Biomedical Engineering Reference
In-Depth Information
40
V = 2.24 Step,
ω
= 0.1 Hz;
Nafion
TM
-117;
Dimension = 7.5
×
70.0 mm
30
PVP treated IPMC
20
Conventional IPMC
10
0
0
1
2
3
4
5
6
Time (sec)
FIGURE 2.22
Potentiostatic coulometric analyses for the additive treated IPMNC and the
conventional IPMNC. This graph shows that an increased current passage (Faraday approach)
can contribute to the observed improvement in the force characteristics of IPMNC strips (see
fig. 2.19).
surface electrode region when the IPMNC strip bends. Thus, such dispersing issues
are rather important in increasing the force density of IPMNCs.
2.2.4
A V
IEW
FROM
L
INEAR
I
RREVERSIBLE
T
HERMODYNAMICS
In connection with the phenomenological laws and irreversible thermodynamics
considerations discussed in section 2.2.1, when one considers the actuation with
ideal impermeable electrodes, which results in
Q
= 0 from equation (2.3), one has
E
L
K
(2.8)
∇=
p
Also, the pressure gradient can be estimated from
2
σ
max
(2.9)
∇≅
p
h
where
σ
max
and
h
are the maximum stress generated under an imposed electric field
and the thickness of the IPMNC, respectively. The values of
σ
max
can be obtained
when the maximum force (= blocking force) is measured at the tip of the IPMNC
per a given electric potential.
In figure 2.23, the maximum stresses generated,
σ
max
, under an imposed electric
potential,
E
o
, for calculated values and experimental values of the conventional
IPMNC and the improved IPMNC are presented. It should be noted that the improved
