In spite of recent advances in technology, using inexpensive yet
reliable devices for the selective and accurate detection of pollutants
in complex samples remains a challenge due to interfering
species often found within the sample matrix. The most commonly
used analytical techniques for detection include gas chromatography/mass
spectrometry (GC/MS) (Auroux et al., 2002) and atomic
absorption spectroscopy (AAS) (Van Loon, 2012). Though highly
sensitive, these analytical techniques are time-consuming, expensive,
require a lot of expertise to be operated and are not easy to
be deployed in the field due to their bulky size. Overcoming these
limitations, chemical sensors have emerged as an alternative, a
simple, rapid, cost-effective and portable tool for analyzing environmental
security threats. Biosensors, a class of chemical sensors,
are self-contained integrated devices that are capable of providing
specific qualitative or semi-quantitative analytical information by
integrating a biorecognition element which is in direct spatial contact
with a transduction element (Thévenot et al., 2001). The
biorecognition element, usually an enzyme, antibody or an
oligonucleotide selectivity binds a specific analyte from the given
sample and the transducer element converts the chemical event
into a measurable signal like current, mass, fluorescence or pH
change. Among these different platforms, sensors based on a
change in electrical property remain an attractive option due to
their simple operation, facile fabrication process and device integration.
They typically operate by measuring the change in conductivity
of the sensor upon adsorption of the analyte molecule onto
the sensory element.