The art of design validation and verification

We've all seen Russian nesting dolls, each perfectly decorated doll giving way to a smaller one inside. Every one of those little dolls is hand turned, carefully decorated and finished with a fine gloss. Medical device design operates on a similar concept, layering smaller components together to form one machine, each component tailored to the needs of the original equipment manufacturer (OEM).Design verification and validation are akin to the finishing gloss, and aren't reserved for the largest doll - or completed product; each component gets the same gloss. Here, Gareth Hancox, engineering and commercial support manager at Accutronics, explains the layers of verification and validation.

The words verification and validation are a little overused, and it can be easy to confuse the two processes or even to think they are the same. However, they are distinct and important practices that OEMs can’t afford to take for granted, especially in medical device manufacturing. The possible repercussions of failing to ensure that your new device is effective, safe and fit-for-purpose in medical and healthcare applications can be severe.

So what’s the difference between the two? Design verification establishes whether you designed the device to the right specification, design validation ascertains whether you designed the right device to meet customer expectations and requirements. The distinction may be subtle, but it is significant.

There’s no room for error when supplying medical devices, so verifying and validating your design proves that you’ve developed the best possible solution to a specific need and that it is safe to use. However, did you know that OEMs designing the machine are not the only ones going through this process? Often, the smaller components within a device are bespoke designs created by another OEM, such as the all important battery.

Much like lining up your Russian nesting dolls in height order before tucking them away, successful design validation and verification requires order and planning. Treating this process as an afterthought will, at best, cause you a headache; at worst it could mean your device fails the procedure.

Testing the waters

The US Food and Drug Administration (FDA) guidelines on the topic stipulate that medical device verification activities must be “conducted at all stages and levels of device design” and say that the “basis of verification is a three-pronged approach involving tests, inspections, and analyses”. In addition, the guidelines state that devices should be “tested in the actual or simulated use environment as a part of validation”.

To ensure our customers’ devices meet all necessary regulatory requirements, we test our batteries in simulated conditions and, to make sure we can do this effectively, we recently upgraded our test facility. Automated testing cabinets linked to climatic chambers tirelessly test cells and batteries for applications ranging from portable instrumentation and medical devices to robotics and defence.

Our new test equipment allows us to really put cells through their paces based on real world usage. We are able to accurately replicate the demands the device will place on the battery so we know the cells will perform as needed.

When making Russian nesting dolls you start with the smallest one first and work out. She has to be perfectly formed and solid, or the rest simply doesn’t fit. Your battery is that tiny figurine; if it is not formed properly the rest of your device will fail. Choosing a battery OEM that can guarantee attention to detail, is the first step in getting your device verified and validated.