Introduction and the flexible future
Like most good ideas, it all started with a pencil. Derived from the graphite that's been used to make the lead in your pencil for over 500 years, graphene has been hailed as the miracle material of the twenty-first century. It's the world's strongest, thinnest and most conductive material, but what is graphene and why is it so important?
Theoretically possible since the 1940s, graphene was discovered and produced by Konstantin Novoselow and Andre Geim at the University of Manchester in 2004. Both scientists won the Nobel Prize in 2010 for their pioneering work, and since then the race has been on to make graphene a commercially viable industrial material.
Super-thin, super-strong and super-flexible, the uniquely two-dimensional graphene conducts electricity better than copper and it conducts heat better than any other known material in thermal conductivity. Near-transparent sheets of carbon graphite molecules just one atom in thickness, graphene sheets are described as 'chicken wire made of carbon atoms'.
But what's it for?
Graphene in tech
In an industry that compares smartphones on how many millimetres thin they are, graphene is incredibly attractive. "It's estimated to take a million sheets of graphene to be just a millimetre thick," says Dr Kevin Curran, senior member at the Institute of Electrical and Electronics Engineers (IEEE) and Reader in Computer Science at Ulster University. "Any technology that can shave millimetres from a gadget is extremely valuable."
Think flexible phones, super-efficient high-speed computing, and wearable devices with total pliability. "Flexible displays on phones are gimmicky to date, but flexible displays on true wearables have potential to transform the wearable space," says Curran. "Graphene is also transparent so this opens up the market to completely new wearables – and all would benefit from the incredible lightness of the material." Despite its lightness, graphene is reckoned to be 200 times stronger than steel.
However, perhaps the biggest advance graphene could make to portable electronics is battery life. "It has the potential to enable lithium batteries to have more than 10 times the electrical capacity of current batteries," says Curran. That would make smartphones last over a week between recharges, and a Kindle as much as a year.
Graphene's flexible future
It's with wearables and the Internet of Things that graphene could find its sweet-spot. Graphene increases the conductivity of radio-frequency identification (RFID) tags by as much as 50 times. Such tags are increasingly used to wirelessly transfer data, largely to track the location of freight, kids and pets. Back in May, scientists at the University of Manchester revealed a graphene antenna capable of delivering more powerful RFID tags and wireless sensors.
Made from compressed graphene ink, the antenna is flexible and can be printed onto paper or plastic – instead of a copper or aluminium-based RFID tag being attached to freight, cargo and luggage, it could be stamped on with ink at an airport check-in desk.
Bandgap problem and cost issuesSuperfast computing
Graphene could also revolutionise telecoms. "Researchers have already demonstrated incredible speeds over 100 times the current speed of the internet backbone in transmitting information," says Curran. "At present, optical switches, which route information over optical cables, respond at rate of a few picoseconds – around a trillionth of a second. With graphene, this can be improved to one hundred femtoseconds, which is almost 100 times quicker."
Electrons can travel across graphene at almost the speed of light, nearly 250 times faster than they move through silicon – graphene's killer app could be ultrafast transistors. On the lookout for silicon's replacement for years, the world of computing is holding its breath.
However, for graphene to replace silicon, scientists need to solve the problem of the on-off state, which could take years, and may not prove possible.
"Currently graphene transistors are difficult to turn off, and that can be a game-stopper because in digital electronics you need the off-state to block current flow, and to have no dissipation when the transistor is in the off-state," says Curran. This is known as the 'bandgap' problem.
The 'bandgap' problem
"We are targeting two-dimensional materials with a bandgap to create a transformational new flexible transistor device that will enable a wide range of high frequency switching applications," says Mike Banach, Technical Director at Cambridge-based FlexEnable. One of those materials is graphene.
FlexEnable has just joined the Graphene Flagship, an EU initiative to support the transition of graphene and other advanced materials from academia to industry. The 140+ members include Nokia, Airbus, Philips, Alcatel Lucent, BASF, Ericsson and BAE, which gives clues as to who's most excited about graphene, and why. Think more efficient electronics, lighter aircraft components and faster telecoms.
So why hasn't graphene been commercialised yet? "Graphene is a material, not a technology," says Banach. "It does take time to develop good technology from new materials, and I believe that the wider commercialisation of graphene will occur as more applications emerge that truly utilise the material's unique properties."
The transition from university labs to the real world all hinges on the development of cost effective industrial processes. That's exactly what FlexEnable is doing – last year it showed off a truly flexible display based on a transparent graphene conductor, which was integrated into its flexible transistor array. Using graphene as the completely transparent conductive layer on plastic, the aim is to create flexible, unbreakable LCD and OLED displays, a market forecast to be worth £25 billion (around $38 billion, or AU$50 billion) by 2020.
The brittle truth
However, there is a major manufacturing problem at the core of the embryonic graphene manufacturing industry. "Graphene frays at the edges in most manufacturing processes, which leads to brittleness," says Curran. "It is also very difficult to manufacture in a pure form over an area, as one of the key beneficial properties come from its symmetrical, honeycomb-like single atomic layer structure."
Graphene is also a potentially hazardous substance. "There is also an issue of these ultra-small sharp edges piercing lung or skin cells and perhaps interfering with their function by rupturing cell membranes," says Curran.
Scarce and expensive
If graphene isn't easily manufactured, neither is it easily sourced; there's a lack of high-quality defect-free graphene available. Though there are graphite producers in South Korea, India, Mexico, Ukraine, North Korea, Brazil, Turkey and the Czech Republic, the majority of graphite mining is in China, and threefold price hikes in recent years have earned it a place on the British Geological Survey's most recent 'risk list' of chemical elements or element groups of economic value.
The price increase is in response to the increased demand for graphite – the most stable form of carbon – to manufacture golf clubs, tennis rackets, and electrical components and circuitry. "The amount of material to cover the head of a pin can cost anywhere between £1,000 to £3,000, so when we scale this up to the size of small handheld consumer appliances, we are speaking about a premium price," says Curran. "By comparison, electronics-grade silicon is about 800 times cheaper." So semiconductors probably aren't going to swap to graphene anytime soon.
That hasn't stopped 10,000 graphene-related patents proposing that this so-called wonder material be used in everything from electric vehicle batteries and aircraft, through to superfast phone chargers, medical diagnostic devices, sports equipment, and even super-high buildings.
Ice on helicopter blades could be melted in seconds. Graphene could even be used as the base material for solar cells, which could lead to innovations like photovoltaic paint – the walls of a house could literally soak up energy from the sun, and heat the house. There are even suggestions that graphene could soak up radiation, and be used to treat paralysis.
However, the true potential of graphene will always remain theoretical until scientists conquer the problems of both mass production and the band-gap. And either of those could take decades to be resolved.
Graphene: the miracle material explained
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Original source: In depth: How graphene could revolutionise the tech industry.
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