Team:Bielefeld-CeBiTec/Project/rMFC/MeasurementSystem

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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 (<a href="#harnisch2012">Harnisch, F. & Freguia, 2012</a>):
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 (<a href="#harnisch2012">Harnisch, F. & Freguia, 2012</a>):
 +
<li><i>Anode:</i><br>
 +
      The electrode where an oxidation takes place.</li>
 +
<li><i>Cathode:</i><br>
 +
      The electrode where a reduction takes place.</li>
 +
<li><i>Current:</i><br>
 +
      The flow of electric charge.</li>
 +
<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>
 +
<li><i>Faradaic Current:</i><br>
 +
      The current generated from the oxidation (positive current) of reduction (negative current) of chemical spezies.</li>
 +
<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>
 +
<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>
 +
<li><i>Peak Current:</i><br>
 +
      The maximum current at the working electrode in a voltammetric measurement.</li>
 +
<li><i>Peak Potential:</i><br>
 +
      The potential of the working electrode at which the peak current in a voltammetric measurement is obtained.</li>
 +
<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>

Revision as of 21:53, 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):

  • Anode:
    The electrode where an oxidation takes place.
  • Cathode:
    The electrode where a reduction takes place.
  • Current:
    The flow of electric charge.
  • Capacitive Current:
    The current related to the change in the electrode surface charge, not related to an oxidation/ reduction reaction.
  • Faradaic Current:
    The current generated from the oxidation (positive current) of reduction (negative current) of chemical spezies.
  • Charge q [C]:
    Cumulative current flow (1C= 1A x 1s). Values can be determined by the integration of current-time curves.
  • Formal Potential Ef [V]:
    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.
  • Peak Current:
    The maximum current at the working electrode in a voltammetric measurement.
  • Peak Potential:
    The potential of the working electrode at which the peak current in a voltammetric measurement is obtained.
  • Potentiostat:
    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.



    • 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.

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