thesis
New approaches and applications in electrochemical scanning probe microscopy
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Abstract
This thesis is concerned with the development of new electrochemical scanning
probe techniques and the application of these to biological problems. These
techniques allow high resolution quantitative investigations of surface processes
through measurements at a precisely placed electrode probe.
A new technique, called intermittent contact scanning electrochemical microscopy,
which allowed the probe-surface distance to be decisively determined
through the physical interaction of the probe with the surface was developed. Separately,
a new type of dual electrode probe was developed and characterised, and a
new instrument (including both hardware and software) capable of a wide range of
electrochemical imaging modes was developed with wide applications.
The quantitative analysis of the electrochemical signal, typically measured
at the probe, requires understanding the mass transport between the probe and the
surface. Finite element modelling was used extensively throughout to solve the mass
transport problem and therefore quantitatively analyse experimental results.
Intermittent contact scanning electrochemical microscopy was used to quantify
the mass transport through a porous biological membrane, dentin, that separates
the pulp and enamel in teeth. Oxygen generation and consumption rates
during photosynthesis were determined by measuring the local oxygen
flux at an
electrode placed a precise distance above a monolayer of isolated chloroplasts or
thylakoid membranes. Finally, the new dual electrode probe was used to measure
the reduction of an artificial electron acceptor by isolated thylakoid membranes