WELCOME TO THE INK-JET AGE

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Date: Monday January 9, 2006 10:28:00 am
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    Welcome to the ink-jet age
    Mention
    the term ink jet and most people will probably think of printers.
    Indeed there can be few computer owners who have not possessed one, and
    although the cartridges can be rather expensive, the printers
    themselves are cheap and give a high quality full colour print out.
    However,
    when the engineers at HP Laboratories first developed the ink jet back
    in 1979 printing was far from being their number one application for
    the new technology. These engineers had visions of using the device in
    applications as wide ranging as medicine and materials science, but, as
    so often happens it was the marketing department that decided upon the
    application, printing would yield bigger profits and take far less
    development.
    So it has come about that ink jet technology is now
    firmly associated in the minds of most people with printing. But the
    vision that those engineers had back in 1979, of ink jets being used
    for a wide range of other applications, was not forgotten.
    Simple technology
    Innovators
    are increasingly realising that although an ink jet is a deceptively
    simple technology – an array of nozzles that moves back and forth
    depositing tiny droplets of ink onto a sheet of paper – it is the fact
    that those ink droplets are so precisely measured and placed which
    means that the range of such a device extends far beyond merely
    printing on paper.
    “Inkjet technology is no longer just being
    harnessed to print coloured fluid inks, but also functional fluids, for
    applications such as electronic circuits, displays, fuel cells, RFID
    tags, live tissue engineering and rapid manufacture.” says Rob Harvey,
    business development manager of inkjet manufacturer Xaar. “Inkjet, and
    Xaar’s solution enables manufacturer’s to take a ‘product’ concept,
    which utilises functional fluids, and build it rapidly from prototype
    to one-off manufacture through to quite large volumes, economically and
    with greatly reduced development time.”
    Secret versatility
    To
    understand why this is so, we need to look at the basics of ink jet
    technology. The secret of the ink jet’s versatility lies in the ability
    of manufacturers to drill an array of very small nozzles, just a few
    micrometers in diameter, in a silicon or composite printhead. The size
    of the nozzle determines the size of the droplets that can be produced.
    Behind
    each nozzle in the printhead lies a small ink chamber with a connecting
    channel that allows it to be filled from an ink reservoir. At the other
    end of the ink chamber from the nozzle lies a piezoelectric crystal
    that is connected to the ink jet control circuitry. When an electric
    current bends this piezoelectric crystal it forces the liquid ink down
    the nozzle at high velocity, and as it comes out of the nozzle it forms
    a small droplet travelling at speed. Each droplet produced is exactly
    the same size and travelling at exactly the same velocity.
    The ink
    jet should not therefore be though of as a printer but is a general
    purpose tool for creating very small precisely measured droplets of
    liquid.
    Over the last twenty years ink jet technology has been
    greatly refined, the number of nozzles in a head has increased from
    just 12 to over 3,000 in some industrial devices. Droplet sizes have
    been reduced to just a couple of micrometers in diameter and the number
    of droplets that can be produced per second has increased considerably.
    Three dimensions
    What
    innovators are realising is that the ink jet allows the engineer to
    precisely place an exactly measured minute quantity of liquid onto a
    surface. In a printer the liquid is coloured ink, but it could be
    anything that comes as a liquid or is suspended within a liquid medium
    – from suspensions of metal particles to living cells. Similarly in a
    printer the head is simply moved from side to side and the paper
    gradually inched up, however, the printhead could equally well be
    mounted on a mechanism that allows a minute drop of liquid to be
    precisely positioned in three dimensions.
    It is the development over
    the last decade of a wide range of substances that can be used as
    ‘inks’ in ink jet print heads, together with developments in printhead
    positioning and control systems that has made possible the developments
    that are now starting to come onto the market.
    One of the first
    applications to use the unique capabilities of ink jet technology has
    been in the electronics industry where special industrial printers are
    being used to print the very high density multi-layer circuit boards
    that are increasingly required by the electronic equipment that we now
    take for granted.
    Printed circuit board
    This
    technique involves printing very fine lines in a conductive ink made
    from very fine silver or copper particles onto a rigid or flexible
    substrate. By using an insulating ink in another print head it is
    possible for the printer to quickly and accurately lay out a printed
    circuit board with conductors just a few micrometers wide.
