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prototype lens featuring a nine-pixel array capable of multiple grey-scale settings. With integrated light sensors, the lens could respond to changes in light conditions and operate as an artificial iris, contracting or expanding its shaded areas. A current solution for people with damaged iris consist of a fixed implant that blocks out excess light, a solution that falls short of the many light conditions outside a set average. De Smet recognizes that the path to designing a full working display on a lens will be a difficult one, as many other aspects need to be taken into consideration, including power and focusing issues. The idea behind this long-term research project is to gather know-how and experiment with various building blocks from different disciplines, possibly with the help of existing passive lens manufacturers who may want to share their knowledge of biocompatible materials for such a project. One thing that De Smet highlighted is that a micro photovoltaic Thermo-plastically deformable circuits. cell (maybe associated with a flexible printed battery), could double up as a light sensor (in effect, not drawing any current but directly driving the light shutters). Coils could also be integrated to recharge the battery at night (when the lenses would be stored into a special inductive charging case). An intermediate step to the full LCD-on-the-eye augmented reality concept would be to enable a multifocal lens that could be switched for close or far focus (using an electro-optic actuator, maybe embedded micro-fluidics to change the lens’ curvature). The researcher would not give out any details on how the lens would detect where to focus, but he said he had some ideas, with a patent pending on an electro-optic actuator. Such a product would address the billion or so people suffering from presbyopia, typically when you reach over 40 and part of your cornea stiffens in the normal ageing process. Soothing flexible electronics take shape Responsible for the research on flexible and stretchable electronics at imec’s Ghent lab, professor Jan Vanfleteren gave us an update on all things flexible and plastic. The initial flexible electronic concepts were to use conventional PCB manufacturing techniques to interconnect functional hard-PCB islands with off-the-shelf electronic components onto a stretchable matrix made of wavy metallic interconnects. The interconnects can be etched or laser ablated from a fully plated temporary adhesive substrate. The full assembly is then encapsulated on both sides into any suitable stretchable rubber or silicone resin, depending on the final application requirements. The metal meander shapes can be optimized as a function of the maximum elongation that the final circuit will have to undergo during its use. So far, Vanfleteren has demonstrated the mechanical reliability of such assemblies encapsulated into different polymers, with over 60,000 cycles reached for interconnects made of 17μm thick copper traces cladded by 50μm IMEC TECHNOLOGY FORUM thin plastic materials and elongated by 20% (the test was actually stopped before reaching failure). 20% elongation is probably much more than what would be needed in most flexible applications, he explained. The tricky part is to ensure that the transition from the hard PCB islands to the fully flexible polymer support are progressive enough in cladding thickness to prevent hard bends that could disrupt contacts with the PCB. The labs have developed several prototypes in a number of European projects, including a platform for low-level blue light therapy, for the treatment of repetitive strain injuries (in cooperation with Philips in the Place-It project). In the future, imec could be looking at integrating flexible electronic component blocks into this scheme (such as flexible OLEDs and thin-film organic circuits) instead of relying on hard component islands. From an industrial point of view, stretchable and flexible circuits may have more applications as a way to build fully conformable circuits, using thermo-formable plastics as an encapsulation material to freely set the deformable circuit into specific but solid shapes. Applications could range from fancy 2.5D light sources to automotive interiors, free form keyboards and other consumer electronics. In fact, to further explore the manufacturability of these concepts, imec and its project partners have just launched TERASEL (Thermo-plastically deformable circuits for embedded randomly shaped electronics), a project under the European Union’s Seventh Framework Programme for Information and Communication Technologies (FP7). Running for the next three years under Vanfleteren’s direction, the project will look at the development, industrial implementation and application of large-area, cost-effective, randomly shaped electronics and sensor circuit technologies. It also aims to set up a complete multi-competence industrial production chain, capable to achieve mature, near-to-production industrial processes for manufacturing these randomly shaped circuits. Apps that will comfort healthy athletes Program director of wearable healthcare at imec, Chris Van Hoof presented the healthcare and fitness markets and the huge potential those represent for wearable sensors and health monitoring devices. Van Hoof first related his experience with a commercialized DNA spit kit, a low cost product (just under $99) that provides statistical data about your health risks based on the analysis of your DNA (the full DNA data is also kept by the lab providing the service, for future data mining). Indeed, for a large part, our genetics defines a baseline for our health (hereditary diseases or susceptibilities) then our lifestyle and our environment complete the picture on the long term. Factor-in unhealthy or healthy behaviours and more or less exposure to contaminants and other health hazards and you’ll increase or decrease your potential for chronic diseases. The idea behind these DNA testing kits is that you could balance your lifestyle to reduce health risk factors known to be associated with certain types of diseases. Then, Van Hoof listed three lifestyle-related risk factors, namely, bad diets (too much fat, sugar, salt), the lack of physical activity, and smoking, all three identified as responsible for most chronic diseases such as heart diseases, strokes, cancers, diabetes, pulmonary diseases. “Epidemiology studies show that only a few hours or moder- A smart lens concept. 16 Electronic Engineering Times Europe November 2013 www.electronics-eetimes.com


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