Biomedical Engineering Reference
In-Depth Information
Fig. 2.33 The plasmonic
resonance behavior
R
1
j 0
0
j
Fig. 2.34 ( a ) Typical
configuration of an SPP
label-free biosensor and ( b )
the SPP resonance variation
with the number of
immobilized biomolecules
a
sensing layer
thin metallic film
incident
reflected
high refractive
index prism
CCD detector
array
b
R
1
increasing the
biomolecule
number
j
0
j 0
resonant reflectivity modifies significantly, even when few molecules are attached
to the sensing layer.
The model of a three-layer system (prism, metal, sensing layer) is used to
understand the SPP label-free sensor. In this model, the variations in the SPP
resonance angle can be written as
' D ˛ 1 n C ˛ 2 t;
(2.83)
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