    This
    manufacturing technique not only provides the next step in
    miniaturisation – Seiko Epson of Japan recently demonstrated a 20 layer
    ink jet printed board that was just 200µm thick – it also helps to
    reduce the amount of pollution produced by the electronics industry.
    Existing circuit board manufacturing techniques rely upon the use of
    photomasks and acid etching, neither of which are required by ink jet
    printers which produce circuit boards using an additive process.
    “Manufacturers
    have already recognised ink jet as a key, enabling technology with the
    potential of becoming the deposition method of choice,” says John
    Attard, a business development manager with Xaar. “Inkjet is ideal for
    applications where the material to be deposited is expensive;
    management of waste fluid is an issue; manufacturing simplicity, yield
    and cost effectiveness is key; and where variable patterns are
    required, particularly on short runs.”
    CAD file
    A
    big advantage of this manufacturing technique is the flexibility that
    it offers manufacturers and designers. Changes to the design can be
    made by simply changing the CAD file that drives the printer, with no
    need to create new photomasks. This makes design and development
    quicker, it makes it possible to economically produce very short runs,
    even one-offs. In fact the combination of all these advantages means
    that many in the electronics industry expect ink jet printed circuit
    boards to be the norm by 2007.
    The techniques for printing circuit
    boards using ink jet printers and conductive ink are giving rise to a
    whole new industry for manufacturing devices using printed electronics.
    These devices include RFID tags – used for wireless identification of
    everything from clothes to automotive components – as well as
    pharmaceuticals and event tickets. With printed electronics such tags
    can be produced on a continuous roll-to-roll basis at extremely low
    cost, a technology that is being pioneered in Germany in a partnership
    between BASF Future Business and Lucent Technologies’ Bell Labs.
    E-paper
    RFID
    tags are not the only product from the printed electronics industry
    that is set to revolutionise the world, an even more significant
    product is the flexible e-paper display. Within three years people may
    well be routinely reading newspapers, magazines and books on light
    weight flexible screens many of which the user will simple roll up and
    slip into a pocket when not in use.
    Such flexible displays are built
    using advanced ink jet printers with inks made from special organic
    electronic polymers. Today dozens of companies around the world are
    racing to commercialise.the technology of flexible plastic screens, in
    the full knowledge that such displays will probably be the key
    component of the next generation of mobile electronic gadgets.
    One
    such company is Philips, which is using a four-head industrial inkjet
    printer with 256 piezoelectric nozzles to print the fine arrays of
    organic light emitting diodes that will be used on paper thin computer
    and television screens. In Korea Samsung have already announced that
    they will be in volume production of 15.5inch OLED displays by May
    2006, and Epson have said that they will be launching a 40inch OLED
    screen at about the same time. Other companies working in the same area
    include Toppan Printing of Japan, Cambridge Display Technology of the
    UK, and Universal Display Corporation of the US.
    In another approach
    to the construction of flexible plastic displays, HP engineers in
    Bristol are using inkjets to print arrays of tiny liquid-crystal cells
    onto a flexible plastic substrate, an array of electrodes printed onto
    the flexible plastic turn the LCD cells on and off. The result is a
    full-colour display manufactured entirely using ink jet technology that
    the researchers believe could, around 2010, rival the printed page in
    flexibility, lightness of weight, colour and resolution.
    Organic electronic circuits
    Meanwhile
    in Cambridge, Plastic Logic have just demonstrated the first
    engineering samples of a flexible display that uses an organic
    electronic active matrix backplane and electrophoretic frontplane. The
    company expect such displays to be in commercial use in e-publication
    readers by 2007. Once again the ink jet is a crucial technology in
    their manufacture, industrial ink jets from Xaar and Litrex are used in
    Plastic Logic’s production line to print the matrix of very small
    organic electronic circuits directly onto a flexible plastic substrate.
    When bonded to the flexible frontplane the result is a thin, light,
    flexible display that can be viewed, like paper, from all angles and in
    any type of light.
    Sensors are another area where printed
    electronics and the ink jet are opening up new markets. In Austria a
    new factory is being built by Nanoident Organic to produce organic
    photo-detectors using ink jet printers. This new generation chip
    factory will use intelligent, highly efficient manufacturing
    technologies.
