Part 7: Leveraging Prototypes in Medical Device Development
There’s a long list of reasons why we believe it’s wise to build prototypes when you’re developing a medical device, but the overriding reason is to facilitate learning. Even experienced designers, aided by powerful design and analysis tools, learn a lot by building prototypes. Predicting things like the best shape for a surgical handpiece or the best way to organize an input form can be difficult without trying it out in actual or simulated use. Performance of mechanical or electronic systems can be simulated, but simulations are rarely complete and can be fooled by unexpected things in the real world. Only by building actual prototypes you can interact with, criticize, and improve can you truly achieve an optimal design for your product.
So, when should you build a prototype? How many should you build? What functionality should they have?
Using our six development phases as a framework, what follows is a discussion of the prototypes that might be made in a project, and their purposes and uses.
Prototypes made in this phase are usually about providing a tangible representation to facilitate user discussions and support presentations for fundraising. They rarely are functional but are sometimes made with fine finishes to appear realistic. Few units are needed, but there are often multiple embodiments depicted. These prototypes are inexpensive and can be produced very rapidly.
In this phase, prototypes are used as tools to prove the product concept. Usually, they’re used in tests of functions where there is some doubt about feasibility. This may mean whether users can accept a surgical tool of this weight in the intended procedure, that a fluidic circuit can separate cells as intended most of the time, or that a patient can understand what a diagnostic device is telling them and act properly. It usually doesn’t take more than a few units to prove out a problem area of a product concept, but there are sometimes several areas that need testing in separate prototypes. Except in cases of high complexity, POC prototypes are usually modest in price and can be built quickly.
Alpha Phase prototypes are used to determine specific use details and performances of the device and to work out details of how it will be put together. These prototypes help work out the specific requirements that are important to safety and efficacy and facilitate major design decisions. Since Alpha testing is more specific and precise, multiple units may be required and their functionality will be greater than POC prototypes. They will also be more expensive and may take longer to build.
Beta Phase prototypes are used to evaluate whole systems in the design. Final component choices are often used, and things like battery life, cabling, ingress protection, grounding, shielding, EMC, and ESD are subjected to preliminary tests. The quantity of Beta prototypes needed varies by type of product, and the tests needed to verify required performances. Cost and lead times are similar to Alpha prototypes.
Pilot Production Phase
Pilot Production prototypes can be extremely important. These units are intended to be functionally equivalent to production units and are used in verification and validation testing. Any design change after V&V testing may create the need for revalidation, so the design is generally frozen after all the learnings of the Beta Phase have been incorporated. V&V protocols will determine the number of pilot production units needed. These units generally cost a bit more than production units due to small batch sizes and more expensive labor and take a little longer to build.
The need for prototypes pretty much disappears when production units appear, but they are still occasionally produced for trade shows and manufacturing operator, user, and sales training. Sometimes units are built to show design options our client would like to explore or lacking expensive or hazardous components to be used for demo only.
At DeviceLab, we make prototypes early and often throughout the process. It’s true that they can sometimes be costly, but the learning they provide is invaluable. They also provide assurance that things are on track in a project and reveal opportunities for design improvements. Altogether, making prototypes is money well spent. Check out the Process and Compliance pages on our website to discover how we do things.
In the next post in this series, we’ll talk about the design process from our client’s point of view and offer several tips on how to successfully outsource design projects to companies like DeviceLab.