Rapid prototyping allows designers to create things ranging from biomedical devices to multi-purpose household objects

Joint replacements, like artificial knees and hips, are increasingly common. They're a boon for people with failing joints, but the replacement parts aren't as durable as the originals. Usually made of metal and plastic and often cemented to the bone, they can deteriorate and come loose, and usually need replacing after 20 to 25 years.

But what if implants were made from materials that would actually allow bone and cartilage to grow into them and eventually replace them? A University of Waterloo research lab, with Toronto's Mount Sinai hospital and University of Toronto, is working on it.

It's one example of the innovative things Canadian researchers are doing with rapid prototyping, also sometimes referred to as three-dimensional printing.

Printers work by depositing toner or ink on the surface of paper. Three-dimensional printing doesn't stop at one layer. These machines lay down layer after layer of material — it may be in liquid or solid form — to build up an object.

As the name rapid prototyping implies, 3D printing has mostly been thought of as a relatively quick way to make models of products in the design stage. But 3D printing is good for more than prototyping, says Dr. Ehsan Toyserkani, a Waterloo associate professor of mechanical and mechatronics engineering, director of Waterloo's Rapid Prototyping Laboratory and one of the researchers in the artificial implant project.

For an artificial implant to really become part of the body, it must be made of material that the body can absorb without harm and be porous enough that tissue can grow slowly into tiny cavities in the artificial part.

It's one thing to machine the outer shape of a part out of suitable material, says Mr. Toyserkani, but "we cannot actually control internal structures." That's where 3D printing comes in. Because it builds up the part in layers rather than carving it out of a block of material, this process can easily leave openings, or pores, throughout the part.

Implants produced this way have been tested in animals, Mr. Toyserkani says, and the researchers hope to move on to human trials soon, with clinical use possible in three to five years.

Researchers in Montreal have put 3D printing to an entirely different use.

Philippe Lalande and Martin Racine are associated with Hexagram, the Institute for Research/Creation in Media Arts and Technologies, which is supported by Concordia, Université du Quebec à Montreal, Université de Montreal, McGill and commercial sponsors. Mr. Lalande says he was interested in rapid prototyping, while Mr. Racine was exploring sustainable design.

So they embarked together on a series of projects linking rapid prototyping and sustainable design.

The first was PRéco, which explored the idea of making consumer products last longer by using 3D printers to make replacement parts on demand. Too many household gadgets are thrown away because replacement parts are hard to find, Mr. Lalande explains. If there were 3D printing machines in hardware stores and parts carried code numbers allowing a store employee to download the design for a part, people could get replacement parts at local stores much as they get keys copied today.

"We found that basically it was a practical scenario," Mr. Lalande says, "but to be really effective, products would have to be designed from the outset with the idea of their being replaced with rapid prototyping."

So In their Metamorphose project the researchers moved on to designing products that could easily be repaired and adapted to other purposes. Using rapid prototyping, they created a series of light fixtures able to be altered to fit different locations and lighting needs, or even turned into other objects — a lamp shade becoming a fruit bowl, for example.

After seeing how difficult these adaptable designs were, Mr. Lalande and Mr. Racine decided to launch an adaptable design contest. Their year-old Metacycle contest has brought more than 130 entries, some produced using rapid prototyping.

Rapid prototyping plays a role in other research work. At University of Calgary, Dr. Simon Park of the Mechanical and Manufacturing Engineering department uses it to create larger-scale models of nano-scale designs such as tiny pumps. Carleton University set up a rapid prototyping lab several years ago with machines available for student and researcher use.

The Waterloo lab is also exploring the use of 3D printing to manufacture tools with embedded sensors that can measure factors like heat and impact. Today such sensors are usually placed on the surface of the tool, Dr. Toyserkani says. Readings would be more accurate with the sensor built in, but that's hard to do with traditional manufacturing methods. Three-dimensional printing could be the answer.

Grant Buckler

March 08, 2010 02:12 PM EDT

Special to The Globe and Mail

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