    Flexonics
    In
    the light of these developments researchers around the world are now
    asking the question – if ink jet printers can be used to create
    electronic circuitry, why not do away with conventional assembly and
    build complete devices using an ink jet printer? At the University of
    California at Berkeley engineering professor John Canny is
    experimenting with ways of doing just this using a concept he calls
    flexonics. Research which could soon lead to a 3D ink jet being used to
    print out complete devices, including the case, electronics, battery,
    and all mechanical components such as switches and plugs.
    High-resolution
    3D ink jet printers from companies like 3D Systems, Z Corporation and
    Stratasys are in fact already being used to ‘print out’ prototypes of a
    wide range of manufactured products. Hundreds of companies around the
    world are now using them, Motorola used one to produce prototypes of
    the casing for its latest mobile phone, and Hyundai have used a 3D
    printer to make prototype vehicle dashboards.
    Some companies in
    Europe and the US are even using them as ‘3D data faxes’ to send design
    prototypes between their design and marketing departments and their
    Asian manufacturing facilities. “Communication is so much more
    effective when you can get a physical product into a customers hands
    rather than a drawing or text,” says Marina Hatsopoulos.
    Bonding glue
    A
    typical 3D printer costs about $30,000 and uses a 448-nozzle print head
    to deposit a pattern of bonding glue onto a layer of powder dusted onto
    an aluminium plate in microscopically thin layers, the glue bonds the
    powder and forms the object, whilst the un-bonded powder acts as a
    physical support for the object as it is built. By dusting and printing
    layer after layer the machine slowly builds up the object using data
    provided by the CAD software running on the attached computer.
    Once
    the printing process has finished, which typically takes about an hour,
    the supporting powder is dusted off leaving a hard finished plastic
    object at an average cost of about $10. This can then be further
    machined, painted, or used as a mould or pattern for casting plastic or
    metal objects.
    “Time to market is extremely important it is no good
    just having a good idea it is how quickly you can get that to idea to
    market otherwise somebody beats you to it, you can try ten different
    designs with 3D printing allowing you to quickly get customer
    reaction,” says Dr Walter Bornhost, chairman Z corporation comments.
    Stereolithography
    rapid prototyping systems, as 3D printers were known when first
    developed back in 1986, have advanced enormously. The rather rough
    jagged products of early machines have given way to smooth surfaced
    products of almost commercial quality. The machines in use today are
    desktop devices that can be used in any office environment says
    Motorola’s global prototyping manager Mike Jahnke. “It is so quiet and
    its so simple anyone can use it.”
    Today with several competing
    companies fighting for market share commercial 3D printer prices are
    rapidly dropping and could soon hit a level that most businesses can
    afford. There are even rumours of a sub-$1000 home model.
    Build living organs
    As
    the price of ink jet based 3D printers drops and the quality of the
    objects produced improves, the latest generation can even produce
    multicoloured objects, so the range of applications for such printers
    grows. Architects are using them to build models of their designs,
    geologists are using them to build models of geological structures, and
    surgeons are using them to plan complex surgical operations by
    producing plastic replicas of the patient’s internal organs using data
    derived from 3D CAT scans. Some biomedical researchers are even using
    3D printers to build living organs from an ‘ink’ of live cells.
    Rather
    than build small plastic models of buildings, an engineer at the
    University of Southern California’s Contour Crafting Centre, Behrokh
    Khoshnevis, is using a giant 3D ink jet printer to print entire
    buildings straight from the electronic blueprints using an ink of quick
    setting liquid concrete. The university has partnered with architects,
    and construction companies to help Khoshnevis develop this concept.
    This system he believes will, within a couple of years, be capable of
    constructing a 200m² building in a single day, including all walls,
    roof, and conduits for electricity and plumbing. This is an innovation
    that could completely change the construction industry.
    The ink jet
    is thus rapidly becoming an important manufacturing tool from
    nanotechnology to construction, and one that will be increasingly
    important in an era of manufacturing flexibility and product
    personalisation. It is also a tool that further increases the
    productivity of manufacturers by facilitating greater automation of the
    manufacturing process.
    Above all, however, the ink jet is a tool
    which is changing the fundamental process of manufacturing away from
    the reductive process of cutting an object from a solid block or sheet
    – whether this is a silicon circuit board or the cylinder block of a
    car engine – to an additive process where material is added in small
    quantities to build up an object. It is a change that will not only
    shake the manufacturing sector to its core, but will also make
    manufacturing far less polluting and far more responsive to consumer
    needs.

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