Engineering Expert Witness Blog

     Last time our discussion of the Concept stage of systems engineering identified stakeholder requirements as being of three basic types, serving the needs of functionality, performance, and constraint.  Once identified, these requirements were incorporated into a detailed specification that is approved by all stakeholders involved, then used to devise alternate medical device concepts in order to really size things up.  Let’s now move on to the Development stage of the design process to see how the alternate concepts are evaluated.

     The Development stage of the systems engineering approach to medical design begins with research and development of alternate device concepts.  Stakeholder requirements as defined in the original product specification are used to guide the process, then mockups and prototypes of the alternate concepts are built, tested, and analyzed in view of the requirements.  Considerations such as cost, ease of manufacture, operation, durability, and potential risk of harm to users are evaluated.

     As often happens, the best alternate concept satisfies all but a few of the specified requirements, resulting in a “good enough” scenario.  That is to say, if stakeholders can agree the requirements not met aren’t all that important in the scheme of things, they may be willing to remove them from the specification, thus approving the concept for further development.  If an agreement such as this cannot be reached, it may be necessary to return to the Concept stage and begin the entire process again.  This re-evaluation of the process should result in a set of requirements that are further refined and from which better options in alternative concepts can be developed.

     Next time we’ll continue our discussion of the Development stage and see what it takes to finalize design and begin manufacture.

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