Displays don’t always have to live encased in glass houses. Instead, a color screen can now be printed on almost any material — plastic, ceramic, paper or textiles — through a process similar to how ink is printed on paper, says Irish startup Ntera.
The new displays, called NanoChromics, use specially synthesized molecules that can produce images with a resolution equivalent to that of a conventional inkjet printer. The difference is that NanoChromics displays are screens that can be changed electronically, like an LCD, instead of being static images.
“The molecules change color when they receive a charge so it can go from a colorless state to a colored state,” says Chris Giacoponello, vice president at Ntera. “We can manipulate that by putting it on almost any surface.”
Ntera’s displays can be viewed from virtually any angle and under a wide range of lighting conditions, says the company. They also don’t consume much power and can be “tricked” into being bistable, which means they’ll retain their image even when the power is turned off, according to Ntera. On the downside, they are currently able to show only one color: blue.
Printed electronics is a emerging field that looks to take common printing techniques, such as screen printing, and use them to create electronic and optical components. For instance, printed electronics, which are produced using roll-to-roll manufacturing similar to how newspapers are printed, can be more efficient than techniques that involve depositing materials on a substrate.
The idea is to create electronics that can be used in applications where low cost is more important than high performance, thus opening up new ways of interacting with digital information. Research firm IDTechEx estimates that printed electronics will be 35 percent of a $1.9 billion market for thin-film electronics this year.
Ntera’s displays can be mass produced and printed on paper, greeting cards and tickets, among other things, says the company. Remember Esquire magazine’s E Ink cover? Ntera says its display can be printed directly on the paper and it can cost a tenth of the $10 price tag that the magazine carried.
“We can get a level of cost effectiveness that other displays can’t,” says Giacoponello. “If you put an E Ink display on a piece of plastic, you have to create a display module to include that display feature on the plastic. We can print directly on the plastic.”
Ntera’s displays are based on a technology called electrochromism. It is a phenomenon where some materials can change color when a burst of charge is applied.
To construct the display, an array is made of electrodes created from a metal oxide semiconductor. The electrodes are mounted on a flexible film, to which electrochromic molecules are attached. A charge applied through the semiconducting particles causes the molecules at the surface to be charged and thus change color.
The film is many particles thick so the change in color, which would otherwise be barely detectable, becomes dramatic, says Ntera. Adding an opaque white layer behind the electrochromic layer as background also makes the display seem more vivid.
The displays can be manufactured on a number of flexible substrates using traditional printing techniques such as inkjet and screen printing, says Ntera.
Unlike LCDs that require a constant electric charge to maintain the image, an NCD image can be bistable to a certain extent — that means it can be active even if the power is lost.
“It’s not 100 percent bistable, but more like a leaky capacitor,” says Giacoponello. “The display slowly reverses and we can engineer the time so the image can stay from minutes to hours.”
Ntera says its display has extremely low power requirements: as low as 0.5 volts for activation, and color changes in the displays are triggered at voltages below 1 volt DC.
The company plans to release color molecules in red and orange soon, which should help expand the range of colors beyond the blue hue it can currently produce. Still, the lack of full color can be limiting, agrees Giacoponello.
“If a customer comes to me and says I have a logo in Pantone color 352 I can’t do that,” he says. “We are limited by what molecules we can synthesize.”
There’s also another problem, says Carl Taussig, director of the information surfaces lab at HP. It’s difficult to produce high-grade displays on paper and textiles, he says.
“These are called low-grade substrates,” says Taussig. “Because of their rough nature it is difficult to make something with a reasonable resolution.”
Plastics, however, are an attractive option and they could open the door for a new generation of display technology, he says.
Ntera says that despite the limited color palette its customers are planning to put the displays into retail store cards, event tickets, transportation passes and even in magazines.
Photo: Ntera display
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