Advancements in rapid prototyping (RP) processes and materials are affecting medical devices, implantables, equipment, and anatomical models.

RP technologies use automated mechanical techniques to build physical 3D models from 3D CAD files. A few examples of medical devices designed using RP include catheters, stents, syringes, retractors, and surgical fasteners. Prototypes are also important in the design and manufacturing of other pieces of medical equipment including MRI machines, hospital beds, handheld testing and display devices, and fluid collection and testing equipment.

Prototypes of anatomical parts help doctors better understand different surgical approaches. They also help doctors explain options and procedures to patients. In these scenarios, it is obvious that there are many advantages to using 3D physical models instead of illustrations or computer images.

Materials for medical

While any common RP material suffices for general fit, form, and function testing, the RP industry continues to develop materials specifically for medical applications.

Some examples:
• Duraform PA, used in selective laser sintering (SLS), is a nylonbased material that meets the requirements for the USP Class VI classification. It is a good choice for medical applications requiring biocompatibility and it is compatible with autoclave sterilization.

• Polycarbonate-ISO (PC-ISO), used for fused deposition modeling (FDM), is an industrial thermoplastic and is compliant in its raw state with the ISO-1099-1 and USP Class VI classification. The material is widely used for medical-packaging applications and by medical-device manufacturers. PC-ISO can also be sterilized using either the gamma radiation or ethylene oxide method.

• RC-79D, a urethane for cast urethane molding, is approved for medical applications such as MRI coil housings. It is a UL 94V0-registered flame-retardant polyurethane.

At your service

One service bureau that helps medical device companies prototype parts is Quickparts. It recently assisted Canadian firm Sentinelle Medical, a developer of MRI technology, in the prototyping of a new design by casting RC-79D urethene. Clinical experience in diagnostic imaging had produced good ideas on how to improve the detection of breast lesions and make intervention more efficient. The Sentinelle Vanguard Breast MR Auxiliary Table arose out of these ideas. It works to detect breast cancer by providing highresolution images, biopsy choices, patient ergonomics, clinical convenience, and health-care economics.

The Vanguard Table with an eight-channel coil array basically transforms a standard GE MRI into a dedicated system for breast MRI. The coils can be custom positioned for every patient, providing image qualities not possible with traditional tabletop coils. Sentinelle chose Quickparts for its two-week turnaround time on cast urethane housings for the coils.

Casting urethane can be an inexpensive alternative to CNC machining. “Quickparts is responsive and its online, QuickQuote feature is convenient,” says Rob Brown of Sentinelle. “It’s easy to submit a file and look at different RP options. The quoting process also lets users get a good idea of part pricing before the part design is complete. And I like getting that quote right away.”

Hammerhead Design & Development, Mount Pleasant, SC, designed an explant tray to secure anatomical models used to teach fellowship doctors about particular disease treatments, such as tumors or bleeders sewn into the porcine anatomy. The firm needed a supplier that could provide a one-stopshop for SLA and cast urethanes. “I needed a tray that would stabilize the organs used in testing,” says CEO Becky Delegge. “I also needed a way to paint the prototypes to match the color of the parts that would go with the trays.”

Hammerhead used the Quickparts online quote feature, which helped speed its design, says Delegge. “It’s easy to modify quotes and the company easily adapts to changes I need to make,” she says. After confirming the tray design with painted SLA parts, Hammerhead opted to use the cast urethane process for the production of the trays.

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