Biomedical Engineering Reference
In-Depth Information
levels have been set and are available (
ISO 15197, 2003
)
.
Lee et al. (2008)
report that electro-
chemical glucose sensors based on modified electrodes with immobilized glucose oxidase are
available (
Sulak et al., 2006
). Disposable biosensors have also been developed (
Lee et al.,
2008
).
Different electrode fabrication methods, including screen printing (
Crouch et al., 2005
) and
other deposition techniques (
Hashimoto et al., 2007
), have been used to develop these
biosensors.
Lee et al. (2008)
point out that carbon-paste electrodes (CPE) have been widely
used for voltametric measurements (
Yabuki et al., 1992; Ge et al., 1998
;
Bouquita et al.,
2000; Hart et al., 2002; Hong et al., 2002; Fahnrich et al., 2003; Gao et al., 2003
, 2005;
Honeychurch et al., 2003; Darain et al., 2005
).
Lee et al. (2008)
report that the application
of carbon paste to make the electrode is a simple procedure and hence economical. However,
up until now the work on low electrical resistance has not been reported.
Lee et al. (2008)
report that they have developed a biosensor with low electrical resistance besides making
the biosensor disposable. The disposable biosensor, according to them, offers a very low
uniform electrical resistance of about 0.01 ohms. They have done this by attaching a
Au/Ni/copper structure to a plastic film substrate using a laminating procedure.
Figure 6.8a
shows the binding of 53 nM glucose in solution to the electroless-plated Au/Ni/
copper low electrical resistance electrode (
Lee et al., 2008
). A single-fractal analysis is ade-
quate to describe the binding kinetics. The values of the binding rate coefficient,
k
, and the
fractal dimension,
D
f
, for a single-fractal analysis are given in
Table 6.5 a
and
b
.
Figure 6.8b
and c show the binding of 27 and 21 mM glucose, respectively, to the electroless-
plated Au/Ni/copper low resistance electrode (
Lee et al., 2008
). Once again, a single-fractal
analysis is adequate to describe the binding kinetics. The values of the binding rate coefficient,
k
, and the fractal dimension,
D
f
, for a single-fractal analysis are given in
Table 6.5 a
and
b
.
It is of interest to compare the binding of glucose in solution to the neodymium
hexacyanoferrate nanoparticle on the glucose oxidase/chitosan-modified GCE (
Sheng et al.,
2008
) with that of the binding of 1-53 mM glucose in solution to the electroless-plated Au/
Ni/copper low electrical resistance electrode (
Lee et al., 2008
). In the first case a dual-fractal
analysis is required to adequately describe the binding case presented. In the second case, a
single-fractal analysis is adequate to describe the binding kinetics for all of the three con-
centrations of glucose (21, 27, and 53 mM) analyzed. In the first case, a complex binding
mechanism is involved since a dual-fractal analysis is required to adequately describe
the binding kinetics, whereas in the second case a simple binding mechanism is involved since
a single-fractal analysis is adequate to describe the binding kinetics. Also, in the second case,
even though the fractal dimension or the degree of heterogeneity on the biosensor surface,
D
f
equal to 2.8850, 2.9788, and 3.0 are higher than those in the second case for the second phase
(
D
f2
equal to 2.604), the binding rate coefficient,
k
, for the second case is lower than the bind-
ing rate coefficient,
k
2
. This is due, of course, to the different biosensor systems involved.
