A Plan + A Printer = A Product!

By Team Digit Published Date
01 - May - 2005
| Last Updated
01 - May - 2005
A Plan + A Printer = A Product!
At the Shared Tissue Engineering Laboratory at the Medical University of South Carolina, scientists use machines to 'print out' skin. The printed skin could eventually replace skin grafting, which is used for burn victims as well as for cosmetic purposes. The machines are shooting out the proteins that will constitute the skin, and the tissue is being captured on specialised gel.

There's probably nothing overly interesting about that, but what's amazing here is that the machines are old HP and Canon inkjet printers!

Whoever said the unassuming inkjet could only be used for printing out documents, reports and such? Certainly not the inventors of the technology! They were experimenting with a variety of uses for it, and it just so happened that printing on paper got most quickly commercialised. Now, researchers are going back to their drawing boards and finding seemingly exotic, yet eminently practical, uses for the technology behind the print nozzle.

You see, the print nozzle is an exquisite piece of technology: it has many, many holes, and squeezes out extremely tiny droplets of whatever is in the cartridge. That's where its potential lies. Instead of just ink, you could think of anything to put in the cartridge, and instead of paper, you could think of just about anything for the 'ink' to be deposited on.

Although printing out skin is an interesting and useful idea in itself, one can easily extend the concept. How about printing out display screens? Printed circuit boards? MP3 players? Entire houses?

But we're getting ahead of ourselves. In what follows, we'll talk about 3D printing-instead of just one print head moving to and fro in one dimension, imagine several print heads capable of moving in all three dimensions, depositing anything you could imagine on any suitable surface. Or, a regular inkjet printer could print layer upon layer, thus making up a 3D object-for example, a bone or an internal organ.

What you have then, are machines capable of printing, well, just about anything. For example, instead of constructing an MP3 player part by part, incorporating the PCB, the plastic moulding, the hard disk and so on, you could just create a blueprint of the entire device and print it all out at once. That's the idea behind most of what follows-a plan being printed out.

Here's a glimpse at what is being printed now, and what will be printed in the near future; and all of it goes far beyond plain old paper and ink.

Skin, Bone And Cartilage
So how does all this work? Like we mentioned, the inkjet printer is a marvel of technology because of the print nozzle, which spits out thousands of microdroplets. As an example, think about grafting skin onto a wound. A 2D inkjet printer will suffice for skin because the proteins shot out can be captured on a flat gel substrate layer. Experts enter the wound's dimensions into the printer to ensure a perfect fit. They then take skin cells from the patient's body and multiply them using biological techniques, and then print out a strip of skin that is tailor-made for the wound-and ready to sew on.

Instead of constructing an MP3 player part by part, you could just create a blueprint of the entire device and print it all out at once

Such a printer has been developed at Manchester University in England; it only takes up the area of three filing cabinets. At the university's School of Materials, scientists have already successfully created skin, and think they will soon be able to create bone and cartilage as well.

Team leader Professor Brian Derby says, "It's not like printing a sheet of paper. We can print a few millimetres in depth and build it up layer-upon-layer until, in principle, we could produce bone fragments the size of a golf ball." Project leaders say the method could eventually be used to build an organ in a day!

The amazing thing here is that it's basically inkjet technology at work.

Inkjets For Just About Anything 
Faxing Up Spare Parts
Think about the plight of an astronaut in space when something breaks. Where would he get a spare part from? Roger Spielman, a scientist for Boeing Canoga Park, has the answer: fax and print. One could 'fax' the 3D computer-aided design file to the International Space Station, where the data would be fed into a machine that assembles the required spare part from a bucket of powder. This, if you think about it, is not very far from faxing a physical object!

