fantastic plastic

According to their press release

Toppan Printing Co., Ltd. has developed an amorphous oxide semiconductor thin film transistor (TFT) array and succeeded in driving an electrophoretic E Ink front panel laminate to fabricate a prototype flexible electronic paper display.

Apparently the amorphous InGaZnO semiconductor used here has a higher charge carrier mobility (> 5cm^2/Vs) than a-Si and can be deposited at room temperature. Flexible TFTs based on a-InGaZnO were first demonstrated by Professor Hosono and coworkers at Tokyo Institute of Technology (Nomura et al, Nature 432, 488 (2004)).
All layers of the 2 inch diagonal (80 x 60 pixels) display were deposited onto the flexible PEN substrate by sputtering, but Toppan plans to deposit and pattern some of the layers by printing.

Toppan plans to develop flexible TFTs with goals to commercialize thin, lightweight and flexible displays such as electronic paper, starting with a practical prototype display in fiscal 2008. In parallel, we aim to introduce printing methods into the fabrication process of flexible TFTs for simplification and cost reduction.

Note: This research was reported at IDW’05 as EP2-4L (International Display Workshop, Dec.6-9, 2005, Takamatsu, Japan)

As reported in Science magazine (”An Integrated Logic Circuit Assembled on a Single Carbon Nanotube”; 24 March 2006; Vol. 311, no. 5768, p. 1735), researchers at IBM in New York and co-workers have created a ring oscillator on a single carbon nanotube.

According to the BBC, running at 50 megahertz,

the circuit is 100,000 times faster than any previously recorded for a device made with a carbon nanotube […].

This article at the New Scientist explains how this research might help to increase the speed of future microprocessors with ever smaller feature sizes:

The problem is that as electrical paths shrink, electrical resistance increases proportionally. Also, the process of doping – adding impurities to the silicon to alter its electrical properties – means that the impurities left behind scatter electron flow, which becomes more of a problem at smaller scales.
The major reason behind the resistance, however, is an odd phenomenon known as plasmonic resonance, in which an electron’s path is hindered when it becomes coupled with vibrations in the surrounding lattice structure. But because the carbon nanotube is a single molecule with electrons passing along the tube, this problem is averted and resistance minimised, even at tiny scales.
Additionally, smaller silicon pathways make it easier for electrons to “jump tract” and leech into other nearby components. But in a nanotube circuit, this would be highly improbable as electrons would be carried down the molecular tract of the nanotube, Appenzeller explains.

EETimes is reporting on a new printhead using an OLED light source.

Epson Corp. said it has developed a print head using an organic light-emitting diode (OLED) light source, which is touted as achieving printing performance comparable to that of laser printer heads.
Sumitomo Chemical Co. Ltd. collaborated with Epson on the prototype printer head from the material side, supplying red polymer OLED material. […]
Epson intends to merge its low-temperature polysilicon TFT technology with the OLED technology to build a one-body printer head module with OLED and IC integrated on it.

Printers using an array of inorganic LEDs instead of a laser as light source have been around for a while. From an article from 2002:

LED (light-emitting diode) page printing - invented by Casio, championed by Oki and also used by Lexmark - was touted as the next big thing in laser printing in the mid-1990s.

Unlike laser printers, LED printers do not require any moving parts (mirrors) to selectively illuminate the photo-receptive drum, but are limited in resolution by the size of the LEDs.

From the BBC:

The aim of the consultation exercise is to gauge reactions to RFID by both businesses and citizens in Europe.
Viviane Reding, the EU commissioner behind the exercise, warned that wider use of RFID would not be allowed to undermine the fundamental liberties that European citizens enjoy.

According to Vint Cerf, one of the “founding fathers of the Internet” and Google’s “Chief Internet Evangelist“,

“RFID could solve the mystery of missing socks and that’s a very important contribution to society,” said Mr Cerf.
As a more serious example, Mr Cerf said RFID tags could be used in hospitals to label medicines to ensure that drugs were used before they expired and, in conjunction with tags worn by patients, could make sure the right treatment was administered.

Regarding privacy issues:

Malcolm Crompton, former federal privacy commissioner for Australia and now a consultant on RFID issues, said it was important that safeguards for personal data were built into any laws governing the use of the tags. […]
For instance, said Mr Crompton, standards could mandate the use of RFID in the form of a tag that a person could snap in half so that it could no longer pass on information.

Nikkei Electronics Asia has a cover story on the growing market for electronic ink applications.
Apparently E Ink has solved the ‘after-image’ or ‘ghosting’ problem seen in early applications, such as the Sony Librie. Two of the products available (in Japan) since January 2006 are the Seiko E Ink Watch and the Ishida shelf price tag system using SiPix. Electronic ink is ideally suited for such applications with very low refresh rates (e.g. 1 update per second), but in the longer run, we can expect to see it used in more demanding applications such as notebook screens:

In March 2005, Intel Corp of the US disclosed that Intel Capital Corp of the US had invested into E Ink. A source at Intel explained: “About a third to a half of power used in today’s notebook PCs is used by the display. If notebooks could use E-paper it would mean a significant reduction in power consumption, and at the same time provide a big improvement in readability outdoors.”

Regarding the different technologies,

the E-papers expected to reach the practical level in 2006 to 2007 can be broadly divided into the particle-based type from firms like E Ink, SiPix Imaging and Bridgestone Corp of Japan, and the cholesteric liquid crystal type from companies including Asahi Glass, Fuji Xerox Co Ltd of Japan and Fujitsu. Even under a single type category, though, the implementation technology may be widely different, with each manufacturer stressing the unique advantages of its own approach (Table 1).

