Biomedical Engineering Reference
In-Depth Information
0.90
0.75
0.60
0.45
A = -1.425
B = -0.675
C = 0.075
D = 0.825
E = 1.575
F = 2.325
⊕
= -10.19E-3
∗
= 16.19E-3
0.30
0.15
0.00
0.00
0.15
0.30
0.45
0.60
0.75
0.90
X (cm)
Time
500.00
FIGURE 6.9
Pressure at time = 500 sec.
laboratory for the deformation of ionic polymeric gels—in particular, polyacrylic
acid plus sodium acrylate cross-linked with bisacrylamide.
The proposed model takes into account the electro-osmosis, elctrophoresis, and
ionic diffusion of various species. It further considers the spatial distributions of
cations and anions within the gel network before and after the application of an
electric field. The model will then derive exact expressions relating the deformation
characteristics of the gel as a function of electric field strength or voltage gradient;
gel dimensions and gel physical parameters such as diffusivities of cations
D
GM
and
anions
D
GP
; elastic modulus
E
; temperature
T
; charge concentration of cations,
C
GM
;
charge concentration of anions,
C
GP
; resistance
R
g
; and capacitance
C
g
of the gel.
Thus, direct electrical and computer control of the expansion and contraction of
these polymeric ionic gels is possible because ionic polymeric gels are electrome-
chanical in nature. Because they can convert electrical and chemical energy to
mechanical energy, they may become of particular importance to some unique
applications in engineering and medical professions.
In order to be able to control the large deformation behavior of ionic polymeric
gels electrically by a computer, it is necessary to develop a model to microelectro-
dynamically simulate the large deformations of ionic polymeric gels and subse-
quently be able to computer-control such large deformations for design of practical
devices and applications. The technical objectives of the proposed model are to
provide a computational tool to design, simulate, and computer-control the electri-
cally induced large expansion and contraction of ionic polymeric gels as smart
materials and artificial muscles for various engineering applications. These novel
applications will include smart or adaptive structures, bionic robots, artificial mus-
cles, drug-delivery systems, large motion actuators, and smart material systems. The
modeling is based on formulating a macroscopic theory for large deformation of
ionic polymeric gels in the presence of an electric field.