Printing Out A Heart
Tissue engineering combines the disciplines of cell biology, materials engineering, and biochemistry to create biological substitutes for human and animal tissue. At Clemson University in South Carolina, chemical engineer Thomas Boland had a novel idea in 2001 that brought the inkjet into tissue engineering. His method was deceptively simple: you could build up a 3D tissue by modifying the printers' output tray to drop down a little bit with each pass of the print head. Boland used his printers to create half a cat's heart-the heart actually beat in a petri dish!
Fuel Injection And Medicine Atomising
Since an inkjet sprays tiny droplets, one of the first uses that springs to mind is fuel injection. A regular injector does the same thing, atomising petrol (or diesel) into tiny droplets, but the smaller the droplets, the more completely they will vaporise and mix with air, making for more efficient fuel burning. An inkjet can therefore be part of extremely precisely controlled fuel injectors.
Think about medical inhalers, such as asthma medication inhalers. As with fuel injection, the task of creating the spray that these inhalers spit out is ideally suited to the inkjet. The problem is that conventional inhalers spray out a mist of drops that are too large, and also uneven. The inkjet can remedy this: digital aerosols, which are thermal print heads incorporated into inhalers that spit out perfectly uniform drops, could come to market as early as the end of 2005. This method of injection is ideally suited to drugs that need to get to the bloodstream-the smaller the size of the droplets, the easier the absorption of the medicine into the bloodstream.
Digital aerosols are being developed by Australian company InJet Digital Aerosols. The inhalers will deliver drugs faster than do tablets or patches.

Flexible Plastic Screens
Several companies worldwide are in the race to commercialise flexible plastic-screen technology. Philips is currently using a four-headed inkjet with hundreds of piezoelectric nozzles to print OLEDs (Organic Light-Emitting Diodes) onto computer and television screens. You have probably heard of OLED screens-OLEDs glow when a current is applied. (Piezoelectric nozzles are one of the two commonly-used types of nozzle-the other is a thermal nozzle. A piezoelectric nozzle works when a current bends a piezoelectric crystal, forcing the fluid down and out of the nozzle. One of the properties of piezoelectric crystals is that they move or bend when a current is applied, and they release a current when bent.)
In Bristol, England, HP engineers are using inkjets to etch tiny liquid-crystal dots onto a plastic substrate-the dots themselves will be the pixels. Electrodes in the plastic, which is bendable, turn the crystals on and off, making for a full-colour display that would, at some point, compare with printed material in terms of resolution.

Circuit Boards
As was proved by Japanese engineers at Seiko-Epson, printing the innards of a gadget is possible using inkjets. In November 2003, they printed a circuit board consisting of 20 layers, and only 200 microns thick. How? They simply swapped copper for conductive inks and silicon for insulating inks. A piezoelectric print head with microscopic nozzles was used for the process. Seiko-Epson is confident that these thin boards will be used in gadgets as early as 2007
3D Printing
Going beyond 2D inkjets, think about 3D printers. A 3D printer is essentially a modelling tool, which can create plastic moulds and such. As an example, Z Corp, based in Burlington, Massachusetts, USA, markets an "affordable 3D printing system", which uses a spray nozzle adapted from an HP inkjet printer, to spray a liquid that binds powdered solid substances into a certain shape.

Z Corp began shipment of its Spectrum Z510 3D printing system in March of this year-the first high-definition colour 3D printer ever to hit the market. The Z510 introduced HD3DP (high-definition 3D printing) for rapid prototyping to designers, engineers, and product developers. (Rapid prototyping refers to a class of technologies that can construct physical models from Computer-Aided Design, or CAD, data.)

Using the system interface, product developers could now efficiently print 3D physical models with smaller features and more complex geometries, in colour, and with high-definition detail. The system software also allows for labelling, enhanced texture mapping, and vibrant product colouring. The Z510 initially retailed at $49,900 (Rs 21 lakh) in the United States.

But such printers can, obviously, be used for more than just modelling and visualisation. It's all about design: you feed in the requisite data to the printer, and it constructs the required object according to the blueprint.

And that is something to think about. You could feed in a blueprint for just about anything! Could such inkjet (and other) printing technologies democratise manufacturing the way the invention of the printing press democratised knowledge hundreds of years ago? Instead of inkjet printers that print just words and graphics on paper, we could all have 3D printers sitting on our desks, printing out whatever we told them to.
And what would that mean in terms of who would make the money? There would be a paradigm shift: you would pay for plans rather than for products. Download a plan, print out the product. You are probably already imagining P2P networks that you could download plans off!

What kinds of product would you really be able to print out? What is feasible in reality? As an indicator, instead of looking at fiction of the future, let's look at what is being done right now.

John Canny, professor of engineering at the University of California, Berkeley, and his co-investigator Vivek Subramanian, are using electroactive polymers, gold nanocrystals and inkjet printers to print devices that can move as well as process information. (Electroactive polymers are substances that respond to external electrical stimulation by displaying a significant displacement in shape or size, and nanocrystals are a non-traditional type of semiconductor.) They call this process 'flexonics'.

