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Figure 2. Input versus output response of a sensor with hysteresis
1.3. Special features of biosensor
Biosensor is a kind of device which senses biomaterial and its concentration, and which
converts the biosignal into electrical signal. Biosensor has the function of acceptor and
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converter, which configuration is seen in figure 3. In biosensor, the physicochemical change
of the biologically active material resulting from the interaction with the analyte must be
converted into an electrical output signal by an appropriate converter. Biosensor’s sensing
components mainly have enzymes, cells, antibodies, DNA (Deoxyribonucleic acid), chemical
electrode, microbe and other biologically active agents in analytical devices. In the course of
detecting the parameters of analytes, biomaterial should be always immobile. In order to
develop biosensor, some biotechnology has to be studied and applied, such as DNA biosensor,
PH sensor, microelectrode, and so on.
The special features of biosensor are the following:
1. Biological active material immobilized is used as catalyst, and expensive reagents could
be repeatedly used to detect same biological parameters.
2. Biosensor has intensive specificity. Biomaterial only senses definitive ingredient and it is
not affected by color and concentration of measured material.
3. Biosensor could quickly analyze the result of the measurand.
4. Biosensor’s accuracy is very high, which relative error could reach one percent.
5. Biosensor’s analyzing system is very simple.
6. The cost of biosensor is very low.
According to biological sensing component, biosensor may be divided into five classes:
enzyme sensor, microbe sensor, cell sensor, tissue sensor, and immune sensors. According to
the signal converter of biosensor, biosensor may be also divided into five classes: bioelectrode
sensor, semiconductor biosensor, optical biosensor, piezoelectric biosensor and thermal
biosensor. According to the interaction between sensing component and measured material,
biosensor can be divided into two classes: affinity biosensor and catalytic biosensor.
Figure 3. Common configure of a biosensor
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