Swedes make talking paper breakthrough

Published: June 8, 2007 | 6354th good news item since 2003

A BUNCH of Swedish boffins has worked out a way of putting touch sensors and speakers onto paper.

Boring billboards can be turned into interactive displays by using conductive inks to print touch sensors and speakers onto paper, say Swedish researchers.

“The first generation of paper was for display, like books,” says Mikael Gulliksson, a researcher at Mid Sweden University, Sundsvall, Sweden, “the second for packaging, and the third for hygiene – we are investigating what the fourth might be.”

Gulliksson and colleagues think “paper four”, as they call it, will be interactive. Prototype billboards currently on display at the university show how that might be possible.

The paper surfaces of the 2 meter high billboards respond to users’ touch by playing clips from music albums, or spoken dialogue from a comedian.

See the talking paper in action below:

Cheap and recyclable

The billboards are made almost entirely from paper materials, making them cheap to assemble, and easy to recycle, says Gulliksson. “We’ve used the roll-to-roll methods used by industry to process paper materials.”

To make the paper surfaces interactive, the team screen prints patterns using conductive inks containing particles of silver that overlap, allowing a current to flow.

The interactive billboard is made in layers with a 3 centimetres thick back layer of Wellboard – a kind of extra-strong cardboard – forming the base. A sheet of paper screen-printed with conductive ink is placed on the base, with a second sheet carrying the billboard’s design placed on top.

The middle conductive layer is connected to a power supply and simple microelectronics that play, pause and rewind sounds when the correct sensors are triggered.

Touch sensors are made using a fine pattern of conductive lines in which the current flow is altered when a hand touches it. Laptop computer touchpads use the same principal.

Speakers are made by printing electromagnets out of conductive ink and stretching the paper over a cavity like a speaker cone behind the billboard. The electromagnets vibrate in response to a current, creating a sound.

Packaging next?

“The result looks and feels like paper but has electronic, interactive features,” says Gulliksson. Changing a display is as simple as removing the two outer paper layers, and adding new ones that also connect to the power supply and electronics.

In future, it may be possible to integrate all the electronics onto the paper surface by printing on semiconducting polymers “Those technologies are a long way off,” says Gulliksson, who is more interested in what can be done with paper right now.

Having successfully demonstrated the billboard prototypes, they are moving onto investigating how the technology could be used on a smaller scale. “We are interested in scaling the technology down to produce interactive packaging for products like chocolates,” he told New Scientist.

Published in Science & Technology
See also: www.newscientisttech.com