vol 8, issue 1

How to... print gadgets

21 January 2013
By Kris Sangani
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Dr Simon Leigh of the University of Warwick

Dr Simon Leigh of the University of Warwick displaying what the future of printing could hold

Dr Simon Leigh of the University of Warwick with a 3D printed games controller

Dr Simon Leigh of the University of Warwick demonstrates a 3D printed games controller

A 3D printed games controller

3D printed goods may not have the quality of the original item, but will be cheap and customised

Making solid objects with simple moving parts is easy. The next challenge is to print the smartphones of the future.

The replicator, that fictional device that no self-respecting starship captain would leave home without, has been the main inspiration for additive printing devices that are poised to come down in price and become available to many consumers.

Some printers - although bear in mind that they cost thousands of pounds - can print functioning mechanical parts. So far there are no commercially available 3D printers that can print complex electronic devices, typically dealing with solid objects. But that may be about to change.

One company, NthDegree, claims to have invented a ground-breaking method of transferring specific semiconductor properties to a chosen substrate using additive printing and inorganic semiconductor inks. These inks are made of microscopic functional devices such as diodes, transistors and other passive components.

These are still built using traditional wafer fabrication technology - there's no revolutionary 'fab in a box' product just yet. By using these tiny semiconductor devices, the company's printing process creates functional inks that can be printed using standard high-speed printing presses.

Using a printing process to create electronic devices would appeal to anyone wanting to create unique form factors that could be incorporated into challenging form factors - phones and tablets, say. This could be accomplished without the need for a huge manufacturing plant. Watch out, Foxconn!

However, the concept of using 3D printers for chips is not new. It has long been proposed for printing photovoltaics.

3D Jet Printing

Optomec, based in Albuquerque, New Mexico, recently announced an additive-manufacturing system designed to print electronics on awkwardly shaped objects - for instance a pair of glasses to be used with augmented reality.

The company demonstrated its process by collaborating with Aurora Flight Sciences, who make unmanned aerial vehicles (UAVs), and Stratasys, a 3D-printing firm, to make a smart wing for a small drone.

The wing was made from a thermoplastic material and Optomec used 'aerosol jets' to print circuits, sensors and an antenna on the wing. The idea is that such technology would allow for lightweight drones that can be customised for specific missions and printed on demand.

Whereas inkjet printing involves a print head depositing droplets of ink on a flat surface, an aerosol jet atomises nanoparticle-based materials into microscopic droplets that are directed using an aerosol gas through a nozzle with microprecision. The nozzle can be moved around irregular-shaped objects and thus can be used on 3D structures and print electronic features smaller than a hundredth of a millimetre wide from a variety of materials.

"Bringing together 3D printing and printed electronic circuitry will be a game-changer for design and manufacturing," says Jeff DeGrange, vice presideny of direct digital manufacturing at Stratasys. "It has the potential to completely streamline production by requiring fewer materials and steps to bring a product to market."

"Manufacturers can implement this hybrid technology in a multitude of applications, not just in aerospace," says Optomec's Ken Vartanian. "This technology can benefit numerous industries by allowing thinner, lighter, fully functional structures that cost less to manufacture."

Even so, printing something as complex as a smartphone or a tablet in its entirety is going to be more than tricky. There are a wide variety of electronic circuits that could be printed, but the main processors would still be the stumbling block. These still require massive wafer fabrication plants (fabs) that cost billions of pounds to build. However, the system has been purchased by a number of organisation including Sheffield University's Mercury Centre, which is currently involved in manufacturing components for the Bloodhound SSC Project.

Carbomorph

The University of Warwick has also made waves recently with the news that it had printed a game controller using a unique material nicknamed carbomorph, which allows users to lay down electronic tracks and sensors as part of a 3D printed structure. This allows the printer to create touch-sensitive areas which can then be connected to a simple electronic circuit board. There could be a big market here for consumers being able to print a custom controller designed to fit perfectly in their hand.

