X-ray: Paperless paper

Current uses and future
Uses of electronic paper as it stands today are many and varied. Obviously we can have digital books, or rather book readers, like Amazon's Kindle that debuted last year, as well low-power portable displays for everything from USB keys (see Lexar's Mercury JumpDrive) and watches through to billboard advertising. Ostensibly, as a film it could be easily integrated into wallpaper to give you a home where you can change its look every day, or into clothing and provide changeable or animated jeans, t-shirts, and jackets.

The most interesting feature of electronic paper is that it, ironically, doesn't so much herald a new age of personal and portable reading, or offices with e-paper in place of paper, but more simply another cheap and flexible mechanism for reading what we already read online, at work, and in our homes.
There's no need, for example, to have e- versions of magazines that magically materialise on a reader – nifty though this might be – because magazines are already evolving into web-based mixed media and. For all intents and purposes, you might as well just be browsing a website on a portable device – for which there are many ways to do this right now (such as the iPhone).

Where e-paper may make an impact however is in replacing – or creating the opportunity for – low-power portable displays that we haven't even imagined yet.

The shape of this future depends, of course, on production costs that will reduce as the technology continues to evolve and, on a tangent, the ancillary technologies any display needs – control circuitry, and power. And funnily enough, both of these are well underway as well – see the sideboxes 'Paper Power' and 'Paper transistors'.

All up electronic paper is one of those innovative inventions that will slowly change the way we live. Widespread use may be a while away yet but the applications of low-power, permanent, flexible displays are far too tempting to let slide. We built our world off the knowledge recorded on paper; it will be interesting to see where the next evolution of it takes us.

Paper power
It's all well and good having thin, flexible, displays but what about the electronics and power sources that go with them?
In terms of power, an Israel-based company by the name of Power Paper has a solution, and it doesn't get any simpler than this: printable batteries.
Power Paper's paper batteries work just like a normal battery, but use zinc and manganese dioxide inks as the cathode and anode, which are printed via silkscreening onto paper, or other fabrics. As these are considered 'dry' batteries, they also don't need casing to contain them.
The result is a battery as almost as thin as paper and, more importantly, just as flexible, making it possible to integrate them into everything from portable devices to clothing.
Currently, Power Paper uses its technology in a range of its pharmaceutical products that require small embedded power sources, but there's no doubt we'll find this technology in all manner of devices in the future.

Paper transistors
With flexible screens, and flexible power sources (see Paper Power sidebox), what's left for a future of truly flexible technology is – at least as a building block – a means to produce flexible transistors.
Which is precisely what some smart researchers at the Centro de Investigação de Materiais in Portugal recently produced – the world's first paper-based field-effect transistors (FETs).
Using paper as the dialectric layer for oxide field-effect transistors, the research team fabricated transistors on both sides to create both an electric insulator and a substrate for the transistors, and a world first in the process. According to the team the performance of the paper transistors is better than current state of the art oxide based thin film transistors (TFTs), to boot.
Interestingly, the motivation for the use of paper -- or rather its cellulose composition -- is the status of cellulose as the world's main biopolymer, making it a cheap and abundant source for building flexible electronics.