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Ease the jump over global design hurdles
Doing homework allows designers to use in-house and out-sourced expertise to meet challenges and opportunities
Rick DeMeis, Senior Technical Editor -- Design News, May 21, 2001
When it comes to designing medical equipment, from electronic-based pacemakers to bio-fluid valve devices, Medtronic (Minneapolis, MN) has found success around the world. Engineers for the company work with design and regulatory experts, both within and outside the company, so they can avoid surprises and smooth out any bumps on the road to delivering safe and reliable products to market.
Jeff Bertrand, manager of applied research at the Medtronic PS Medical operation (Goleta, CA), is typical of the medical designers. He notes that while most design on medical valves is done at his facility, the designers will contract outside help as well as rely on assistance from Minnesota—all the while gathering information needed to meet market and regulatory requirements from around the world.
For the recently developed Strata valve for brain fluid management, "The computer modeling group in Minneapolis assisted with fluid mechanic analysis of flow paths and FEA on the valve's springs," Bertrand says. The same group will analyze, say, the fatigue life on pacemaker leads that flex with a heartbeat 84,000 times a day. An industrial design firm was hired for their ergonomics expertise to design the hand-tool kit that allows a doctor, in an office setting, to adjust the brain-fluid valve magnetically. And a materials testing firm, once given Medtronic's applicable protocols, confirmed biocompatibility of the implantable valve's materials.
Meeting regulations. For design collaboration, engineers have access to a secure intranet that Medtronic setup for posting and e-mailing CAD files. Close communication between designers and regulatory experts at various Medtronic locations, usually via fax and e-mail, is critical, adds Bertrand, "Because half our business is in overseas markets, we have to keep other countries' standards well in mind." For instance, to earn a CE mark, "Our people in Europe" he notes, "keep us on top of what device directives are applicable. We work with our European group to interface with the approving bodies. Many countries not part of the EU will look to it and honor a CE mark in lieu of their own approval. In Japan, we work with the Japanese Ministry of Health and Welfare and with our distributors."
One interesting issue Bertrand notes as critical in global design is labeling and marking a product to meet regulations or show approval. "With some devices, the label could be bigger than the product itself," he says. "Mark location and size have to be addressed."
"But the biggest challenge," Bertrand adds, "is in standards and communications issues that leave room for interpretation," possibly with the decision of a single individual. "These then have to be settled," he says. "For instance, in Japan it's a long process clarifying issues about certain kinds of materials" that may require their substitution. Similarly, he notes with the U.S. FDA, "If you can use a material used before, then you will not need a higher level of review that new materials require."
The best advice Bertrand offers is to get input from people who will be using the product as well as marketing it, along with obtaining all applicable standards. "Many of these standards may not apply," he says. "But you have to be aware of the ones that do. If one does not apply, you still should have a rationale available as to why it doesn't. This shows you are thorough in addressing all the standards that might apply."
Bertrand concludes, in Medtronic's case, "We get out with doctors and attend surgeries to know what's involved in the environment in which our product will be used." Good advice for any design engineer.
Success story
Success story
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| A pacemaker is comprised of an implantable pulse generator (battery, microprocessor, A/D converter), atrial and ventricular pacing leads, and an external programmer. Devices like this Medtronic Kappa 700 must be immune to EMI and meet mechanical and electrical shock requirements. |
Company: Medtronic
Product: Kappa 700 pacemaker for patients with heart rates less than 60 beats/min
Location of design team: Minneapolis, MN
International markets for product: Approved in 120 countries worldwide
International standards met: Numerous including FDA, ISO, CENELEC (the European Committee for Electrotechnical Standardization), France, and Japan
Biggest design challenges:
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Add additional sensing, diagnostic, and therapeutic features to existing product without impacting battery life or increasing product size.
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Eliminate EMI to avoid "mispacing" or "no pacing."
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Mechanical robustness in shipping (while maintaining sterility) and long lifetime of mechanical components
Keys to success:
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Up-to-date IC fabrication processes, battery chemistry, capacitor and resistor technology
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Efficiency in design via thorough understanding of physiology (RF data links, obviating leads, which can act as noise-gathering antennae
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