Particle-based E-paper uses an electric field to move black and white particles up and down to change the image. The E Ink method of handling black and white particles is probably the best-known of the microcapsule liquid approaches, but the Bridgestone approach, for example, moves the particles up and down in air for an extremely fast response speed of only 0.2ms. Unlike E Ink’s device, which is designed for dot display with active drive, the Bridgestone design offers high-definition dot displays even with a passive drive. Dr Hiroaki Wada, general manager, Dept of High Performance Product Development, Research & Development Div, Bridgestone, pointed out: “We have already prototyped a high-definition E-paper using the cheap and simple passive-drive design, achieving XGA resolution (1,024 x 768 pixels) on a 7.5-inch screen.”

Cholesteric liquid crystal E-paper is stable in both transparent and reflective states, making use of the unique properties of liquid crystal. Fujitsu stacked three cholesteric liquid crystal layers, each selectively reflecting a different wavelength, to prototype a 4,096-color design. The firm’s Hashimoto commented, “We will also develop a 260,000-color model before the end of fiscal 2005.” Asahi Glass’s Satoshi Niiyama, unit leader, Research Center, said, “We have built in a technology to eliminate the ‘burning in’ that can occur with cholesteric liquid crystal.”

The article discusses optically rewritable e-paper, where

new data can be projected onto the paper from the rear to rewrite the displayed image. This is possible because of a unique structure, with a photosensitive layer positioned under the cholesteric liquid crystal film. When irradiated by light from the side opposite the liquid crystal, the resistance of the photosensitive layer changes in proportion to optical intensity. The liquid crystal film, connected in series to the photosensitive layer, changes the displayed image because the voltage input changes in relation to that resistance.

This principle of operation makes it possible to eliminate electrode patterning, for pixels. In fact, the only drive electrode is the single one covering the entire plane. Because of this, explained Fuji Xerox’s Mita, “Our approach is not limited by the drive electrodes, making it a lot easier to drop costs and fabricate larger screen sizes.”

In the future, the firm hopes to make it possible to just press this E-paper against a computer monitor in the office to automatically write the screen image to the E-paper. At present, however, a dedicated writer is required to provide the high optical intensity and directional light beams required.

Color and flexibility of the display are also addressed:

The most aggressive player in this field is E Ink, which displayed a prototype E-paper full of original technology at FPD International 2005, in October 2005. The prototypes included a 4,096-color model made using color filters developed by Toppan Printing Co, Ltd of Japan; a model with improved display performance, such as reflectivity, made with an improved ink which retains brightness even when used with color filters; and a flexible model using thin-film transistors (TFT) on a stainless steel substrate, developed jointly with LG Philips LCD Co, Ltd of Korea and others. At present these characteristics are implemented in independent products, but the firm plans to bring all of the constituent technologies together into one E-paper product in about 2007.

Regarding available technologies for the TFT backplane on a flexible substrate the article states:

Organic TFT and other materials are not expected to be ready for commercial use by around 2007, though, meaning that the firm [E Ink] could lose the business window of opportunity. It identified TFT on stainless steel substrate as a strong candidate; it can be manufactured on the same equipment used to make amorphous Si TFT, leading Kuwada to believe that it “…is the technology for TFT on a flexible substrate likely to be brought to the practical level first.” […]
[There] are a number of competitors for TFT on flexible substrate. Seiko Epson has a proprietary technology to transfer TFT from a glass substrate to a plastic one, using Surface Free Technology by Laser Ablation/Annealing (SUFTLA). The firm is applying SUFTLA in the development of peripheral technologies such as microprocessors and memory, in addition to E-paper (Fig 4).

Acreo, in collaboration with Linköping University, are developing low-cost electronics printed on paper. Their focus is on electrochemical devices, such as electrochromic displays. The change between bright and dark state is based on the difference in absorbtion of a polymer, e.g. PEDOT:PSS, in the oxidised versus the reduced state. Switching occurs at low voltages (0.6 to 0.9V), but is inherently slow (~1s).
The difference in conductivity of polymers, such as PEDOT:PSS, PANI, Polypyrrole and Polyhexylthiophene, between different redox states can be used to fabricate electrochemical transistors.

Other applications exploiting a change in material properties upon oxidation/reduction are a wettability switch and and a switchable polariser.

Acreo is using different printing techniques (e.g. screen- and offset-printing) to deposit layers such as the conducting polymer and polymer electrolyte layers.

Thin Film Electronics (TFE) are developing low-cost non-volatile memory, consisting of a bistable polymer layer between two arrays of orthogonal addressing lines. This technology provides several advantages compared to conventional, silicon-based memory. As the memory function is a property of the acticve layer, no circuitry is required in the actial memory element. Further, the simple architecture allows stacking of multiple layers for greater capacity per unit area. Using printing methods to deposit the solution-based promises low manufacturing costs.

From recent coverage of Printed Electronics USA 05 by IDtechEx (Feb 13, 2006):

Thin Film Electronics of Sweden described how it can print memory on plastic film. It has now demonstrated kilobit level memory but seeks to license not produce and the gigabyte on a postage stamp, with its immense commercial potential, is still elusive.

TFE’s website does not provide a lot of information on the material used for the active layer, but according to some of their patents (US 6,982,895, US 6,937,500, US 6,841,818) a polymeric ferroelectric or electret material, such as PVDF, can be used. A more recently filed patent (US200524343) concerns interlayers (e.g. metal oxides or ternary ceramics) between the electrode(s) and the active polymer layer.