Biomedical Engineering Reference
In-Depth Information
TABLE 2.1
Current Capabilities of IPMNC Materials
Young's modulus,
E
Up to 2 GPa
Shear modulus,
G
Up to 1 GPa
Poisson's ratio, ν
Typical: 0.3-0.4
Power density (W/volume))
Up to 200 mW/cc
Max force density (cantilever mode)
Up to 50 kgf/kg
Max displacement/strain
Up to 4% linear strain
Bandwidth (speed)
Up to 1 kHz in cantilever vibratory mode for actuations;
up to 1 MHz for sensing
Resolution (force and displacement control)
Displacement accuracy down to 1 µm; force resolution
down to 1 mg
Efficiency (electromechanical)
More than 25% (frequency dependent) for actuation;
more than 90% for sensing
Density
Down to 1.8 g/cm
3
1000
Natural muscles
R. Full
100
10
1
0.1
0.01
0.1
1
10
100
1000
f (Hz)
FIGURE 2.24
Specific energy as a function of frequency for typical IPMNC samples.
Typically, such a bending force is electric field dependently distributed along the
length of the IPMNC strip, as noted in figure 2.23. Further, note from figure 2.21
that a surface voltage drop occurs, which can be minimized (Shahinpoor and Kim,
2000a). The IPMNC strip bends due to this ion migration-induced hydraulic actua-
tion and redistribution.
The bending force of the IPMNC is exerted by the effectively strained IPMNC
due to hydrated ions transport. Typically, such force is field dependently distributed
along the length of the IPMNC strip. The IPMNC strip bends due to this force. The
total bending force,
F
t
, can be approximated as
L
∫
0
F
≅
f dS
(2.10)
t
