Potentiostat

Definition - What does Potentiostat mean?

A potentiostat is an electronic instrument that measures and controls the voltage difference between a working electrode and a reference electrode. It measures the current flow between the working and counter electrodes.

This instrument is fundamental to modern electrochemical studies for investigations of reaction mechanisms related to redox chemistry and other chemical phenomena. Potentiostats control most electroanalytical experiments. They can be used to test for electrochemically active compounds and microbes in solution, and thus have applications in many areas, such as:

  • Environmental monitoring
  • Drug testing
  • Identifying contaminants/toxins in water
  • Identifying toxins/ingredients in food

A bipotentiostat and polypotentiostat are capable of controlling two working electrodes and more than two working electrodes, respectively.

Corrosionpedia explains Potentiostat

A potentiostat works with three electrodes immersed in a conductive electrolyte:

  • Working Electrode - A sample of the corroding metal being tested
  • Reference Electrode - An electrode with a constant electrochemical potential
  • