Last time we opened our discussion on the Development stage of the systems engineering approach to medical device design and discovered that the best design concept is the one that meets all stakeholder requirements. Let’s use the flow chart shown in Figure 1 to illustrate what comes next in this stage.
Figure 1To begin the transformation from concept to completed design, engineers review documentation created during the Concept stage, including design notes, concept sketches, and of course the final requirements specification which has been approved by all stakeholders. Once the review is completed, it serves as a guide to the creation of detailed design documentation, including mechanical drawings, electrical schematics, and wiring diagrams. A bill of materials, or BOM, is also created, listing all parts needed to produce the final product. Each part designated within the BOM is associated with a specific manufacturer or supplying vendor, and each has been qualified with regard to price, availability, functionality, and quality. The design documentation and BOM are also subject to a review by a fresh set of eyes, engineers who have no involvement in the project. If they should discover a problem, the design is rejected and sent back to the design engineers for revision. This process of evaluation and correction are repeated until the design successfully passes a final review. Only then can the fully approved finished design move on to the production stage. Next time we’ll continue our discussion of the Development stage, moving our concept medical device further along its journey to the Production stage. ___________________________________________ |
Posts Tagged ‘requirements specification’
Systems Engineering In Medical Device Design – Concept Evaluation
Monday, December 17th, 2012| How many times have you bought something and lugged it home, only to discover that it didn’t work as advertised? These days this scenario is all too common. Chances are it was developed haphazardly and rushed into production without adequate research and testing. A chief contributor to the product’s not living up to expectations is very often the result of a poor beginning. In its concept and development stages, design engineers failed to use a systems engineering approach.
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. ____________________________________________
|
