In particular, the
current at each electrode is proportional to the width (w) times
the length2/3 (x2/3). In any comparison between the currents at
electrodes, a factor wDx
2/3
D /wPx
2/3
P must be applied. For the
dimensions of the biosensor here, this factor is 0.119±0.008.
The determination of sulfite using sulfite oxidase in a channel
biosensor is, however, more complicated. The complications
arise from two aspects of the chemistry of sulfite. First, sulfite
is also electroactive at the potentials used and therefore both
the predictor and detector electrode currents will have a contribution
from sulfite oxidation.