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Printed Electronics World
Posted on October 12, 2005 by  & 

RFID Copying Nature

As the saying goes, there is nothing new under the sun. Still, it is prudent to look at what went before and to avoid reinventing the wheel. This is particularly true of nature. Biomimetics is the mimicking of nature to create manufactured products. In RFID it is not new but there is much more to come and nature has lessons for those going in the wrong direction.
Animals identify each other using many forms of mark and emission, including features that glow in the dark. Interesting then that Brady has recently announced RFID tags that fluoresce. Velcro was invented when someone saw hooked seeds sticking to his socks and it is used on RFID wristbands, used, for instance, by UPS drivers for vehicle access.
The recent emulation of Geckos gripping the ceiling by van Der Waals forces without adhesive has led to labels that do the same, possibly useful in some RFID applications. Biomimetics is now assisting plastic electronics, where we hope to print the RFID logic, replacing silicon with something cheaper, fault tolerant and less easily damaged in the first place. For example, cell structures throughout nature are based on hydrophilic and hydrophobic surfaces side by side and that is now the basis of high resolution ink jet printing of transistors at Plastic Logic.
The sensors in nature are often porphyrins, so we are now using them, experimentally at least, for printed sensors. For example, Professor Natale of the University of Tor Vergata, Italy has noted the great need for better disposable health testers. His fascinating work has demonstrated gas detection of diseased citrus fruits, gas detection of apple ripeness and, in healthcare, distinct differences between the skin odour of mentally ill people (including specifically schizophrenics) and normal people and a correlation with certain types of human breath with lung cancer. Much of this has been achieved with organic porphyrin layers and there have been favourable first tests of the four key parameters of wine using printed electronic noses. Less work has been done on electronic tongues (testing of liquids) but for both gases and liquids, porphyrins are particularly promising if the problematic electronic drift can be allowed for. Often the sensors will be combined in an RFID label.
Adaptronics, in plastic electronics research, is based on responsive devices in nature that adapt in the face of circumstances. We see this with active RFID tags programmed to wake say every hour but if they detect something serious like the ammunition box is being moved, they send alerts and start monitoring in real time. Ad hoc networks occur in nature and they are mimicked by the RFID networks in some military programs and the European Commission ParcelCall research program. Self-healing materials in nature are copied with self healing materials in mechanical engineering. Can we hope for self-healing RFID?
Lizards gain energy from the sun and it is interesting that active RFID labels are no longer limited to battery power. South Georgia Tech has ones using printed photovoltaics.
Then there is the use of very crude devices in a very appropriate and cost effective way. In nature, the eye does track motion with the cleverest sensor. It uses many crude sensors very cleverly. Now we see some of the world's worst transistors made from electrolytic ink on paper - switching time measured in seconds -having potentially huge markets, not least in RFID for logic or power when intelligently applied at stunningly low cost. Professor Margit Harting of the University of Capetown South Africa is trialling photovoltaics and transistors from painted crushed silicon - a similar crude, cheap and potentially very ubiquitous technology. They will provide electricity generation, smart packaging, medical disposables and so on.
Nature rarely chases perfection - it provides massive redundancy and clever use of simple devices, if necessary in large numbers. These technologies and the 30 plus companies developing chipless RFID labels, mainly by making printed transistor circuits, will get back to the basics of nature and offer very simple RFID labels, even RFID printed directly onto things. Then we shall see trillions sold - approaching numbers commonly encountered in nature.
VTT in Finland, ACREO in Sweden and other bottom of the market innovators have got this message. At the recent Printed Electronics conference in Frankfurt, some speakers felt that much more could be done to sell products incorporating today's relatively slow transistors, short life organic light Emitting Diodes OLEDs and so on. As one speaker said, the life in use of certain disposable medical test equipment can be adequate if only measured in seconds - there are equivalents in nature. Printed electronic gifts on consumer goods and smart packaging such as self adjusting use by dates that monitor if something has been heated, can be adequate with a life of only two years.
There is more to come from biomimetics...........
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