Phase 2: What Happens During the Design and Development Phase

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In our article, Medical Device Concept Generation and Prototyping: The Concept or Feasibility Phase Clarified, we discussed Phase I of the Medical Device Development Process: how user needs and technical specs are determined, concepts are generated and down-selected, and a working prototype is made. With this creative blue-sky phase complete, it’s time to move on to Phase II, the Design and Development Phase, in which the bulk of the engineering work takes place.

While a working prototype is necessary to prove out a concept, it may not be the best version of that concept. And while there is rarely a “golden ticket” design that perfectly solves every problem in the project, the goal of the Design and Development Phase is to tune that concept so that it optimally balances functionality, cost, and risk. Those three aspects are often at odds with each other, and it’s up to the team of engineers to decide what balance represents the optimal design.

Graphic depicting the relationship between functionality, cost, and risk


By optimizing the functionality, we ensure all user needs are met and the user has the best possible experience with the device. For example, does the device need to deliver a cardiovascular implant? If so, then let’s optimize that delivery process by determining:

  • The catheter dimensions that allow the user to track the device to the deployment site with the least amount of resistance possible
  • What catheter shaft construction provides the best lubricity, strength, and flexibility necessary for this tracking step
  • What mechanism minimizes the deployment force

While a single prototype may have been enough to advance through the Concept or Feasibility Phase, multiple rounds of prototypes are typically produced during the Design and Development Phase, as the design continues to evolve. CAD models are produced and revised as necessary, as rounds of prototypes and testing provide valuable information on the progress of the design. When the engineering team is confident that all user needs have been met and the overall design has achieved near-peak functionality, details are examined to optimize the cost.


With a locked-in design, it’s time to focus on three more aspects of the Design and Development Phase, which are all intertwined with one another. These largely dictate the cost of the device: component materials, manufacturing methods, and engineering drawings.

Component Materials

While some designs may require a specific material to meet certain performance specs, others may allow for a range of options. In these cases, the best material may not be the one that provides the best test results, but rather one that simply meets the requirements–and does so in a less-expensive and faster way.

For example, titanium may provide the design with an enormous factor of safety, but machining it can be costly and time consuming. The optimal material may be a strong plastic that results in a lower, but acceptable, factor of safety, and that can be injection molded quickly at a fraction of the cost.

Manufacturing Methods

The chosen manufacturing method goes hand-in-hand with the material selection, as one often leads to the selection of the other. Other factors for choosing a method include turnaround times, build quantities, component shapes, required precision, and of course, the cost.

Engineering Drawings

Finally, in order to relay a part’s shape and required precision to the manufacturer, engineering drawings are created. These drawings define the part’s shape, dimensions and tolerances, as well as any other information the manufacturer may need to make the part. The engineer needs to carefully consider these details, as keeping requirements on manufacturing loose helps keep the cost down, while keeping those tolerances tight can help reduce risk.


An ideal medical device would be manufactured to perfection every time, and always work perfectly in the user’s hands. However, mitigating risk comes at a price. Tightening the drawing tolerances, adding inspection requirements, and building assembly fixturing can ensure a manufactured part or device always meets the engineer’s vision but all those items add to the cost of the device. An effective engineer will find the optimal balance and mitigate risk down to an acceptable level in a cost-effective way.

Moving Into Verification and Validation

With the bulk of the engineering work complete, the device’s design has met its full potential as the function, cost and risk have been optimized. The device can move on to Phase III of the development process, in which the design is rigorously put to the test – the Verification and Validation Phase.

Graphic depicting an optimized functionality, cost, and risk.

Please reach out for information about how our experienced, creative team can help your company overcome complex design challenges to create innovative, life-changing medical devices.