This one day meeting organised by the Institute of Engineering and Technology and the Institute of Nanotechnology started with Professor Sir Richard Friend explaining the theory behind printed polymeric transistors, OLEDs and photovoltaics. The transistors have little problem with life and are reaching commercialisation as electrophoretic display backplane drivers for example. By contrast, the life of OLEDs and photovoltaics is only acceptable for mass markets when they are expensively encapsulated - lower cost barriers against oxygen and water ingress into the desired flexible versions being very much work in progress.
Wolfgang Mildner of PolyIC covered printed RFID and allied flexible polymer electronics. Stephen Clemmet of new start up Polymertronics covered OLEDs for photodynamic therapy. Here the currently short life of affordable flexible OLEDs need not be a problem.
Andrew deMello, of Imperial College London and co-founder of Molecular Vision, described his work on polymer electronics for point of care diagnostics where conventional solutions are slow and expensive and disposable testers are the way of the future.
Source: Molecular Vision
He prints both photodetectors and light sources in OLED type structures and uses microfluidics, as also pioneered by the late lamented Nanoident/ Bioident in the US/Austria. His photodetectors now have excellent shunt resistance approaching that of the best silicon photodetectors but potentially at a fraction of the cost. Organic photovoltaics (classicalP3HT plus C60) has high sensitivity, medium bandwidth, low voltage, very low cost , very good ease of integration and high strength when compared with conventional versions. The main reasons for introducing them are flexibility, large area capability and cost, he said. Currently, his diagnostic devices cost several pounds each and he seeks to achieve penny costs by introducing printed polymer electronics. His team are developing interlayer lithography - where the photoresist is put down first - for these purposes. His high performance integrated filters will be incorporated into the microfluidic device.
Introduction to Molecular Vision
Molecular Vision is an Imperial College spin-out company that develops low-cost diagnostic devices for use in the doctor's surgery and in the home. Its proprietary devices combine microfluidic chips with organic-semiconductor light-sources and photodetectors to provide lab-quality diagnostic tests in a miniaturised, easy-to-use, disposable format. Molecular Vision's prototype fluorescence devices offer sub nanomolar sensitivities in a portable low-cost format. Absorbance and chemiluminescence based detection platforms are currently under development.
"Smart Packaging Printed Intelligence in High Volume Packaging" was the subject covered by Jani-Mikael Kuusisto of VTT's Centre for Printed Intelligence in Finland. He described the needs and the printed electronics value chain, noting that it is all about disposable labels and laminates and introduction into the printing/ converting line without slowing it down. He said inks are the most important technical aspect. VTT's activities include primitive RFID and printed indicators of oxygen, humidity etc., gravure printed solar cells, printed disposable fuel cells, bioactive paper and functional coatings, holographs printed directly onto packaging, printed passive components and what he claims are the world's first OLEDs that are entirely printed. These OLEDs have been put into packages where an RFID reader powers them and they light up to indicate if the package has been opened or not. This is a demonstrator rather than a serious market proposition.
Dr Tom Taylor of the new Printed Electronics Technical Centre discussed "Developing a Printable Electronics Industry in the UK", including why customers like these new technologies and the task of creating a printed electronics supply chain in the UK. Dr Peter Harrop then gave a summary of the many applications, the technical challenges, the market forecasts and trend to use inorganic, organic and combined chemistry as appropriate.
Top image: Courtesy of Molecular Vision