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| CSIRO | SOLVE | Issue 1 Nov 04 | |
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MICRO-TEXTURING
Macro Problems:
Micro Solutions By Sue McCalister
The World Focus on Security is bringing an Australian-developed technology to the fore. Drawing on its own ground-breaking technologies already developed and used around the world to eradicate banknote counterfeiting, CSIRO, through its expertise in ‘microtexturing’, is already working on the next generation of invisible security devices.
But the more immediate opportunities are coming from CSIRO’s development of methods to manipulate surface features, on a range of materials, at the micron level. This stems from a successful technology first developed by CSIRO to eradicate bank note counterfeiting. This is already finding new uses in other commercial applications, such as improving identity and brand protection, and biomedical engineering. The technology, known under CSIRO trademark Exelgram, launched CSIRO as the world leader in commercial micro-texturing – the controlled production of surface features on various materials, and down to microscopic levels. Over the past decade, CSIRO’s Exelgram has, among other things, protected Hungarian, Estonian and New Zealand banknotes, Ukrainian visas,Vietnamese bank cheques, and Saudia Arabian security seals. When American Express chose to incorporate Exelgram into its US dollar and Euro travellers’ cheques in 1997, it expected a 30 per cent reduction in counterfeit losses – but achieved instead a 90 percent reduction. The Melbourne-based CSIRO microtechnology team is the only one in the world with both the expertiseand equipment for this type of commercial microtexturing. Dr Davis says that although initiating customised commercial applications of the technology entails significant financial outlays, it has proved cost-effective – and “spectacularly so”, according to Opsec International, the US company that licensed Exelgram to American Express. Dr Davis says the team welcomes approaches from organisations with problems to solve and ideas that can be turned into commercial reality. Most of his team’s successes have involved the high-growth security industry in which the sky is potentially the limit for applications of CSIRO technology. Identity fraud, for example, not only endangers national security, but costs Australia an estimated $2-$4 billion each year. For Exelgram, CSIRO created ‘diffractive optically variable devices’ with electron beam lithography. These provide far greater security than traditional hologrambased devices. A new version of this technology is used to create arrays of mirrors down to a few tens of microns in width.The mirrors are arranged on a material’s surface to reflect light differently, making the design they form change as the material moves. This effect hinders forgery because it cannot be achieved with industrially available optical equipment. CSIRO is now exploring uses that extend beyond the security market, having advanced micro-texturing to where it can create myriad surface textures and patterns by controlling the topography of metal, plastic, fabric and other materials. The results are like dot matrix pictures, except that individual ‘dots’ in micro-textured designs are invisible to the naked eye, some being less than one micron across. Moreover, the designs are truly textured, with features varying in depth and shape. Dr Davis says there are potential uses for micro-texturing in the biomedical industry, and that medical centres in Australia and overseas are already showing interest. For example, the development of stem cells can be controlled by the topography of the surface on which they grow. Because micro-texturing is capable of creating artificial surfaces that mimic real ones down to microscopic levels, it could potentially produce human tissue designed for specific organs. Other applications exploit how micro-textures can control fluids. A European commercial paint cleans buildings by causing water to form beads that collect dirt as they roll off surfaces. CSIRO could extend this to embossing water-controlling patterns directly onto all kinds of surfaces, from boats to swimsuits. Micro-texturing technology involves two hi-tech equivalents of etching or relief-sculpting, using electrons and ultraviolet radiation instead of an artist’s chisel. In electron beam lithography, the beam shapes a relatively simple pattern in the surface of an electron sensitive polymer. The pattern is transferred into metal using precision electroforming to create a metal stamping tool. Complex surface topography requires a two-step process: a pattern including half tones is created by electrons and then transferred by ultraviolet lithography into a surface relief (similar to twodimensional wall sculptures) in a thicker photosensitive polymer.This is copied by precision electroforming to create the metal stamp. For further information contact: |
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Team
leader for microtechnology, Dr Tim Davis, says that combining micro-texturing
with optical sensors, for
example, will allow the detection of molecules or chemical compounds – such
as potentially explosive vapours released inside an aircraft, or the presence
of biological agents.
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