Electronic sensors built into paper could be used in a range of ways from information storage to touch screens and more.
Electronic sensors built into cartons（纸盒） may make it easier to tell when it's time to throw out rotten milk or orange juice. And that's just the start. At least that's the goal for researchers working on putting electronics into paper. They're trying to figure out how to combine the flexibility, low-cost and recyclability of paper with the information-carrying ability of electronics.
Daniel Torbjork, a physics graduate student in Finland, has been working on the problem. He's published a review of the field in the journal Advanced
Materials.
Much research has been focused in this area. While most electronic applications require patterned conducting structures, conductive paper could be used in applications such as energy storage devices, sensors, electric heaters and others, according to Torbjork.
"You could even have some interactive functions in magazines," Torbjork said, "You could put a simple game in a package. If you want a touch screen, press a button and then something happen. Sensors in paper could tell us when something has gone bad."
Additional applications, such as information storage and security paper,
have been suggested for magnetic papers containing magnetite. In Massachusetts, researchers have figured out how to post a video of such a device put into a paper airplane.
German researchers have also put electronic chips in paper bank notes to defend counterfeiters （造伪币者） .Paper is a good material but printing electronics also requires low-cost manufacturing. As many US and European paper makers lose market share to cheaper paper from China, these big paper companies are looking for added value products. That's where electronic paper devices could make a difference.
"The major obstacles are paper's large surface roughness and chemical impurities."Torbjork says. But others in the field think that electronic sensors in paper are still far from the consumer marketplace.
"I don t think it's going to happen." said Roy Horgan. "You need a conductive surface. It could be 10 years out. What we are looking for are solutions that you can commercialize today."
Solar Print is partnering with Italian automaker Fiat to develop a unique auto-glass with tiny photostatic cells （光电） that can capture electricity from the sun. In the meantime, using paper to conduct electricity is still a "blue-sky" project.
"I would love to see someone prove me wrong, because that means that it's actually happening." Horgan said. "If someone comes up with conductive paper, then that's a very interesting technology."