In-House Tests Reveal Early Problems in Medical Device Designs

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Within medical device companies, a dedicated team — either quality assurance (QA) or verification and validation (V&V) groups — is often tasked with ensuring that products in development meet a range of standards. Verification involves lab-based prototyping and simulation of products “on the bench”; validation is done out in the field with the real product and real users in a real environment.

Every medical device designer and manufacturer works toward the International Electrotechnical Commission’s 60601-1 standard, widely considered the baseline requirement for basic safety and performance of medical electrical devices. Products can’t win regulatory approval without meeting the standard.

While you’ll need to take the final product to a recognized testing lab for certification that it complies with IEC 60601-1, you can perform incremental verification tests in-house to streamline your design and engineering process and, importantly, save money.

Why Test Medical Devices During Development

Basic verification testing in your own lab allows you to identify problems and iterate solutions before you get to the final device.

Testing by independent, accredited laboratories is expensive. We have a saying that going to a test lab is like going to court: Just as a lawyer doesn’t ask questions he does’t have the answer to, engineers don’t want to test a product unless they can anticipate how it will perform.

Running mechanical strength tests on end-stage prototypes means you’re putting these expensive samples through the wringer not knowing if they’re going to hold up. Instead, you can test components in-house as you work through the development process, make design adaptations early on and be reasonably well-assured that the product will pass final testing.

Six Mechanical Strength Tests to Do In-House

Let’s look at several basic mechanical strength tests you can conduct in your own lab, without any specialized equipment or facilities like temperature or altitude chambers. The particular instructions for each test are outlined in IEC 60601-1 Section 15.3.

These tests can answer questions like: Is the enclosure strong enough? Are the components mounted strongly enough to withstand physical stress? Will the components themselves meet standards?

  1. Push test. Is the enclosure of the equipment rigid enough to resist a steady force? The test involves applying a defined force to the outside of the device for 5 seconds.
  2. Impact test. Does the enclosure have enough resistance to impact to protect against risk? In this test, the enclosure of the device is subjected to impact from a heavy steel ball.
  3. Drop test. Are the device and its components strong enough to resist being dropped? This test evaluates mechanical stress caused by being released from a height of 1 meter (or the height at which the device is normally used).
  4. Rough handling test. Are the device and its parts strong enough to withstand rough handling due to standard use? This test includes a series of realistic scenarios, like pushing the equipment down a step or over a door frame.
  5. Mould stress relief test. Are plastic components manufactured so that they won’t shrink or distort due to inherent stresses resulting from the injection moulding or forming process? This test subjects the entire device (or the enclosure with supporting framework) to a specific temperature for 7 hours.
  6. Environmental influences test. Is the equipment built to withstand wear, corrosion, degradation or other issues endemic in the environment where it’s to be used? This commonly involves chemical testing to be sure the device can handle solutions and processes used to clean and disinfect it.

The Cost of Failure

Designers and mechanical engineers can run working prototypes through these six basic strength tests, so when they eventually submit the finished product for official testing and certification, they can have a high level of confidence that it will pass.

Executives and product managers may balk at the cost of using additional materials and prototypes for testing. Particularly if you’re developing a large, complex product, such as a mobile lab or patient care cart, this isn’t a small expense. It’s difficult to fathom spending project dollars on stuff you’re planning to drop, mishandle and try to break.

The real risk, though, isn’t in testing a component that fails. It’s in learning too late in the process — when manufacturing is ramping up and sales forecasts are already baked into the bottom line — that the device doesn’t meet standards and has to be completely overhauled.

When a finished product fails in stringent testing by an approved laboratory, the design and engineering teams have to go back to the proverbial drawing board. That rework, in turn, delays the product launch and delays sales. Imagine a device that’s expected to do $1 million in sales per month; a month’s delay has a major financial impact. And making last-minute changes in manufacturing, for example re-engineering a $30,000 tool to make a 25-cent part, is costly as well.

Better to discover early on that a single component doesn’t meet standards and to spend an extra day or two to address it than to encounter failure when it gets really expensive.

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