Biology Reference
In-Depth Information
a linear relationship is observed between the signal range and ionic
strength on the log scale. These results further support that PNA is
better as sensorprobe than DNA for EIShybridization detection.
6.5 Application of FETs on Biosensor Arrays
Application of biosensors in areas such as pathogen identification
and gene expression requires a large number of sensor elements
to work simultaneously in an array format. As an example, current
fluorescence-based optical DNA microarrays for genotyping and
gene expression often involve
∼
500,000 spots, where an individual
probe is deposited at each sensor element [40, 41]. High level of
integration and performance is clearly required in those devices.
Thedevelopmentofopticalbiosensorarraysislimitedbytheoptical
scanner's high cost, the unreliability of the optical labeling process,
and the complex data processing procedures. Considerable efforts
have been devoted to the development of alternative biosensor
array platforms suitable for low-cost production and higher level of
integration.
Fully integrated label-free electronic biosensor arrays based on
well-established microfabrication methods are believed to be able
toadequatelyaddressthedisadvantagesofopticalarrays.Label-free
electrochemical characterization techniques can be implemented
directly using integrated electronics, achieving significant cost
reductionandbettersystemintegration.Theseelectronicbiosensor
arrayscanbeeasilyconnectedtosimplehandheldreadersforpoint-
of-care applications. Moreover, studies have shown that electrical
stimulation can significantly affect the kinetics of biomolecular
interactionatsolid-liquidinterface[42-44],whichiseasilyachieved
withelectronic biosensorarrays.
6.5.1
FET-Addressed Biosensor Arrays
Besidesthebiomolecularprobesandthepackagingcomponents,the
electronic components of a fully integrated biosensor array can be
divided into three categories: transducer, array addressing circuit,
and measurement unit. As the most widely used microelectronic
devices, FETs play an important role in all these three categories.
