A prototype display developed by Opalux.

Last week, a panel of experts at EmTech@MIT discussed technologies that could hasten the arrival of color e-readers.

While the panelists agreed that high-quality color displays could make portable reading devices more attractive to advertisers and deliver a richer experience for readers, they were less unanimous on the best way to deliver color screens.

Two companies are hoping to use reflective microstructures--the same kind seen in opals and on butterflies' wings--to develop color displays.

Opalux uses a sponge-like polymer structure that mimics that of an opal. When a voltage is applied, the material expands, changing the wavelength of light that it reflects."So you can basically take one material and get all the colors you want," says the company's CEO, Andre Arsenault.

Qualcomm is also making color displays with photonic microstructures. The company has developed a MEMs structure that sits on glass and opens and closes depending on the voltage applied, imitating the way gaps on the surface of a butterfly's wings allow certain wavelengths of light to reflect back.

Achieving high quality shades of black, white and gray remains a challenge for such screens. And, just like a stone sparkling at a certain angle of light, the color can sometimes change when viewed from different angles.

Another company, Kent Displays, has developed a technology that reflects different colors using three colored layers of liquid crystals placed on top of glass or plastic LCDs. The company has so far made thin, flexible display sthat consume little power, says CTO Asad Khan.

E-Ink, which makes the displays for Amazon's Kindle, uses micro-encapsulated charged particles that move in response to an electric field. In 2010, the company plans to put a color filter over the electronic paper to add color. However, Schwartz says that the industry needs to make sure the devices are low cost and low power and are usable in direct sunlight.

The annual meeting of the ACM's Special Interest Group on Graphics and Interactive Techniques, SIGGRAPH 2009, takes place in New Orleans this week. The event brings together some of the world's best digital artists and computer researchers and is a showcase for some interesting new interfaces.

Here are five particularly cool ideas that will be on display at this year's event.

1. Touchable Holography

A team of researchers at the University of Tokyo led by Hiroyuki Shinoda has developed a display that lets users "touch" objects that appear to float in space in front of them.

The virtual objects appear in mid-air thanks to an LCD and a concave mirror. The sensation of touching the objects is created using an ultrasound device positioned below the LCD and mirror. The airborne ultrasound tactile device used to produce the sensation of touch was demoed at SIGGRAPH in 2008.

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2. Augmented Reality for Ordinary Toys

Frantz Lasorne, a student at L'École de Design in France, has invented an ingenious way to breathe new life into old toys.

Lasorne's Scope display automatically recognizes ordinary toys that have been mounted onto platforms covered with hexagonal patterns. Viewed through the augmented reality display, these patterns become interactive buttons and can be used to make virtual modifications to the toy. As the video below shows, a Lego person can, for instance, be instantly armed with a giant virtual bazooka.

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3. Hyper-Realistic Virtual Reality

A team from INRIA and Grenoble Universities in France will demo a new virtual reality system called Virtualization Gate that tracks users' movements very accurately using multiple cameras, allowing them to interact with virtual objects with new realism.

The user wears a head-mounted display (HMD) and moves through a virtual space while several cameras track his movement. The video here shows a guy kicking over virtual vases and pushing around a virtual representation of himself. A cluster of PCs is needed to perform the necessary image capture and 3D modeling.

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4. 3D Teleconferencing

Researchers at the University of Southern California will demo Headspin, a 3D teleconferencing system that maintains eye contact between a three-dimensional head and several participants on the other end of a connection.

To capture an image, a polarized beam-splitter "places" the camera virtually near the eyes of the speaker. The 3D display works by projecting high-speed video onto a rapidly spinning aluminum disk to generate an accurate image for each viewer.

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5. Scratchable Input

Chris Harrison, a researcher at Carnegie Mellon University whose human-computer interaction work we've written about previously, will demonstrate his new scratch input technology. The system turns any surface into an instant input device by sensing the unique sound produced when a fingernail is dragged across it.

The interface is small enough to fit into a mobile device, Harrison says, and could thereby turn any surface the device is placed upon into an interface.

Not many things that come up on my work RSS feed make my jaw drop. The video below, which shows a thin-film loudspeaker playing dance music while mounted on a waving flag, is pretty amazing. The nanospeaker in the video is 8.5 by 14.5 centimeters.

Video by American Chemical Society

Made by researchers at Tsinghua University in Beijing, the carbon nanotube speakers can play music just as loud and just as high quality as conventional loudspeakers do, even while being flexed and stretched.

Conventional loudspeakers use magnets and moving parts to produce sound-pressure waves. The nanospeakers work by the thermoacoustic effect. Alternating electrical current running through the thin films of nanotubes heats the surrounding air, causing it to expand and contract, creating sound waves.

These transparent thin-film speakers could be mounted on displays, eliminating the need for separate speakers. But one of the coolest things about the loudspeakers is that they're flexible and stretchable, allowing the researchers to imagine singing jackets.

The research was published online in the journal Nano Letters.

Stretchy sound: This thin film of carbon nanotubes acts as a loudspeaker when carrying alternating current supplied by electrodes at either end. Credit: American Chemical Society