Biomedical Engineering Reference
In-Depth Information
FIGURE 4.1
Assortment of pH muscles made from PAN fibers. Clockwise from left: encap-
sulated biceps muscle, triceps muscle, linear fiber bundle, linear platform muscle, encapsulated
fiber bundle, and parallel fiber muscles.
FIGURE 4.2
Two PAN muscles (50-fiber bundles) encapsulated with latex membrane incor-
porating three-way glass fittings at each end to allow for the transport of pH solutions within
the fiber bundles (relaxed length is 3 in.).
smaller segments called sarcomeres. The additive effect of each segment improved
the speed of response. Incidentally, in biological muscles, the maximum tension
force due to contraction occurs at about 70-130% of the relaxed state of the sar-
comere (refer to appendix B).
As seen in the preceding figures, latex sheets were commercially acquired, cut
to size, and patterned for specific muscle groups. After encapsulating the bundle, it
was then sealed using a special silicon rubber adhesive to allow for frequent expan-
sion and contraction of the fiber bundles in the latex enclosure. To completely seal
the assembly, epoxy resin was used at each end of the bundle followed by a nylon
string wrapping. This proved to be a most reliable method for a large loading
condition to avoid damage to the individual fibers and muscle assembly. In more
advanced versions, each end of the bundle was especially fitted with rubber stoppers
with a concentric hole and with a specially designed three-way glass fitting to allow
for transport of acids and bases into the fiber bundle (figs. 4.2 and 4.3).
