Biosensors for the Detection of Waterborne Pathogens - Waterborne Pathogens: Detection Methods and Applications - page 193

Figure 7.5 Schematic diagram depicting a typical surface plasmon resonance (SPR)
experiment. (a) The ligand (shown as an antibody) is immobilized on the biosensor
chip surface. The analyte (which represents the antigen) passes through a microfluidic
flow cell, and SPR is used to monitor the change in refractive index caused as analyte
accumulates on the biosensor surface. (b) Salient features of a typical sensorgram.
Before injecting analyte, the baseline response should be stable. An increase in response
during the association phase represents complex formation in real time. Equilibrium is
achieved when an equal number of analyte molecules associate with and dissociate
from the surface at the same time. The surface can be washed and the decay rate of the
complex obtained during the dissociation phase. Following regeneration, the binding
response should return to the starting baseline position. Source: Figure 1 from Ref. 28 .
Reproduced with permission.
or the potential of the working electrode is imposed, and the response of
the system to those perturbations is observed. In terms of electrochemical
biosensors, there are various approaches that can be employed for the detec-
tion of the target, including amperometry, potentiometry, conductometry,
and voltametry. Other electrochemical methods, such as impedance, were
covered in Chapter 6. A brief review of electrochemical methods is given
in Refs 1 and 29 .