TOKYO — Infineon Technologies AG has developed a 3 x 3-cm audio module that can be woven into clothing with ribbons of conductive wire, paving the way for a wearable MP3 player. Infineon expects the technology will enable other wearable electronics such as a cellular phones and medical sensors.

Infineon said it will not sell clothing with so-called "ambient intelligence," but is pursuing technology that will make such items possible. "We have calculated the price of the electronics may be about 10 euros [$9.86], and this is quite a realistic price," said Werner Weber, senior director of Infineon Corporate Research. Infineon's audio module includes a 5 x 5-mm controller, a detachable battery, multimedia card, earphones, microphone and touch-sensor switches.

The module is molded onto a flexible plastic that allows the electronics to be connected to woven fabric. "Our innovation is packaging," said Weber. "Connecting the very dense pitch of connectors to the relatively wide pitch in the fabric has been realized."

Infineon researchers developed copper wires encapsulated by silver and then by polyester, which insulates the wiring and allows the clothing to be washed or dry cleaned. "Water cannot penetrate the package," Weber said.

Infineon is studying the possible application of its technology for various communications functions such as cellular phones, GPS and Bluetooth, and for use in RF ID tags and security functions. Even a Pentium processor could be mounted on the module, but it would soon drain the battery's power, Weber said.

"We are thinking of several applications, with an electronic replacement for bar codes likely to be the first application," expected in two to three years, Weber said. A wearable MP3 player will take "three to four years, because it is a relatively complicated application," he said.

The prototype module uses a detachable battery, but Weber's team is developing a silicon-based thermo generator as a replacement. A thermo generator uses the temperature difference between the human body and its outer environment to generate electricity. A 5°C difference in temperature can generate several microwatts per square cm with a voltage load of 5 V/cm², which could run a wristwatch, said Weber.

The team is also trying to develop a thermo generator that would be able to operate a hearing aid. "We are working in this direction," Weber said. "When it is achieved, this will be very important. One square [of] silicon is much cheaper [than hearing aid batteries]."