Salvador Dalí style floppy iPad on the way, seemingly

Engineers in California say they have developed a way of making touch- and pressure-sensitive material which is also bendy and flexible. The new technology could be used to make flexible touchscreen devices - or, its designers say, to build robotics or prosthetics capable of such delicate tasks as handling eggs or emptying dishwashers.

"Humans generally know how to hold a fragile egg without breaking it," said Ali Javey of the US Lawrence Berkeley national lab and UC Berkeley. "If we ever wanted a robot that could unload the dishes, for instance, we'd want to make sure it doesn't break the wine glasses in the process. But we'd also want the robot to be able to grip a stock pot without dropping it."

To that end, Javey and his colleagues have come up with a thing they call "e-skin", in which germanium/silicon nanowires are printed onto a bendy substrate such as film, plastic, paper, glass etc. This, they say, offers the flexibility of an organic material but the electrical properties of normal digital components.

"Organic materials are poor semiconductors, which means electronic devices made out of them would often require high voltages to operate the circuitry," says Javey. "Inorganic materials, such as crystalline silicon, on the other hand, have excellent electrical properties and can operate on low power. They are also more chemically stable. But historically, they have been inflexible and easy to crack. In this regard, works by various groups, including ours, have recently shown that miniaturized strips or wires of inorganics can be made highly flexible – ideal for high performance, mechanically bendable electronics and sensors."

Javey and his collaborators' test project involved the production of a 7x7cm, 18x19 pixel unit which could detect pressure in the range of 15 kilopascals and below - the same kind of force used for activities such as typing or picking up light, fragile objects. So far, so ordinary: but the array still worked on less than 5 volts of juice after being bent and then straightened 2,000 times.

"This is the first truly macroscale integration of ordered nanowire materials for a functional system – in this case, an electronic skin," says Kuniharu Takei, engineering and computing postdoc. "It's a technique that can be potentially scaled up. The limit now to the size of the e-skin we developed is the size of the processing tools we are using."

Quite apart from its applications in robotic arms - for either robot-butler or human use - it would seem possible to combine the bendy e-skin touchscreens with the more and more flexible displays now coming out. This would offer manufacturers the option of building fondle-slab tablet style devices which one could roll up or drape casually over the arm of the sofa (and of course one could then sell rigid backboards to make the device usable without a table as an expensive optional accessory).

The engineers' new paper on e-skin can be read here by subscribers to Nature Materials. ®