MRS Fall 2013 highlights – part two

My sketch of the roll-to-roll set-up proposed by the Mechanosynthesis group now based at MIT for high-throughput production of graphene.

My sketch of the roll-to-roll set-up proposed by the Mechanosynthesis group now based at MIT for high-throughput production of graphene.

A packed session on large-area graphene synthesis re-enforced the fact that there’s growing interest in making the material in amounts that push beyond lab-scale studies. On TMR+ this year, we’ve already featured a trio of commercial operations: Haydale in the UK, Graphene Nanochem, which has its production site in Malaysia, and – from the US – the University of Pennsylvania spin-out, Graphene Frontiers.

Graphene Frontiers has won a number of fans thanks to its roll-to-roll approach (see: roll-to-roll production could ramp up market opportunities for graphene), but they’re not the only ones exploring the concept.

A new twist on roll-to-roll production

Eric Polsen talked the audience through a concentric tube furnace design, which features an interesting twist on the roll-to-roll idea. Polsen is a member of the Mechanosynthesis group led by John Hart, who was previously at the University of Michigan and is now based at MIT.

As Polsen commented, roll-to-roll opens to the door to high-throughput production and has proven successful in delivering numerous materials, such as carbon fibre, in large quantities. He also acknowledged that they weren’t the first to look at how roll-to-roll techniques could be applied to graphene, citing studies by Hesjedal (2011) and Kobayashi (2013).

What does make the Mechanosynthesis team’s approach special though is the path that the copper foil (the substrate for CVD growth of graphene) takes from the feed spool through the tube furnance and into the collection chamber. The design features concentric tubes in which a carbon source (ethylene) is passed through the centre and the reducing agents (He/H2 are routed around the annulus. Wrapped around the inner tube is the copper tape, which can then travel through two distinct zones – first, an annealing zone, and then the growth zone, which is created as the carbon source enters through holes halfway along the inner tube.

Polsen explains that the tubular approach gives them much better control over vacuum conditions. The next step for the team is to ramp up the throughput via optimization of the synthesis recipe to acheive full coverage at speeds greater than 1 m/min.

Further reading on TMR+

MRS Fall 2013 highlights – part five (final)
MRS Fall 2013 highlights – part four
MRS Fall 2013 highlights – part three
MRS Fall 2013 highlights – part one

Webinar round-up: no one-size-fits-all solution for transparent conductive films

Khasha Ghaffarzadeh, head of consulting at market analyst IDTechEx, told attendees at yesterday’s webinar that there is currently no one-size-fits-all solution for transparent conductive films (TCFs), and new and expanding applications are opening up the market to include a range of materials.

One such driver is the demand for touchscreens, and although indium tin oxide (ITO) deposited on glass remains the dominant technology, it is being challenged on a number of fronts – for example, larger display sizes require films with lower sheet-resistance to manage current flow. Also, displays that are designed to bend or flex present another set of problems for touchscreen makers.

Ghaffarzadeh pointed out that switching from ITO-on-glass to ITO-on-film is one option, but for applications that require tight bending radii or for devices that are designed to flex many times, developers will have to consider alternative materials.

Here, graphene could be one to watch, especially given recent developments in roll-to-roll production (a topic covered on TMR+ last month). The material is flexible and robust, but these properties need to be matched by other parts of the device for the final package to be a success.

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Lab-on-a-chip production gets manufacturing rethink

Microfluidic negative for structuring films - click on image to expand (Credit: Fraunhofer IPT)

Microfluidic negative for structuring films – click on image to expand (Credit: Fraunhofer IPT)

Lab-on-a-chip (LOC) technology provides an ultra-compact solution for environmental monitoring and point-of-care diagnostics, to name just a couple of key applications. Measurement systems can be portable, easy-to-use, and require only small quantities of sample and reagents, but despite these strong selling points LOC devices have yet to realize their full potential in terms of market success.

“One of the main reasons LOCs don’t make it to market is that the methods used to fabricate them are often not transferable to industrial-scale production,” commented Christoph Baum, group manager at the Fraunhofer Institute for Production Technology (IPT) in Aachen, Germany.

To tackle the problem, IPT has teamed up with 11 European partners to streamline LOC production. Their plan is to develop a common manufacturing platform that combines roll-to-roll and inkjet printing, and integrates the key components of a LOC – microfluidic channels for liquid transport, optical components for analysis, and electrical circuits for channel heating and readout – on a layer-by-layer basis.

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Nanoimprint foundry launches in Singapore to bridge gap between lab and market

IMRE prototype roll-to-roll nanoimprinter (Credit: A*STAR IMRE, Singapore)

IMRE prototype roll-to-roll nanoimprinter – click on image to expand (Credit: A*STAR IMRE, Singapore)

The Singapore Agency for Science, Technology and Research (A*STAR) is backing nanoimprint lithography as a key technology for bridging the gap between laboratory-based nanotechnologies and market-ready products and devices.

Together with industrial partners and with the support of other government organizations, the agency has launched a nanoimprint foundry based at the Institute of Materials Research and Engineering (IMRE).

Companies participating in the initiative include Toshiba Machines of Japan and also local firms such as precision equipment manufacturer Solves Innovative Technology.

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Roll-to-roll production could ramp up market opportunities for graphene

Graphene Frontiers, a spinout from the University of Pennsylvania, US, has been awarded $745k from the National Science Foundation (NSF) to demonstrate and develop roll-to-roll production of continuous graphene film.

The company, founded in 2011, is using atmospheric-pressure chemical vapour deposition to produce graphene on continuous tapes of copper foil passed through a growth region. This eliminates the need for an expensive vacuum furnace and enables fabrication of graphene films larger than the furnace size.

The funding will allow the firm to show that these sheets can be transferred from the metal catalyst to nearly any smooth surface without any high-temperature steps and without the use of harsh chemicals. It’s also worth noting that the transfer process preserves the original metal substrate for reuse, which both lowers production costs and reduces waste.

Attracting investment
The award is part of the NSF’s Small Business Innovation Research programme, which recognizes “transformational technology with significant societal or commercial impact” – a phrase that could almost be a tagline for graphene, or at least that’s the hope.

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