UHF RFID tracking now possible for tags embedded in carbon fibre composite
06 July 2013
Fraunhofer researchers have embedded RFID transponders in fibre composite components, allowing them to be tracked through the manufacturing process.
The new ultra-thin RFID transponders. Right: UHF (868MHz); left: HF (13.56MHz)
At the moment, only a handful of companies use RFID technology for documentation purposes in production processes. Most often, RFID is used for access control purposes, or to record time on employee smart cards.
How well an RFID transponder works depends mainly on the material that surrounds it. The material can have a negative influence on the transponder antenna’s range, as well as on the quality of data transmission.
Components made from glass or carbon fibre reinforced composites are both lightweight and robust, and are increasingly being used by the aerospace and automotive industries. However, these fibres have a particularly strong influence on wireless transmission. Their effects on RFID are not well known, which is why production documentation in these industries is still reliant on pen and paper.
Now, researchers at the Fraunhofer Institute for Integrated Circuits IIS in Nuremburg have developed an RFID transponder whose antenna works reliably when embedded in fibre composites - including carbon fibre reinforced composites.
“We took a close look at the frequencies relevant to RFID technology: 125kHz, 13.56 MHz and 868MHz," says Tobias Dräger, an IIS team engineer. "We measured the extent to which glass and carbon fibres affect the reliability of the transponder. The result: while all these frequencies work well with glass fibres, there were weaknesses with carbon fibres due to its conductivity. " Signal attenuation was especially high at 868MHz (UHF).
Thanks to their relatively wide range of up to 15m, UHF frequencies are very well suited to applications in logistics and production. In the past, if RFID was used with incompatible materials such as metals, a very expensive transponder was required to reach this level of performance.
Together with partners from the aerospace industry, the IIS team has successfully developed a transponder that can operate reliably within conducting components, which are also subject to physical stress. The scientists have designed an ultra-thin antenna that can be embedded in materials beneath a protective glass fibre layer. Together with Schreiner LogiData, a manufacturer of RFID transponders, IIS has already developed the first test series.