Researchers report progress embedding devices in fabrics
By Nicolas Mokhoff
EE Times
December 9, 2003 (12:18 p.m. ET)
WASHINGTON — The idea that electronics should blend into the fabric of people's lives is taking on a whole new meaning when devices are embedded in clothing. At the International Electron Devices Meeting here this week, several researchers detailed what is becoming known as "ambient intelligence," a concept expected to be implemented over the next decade.
"Ambient intelligence is the vision that technology will become invisible, embedded in our natural surroundings, present whenever we need it, enabled by simple and effortless interactions, attuned to all our senses, adaptive to users and context and autonomously acting," said Werner Weber of Infineon's Corporate Research Laboratory of Emerging Technologies.
In a keynote speech here, Weber cited the history of computers to explain the trend towards ambient intelligence: "While in the 1970s one computer served many users, and in the 1990s the personal computer served humans on a one-to-one basis, today more than one computing device serves each user. This trend towards distributed electronic intelligence will likely prevail in the near future."
Infineon (Munich, Germany) hopes to deploy application-oriented "ambient intelligence" in the next five areas. The first application could be a low-cost wireless network for ambient intelligence environments such as smart homes and hotels along with smart RF ID tags for distributed intelligence.
"Edutainment" devices with speech recognition are also being investigated for children as a natural and intuitive computer interface.
Infineon also is trying to integrate electronics into clothing while developing sensor and display functions distributed in a regular grid, especially for textile applications. The idea is to provide security and surveillance functions embedded in carpets, wallpaper and various kinds of canvas covers.
In developing a low-cost smart RF ID tag, Infineon is working on a sequence of process steps that will yield tags that cost one to five cents each. Chip size will be reduced by using ac-powered circuits leading to a system design with a silicon area measuring 0.02 mm2 for chips using a 128-bit code word.
Several milestones have already been reached to come up with a 1-cent RF ID tag, said Weber, "a cost that most businesses are willing to bear for such a device." But he cautioned there is more work to be done before a full working system can be realized.
Infineon is also exploiting interconnect and packaging technology for textiles using a polyester narrow fabric with several warp threads replaced by copper wires. The wires is coated with silver and polyester and a thin flexible printed circuit board is attached to the polyester fabric. The module is then encapsulated for mechanical protection.
The complete unit is molded forming a hermetically sealed casing that protects it against mechanical and chemical stresses. A speech-controlled MP3 player system was developed using the technique, and is based on a DSP/microcontroller processor system. The system is controlled either by speaker-independent voice recognition or by a keypad.
Researchers at 3M Co. also presented results of their work in organic semiconductor RF ID transponders. They developed pentacene-based transponder circuitry, patterned entirely using flexible shadow-masks and operating at frequencies greater than 1 MHz. The circuits are powered using near-field inductive coupling, and designed for operation without a rectification stage.
The thin-film ICs were formed on glass substrates, as large as 6 square inches, using vacuum deposited layers patterned through a 25-micrometer thick polymer shadow mask. The mask is formed using excimer laser ablation through a glass photomask.
Researchers at the University of California at Berkeley reported on organic transistors in fiber. According to the researchers, flexible transistors were formed directly on fibers, a significant step towards the realization of electronic textiles. The fiber transistors exhibit mobilities of greater than 10-2 cm2/V-s measured at 20V VDD. The entire transistor was fabricated without resorting to conventional lithography techniques with patterning achieved by shadowing from overwoven fibers. The process is compatible with textile manufacturing, and is therefore a promising technology for scalable e-textile fabrication, the researchers said.
A team from the Univeristy of Tokyo has meanwhile integrated organic field-effect transistors and rubber pressure sensors for possible artificial-skin applications. Sense of touch is important for next-generation robots which will require an acceptable artificial skin large enough and mechanically flexible to fit any shape. The researchers claimed that integration of organic transistors and rubber pressure sensors, both which can be produced using low-cost processing technology, could provide a solution for a practical artificial skin.
