Annual Report 2007 - The Australian Nanotechnology Network

• A vast range of optimised experimental geometries can be rapidly fabricated
and tested;
• The minute mixing and reaction chambers offer significant improvements in
analysis times and the sample volumes required;
• Wide ranges of sensor applications are possible (eg biochemical,
electroanalytical chemistry, modified electrodes, etc).
(2) Computer aided design
The electrochemical responses were modelled using similar strategies to those
developed by Dr. Fisher’s group (Henley, Fisher et al. 2005; Sullivan, Johns et al.
2005; Matthews, Du et al. 2006). We employed simulations that exploited a mesh of
triangular elements with a linear interpolation polynomial to approximate the
variation of the concentration across each element. In these simulations finite
element based codes were used in order to
• Predict the fluid flow properties within candidate reactor designs;
• Calculate the chemical reactant/intermediate/product distribution within the
cells; a vast range of optimised experimental geometries can be rapidly
fabricated and tested;
• Extract kinetic/mechanistic parameters for processes of interest;
• Act as a computer aided design tool for the optimisation of candidate sensor
configurations.
The time dependent concentration variation of the chemical species within the cells
was calculated. The simulations were performed in two stages. First the velocity
profiles within the devices were calculated by solution of the appropriate form of the
Navier-Stokes equations, in an analogous manner to those applied to larger scale
flow through electrochemical devices. A weighted residual method was used to
formulate the system equations required, in an analogous manner to those
employed previously by the group for fluid dynamic problems. Solution of the
system equations generated was achieved using standard matrix routines. The
second stage of the simulations used the velocity profiles generated from the fluid
dynamic calculations with a code employed to tackle the time dependent coupled
convection-diffusion-reaction transport problems.
(3) Bioelectrochemical Processing and Analysis
By taking advantage of our established approach in Dr. Fisher’s group, glucose
oxidase and peroxidase were used as model enzymes and immobilised onto a
vertically-aligned single-walled carbon nanotube array directly anchored to a
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