RFID chip lets readers talk first for use in retail apps

Researchers at Imec, Holst Centre and their partners have fabricated a radio frequency identification circuit made in low-temperature thin-film technology that allows reader-talks-first communication.
Today, thin-film RFID chips are based on a tag-talks-first principle: as soon as the RFID tag gets powered from the RF field of the RFID reader, it transmits its code to the reader.  In retail applications, many tags will try to contact the reader at the same time, requiring an effective anti-collision mechanism.
“When the RFID reader first powers and contacts the tag, it transmits a clock and identification data. The tag then uses this data and clock to determine when to send its code. This mechanism for the first time allows implementing a practical anti-collision scheme for thin-film RFID tags,” said Paul Heremans, imec director large-area electronics and coordinator of Oricla, in a statement.
The new RFID tag is a complementary hybrid organic-oxide device that combines a 250°C solution-processed n-type metal-oxide TFT with typical charge carrier mobility of 2cm2/Vs, with a pentacene p-type TFT with mobility of up to 1cm2/Vs. A high-k Al2O3 dielectric was used, which increases the transistors’ current drive.
According to the researchers, the technology behind this prototype is indispensable to create RFID tags that are cheap enough and have enough performance to be used as intelligent item-level tags on the packaging of retail consumer goods. Such tags can be used to provide buyers with information on price, characteristics, or freshness, or to allow vendors to implement automated billing and inventory management.
The technology development is supported by the EU FP7 project Oricla, with project coordinator imec (Belgium), Holst Centre – TNO (The Netherlands), Evonik Industries AG (Germany), and PolyIC (Germany).