Page 25 - Biomedical Engineering and Design Handbook Volume 2, Applications

4 MEDICAL DEVICE DESIGN
idea, and to devote some resources toward that effort. At that point
there is an embryonic project, and the device development effort
has begun. A preliminary examination is made, a goal is defined,
perhaps a report is prepared, some estimates are made of the
market, the cost of development, the time to market, the fit with the
existing organization plans, and the competition. If the aggregate of
these estimates is attractive, a decision is made to develop a new
product, and a planning stage is funded. The process here will start
with that planning activity.
Sometime before, after, or during the planning process, the
development team is assembled. Even though it may not follow in
that sequence, the process of building the team will be discussed
even before the planning phase. The steps in building the team are
probably as important as any in a serious development task. Even if
it is to occur later, it must be considered carefully in laying out the
plan.
With a plan and a team in place, the next step is to carefully
define the characteristics that the product is to have. A medical
product fulfills a set of needs, which are referred to here as the user
needs. It is most important that the product does indeed fill a legit-
imate and clearly defined need. A process is described here for
FIGURE 1.1 Elements of the arriving at and documenting the need, through contact with poten-
medical device design process.
tial users, medical professionals, patients, and others who will be
affected by the device.
With a clear vision of the desired outcome, the team can then
proceed to converting the desires of the various parties into a set of
specifications for the design. These requirements are to be stated in measurable terms, allowing for
careful evaluation of ideas in the early stages and progress as the design is solidified.
The next step in the process is to generate concepts. Although it is frequently the case that a
program starts with a solution, all too often the starting idea is not the best one. A concerted effort
must be made to seek the best possible idea or concept to exploit. The approach taken is to generate
as long and broad a set of alternatives as possible. The logic and some processes for doing this will
be discussed.
With a large set of alternatives in hand, the list must be winnowed down to a number that can be
pursued. This may be a single idea, but it is preferred that several are taken through the next few
steps. There are selection tools or methodologies that can help in this process. A great deal of judg-
ment is required, and great care is advised here.
With the concept selection completed, a design must be executed. This is accomplished in the
system and detail design phases. Elements here are highly dependent on the nature of the product,
so that the process here is less explicitly described than the previous steps. This activity is greatly
influenced by several of the issues mentioned previously, so a framework will be laid here and then
these ancillary issues will be discussed along with ways they might interact with the design itself.
With a medical product designed, it must be tested thoroughly, not just to verify its efficacy and
safety, but to assure that it has those characteristics that embody a successful product. There are
strategies for managing the prototyping and testing process in ways that enhance the product’s like-
lihood of success.
The last activity in the process is the start-up of manufacturing and the product rollout. This
event is the result of careful planning done though the duration of the project, often starting on the
very first day! Some of the special considerations discussed here cannot be allowed to wait, but
are integrated into all the activities. Nonetheless, it will be discussed as a phase near the end of
the section.
The last part of this discussion will be devoted to some overarching issues: documentation,
the roll of design tools and other resources, and regulatory issues and their impact on the design
activity.