Biomedical Engineering Reference
In-Depth Information
(a)
(b)
3
3
2
2
1
1
1A
1A
0
0
100
200
300
400
500
600
100
200
300
400
500
600
E(mVvs.Ag/AgCl)
E (mV vs. Ag/AgCl)
Fig. 4.20.
The catalytic electrochemistry of the enzyme electrode with redox poly-
mer: the effect of enzyme content. Cyclic voltammetry was carried out in a deoxyge-
nated phosphate buffer containing (1) 0, (2) 1, and (3) 2 mM glucose. The enzyme
electrode was prepared by loading with a 2.0
l (BL suspension of polymer-protein
mixture. The ratios of the mixture were redox polymer : GOx : BSA = (
a
) 200 :
5 : 150 and (
b
) 200 : 50 : 150 (mg/ml). The scan rate was 1 mV/s
μ
was observed at low substrate concentration. On the contrary, at high me-
diator concentration, a steady state current in the cyclic voltammogram was
not obtained at low substrate concentration, and a time-dependent current
decrease was observed. Therefore, if the steady state current at high redox
polymer content is discussed, there is some possibility that the response to the
first glucose injection is less than that for the further injection. Figure 4.22
shows the correlation between the steady state response and the glucose con-
centration. The response current depended on the redox polymer-enzyme
content and increased with an increase in the redox polymer content. This
figure demonstrates that it is possible to determine glucose concentration up
to7mM.
4.3.3
Glucose Sensors on the Market
There are many different blood glucose sensors on the market that are faster
and less complicated to use. Manufacturers have developed sensors and test
strips that require less blood, conduct the test faster, and offer a variety
of functions and data management capabilities to match individual testing
needs. This section covers blood glucose sensors for self-testing on the market.
Commercial glucose sensors are based on enzyme-photometric or am-
perometric biosensor technology. Bayer's Glucometer Encore, LifeScan's One
Touch Basic, Profile, and SureStep, and Roche's Accu-Chek Easy use the
former technology. Most of the other sensors are based on amperometric de-
tection. The characteristics of the blood glucose sensors on the market are
reviewed below.
