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Tool kit: Rapid prototyping machines

By Eleni Kanavas  •  October 18, 2017

Real-time 3-D printing technology is transforming medical device development. At Sunnybrook Research Institute (SRI), researchers in Physical Sciences are using two rapid prototyping machines, or 3-D printers, to design and fabricate technologies like therapy delivery probes and imaging detectors inside the device development lab (DDL) at SRI’s Centre for Research in Image-Guided Therapeutics.

The Viper SLA (stereolithography) by 3D Systems uses a liquid photopolymer resin and an ultra violet (UV) laser to build parts of a model layer by layer. A laser beam forms each layer by drawing a cross-section pattern on the surface of the liquid resin. The UV laser light then cures and solidifies the pattern outlined on the resin and sticks to the layer below. Once a complete 3-D part is formed, the plastic model is cured in a UV oven.

The machine can print models up to 10 inches in size in anywhere from 30 minutes to 40 hours, depending on the intricacy of the design. The parts are waterproof and ideal for devices that are small, thin and finely detailed. Most projects are used in MRI testing. Examples include a part for an MRI jig or a tiny, fine-line grid that makes up a transducer array. The plastic material is of medical grade and can have contact with skin, but cannot be implanted in patients.

The second 3-D printer is the Fortus 400 FDM (fused deposition modeling) by Stratasys. It can build larger parts with the choice of using thermoplastic polymer materials like ABS (acrylonitrile butadiene styrene), polycarbonate and ultem, an amber-to-transparent thermoplastic.

“You can do things on a 3-D printer that you cannot do in a machine shop. [These] machines are capable of doing custom or prototype parts at a quicker speed and cheaper price,” says Michael Pozzobon, manager of SRI’s advanced machine shop in the DDL. “Our machines are good for end-use parts. They are repeatable and consistent. If you can draw it up, we can make it.”

Several researchers at SRI use the industrial machines, including Drs. Brian Courtney, Kullervo Hynynen and Graham Wright, as well as clinicians at Sunnybrook. External users include those from Princess Margaret Cancer Centre, SickKids and St. Michael’s Hospital.

The 3-D printers were purchased with funding from the Canada Foundation for Innovation.