Biomedical Engineering Reference
In-Depth Information
specification should address this need. A further example is that the device will need
instructions for use; the specification should address this too. It is too late to consider this at
the end when the device has been made. It is obvious that the holistic model best suits this
phase - talk to everyone !
4.5.3 Detailed Design Procedure
It is noteworthy that this procedure is important to the realization of a design but there is
no direct section in either FDA or ISO for that relates to it. However it is argued that one is
required to demonstrate meeting the requirements of Table 4.1 Row #2: Design Planning. In
relation to the overall procedure it is easier to combine the creative phase and the detailed
design phase into one then to split them. Although they work as two separate phases, to show
them as two separate procedures makes little sense as they are so entangled.
It is important to note that the first phase (creative phase) is intended to expand the design
space and then condense it to one embodiment. The actual methodology will be examined in
more detail in subsequent chapters. The subsequent phase (detailed design phase) takes this
concept and “makes it real.”
It should be noted that Figure 4.5 could be used for any of the embodiment phases of
design. It could be used for the first prototype; it could also be used for the final design
for manufacture; it could even be used to select an evaluation method. The same overall
process applies. As with previous procedures risk analysis at each approval stage is of great
importance. However this procedure also writes it into the specific design activities; as each
of them will result in judgments being made, a risk analysis helps to justify the judgments.
A further noteworthy item is that this procedure starts with the setting up of a team. This
means selecting the appropriate members (both internal and external); it also means the
setting up of milestones and timescales.
4.5.4 Design Verification/Validation/Evaluation Procedure
To meet the requirements in Table 4.1 Rows #13 & 14, the design needs verifying and
validating. Verifying is concerned with making sure the outputs meet the inputs. Validation is
concerned with checking that the output works within a clinical environment. Both are very
similar in concept hence one procedure could be used to form the basis for both; I have called
this design evaluation ( Figure 4.6 ).
The important aspect here is the fact that the device will need validating or verifying against
some criteria. These criteria need to be selected and the evaluation protocol must be devised
and approved. During the design process this procedure will be used and tested lots of times,
as it is the basis of checking appropriateness of a design. It should be noted that clinical trials,
etc. come under this procedure. It is also worth noting that the final evaluation, verification,
and validation will have been specified in the initial product design specification.
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