Flexible friend

In the area of industrial eastern Germany affectionately known as ‘Silicon Saxony’ fledgling electronics company Plastic Logic is about to take a giant step. Thanks to a £51m windfall of equity funding from a range of venture capitalists and other interested parties — including big-hitters and potential rivals such as Intel — the Cambridge University spin-out is about to move into the brave new world of full-scale commercialisation.

Born in the university’s Cavendish laboratory — the same lab that developed the world’s first OLED displays — Plastic Logic has high hopes for its innovative plastic electronics technology, which could spell the beginning of the end for the printed word and a new era for magazines such as this one.

The technology that is threatening this seismic shift is the development of flexible, robust electronic circuits that can be integrated into flexible display screens.

Plastic Logic’s team of 60 staff — soon to be boosted to 90 — at its Cambridge headquarters now have the facilities to make flexible displays on a small scale for product trials. But its new facility in Dresden will have the capacity to produce more than one million units a year when it opens in 2008.

Simon Jones is the company’s vice-president of product development and, having spent some time working in the semi-conductor industry in the real Silicon Valley, he is excited about the massive change of scale and signal of intent that Plastic Logic’s move heralds. So far his career has focused primarily on the development of applications for new technologies and, in the field of plastic electronics, he believes his idea could loosen the silicon industry’s grip on the electronics market.

In Jones’ opinion it is time for printed text to follow other media, such as audio and video, into digital form. The content is already available. Early initiatives such as Google Book Search, which now has more than 10,000 books digitally stored in an online database, and Project Gutenburg, which has digitized more than 20,000 titles, are being joined by mainstream publishers such as Penguin, which lets users download books in e-book format from its website.

However, the reading devices used for such ‘e-books’ are still highly problematic. ‘All the displays we’re used to are built on a glass substrate. This is the reason why notebooks are so heavy and fragile,’ he said. ‘Also, people don’t want to read vast quantities of text on a screen for a long period of time. It flickers and the fact that the emissive screen doesn’t work well in the sun makes it very limiting, so people still print off lots of stuff on paper to read. When you read paper you constantly move it around, letting your eyes adjust and re-focus.’

Early products for reading e-books have relied on conventional LCD, glass-based screen technology that is heavy, fragile and uses a lot of power.

The development of electronic paper has helped solve at least some of those problems. E-paper is an easy-to-read, reflective material that looks much like paper and is bi-stable, meaning power is only used to change the displays.

The technology has been a huge improvement on existing LCD screens for comfortable reading but to switch the pixels in the screen, a glass substrate of silicon transistors has always been required. Not good enough, according to Jones.

‘This first generation of e-paper readers look like paper but because they still need the silicon substrate they feel a bit more like a notebook PC or a PDA than a book,’ he said.

In the active-matrix displays used for electronic readers each dot in the display is controlled by an electronic component, usually a thin film transistor (TFT).

Plastic Logic has developed a method for printing plastic transistors, rather than silicon, onto a flexible, plastic substrate. Its proprietary technology allows organic TFT’s to be embedded within specially developed polymer materials, which can then be printed as a solution onto the substrate. The process uses semi-conducting polymers and a series of direct-write techniques, including laser patterning.

At the spin-out’s lab in Cambridge the team has been able to manufacture flexible active-matrix displays that are up to 25cm in diameter at a resolution of 150 pixels per inch. Even better resolution has been demonstrated for smaller size displays. Jones hopes that, combined with e-paper, these thin, light and robust electronic modules could provide a far more acceptable digital reading experience.

‘It is much closer to the paper-reading experience than any type of screen there has been before,’ he said. ‘It makes it much more comfortable and natural to read digital text. You could read this on the sofa or in bed in a way that most normal people wouldn’t take a notebook PC to bed.’

Printable electronics has a number of other things going for it. Silicon transistors are made using a number of mask-based processes. The transistors are made up of a number of differently patterned layers, which are constructed by exposing the top surface to a photosensitive material that is deposited through gaps in the mask. This process is repeated a number of times to build up the silicon transistor.

According to Jones, printable plastic electronics have the distinct advantage that the materials can simply be printed on the substrate where they are needed. This means that just by changing the print file, different sizes and a wide range of products can be produced without all the re-tooling that the silicon industry requires, making it considerably cheaper.

As well as its potential low cost, it is the flexibility of plastic electronics that makes it such an exciting prospect for the future, in Jones’ opinion.

‘The wonderful thing about printable electronics is not only that it can be done at a very low cost but that it can be printed on soft objects,’ he said. ‘The vision of Plastic Logic is: “What if you can print electronic functionality on almost anything?”’

From clothing to mobile phones, Jones envisages a huge range of products that could be imprinted with plastic electronics. From moving advertisement hoardings to supermarket goods imprinted with electronic capability, Jones believes this technology could ‘entertain, inform and really do almost anything you can think of’.

He betrays some justifiable pride that a UK company is at the forefront of this technological breakthrough — albeit one about to begin manufacturing in Germany.

‘There has been a lot of R&D over the years put into getting plastic transistors right before someone could invest in the first full-scale commercial production, which is what we’ve done,’ he said. While there are a number of other plastic electronics R&D programmes under way in other parts of the world, particularly in France and Japan, Plastic Logic is already well ahead of the pack in terms of mature technology.

He added: ‘The common thread for all these other research programmes is that they are all still R&D efforts. We’ve already got a head-start and as soon as you start to scale up, your lead increases as you are continually learning more and more.’

Jones believes there is still room for traditional silicon transistors due to silicon’s high performance and density, which makes it suitable for use in computer CPUs. However, plastic electronics has the ability to move into new areas where silicon’s rigidity makes it unsuitable. That is where Jones believes its market lies in the future. For the time being, however, Plastic Logic’s plans for world domination are limited to the development — alongside e-paper producers — of a real alternative to paper-based reading.

But lovers of the paperback need not be concerned just yet. ‘Of course traditional books and publications will be around for quite a long time yet but there is a lot of reading that people would rather do digitally if it was easy and comfortable to do so,’ he said.

‘It only takes a small amount of that reading to go electronic to make it a fantastic opportunity. That is why our investors have backed us and why it is so exciting.’