| 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.
To 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 ‘design review’
| Recently my wife was on a quest to make the perfect pound cake, but before she put butter to flour she did her research. What’s the best butter? Best flour? Eventually she came up with a recipe she felt would prove to be the Queen of all pound cakes. After the recipe came reviews by her test panel, or family members, including myself. Questions were asked, such as, When you first bite into a pound cake, do you want to be aware of vanilla or lemon? It was only then that she would begin to combine ingredients for the final mouth watering product. Very much this same procedure is used when coming up with a new medical device.
Previously we’ve discussed FDA requirements for medical devices as they concern design controls with respect to design and development planning and design input procedures. We’ll now focus on requirements for Design Output, Design Verification, and Design Review Procedures.
Design Output and Design Verification Procedures go hand in hand to ensure that design output is properly documented, organized, reviewed, and evaluated in light of design input. What this means is that medical device companies must scrutinize and evaluate what is going into the design process, then make a comparison to what is coming out. The design is ultimately verified when all requirements for the medical device as previously set out have been met.
“Design output” is just another name for work product after major phases of the design project are completed, such as when my wife determined which butter would produce the best pound cake. Design output typically takes the form of specifications, notes, calculations, computer programs, mechanical drawings, electrical schematics, printed circuit board (PCB) layouts, bills of materials (BOM), mockups, prototypes, test data, and test reports. These are then utilized by people outside engineering circles to manufacture components and assemble them into a final product.
Design Review Procedures ensure that the design output is evaluated by others not directly involved in or responsible for the design work product, much as when family members served as a reviewing committee for my wife’s inquiries into taste preferences in pound cake. Sometimes she’d even ask a friend or neighbor to put their two cents in, and companies, too, will at times go outside and hire consultants to perform this function. By so doing, unbiased opinions are sought out, in the hopes that this fresh set of eyes will be more likely to spot errors, omissions, and misinterpretations that could prove disastrous if put into play. Design reviews are typically conducted after each major phase of a design project is complete.
Just as a recipe that looks good on paper may not necessarily taste good, a device design will often seem to work perfectly on paper, then prove otherwise when its manufacture begins or it’s used in the field. Ideally bugs are worked out before the product hits production and, later, the marketplace. Design Validation Procedures make use of prototypes for testing and careful evaluation under simulated or actual use conditions. Does the design safely meet requirements for intended use? Does it conform with industry standards? If not, there’ll be a lot of wasted “dough” going into the trash — pun intended!
Next time we’ll explore FDA requirements for Design Transfer and Design Changes. We’ll also talk about procedures for Design History Files.