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Team:Bielefeld-CeBiTec/Project/rMFC/MeasurementSystem
From 2014.igem.org
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<li><i>Cathode:</i><br> | <li><i>Cathode:</i><br> | ||
The electrode where a reduction takes place.</li> | The electrode where a reduction takes place.</li> | ||
| + | <br> | ||
<li><i>Current:</i><br> | <li><i>Current:</i><br> | ||
The flow of electric charge.</li> | The flow of electric charge.</li> | ||
| + | <br> | ||
<li><i>Capacitive Current:</i><br> | <li><i>Capacitive Current:</i><br> | ||
The current related to the change in the electrode surface charge, not related to an oxidation/ reduction reaction.</li> | The current related to the change in the electrode surface charge, not related to an oxidation/ reduction reaction.</li> | ||
| + | <br> | ||
<li><i>Faradaic Current:</i><br> | <li><i>Faradaic Current:</i><br> | ||
The current generated from the oxidation (positive current) of reduction (negative current) of chemical spezies.</li> | The current generated from the oxidation (positive current) of reduction (negative current) of chemical spezies.</li> | ||
| + | <br> | ||
<li><i>Charge q [C]:</i><br> | <li><i>Charge q [C]:</i><br> | ||
Cumulative current flow (1C= 1A x 1s). Values can be determined by the integration of current-time curves.</li> | Cumulative current flow (1C= 1A x 1s). Values can be determined by the integration of current-time curves.</li> | ||
| + | <br> | ||
<li><i>Formal Potential E<sup>f</sup> [V]:</i><br> | <li><i>Formal Potential E<sup>f</sup> [V]:</i><br> | ||
Replaces the standard potential when the activities of the species involved and of the side-reactions are unknown or too complex. It is the favoured value for reactions that take place in a biological environment.</li> | Replaces the standard potential when the activities of the species involved and of the side-reactions are unknown or too complex. It is the favoured value for reactions that take place in a biological environment.</li> | ||
| + | <br> | ||
<li><i>Peak Current:</i><br> | <li><i>Peak Current:</i><br> | ||
The maximum current at the working electrode in a voltammetric measurement.</li> | The maximum current at the working electrode in a voltammetric measurement.</li> | ||
| + | <br> | ||
<li><i>Peak Potential:</i><br> | <li><i>Peak Potential:</i><br> | ||
The potential of the working electrode at which the peak current in a voltammetric measurement is obtained.</li> | The potential of the working electrode at which the peak current in a voltammetric measurement is obtained.</li> | ||
| + | <br> | ||
<li><i>Potentiostat:</i><br> | <li><i>Potentiostat:</i><br> | ||
An electronic amplifier that controls the potential drop between an electrode (the WE) and the electrolyte solution; it usally constitutes a reference electode (RE) as a sensing component and a counter electrode (CE) for balancing the current flow.</li> | An electronic amplifier that controls the potential drop between an electrode (the WE) and the electrolyte solution; it usally constitutes a reference electode (RE) as a sensing component and a counter electrode (CE) for balancing the current flow.</li> | ||
| - | + | <br> | |
| + | <li><i>Reference electrode (RE):</i><br> | ||
| + | A non-polarizable (stable) electrode with a fixed potential that sets or measures the potential of the WE.</li> | ||
| + | <br> | ||
| + | <li><i>Working electrode:</i><br> | ||
| + | An electrode at which a given electrochemical reaction of interest is examined; its potential is controlled versus the RE in a three-electrode system.</li> | ||
| + | <br> | ||
| + | <li><i>Scan rate [mV s<sup>-1<sup>]:</i><br> | ||
| + | The speed of potential change per unit of time in a voltammetric experiment.</li> | ||
| + | <br> | ||
<br><br><br> | <br><br><br> | ||
Revision as of 22:04, 14 October 2014
rMFC
Measurement system
Introduction to electrochemistry
The investigation of electroactive microorganisms affords an appropriate measurement system. To perform highly sensitive measurements we used a Potentiostat. For the understanding of the mode of operation of a Potentiostat it is necessary to define a few basic principles of electrochemistry. The following definitions come from (Harnisch, F. & Freguia, 2012):
The electrode where an oxidation takes place.
The electrode where a reduction takes place.
The flow of electric charge.
The current related to the change in the electrode surface charge, not related to an oxidation/ reduction reaction.
The current generated from the oxidation (positive current) of reduction (negative current) of chemical spezies.
Cumulative current flow (1C= 1A x 1s). Values can be determined by the integration of current-time curves.
Replaces the standard potential when the activities of the species involved and of the side-reactions are unknown or too complex. It is the favoured value for reactions that take place in a biological environment.
The maximum current at the working electrode in a voltammetric measurement.
The potential of the working electrode at which the peak current in a voltammetric measurement is obtained.
An electronic amplifier that controls the potential drop between an electrode (the WE) and the electrolyte solution; it usally constitutes a reference electode (RE) as a sensing component and a counter electrode (CE) for balancing the current flow.
A non-polarizable (stable) electrode with a fixed potential that sets or measures the potential of the WE.
An electrode at which a given electrochemical reaction of interest is examined; its potential is controlled versus the RE in a three-electrode system.
The speed of potential change per unit of time in a voltammetric experiment.
The Potentiostat
Figure 1: Principle of the circuit for potentiostatic measurements with a four electrode set up.
Cyclic voltammetry
Chronoamperometry
References
-
Harnisch, F. & Freguia, S., 2012. A Basic Tutorial on Cyclic Voltammetry for the investigation of Electroactive Microbial Biofilms. In: Chemistry – An Asian Journal, 7 (3), pp. 466–475.
