Invisible Electronics for Packaging Applications

One of the hottest topics in technology today is printed electronics. It is evolving so fast that the full variety of benefits arising has yet to become clear. Take invisible electronics where complete transparency, hiding from sight and possibly light bending may be involved. The world’s largest conference and exhibition on printed and potentially printed electronics - the IDTechEx “Printed Electronics Europe” event - took place on 8-9 April in Dresden, Germany, a centre of excellence for the subject. Here, local startup Novaled revealed record breaking performance of its light emitting inks and hosted visits to its superb new facility. One capability that was demonstrated was the totally transparent glass window that becomes a white light when electricity is applied.

Lecturers at the conference revealed that total transparency is now also possible with printed transistors and many other forms of electrical and electronic devices. For example, a watch is on the way that generates electricity invisibly from a solar cell coating on the viewing glass.

Light emitting plastic was first discovered in Europe, at Cambridge University in the UK, and the Dye Sensitized Solar Cell was invented in Switzerland and is now in production - printed reel to reel - in the UK. Nanosolar described how it will soon be printing an alternative, the Copper Indium Gallium diSelenide DSSC photovoltaics reel to reel in Berlin, another world first. Markets inaccessible to silicon chips will be accessed by transistors printed reel to reel, PolyIC of Germany being in the lead, and photovoltaics cleverer than silicon solar cells (for instance transparent, tightly rollable and working from heat as well as light) have arrived.

Another form of invisibility is replacing something ugly on the outside of a package such as a barcode with something that will still work when printed on the inside of the package - the printed RFID label. Indeed, some RFID will be printed directly on the inside of a package - even in the glue flap. MAN Roland, which makes some of the world’s largest and fastest printing machines, emphasized the importance of eliminating visible barcodes and conventional RFID tags on the outside of packages, noting that successful RFID integration in sales packaging needs the know-how of the printers. Thomas Walther, Head of New Product Technology at the company, revealed market studies showing that both experts and consumers find packaging the most effective promotional medium, not to be unnecessarily debased with visible stock control devices.

Starting with the printing of invisible RFID antennas, there is a need for compatible operator friendly software and post press equipment and ecological aspects are also being considered. One impediment is the large number of patents to be navigated. However, work on fast antenna and chip placement (later transistor printing) is proceeding with the objective of RFID hidden in packaging of items offered in shops and pharmacies. This printed electronics will serve such purposes as anti-counterfeiting and making empty shop shelves, due to stockouts, a thing of the past. Potential includes replacing ten trillion barcodes yearly that deface consumer goods and improving customer service with what will soon be one trillion postal packages yearly. The potential for this new electronics is huge.

However, as MAN Roland pointed out, printed electronics inside packaging is about more that hidden circuits. It involves promotion and entertainment. Lights and images, even games can be revealed when a package is touched or otherwise activated. One developer had paper that comes alive with moving images when you breathe on it and all agreed that printed electronics is a cornucopia for innovative design - indeed two artists gave presentations and demonstrations that were very well attended and rated. They revealed many things from animated wallpaper with growing, light emitting images, to the prayer mat that lights up when accurately oriented towards Mecca. These exist today. Another delightful idea was the paper box alarm clock you can screw up and throw, with satisfaction, into the trash bin when it wakes you. However, these new printed devices are so rugged, it may continue to ring!

Smart substrates are an important part of this new electronic world. For example, the presentation “Skin-like Electronics: Fabrication of Thin Film Devices with Ultra-low Temperature Process” by Ingrid Graz of the Nanoscience Centre, University of Cambridge UK described her work with StÈphanie P. Lacour on this topic. She gave three related objectives - electronics that can be shaped, stretched and interfaced with biological tissue. She pointed to potential applications at the human-machine interface and both on and in the human body, from fashion and e-textiles to prosthetic skin and even neural interfaces. Sometimes it is useful if the device stretches but returns to its original form, including the functioning printed electronics on the surface. That is beginning to be achieved.

So what about bending light to make something transparent? Surely the James Bond vanishing car is a scientific impossibility? Well, the physicists are not so sure any more, since they have recently been able to bend microwaves around “metamaterials” making them invisible at that frequency. Relying on new microstructures, these materials may lead to new types of beam steerers, modulators, band-pass filters, lenses, microwave couplers, and antenna radomes and, yes, there is even now talk of making things invisible at the press of a button, because they have been coated with magic material.

Dr Peter Harrop, Chairman of analysts IDTechEx says, “We stage the sister event Printed Electronics USA in San Francisco on December 2-5 and expect at least 1000 delegates and a record exhibition with at least six visits to local universities and companies creating these fabulous breakthroughs. We shall certainly cover new materials and the way in which smart substrates can electrically change shape, sense, act as loudspeakers and so on. They can leverage the function of the printed electronics on top.

Meanwhile, in June, we have a conference on Photovoltaics beyond Conventional Silicon where that particular aspect is all happening - in Colorado USA. The number of organizations working in printed electronics is doubling every two years and its impact will reach all parts of society.”

If you missed this event, purchase the Printed Electronics Europe 2008 conference proceedings. Also read Clear future for transparent electronics.

By Raghu Das