the characteristics of laser-induced chemical liquid deposition (LCLD) and of sol-gel synthesis was proposed. The technique is very simple and consists of three steps. A precursor solution is first prepared. Next, a droplet of a controlled volume is transferred on a substrate by means of a micropipette. The droplet is then irradiated using a laser emitting in the infrared to induce the fast synthesis of nanostructures.
Freeform fabrication is a type of manufacturing process that allows the fabrication of 3D objects with a large variety of shapes, structure and composition. Laser-assisted chemical vapor deposition (LCVD) is a freeform fabrication technique that allows the deposition of micro-scale structures at a high growth rate with the flexibility of conventional CVD.
The LCVD process
During chemical vapour deposition (CVD), energy is given to a gas (the precursor gas) which contains the atom that we want to deposit. This energy dissociated the gaseous molecules by a series of chemical reactions in order to obtain a solid product (the deposit) on a surface where we want the deposition to occur (the substrate). This can be conceptualized by the following equation which describes the deposition of the gaseous species ABu :
ABu → A(↓) + u B(↑)