The development of commercially viable thin-film radio frequency identification (RFID) tags that can be integrated into flexible packaging has taken a major leap forward after scientists made a significant technological breakthrough.
Previously, thin-film RFIDs, which are produced on plastic foil, did not have this capability and instead emitted a continuous code when powered by the reader, Kris Myny, a researcher with project coordinators Imec, told FoodProductionDaily.com.
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RFIDs are widely acknowledged to have huge potential in the food packaging sector in recording and sharing such data as temperature and freshness of produce as it travels from farm to fork – but wider take up of silicon-based RFIDs has been hampered by cost concerns.
A key aim of the sector is to create intelligent RFID tags that are intelligent enough and cheap enough to be printed and used on mass-produced retail products.
As a result of the advance, the cost of the devices could drop by more than 80% and now have the potential to be used on consumer retail packaging, said Myny.
“Until now many thin-film RFID tags would try to connect with a reading device at the same time. Imagine it is like everyone in a room all talking simultaneously – making it very difficult to understand what any single person is saying,” said organic circuitry expert Myny. “This is why the development of an anti-collision capability was so important. This is a big step forward.”
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The RFID device needs no batteries and is powered by drawing energy from the electro-magnetic field generated by the reader.
It uses a complementary hybrid organic-oxide technology, combining 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, said Imec.
Low cost
The development paves the way for low-temperature thin film transistors (TFT) RFID circuits, added Paul Heremans, Imec director large-area electronics, as he explained how the technology functions.
“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,” he said. “This mechanism for the first time allows implementing a practical anti-collision scheme for thin-film RFID tags."
Myny estimated that it would take a further four years before the lower-cost thin-film device was likely to be ready for launch; two years to perfect the technical aspects and another couple of years to address the cost issue.
Other project partners are Holst Centre – TNO, from the
