Biomedical Engineering Reference
In-Depth Information
Schuler et al. (2009)
emphasize that their screen-printed chips may be produced at a cost that
is an order of magnitude less than that of the chips produced by photolithography. The pri-
mary reasons for this, these authors indicate, are the expensive clean room technology
required for photolithography, the equipment required, and the size of the chips. Photolithog-
raphy becomes economical, according to these authors, if the size of the chips becomes very
small. This, however, implies a larger number of chips will be required.
Schuler et al. (2009)
point out that the size reduction in chips is difficult, because the chip size is dependent on the
number of measurement points, the size of the electrode gap, the distance between the con-
ducting paths, and the contact areas for the electrical readout.
Finally,
Schuler et al. (2009)
conclude that screen printing technology is a cost-effective pro-
cedure to establish platforms for the chip-based analysis of biomolecules. They report that
this method is an alternate technique which is especially suited for systems with sophisticated
electrode layouts and structures. They point out that their screen printed substrates exhibited
the same sensitivity and specificity of DNA chips when compared with standard photolithog-
raphy on silicon techniques to produce these DNA chips. Their electrode structures did
exhibit a high degree of stability. These authors intend to use their screen printed biochips
to further detect proteins and RNA.
3.2.8 Fabrication of Microband Glucose Biosensors: Use of Screen-Printed
Water-Based Carbon Ink and Use of the Biosensors in Serum Analysis
(
Pemberton et al., 2009
)
Pemberton et al. (2009)
have recently fabricated a microband glucose biosensor by screen-
printing a water-based carbon ink formulation containing cobalt phthalocyanine redox medi-
ator and GOD enzyme. They investigated the performance of these biosensors at 25
C. They
optimized the working pH at 8.0. These authors were able to obtain steady-state responses
under quiescent conditions. This suggested to the authors that a mixed mechanism is involved
which is predominantly radial diffusion. This was indicative of microelectrode behavior.
Pemberton et al. (2009)
report that electrochemical enzyme biosensors are commonly
fabricated by screen printing of carbon inks as transducers along with inorganic mediators.
These authors indicate that the screen-printing approach is adaptable to an industrial mass-
production scale (
Newman and Setford, 2006
). Thus, it is suitable for producing low-cost dis-
posable devices, and has been used to manufacture the amperometric test strips used to mon-
itor sugar levels by diabetics (
Matthews et al., 1987
).
Hart et al. (2004)
indicate that SPCEs
are used in combination with the enzyme GOD (
Wilson and Turner, 1992
).
Pemberton et al. (2009)
point out that amperometric responses obtained at planar electrodes
do not maintain steady-state conditions. Thus, this prevents their use in monitoring
conditions. However, microelectrodes including microbands provide for efficient mass
