The Truly Integrated Circuit Is Printed and Flexible
In a completely different approach, the electroactive devices of Artificial Muscle AB in Sweden, with stretchable printed electrodes, make surgeons' tools snake through the human body.
Researchers at Purdue University have created a magnetic "ferropaper" that might be used to make low-cost "micromotors" for surgical instruments, tiny tweezers to study cells and miniature speakers.
Control and monitoring electronics and electrics can be printed onto this new smart paper. The material is made by impregnating ordinary paper -- even newsprint -- with a mixture of mineral oil and "magnetic nanoparticles" of iron oxide. The nanoparticle-laden paper can then be moved using a magnetic field.
"Paper is a porous matrix, so you can load a lot of this material into it," said Babak Ziaie, a professor of electrical and computer engineering and biomedical engineering.
The new technique represents a low-cost way to make small stereo speakers, miniature robots or motors for a variety of potential applications, including flexible fingers for minimally invasive surgery.
"Because paper is very soft it won't damage cells or tissue," Ziaie said. "It is very inexpensive to make. You put a droplet on a piece of paper, and that is your actuator, or motor."
Kimberley Clark is one of the latest to announce a smart substrate suitable for printed electronics. Its cPaper is paper impregnated with carbon rather than the more expensive carbon nanotubes and it can be used as heating elements, electrodes in printed supercapacitors and supercabatteries and in many other applications.
Organic impregnated conductive paper
In a different approach, the University of Uppsala in Sweden may be on the way to improved printed batteries.
It is developing a novel nanostructured high-surface area electrode material for energy storage applications composed of cellulose fibers of algal origin individually coated with a 50 nm thin layer of polypyrrole.
Results show the hitherto highest reported charge capacities and charging rates for an all polymer paper-based battery. The composite conductive paper material is shown to have a specific surface area of 80 m2 g−1 and batteries based on this material can be charged with currents as high as 600 mA cm−2 with only 6% loss in capacity over 100 subsequent charge and discharge cycles.
The aqueous-based batteries, which are entirely based on cellulose and polypyrrole and exhibit charge capacities between 25 and 33 mAh g−1 or 38−50 mAh g−1 per weight of the active material, open up new possibilities for the production of environmentally friendly, cost efficient, up-scalable and lightweight energy storage systems.