The University of Warwick researchers have created a simple and inexpensive conductive plastic composite that can be used to produce electronic devices using the latest generation of low-cost 3D printers designed for use by hobbyists and in the home.

The carbomorph enables users to lay down electronic tracks and sensors as part of a 3D printed structure, allowing the printer to create touch-sensitive areas, for example, which can then be connected to a simple electronic circuit board.

So far the team has used the material to print objects with embedded flex sensors or with touch-sensitive buttons such as computer game controllers or a mug that can detect how full it is. The next step is to work on printing much more complex structures and electronic components, including the wires and cables required to connect the devices to computers.

The research was led by Dr Simon Leigh in the School of Engineering at the University of Warwick. He says: "It's always great seeing the complex and intricate models of devices such as mobile phones or remote controls that can be produced with 3D printing, but that's it, they are invariably models that don't really function.

"We set about trying to find a way in which we could actually print out a functioning electronic device from a 3D printer."

He continues: "In the long term, this technology could revolutionalise the way we produce the world around us, making products such as personal electronics a lot more individualised and unique and, in the process, reducing electronic waste. Designers could also use it to understand better how people interact with products by monitoring sensors embedded into objects.

"However, in the short term I can see this technology having a major impact in the educational sector," Dr Leigh adds, "for example allowing the next generation of young engineers to get hands-on experience of using advanced manufacturing technology to design fairly high-tech devices and products right there in the classroom."

Flexible electronics

The printed sensors can be monitored using existing open-source electronics and freely available programming libraries. A major advantage of using 3D printing is that sockets for connection to equipment such as interface electronics can be printed out instead of connected using conductive glues or paints.

Clearly, flexible electronics are a major plus with many emerging electronics printing processes that are emerging as they are lightweight, rugged, bendable, rollable, portable, and potentially foldable.

Xerox, a company that made its fortune from printing, has expertise in large-area electronics extending back to the 1970s. Their current research involves thin-film transistors (TFT) and p-i-n photodiodes for flat-panel display and image sensor backplanes.

But Xerox company PARC has also developed jet-printing processes for organic semiconductors. As well as currently being used for displays, the research centre discovered that these processes could also be applied to consumer health and electronics products, which rely on high-functionality packaging and electro-mechanical sensing.

Stephen Hoover, chief executive of PARC,'believes that these processes would be able to increase the amount of materials and the complexity of current printed products sooner than we think.

Contraband

Printing processes such as selective laser melting (SLM) and selective laser sintering (SLS) are being used to create incredibly rugged parts out of metal. Nasa, for instance,'is producing rocket parts with 3D printing. It is really only a matter of time until everyone has the hardware at home to print a complete firearm - or, well, any weapon really.

A gun advocacy group is already working on this and has uploaded an open source design for anyone to print a gun. Fortunately, this can only be printed on equipment out of the budget of the ordinary consumer - but who knows what the future holds?

It is easily conceivable that not just weapons but bombs could be printed. Therefore, policing the intellectual property becomes the next challenge.

So how far are we from the day where you could avoid having to wait for the post to deliver your shopping and all you would have to do is download the blueprints of your order to be printed on demand?

PARC's chief executive, Hoover, predicts the initial applications will emerge in about two years, including wearable sensors that can be put onto any product.

Other possibilities include printed batteries, memory chips and displays. "The performance isn't as high as traditional electronics," Hoover concedes. "But for a lot of things you don't really need high performance. You just want cheap and customised."

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How to print 3D

3D printed goods may not have the quality of the original item, but will be cheap and customised

Simple electrical devices can be printed on small 3D printing devices

1 Complex electronics require the the investment of a huge wafer fabrication facility costing billions of dollars. These are additive process and therefore would need to be shrunk down significantly.

2 Alternatively, as in the example of Optomec, semiconductors could be introduced into the printing process in their entirety.

3 These components would then be connected using 3D printed interconnects.

4 The operating environment would need to adjust to the different materials. A series of 3D printers designed for different materials could be incorporated into a production line.

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