Aspecialist company in the field of polymer electronics has introduced the world’s first fully functioning polymer-based eight-bit radio frequency identification (RFID) tag that operates at the industry standard radio frequency of 13.56MHz.
While this particular transponder chip has been produced using conventional clean room processesthe goal for its manufacturer – PolyIC – is to manufacture low cost electronic components for RFID tags using high volume printing techniqueswith the first fruits of this labour due to be unveiled later this year.
The market capacity for a step-change in technology of this magnitude is substantial. For RFID alonethe potential to replace optical barcodes is now tangible.
Using printed polymer technologythe application of RFID will be broadened to price sensitive mass markets such as the packaging of consumer goodsbrand protectionanti-theft devicessimple identificationaviation baggage tracking and electronic ticketing. In factmany of these applications are currently being assessed as part of the three-year printed smart labels (PRISMA) project being promoted by the German Federal Ministry of Education and Research. PolyIC is co-ordinating the project.
RFID tags based on printed polymer electronics will also bring with them a higher level of ‘intelligence’making it possible to differentiate between separate product items. The vision of individual yoghurt pots with RFID on supermarkets shelves could soon become a reality.
Affixed to productsthese radio chips can open up new possibilities in terms of deliveryinventory management and labelling of goodsparticularly when combined with software such as Simatic RF-Manager – a new product from Siemens Automation & Drives. This manages read/write devicescollects and compresses RFID data and makes it available to the merchandise information systempotentially recording entire goods flows.
One of the great advantages of printed electronics is its ease of integration into products or packages. For examplethey can be applied easily to flexible packaging materials by laminating or labellingor by direct application. Thusas a first step it becomes possible to apply labels with printed electronicsfor example as an RFID tagon to a product.
Secondlyprinted electronics can be integrated directly into the package and thus become ‘intelligent’ or ‘smart’ products. This means that packages/products can communicate through their RFID tag with a respective reader – hereby the vision of ubiquitous computing or the so-called ‘internet of things’ will be made possible.
Conceivable applications for this technology include intelligent fridgeswashing machines or better automation in production processes.
The automatic supermarket checkout is another potential realitywhere customers will simply move their shopping trolleys past a radio scanner that automatically registers everything the customer has collected in an instant.
Since its formation in 2003PolyIC – a joint venture between Siemens and Leonhard Kurz – has been striving towards the production of flexiblelow costpervasivedisposable polymer electronic components for use in RFID tags.
Just three years laterthe company’s goal is set to become a realitya development that will change the face of RFID forever.
So how does it all work? The astonishing electronic properties of polymers are derived from their chemical structurewhich contain so-called conjugated polymer main chains that consist of a strictly alternating sequence of single and double bonds.
As a consequencethese polymers possess a delocalised electron system that provides semi-conducting properties. Following chemical doping processespolymers that are fully conductive can then be created.
Conclusions from extensive research have established that soluble polymers that become fluid in a special dissolvent can be used in a printing process as electronic inkreleasing the potential to revolutionise the production of electronics. With this processit is possible to fabricate low cost electronics in a continuous printing process on flexible polyester (PET) foil substratemore or less similar to the way a newspaper is printed on paper.
To print a functioning transistoran organic semiconductor such as polythiophene and an insulator are required. These consist of polymers and are printed as liquids. Printing is the most direct way of achieving structured layer deposition and is much more attractive to manufacturers in terms of volume and costs than conventional electronics production processes.
Polymer electronics are thin and flexible and can be printed on to polyester film in several layers. For this processdifferent polymers and printing techniques are used.
PolyIC is using continuous printing methods thatin the long-termcould realise production costs of less than one cent per chip.
These methods are essentially based on established printing techniques such as:
- Flexoprinting: a high-pressure method that is especially suited to printing on plastic substrates.
- Offset printing: a flat printing technique that makes high resolution possible.
- Gravure printing: a low pressure printing method that permits high volumes and the use of organic dissolvent.
- Rotary screen printing: a method that allows printing in thick layers.
- Coating methods: diverse techniques to apply homogeneous and thin layers.
Of coursethese methods have to be adapted to the special requirements of polymer electronicssuch as exceptionally high resolutionhigh cleanliness and precision of register. PolyIC has developed suitable production techniques for polymer electronics based on high volume roll-to-roll processes using flexible substrate films.
To design printed electronicsa number of different materials are required that have completely different featuresbut which need adjusting to suit one another (Fig.1). T
he most important materials are: the substrate – a flexible polyester film on which the electronics are printed; the conductor – electrical conducting polymers for electrode structures; the semiconductor – electrical semi-conducting polymers for transistors and diodes; and the dielectric – electrical insulating polymers to divide between semi-conducting and conducting polymer layers. .
Concerns about suitability
Typicallythe distance between the two conductors is less than 0.05mm. Considering the nature of the materialsome could be forgiven for raising an eyebrow concerning suitability.
Howeverthese chips will even function after being stored for two days at a temperature of 60°C and 100percent humidityand will continue to work until temperatures exceed 120°C.
Printed electronic applications have enormous market potential. In a 2005 studythe British market research companyIdTechExestimated the market for organic electronics at E30billion in 2015.
Printed RFID tags will undoubtedly constitute a considerable part of this market. PolyIC intends to gradually produce more complex circuits with several thousand transistors and up to 128-bits of memory. Today's barcodes can typically store 44 bits.
Brian Holliday is General Manager Industrial Automation Systems at Siemens Automation and Drives. For more informationvisit www.siemens.co.uk/automation
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