Our plastic transistors are made from an organic semiconductor in place of silicon and plastic insulators to replace the thin layers of glass in a conventional display. E Ink's Visplex material has the highly desirable property that once an image has been written to it, it can retain the image for many years with little degradation. We use the storage capacitor memory element for the second or so that it takes to put the image on the display."
However, what about the Visplex frontplane? I asked E Ink's Sriram Peruvemba, VP of Marketing, to describe how that works. "Electronic ink is a proprietary material that is processed into a film for integration into electronic displays," he explained.
"Although revolutionary in concept, electronic ink is a simple fusion of chemistry, physics and electronics. The principal components of electronic ink are millions of tiny microcapsules with the rough diameter of a human hair. In one incarnation, each microcapsule contains positively charged white particles and negatively charged black particles suspended in a clear fluid. When a negative electric field is applied, the white particles move to the top of the microcapsule where they become visible to the user.
This makes the surface appear white at that spot. By reversing this process, the black particles appear at the top of the microcapsule, making the surface appear dark. These microcapsules are suspended in a liquid 'carrier medium', allowing them to be printed using existing screen printing processes onto virtually any surface, including glass, plastic, fabric and even paper."
It's clear that plastic displays are light and tough, and they can also be flexible, but what does this mean in terms of applications? I put this question to Joe Eschbach, VP of Marketing with Plastic Logic.
"Today, the first application of our plastic electronics technologies is in incredibly light, thin and large displays. These displays will be a key part of a consumer electronics product that we will be shipping in early 2009 to acquire, manage, and consume business and recreational digital content for greater productivity at work and enjoyment at home. Extending our technology, one can imagine other products that might include immersive displays for online gaming and social networks, home theatre screens replacing today's bulky and very heavy displays, large format devices the size of newspapers, smaller rollable-displays for mobile devices, displays embedded in clothing and so on."
Power supplies
We might like to think that we enjoy a mobile lifestyle, but drained batteries are a fact of life. However, developments in the area of plastic power sources might just change all that – as scientists at Brown University, Rhode Island have demonstrated.
Tayhas Palmore, an associate professor in Brown's Division of Engineering, explained that batteries have to be recharged, are expensive and don't deliver a lot of power ,whereas the alternative of super-capacitors can deliver that big blast of power, but don't have much storage capacity. The work at Brown, therefore, has involved the use of plastics to combine elements of both a battery and a capacitor.
Their prototype battery consists of strips of gold covered with two conductive polymers, separated by a papery membrane to prevent a short circuit. This hybrid battery has some remarkable properties. It can be charged very rapidly, like a capacitor, and it can store and deliver that charge over long periods of time, like a battery. It has twice the storage capacity of a double-layer capacitor and it delivers more than 100 times the power of a standard alkaline battery. However, perhaps even more significant is its physical properties. The new battery is smaller than an iPod Nano and as thick as an overhead transparency.
