Team:Bielefeld-CeBiTec/Project/rMFC/MeasurementSystem

From 2014.igem.org

Revision as of 22:12, 14 October 2014 by DaveWo (Talk | contribs)


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.

  • Reference electrode (RE):
    A non-polarizable (stable) electrode with a fixed potential that sets or measures the potential of the WE.

  • Working electrode:
    An electrode at which a given electrochemical reaction of interest is examined; its potential is controlled versus the RE in a three-electrode system.

  • Scan rate [mV s-1]:
    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.

    Retrieved from "http://2014.igem.org/Team:Bielefeld-CeBiTec/Project/rMFC/MeasurementSystem"