Science Interviews


Sun, 30th Sep 2007

Plastic Logic - Plastic Paper and E-Ink

Professor Henning Sirringhaus and Simon Jones, Plastic Logic

Listen Now    Download as mp3 from the show Smart Materials

Now, if you listen carefully you will notice that we, in the Naked Scientists are surrounded by paper. We usually try not to make you hear but similarly in offices all around the country incredible amounts of paper are thrown away on a daily basis. Iíd just like to point out that I take all my paper home to recycle. Maybe a better solution would be to remove the need to use all this paper in the first place and do away with all those hours spent photocopying and all those pages that come out of printers. We sent Azi to find out about the design and uses of plastic electronics and e-ink.

Azi - Iíve come to Cambridge Universityís Cavendish Labs and Iím joined by Professor Henning Sirringhaus, who is a founder and chief scientists for a company called Plastic Logic. Now, Professor Sirringhaus what exactly is Plastic Logic?

Henning - Plastic Logic is a little start-up company in Cambridge that make plastic electronics. So if you imagine your plastic bag that you use to do your shopping thatís a very uninteresting thing. It doesnít do much. But you can make electronic devices such as transistors, light emitting diodes, solar cells using these plastic materials in the same way that you would use silicon for conventional electronics. Plastic Logic is a company thatís exploiting this materials research for displays.

Azi - But how do you make plastic do the things that silicon does?

Henning - If you imagine a normal plastic material is made out of long-chain organic molecules, and depending on the way the atoms are arranged with respect to each other, that affects the electronic properties the material has. You can make it so that the material is completely insulating, conducting (like gold or copper) or a semiconductor.

Azi - So how do these flexible plastic displays actually work?

Henning - The core of the technology is to make plastic transistors using a plastic semiconductor. So what you need for a flexible display are lots of transistors on a flexible substrate. Plastic Logic uses PET, which is the material from which coke bottle are made as a substrate. It then deposits an array of transistors onto that substrate. It can be up to a million transistors. You then put that together with a display medium which consists of solid capsules that are filled with a liquid. Inside the liquid are coloured particles: some are white, some are black. The white ones are negatively charged and the black ones are positively charged. So when you apply a voltage the white ones might go to the top or the black ones might go to the top. Whether you get white or black is determined by the signal that the transistor beneath applies to the display medium. This is how you build up an image. Then you can make this flexible display: if you talk to my colleague, Simon Jones, he can tell you all of the wonderful things that you can do with it.

Simon - Iím Simon Jones and Iím responsible for product development at Plastic Logic.

Azi - Can I just ask you to explain what youíve got here?

Simon - Iíve got a couple of examples to show you. One is a thin sheet of plastic, which Iím bending in my hands. But itís a real display. Itís nothing like the display on your laptop screen. You could throw this to the other side of the room and it would not break. If you integrate a display like this with some electronics you can make a reading device and this is the other demonstrator Iíve got here. This screen is very unusual because it looks very much like paper. You can look at it from any angle and read it, which you canít do with a laptop screen. It only uses battery power when you change whatís on the screen. Itís incredibly power efficient.

Azi - So are you competing with pre-existing displays that are already incorporated into mobile phones and laptops?

Simon - No, weíre not competing. Weíre enabling a brand new kind of consumer activity which is comfortable digital reading. If weíre competing with anything, weíre competing with paper. Weíre seeking to replace the amount of paper that people print and carry around with them. Independent research has shown that it generates about 3kg of CO2 to get an average paperback book into the hands of the consumer. Depending on how much people read on these devices there could be a fantastic environmental benefit because of the paper that hasnít got to be manufactured.

Azi - Professor Sirringhaus, do you thin that a lot of people will rush to the shops to buy a paper substitute product?

Henning - I think there are a number of interesting applications that might convince people to rush to the shops and buy one. If you imagine for example, that you travel a lot around the world but you would still like to read your Cambridge Evening News when you are in Singapore you could download your newspaper from the internet and display it on this flexible display. That is clearly an application that some people might find attractive.

Helen - That was professor Henning Sirringhaus talking to Azi at the Cavendish Labs in Cambridge about a revolutionary design for reading. I certainly think it would be lovely to take the newspaper around the world with you as I do a bit of travelling myself. It may be the end of the crosswordÖunless you have a wipe-off pen.

Chris - Iíd be quite disappointed because I do like the crossword. Iím struggling with the Telegraph one: Iíve done half of it and I canít do the rest.


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