Biomedical Engineering Reference
In-Depth Information
0.008
0.006
0.004
0.002
0.000
−
0.002
−
0.004
−
0.006
0.0
0.5
1.0
1.5
Time (sec)
2.0
2.5
3.0
3.5
FIGURE 7.2
0.2 mm) in a
cantilever mode as depicted in figure 7.1 is connected to an oscilloscope and is manually
flipped to vibrate and come to rest by vibrational damping.
A typical sensing response of an IPMNC. The IPMNC (5
×
20
×
preceding equations provides a compact view of underlining principles of actuation
and sensing of IPMNCs.
Figure 7.2 shows dynamic sensing response of a strip of an IPMNC (thickness
of 0.2 mm) subject to a dynamic impact loading in a cantilever configuration. A
damped electric response is observed that is highly repeatable with a high bandwidth
of up to 100 Hz. Such direct mechanoelectric behaviors are related to the endo-ionic
mobility due to imposed stresses. This implies that, if we impose a finite solvent (=
water) flux,
= 0—a certain conjugate electric
field is produced that can be dynamically monitored.
From equations (7.1) and (7.2), one imposes a finite solvent flux
Q
—not allowing a current flux,
J
E
Q
while having
zero current (
= 0) and nonzero bending curvature. This situation certainly creates
an intrinsic electric field
J
E
, which has a form of
(
)
E
12 1
12
−
ν
νσ
L
L
h
p
=∇=
p
{}
Γ
(7.3)
σ
(
−
)
3
p
are, respectively, the Poisson ratio, the strip thickness,
and an imposed torque at the built-in end produced by a force
Note that notations
v
,
h
, and
Γ
p
F
applied to the free
end multiplied by the free length of the strip
l
.
g
7.2.2
E
P
LECTRICAL
ROPERTIES
In order to assess the electrical properties of the IPMNC, the standard AC impedance
method that can reveal the equivalent electric circuit has been adopted. A typical
