Page 32 - Biomedical Engineering and Design Handbook Volume 2, Applications

MEDICAL PRODUCT DESIGN 11

idea, it’s not like searching for a needle in a haystack, but perhaps something slightly larger than a
needle. If we search for a while, we may find an attractive idea. If we search further, we may find a
better idea. If we walk away from the haystack, someone else may come along and find a better idea
than the best one that we found and bring it to market shortly after we bring ours—and our product
will be obsolete.
The primary argument for shortening the development time, or the “time to market” as it is
thought of, is that eventually another product will displace ours. If we think of that product’s intro-
duction as an event over which we have no control, we lengthen our market window by an early
introduction. If, however, we pass up the best product to get to market a short time earlier, we are
inviting the early arrival of product termination.
Generating a long list of alternative design ideas is a very difficult task, requiring creativity,
resourcefulness, energy and, most importantly, stamina. It is for this reason that so much emphasis
has been placed on the quantity of concepts. After a short time and a few seemingly credible ideas,
it is hard to continue to dig for alternatives. Different teams and leaders advocate different modes of
idea generation, each having worked well for them. A starting point is to ask each team member to
spend some time alone making a concept list. A comfortable place to work undisturbed, a pad of
paper, and a few hours should produce many more ideas than each had at the outset. These lists can
be brought together in a team meeting or brainstorming session. (Brainstorming has two working
definitions. One is a formal process developed to produce ideas from a group. It has a clear proce-
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dure and set of rules. The word is also used to describe any group working together to find a problem
solution. Either definition could be applied here.)
At this point in our project we do not want to discard ideas. It is widely believed that some of the
really good ideas are stimulated by some less sane proposals, so the objective is to lengthen the list,
and hold off on criticism or selectivity.
There are some techniques that can assist when things begin to slow down here. One is to break
out some characteristic of the device and make a list of all of the ways one could supply that func-
tion. For example, an active device requires energy. Ways to supply energy would include electric
power from the utility, batteries, springs, pneumatics, hydraulics, hand power, and foot power. Trying
to think up design ideas that use each of these functions will often lead to some different kinds of
solutions. Other types of characteristics are specific material classes, cross-section shapes, etc.
It is also fruitful to look at the ways that analogous medical devices function. Is there an equiva-
lent functionality that has been used in a different medical problem? One example of this is access
ports that might function for feeding in one instance, as a drug-delivery mode in another, and as a
monitoring channel in a third. All have similar problems to overcome. Surgical instruments can
provide many examples of devices that are variations of previous designs.
Another means of expanding the list is to combine ideas with features from other ideas. Look
especially at the ideas that seem novel and find as many permutations on them as possible.
Some means of compiling the concept list is necessary. Index cards, spreadsheets, or even
Post-it Notes® may be used. It helps if the scheme allows the ideas to be sorted and rearranged,
but the importance of this will vary a great deal with the situation. Ultimately, you should emerge
from this phase with a list of ideas to be considered. The list should be long, have many ideas
that are of little value, and hopefully have several that have the potential to turn into world class
products.

1.11 CONCEPT EVALUATION

Having spent a great deal of time and effort developing an extended set of concepts, the team must
now select those that will be developed further. There are several important points to keep in mind
as this process begins. The first is to have an even-handed approach. It is unwise to compare an idea
that has been sketched out in 30 s to one that has had many hours of development, and discard the
first because it isn’t understood. As much as is reasonably possible, concepts should be compared at
an equal state of development. That having been said, there will be ideas brought up that can be