Biomedical Engineering Reference
In-Depth Information
Interdigitated electrodes are of particular interest in the detection
of electroactive species, as they allow for redox cycling. The effect
of various interdigitated geometries on the redox cycling amplifi-
cation factor have been investigated and recently reported.
190, 191
Finot et al. employ interdigitated electrodes to detect DNA hybrid-
ization.
192
The DNA was coupled with an electroactive species to
facilitate detection. They show that using interdigitated nanoelec-
trodes in combination with square-wave voltammetry improves the
signal-to-noise and concentration sensitivity versus standard mac-
ro- or microelectrodes.
Geometry can also be used to manipulate chemical properties
at the nanoscale. Under physiological conditions, adrenaline un-
dergoes cyclization when oxidized, therefore making it difficult
detect at very low concentration. By employing a nIDEA, at low
concentrations it is possible to reduce the oxidized adrenaline back
to its stable form before it reacts with another molecule and thus
measure a redox current.
193
In recent work by Goluch et al. the
stability of a molecule was exploited to achieve the opposite effect.
It is difficult to detect electroactive species in bodily fluids be-
cause high concentrations of ascorbic acid are present that mask
the target signal. By confining the sample inside of a nanofluidic
channel placed over a nIDEA, as shown in
Fig. 9
, the signal from
ascorbic acid was suppressed by oxidative decomposition of the
molecule, allowing paracetamol (a.k.a. acetaminophen), present in
much lower concentrations, to be detected.
190
Figure 9. nIDEA with nanofluidic channels placed over
it to confine molecules near the electrodes.
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