Biomedical Engineering Reference
In-Depth Information
fibers with Pt. After platinum deposition, the C-PAN fibers were activated by the
method described previously.
The results of electrical contraction and elongation of a C-PAN platinum muscle
are shown in figure 4.69. As can be seen, the electric activation of C-PAN was successful
to produce the approximate mean rate of contraction of
L
/
L
≈
5%/min, while the
approximate mean rate of elongation was
L
/
L
3%/min. The anomaly in both con-
traction and expansion is believed to be due to the fact that the electro-osmotic diffusion
rate of H
+
cations and OH
-
anions into and out of the C-PAN fiber bundle is not uniform.
In this approach, we have found that delamination of Pt layer (see fig. 4.70) occurred
over a repeated period of contraction and elongation of such C-PAN. As a result, a
much higher overpotential was needed to produce the same contraction and elongation
speed. In addition, it has been seen that the muscle expanded from the starting length
but did not return to it, probably due to the resistive force induced by the Pt layer.
≈
100
Contraction
Elongation
80
60
40
Contraction
Elongation
20
0
0
10
20
30
Time (min)
FIGURE 4.69
Electrical activation of muscle made up of fiber bundle of 50 C-PAN platinum
fibers. Initial muscle length = 5.0 cm; number of fibers = 50; cell voltage = 20 V; current =
120 mA. Polarity of electrodes reversed at
t
= 10 min.
50µm
FIGURE 4.70
SEM micrograph shows platinum delamination over a number of cycles (right).
