Design ingenuity fashions truly

If you are a leading semiconductor vendor, it is not sufficient these days to make the best ASIC in the business; you should also come up with a reference design that will ensure a “killer”application or product success in the hands of a design engineer. Munich-based Infineon Technologies, one of the world's leading semiconductor vendors, is doing just that with its MP3 module to enable “smart” fashions.

Leveraging its semiconductor manufacturing prowess and interconnection expertise, Infineon Technologies has created functional prototypes of microelectronic devices that integrate electronic components within textiles, to enable applications ranging from personal entertainment and communications to logistics, healthcare and security. Infineon has developed an MP3 player that is production-ready for integration into clothing. The components are designed so that the player electronics and interconnections between the textile fibers make for comfortable wear, and are easy to use. Since all the electronics are encapsulated in plastic, you can wash the clothes in a washing machine without having to remove the MP3 module.

Thermogeneration relies on body heat to power electronics embedded in clothing.

Measuring only 25×25×3 mm, the MP3 audio module comprises four units: a µC and sound processing chip, removable battery/multimedia card (MMC) module, earplug/microphone and flexible sensor keyboard. Fabric strips with embedded connectors ensure electrical interconnection of all components. The audio chip connects to microphones, earplugs, memory, keyboard, display, sensors, and actuators. Embedded software lets you define the operating mode of the audio module. The modes include an MP3 player, speaker-independent voice recognition, text/speech conversion, and music synthesizer. Naturally, your software can define other applications as well.


Together, the Li-ion battery and MMC module weigh around 50 grams. A simple connector keeps the module attached to the clothing. The MMC module can store up to 64 Mbytes of digital audio data. You can easily detach the MMC module and use a PC to input data.


You can operate the module through a key switch matrix built with metallized films on an electrically conductive fabric strip. The metallized films (switches) are attached with an adhesive to the clothing. User key actions are sensed through a tiny sensor module connected to the metallized films. The fabric strip also connects the earplug/microphone set to the audio module.


How do you link textiles and device electronics? The critical challenge for Infineon was that the signal connector structure in device electronics is in the micrometer range, whereas it must be in the millimeter range for textiles. Infineon came up with two different approaches to resolving this issue. You can connect the chip module to the conductive fabric strips as you would in wirebonding, or you can use a flexible plastic film, like a flexible pc board, with appropriate connection pads soldered to the textile structure. For practical reasons, you need to have the module and the connection area hermetically sealed.


To make "smart" textiles a reality, you still need a power supply with precise power-management that can drive the electronics. Still in the research stage, Infineon has demonstrated the concept of a thermogenerator that uses human body heat to generate electrical power. The thermogenerator concept is not new; space technology has successfully employed this principle. Advances in material science research, power-frugal semiconductor devices, and lower production costs are now enabling a larger range of applications. The final goal of this approach is to enable users to operate wearable electronics without a battery.


Infineon's silicon-based thermogenerator chip outputs an electrical power of several µW/cm2. Under ambient conditions, Infineon claims that the temperature differential between the clothing and the human skin surface is at least 5°C. A thermogenerator chip working under these conditions can supply more than 1.0 µW/cm2 and a voltage of 5V/ cm2 under load.


With the MP3 implementation, Infineon has demonstrated the functional, production-ready and robust integration of electronics in "smart" textiles. This development should open up an enormous range of future applications, which will be expanded still further by a new generation of chips and technologies.


Infineon Technologies
Fax (65) 6840-0082
www.infineon.com