Page 36 - Biomedical Engineering and Design Handbook Volume 2, Applications

MEDICAL PRODUCT DESIGN 15

the marketing function of the team should have been updating these estimates throughout the
development and trials. Products are often introduced at shows, resulting in a national or even inter-
national introduction. This means that there should be sufficient quantities of product “on the shelf”
to meet the initial round of orders. It is difficult to recover from a product scarcity that develops in
the initial launch. All of the stakeholders become disenchanted.
The arrangements for product sales and distribution are not within the scope of this book, but the
plan for this should be understood by the development team well in advance of the introduction.
Issues like training the sales staff, providing printed materials, and samples should have been worked
out well in advance.

1.16 PROCESS REVIEW

This is also the time for the team to evaluate the job it has done, the lessons it has learned, and
specifically how it performed against the five objectives set forth at the start of this section. Quality,
cost to manufacture, time to market, and cost to develop will be well recognized. The fifth objective
of improving the capability of the organization will require some thought. An effort should be made
to determine what aspects of the process did not work as well as they should have. A team meeting
may be the best way to do this, or the team leader may choose to meet members individually.
The basis for assessment should be the plan and the process. Were the plan and the process
followed closely? If not why? Should the plan have been different on the basis of the knowledge at
the time it was drawn? Is the process, as laid out, the best approach for this group? How should it be
altered? Were the resources and external support adequate? If not, in what way?
The answers to these and related questions should be compiled into a report and that document
circulated in a way that maximizes the learning function of the project. It is important to review this
document again as the next product development project is being proposed.

1.17 PROTOTYPING

Making prototypes is so much a part of device development that it is often taken for granted.
Prototyping plays a very important part in the process but it must be thought out and planned, if the
maximum benefit is to be derived. Clearly the size and scope of the product and the effort will con-
trol to some extent this activity. In some cases, many prototypes will be built before the design is
frozen while in other projects one or two may be an efficient plan. Of course, a clinical trial will
require many copies of the prototype design in most cases.
In planning the project, the goals of each prototyping effort should be defined. They are often
associated with milestones in the plan. A prototype having particular working characteristics is to be
functional by a particular date. In setting that goal, the purpose of that prototype should be under-
stood and stated. We generally think of the prototype as proving the feasibility of the design, but
close examination often shows that not to be the case. Clausing 10 describes situations where the
effort that should be focused on the design is going into debugging prototypes that have already
become obsolete. We need to have focus.
In many situations a partial prototype, one that might be more properly termed a test bed, is in
order. This is a device that mimics some part of the proposed design, and allows critical characteris-
tics of the design to be altered and tested. This system may bear little resemblance to the final product;
it really only needs to have the significant physical characteristics of the segment under study. This
might be the working parts of a transducer or the linkage of some actuator. It may be constructed to
evaluate accuracy, repeatability, durability, or some other critical feature. It should be thought of as
an instrument. If it is worth the trouble, time, and effort to build it, then an experiment should be
designed to garner as much information as it has to offer.
With partial medical device experiments, usually called bench testing, an often-encountered
problem is the replication of the biological materials that the device interacts with. If we return