Page 494 - Biomedical Engineering and Design Handbook Volume 2, Applications

472 REHABILITATION ENGINEERING AND PROSTHETICS DESIGN

of someone’s leg to be used in a gait analysis (how someone walks)? The tables are based on cadav-
eric studies with a sample of generally fewer than a dozen. Did any of the cadavers fit the build of
your target consumer? 16
Disability categories include vision, hearing, speech, limb loss, neuromuscular impairment,
10
other, and multiple impairments. Categories may easily be subdivided. For example, vision may be
divided into low vision and blind. Each may lead to different solutions. Similarly, is a person hard
of hearing or profoundly deaf? The following is a list of suggestions or questions to consider in your
design. It is a starting point, not a comprehensive list. Some are geared more to the design of a device
for a sole user and others to a mass market:
1. What are a child’s personality traits, intelligence, developmental and functional levels, physical
size, and growth factors? Do we understand their physical, financial, and social environment? 18
2. What is the diagnosis and prognosis?
3. Is the product compatible with the user’s existing I/O devices? If computer-based, can it be operated
without a pointing device such as trackball or mouse? Will it interface with a voice dictation system?
What about speech output? Can keystroke commands be entered sequentially? For example, press-
ing the Control, Alternate, and Delete buttons simultaneously is impossible for many people. 17,18
4. Is documentation in Braille, electronic format, large print, or on audiotape, etc.? 17,19
5. How can print be made more readable for someone with low vision? Use an 18-point font (but no
less than 16 points) in standard roman or sans serif. Avoid decorative fonts, italics, and all capital
letters. Bold type increases the thickness of the letters and is preferable. Avoid the use of color
fonts for headings. However, if used, consider dark blues and greens. Maximize contrast. Some
people prefer white or light-yellow letters on a black background over the reverse. Avoid glossy
paper due to the glare. Use a line spacing of 1.5 rather than single space. Spacing between letters
should be wide. Since low-vision devices such as closed-circuit televisions and magnifiers often
require a flat surface to read, use a margin of 1.5 in (but no less than 1 in). 19
6. How can one design a product to be easier to use by someone with low vision? Maximize con-
trast between components. For example, use a dark switch on a light device or a light handle on
a dark door. Avoid glares. 20
7. How can my software application be improved to help those with visual impairments? Use stan-
dard user-interface elements compatible with screen readers. Is the application compatible with
screen-magnification and speech-synthesis software? Do not require a pointing device and allow
the user to modify the interface. For example, can the user select the font style, color, and size?
What about the background color? Do not place time limits on input activities or messages. Do
not rely on color alone to convey information. For example, a green-filled circle that becomes red
when done may not be seen. 18
8. Have I considered the ergonomics of the design? Is the device easy to grip? What does it weigh?
How must the user be positioned to operate the device? Will its use lead to back or neck pain?
Are repetitive-motion injuries a concern? There is commercial software available to determine
forces at the back and extremities for various anatomic positions and loading cases. Parameters
such as the user’s height may be specified.

Universal Design. Over the years, industry has moved away from telling consumers that they
know what is best for them to seeking their input early on in the design process. Designing
quality into the product has also become the norm. There is a great need for universal design to
become the industry standard as well. Universal design results in a more usable product for all
consumers, improves sales by increasing the customer base, and is good for society as a whole.
There will likely be great resistance and some problems in the transition phase as industry learns
these new requirements. Ultimately, it will be profitable, as corporations have seen with total quality
management.
Universal Design Principles. Universal design, as in all other design requirements, depends on
sufficient and correct background information. Many codes and standards actually meet only minimum