Biomedical Engineering Reference
In-Depth Information
30
×
10
6
25
×
10
6
heoretical
20
×
10
6
15
×
10
6
Experimental
(improved IPMC)
10
×
10
6
Experimental
(conventional IPMC)
5
×
10
6
0
0
1
2
3
4
5
6
E
ο
(volts)
FIGURE 2.23
Maximum stresses generated by the IPMNCs at given voltages.
IPMNC (by the method of using additives) is superior to the conventional IPMNC
approaching the theoretically obtained values.
For theoretical calculation the following experimentally measured values were
used:
L
12
=
L
21
= 2
×
10
-8
{cross-coefficient, (m/s)/(V/m)}
k
= 1.8
×
10
-18
{hydraulic permeability, m
2
(Bernardi and Verbugge, 1992)}
where
h
= 200
EEh
=
0
/
µ
m {membrane thickness}
Table 2.1 lists the current capabilities of IPMNCs. These capabilities can be
built into IPMNC samples by changing some 18 parameters. These parameters can
be tweaked to manipulate the performance of IPMNCs. This will be discussed in
the next chapter on manufacturing methodologies. Furthermore, the energy and
power densities of IPMNCs and IPCNCs appear to be very compatible with mam-
malian muscles, as depicted in figures 2.24 and 2.25.
The sample dimensions in creating these graphs were 20-
1.6-mm thick-
ness. A maximum square-wave voltage input at 16 V was applied and the samples
contained Li+ as cation.
Note the locus of specific energy versus frequency of a broad spectrum of
biological muscles as reported by Robert Full of UC Berkeley (Full and coworkers,
2001-2002). IPMNCs have a broad frequency spectrum as shown in figures 2.24
and 2.25. Figure 2.25 depicts the variation of power output as function of frequency
of excitation for the same sample described in figure 2.24.
×
5-
×
2.2.5
T
HERMODYNAMIC
E
FFICIENCY
The bending force of the IPMNC is generated by the effective redistribution of
hydrated ions and water. This is an ion-induced hydraulic actuation phenomenon.
