Biomedical Engineering Reference
In-Depth Information
electroless deposition. Their glucose biosensor was made by covering this CNTs/Osmium com-
plex modified electrode with a thin film of glucose oxidase. Using a decreasing cathodic peak
current of oxygen these authors were successful in detecting glucose. The performance cha-
racteristics of their biosensor was good exhibiting a high sensitivity of 826.3 nA/(
m
Mcm
2
),
a low detection limit of 56 nM, a response time of less than 3 s, and a three-order calibration
range of 1.0
m
M-1.0 mM. The authors assert that the selectivity of their biosensor was very
good as, owing to the relatively low potential applied, the interference from electroactive
species was minimized. Furthermore, their glucose biosensor exhibits high stability and is
technically simple.
3.2.12 Fabrication of a Porous Silicon-Based Biosensor (
Matthew and Alocilja, 2003
)
Matthew and
Alocilja (2003)
have fabricated a porous silicon-based biosensor to detect bac-
teria. The authors used a sponge like porous layer of silicon. For the fabrication of their bio-
sensor the authors report that anodizing conditions of 5 mA/cm
2
were the best. Their porous
silicon chips were functionalized using silanization and antibodies immobilized to the porous
surface. They assessed the functionalization of their biosensor using a chemiluminescence-
based assay. They report that light emission for the silanized porous silicon biosensor chip
with
Salmonella
was an order of magnitude greater than that of the control and nonsilanized
porous silicon with
Salmonella
. Also, these authors noted that a higher light emission was
observed for the porous silanized biosensor with
Salmonella
compared with that observed
with the nonporous chip. Thus, these authors fabricated the porous silicon-based biosensor
and functionalized it to successfully detect
Salmonella.
3.2.13 Recrystallization Technologies to Fabricate a Low Cost Si Nanowire Biosensor
(Ashburn and Sun, 2009)
Ashburn and Sun (2009)
report that approximately one billion diagnostic tests are performed in
the United Kingdom every year to obtain an accurate diagnosis of a patient's condition. These
authors point out that for the routine application of these diagnostics tests they need to be per-
formed at a much larger scale, at a lower cost, and at POC (point-of-care ) locations rather than
at clinical laboratories. Thus, they note the need to develop newer fabrication technologies to
yield a cost-effective biosensor. These authors emphasize that silicon nanowire biosensors
exhibit the potential to provide real-time, high sensitivity, high selectivity, and label-free
biosensing. They emphasize that the nanoscale diameter of the nanowires leads to high sensi-
tivity. They further indicate that current fabrication techniques are expensive owing to the use
of silicon-on-insulator wafers and electronic lithography.
Ashburn and Sun (2009
) have devel-
oped a low-cost fabrication process for silicon nanowire biosensors. These authors used thin
film transistor technology. They used plastic substrates, which, according to them, require a
low thermal budget process for their nanowire biosensor fabrication process.
