Behaviour and improvement of screen printed reference electrodes : application to a commercial glucose sensor
Behaviour and improvement of screen printed reference electrodes : application to a commercial glucose sensor
The factors that limit the performance of the counter-reference electrode in a commercial Ag/AgCl screen printed biosensor (SPE) for the quantification of glucose in whole blood have been investigated.
We have proposed two different types of counter reference electrodes. One type is based in replacing the Ag from the ink with carbon, meanwhile the other one uses the same Ag/AgCl ink, but adding different amounts of KCl. SPEs employing the first approach show potentials more negative than those of the commercial SPEs due to the increase of the resistance of the track. Also these electrodes are unable to transfer the required charge predicted for the overall sensor in working conditions, so this formulation was discarded.
The SPEs loaded with KCl show shorter equilibration times than the commercial electrodes. The potential of the transient part of the curve is very reproducible. During the transient part of the chronopotentiometry, the potential is established by the gradient of Cl- created by the dissolution of the Cl- embedded in the ink.
Finally, SPEs treated with light and air show an anomalous behaviour compared with fresh SPEs. This negative effect consisted in a shift towards less negative values of the potential recorded in a cathodic galvanostatic experiment. This anomalous behaviour was similar to that produced by oxidising the Ag in the SPE to Ag2O, but no mechanism that explains this similarity was found. Also SPEs partially oxidised and reduced in Cl- solutions showed this shift of the potential to less negative values. Since this shift means that it is easier to reduce these oxidised and reduced electrodes we believe that the mechanism involves a facilitated nucleation process at the oxidised or reduced electrodes.
University of Southampton
Martinez Montequin, Sergio
94460d02-dca7-4f86-9572-a4f192350e7e
2005
Martinez Montequin, Sergio
94460d02-dca7-4f86-9572-a4f192350e7e
Martinez Montequin, Sergio
(2005)
Behaviour and improvement of screen printed reference electrodes : application to a commercial glucose sensor.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The factors that limit the performance of the counter-reference electrode in a commercial Ag/AgCl screen printed biosensor (SPE) for the quantification of glucose in whole blood have been investigated.
We have proposed two different types of counter reference electrodes. One type is based in replacing the Ag from the ink with carbon, meanwhile the other one uses the same Ag/AgCl ink, but adding different amounts of KCl. SPEs employing the first approach show potentials more negative than those of the commercial SPEs due to the increase of the resistance of the track. Also these electrodes are unable to transfer the required charge predicted for the overall sensor in working conditions, so this formulation was discarded.
The SPEs loaded with KCl show shorter equilibration times than the commercial electrodes. The potential of the transient part of the curve is very reproducible. During the transient part of the chronopotentiometry, the potential is established by the gradient of Cl- created by the dissolution of the Cl- embedded in the ink.
Finally, SPEs treated with light and air show an anomalous behaviour compared with fresh SPEs. This negative effect consisted in a shift towards less negative values of the potential recorded in a cathodic galvanostatic experiment. This anomalous behaviour was similar to that produced by oxidising the Ag in the SPE to Ag2O, but no mechanism that explains this similarity was found. Also SPEs partially oxidised and reduced in Cl- solutions showed this shift of the potential to less negative values. Since this shift means that it is easier to reduce these oxidised and reduced electrodes we believe that the mechanism involves a facilitated nucleation process at the oxidised or reduced electrodes.
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Published date: 2005
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Local EPrints ID: 466343
URI: http://eprints.soton.ac.uk/id/eprint/466343
PURE UUID: 27db5282-c1e8-4cc8-9d07-d7aacab0d2e9
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Date deposited: 05 Jul 2022 05:11
Last modified: 16 Mar 2024 20:38
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Author:
Sergio Martinez Montequin
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