This revolutionary approach to desktop manufacturing has been enabled by recent advances in 3-D printers and organic electronics.

Printing Out Houses 
Better inhalers for better delivery of drugs. Plastic screens. Tissue engineering. Fuel injection. Rocket spare parts. Bones. Organs. Skin. What is not possible with inkjet technologies? Houses? As it turns out, houses can be printed out, too. One researcher has plans to, as he puts it, "be able to completely construct a one-storey, 2000-square foot home on-site, in one day and without using human hands", by 'printing' the house.
Engineer Behrokh Khoshnevis, at the University of Southern California, has been perfecting his 'Contour Crafter' for more than a year now. It 'prints' houses, and is to be tested by the construction industry. It takes instructions directly from an architect's computerised drawings and then squirts layers of concrete one on top of the other to build vertical walls. The precision automaton could revolutionise building sites, for the simple reason that it can work round the clock, in darkness and without breaks.
 The key to the technology is a computer-guided nozzle that deposits a line of wet concrete, something like toothpaste being squeezed out. Two trowels, attached to the nozzle, move to shape the formed deposit. The robot repeats the same step many times to give height; hollow walls are built and the machine returns to fill them.
 Degussa AG, of Düsseldorf, Germany, will collaborate on Khoshnevis' project to help him find the best kind of building material. Khoshnevis has tested his prototype with cement, but believes that adobe-a mix of mud and straw dried by the sun-might be suitable.
Khoshnevis' prototype robot hangs from a movable overhead gantry (a large supporting structure). The first house will be built later this year. If the technology proves successful, the robot could enable new 

Their research will allow fully-assembled electric and electronic gadgets to be printed in one go, instead of going the traditional way-creating a casing and then filling it with electronic circuit boards and components. Printing a complete and fully-assembled device by printing layer upon layer of conducting and semiconducting polymers, the device circuitry is built up as part of the bodywork.

When the technique is perfected, devices such as light bulbs, cell phones, radios, remote controls and toys will be spat out from printers as individual, fully-functional systems without expensive and labour-intensive production on an assembly line.

Three-dimensional printers are valuable tools for making prototypes of new designs. They deposit layers made from droplets of smart polymers, which gradually build up into 3D shapes. (Smart polymers are fascinating materials that show distinct responses to differences and variations in the environment, such as thermal gradient. They are called 'smart' because one can actually harvest their odd properties to benefit a wide range of applications.)

Such printing techniques have now become so sophisticated that it is possible to print working prototypes with mechanical parts that move just as they would in the final product.

The University of Berkeley's important addition to this art is to allow the electronics to be included in the printed device, rather than being added at a cost later.

Already, the Berkeley team has worked out how to print out electronic components such as transistors, capacitors, inductive coils and other semiconductor components. "These may be connected to form complete circuits for actuation and control," says Canny. He also believes that once they develop inkjet cartridges that can handle all the polymers needed for casing and circuit printing, they would be able to make, say, a remote control.

 It would be printed as a single component, rather than being built up of smaller components. The infrared emitter and all the other electronics would be polymer-based.

Is There Anything We Can't Print?
Brains, probably!

There are so many uses for the inkjet, 3D or otherwise, that it's overwhelming. You sort of get the idea that there is nothing that cannot be printed out.

The point here is twofold: first, desktop manufacturing will revolutionise the way we think of products. With flexonics maturing, and with high-quality 3D printers getting cheaper, we will soon enter an age where, like we mentioned, you will pay for plans rather than for parts.

Second, one needs to remember that not all materials and substrates have been researched. For example, to print out, say, a handbag, you would need a process that could extrude leather out of a nozzle, which is not very realistic, at least for now.

Another limiting factor is how easily plans can be laid out for the object: if it's something like a screwdriver, it's relatively easy because the dimensions and other properties are well-known and easily documented. And as we mentioned, it would be difficult to print out a handbag because it's not quite so easily defined.

Desktop manufacturing could easily become a buzzword in the near future. Remember, you read about it first in Digit! Research in the areas we've mentioned is ongoing and exciting. Roger Spielman of Boeing probably sums it up best: "It's actually happening. You're going to hear a lot about this in the near future. There are hundreds of uses. You can build a part in a part. You can build a ship in a bottle. We can make real things out of dust."

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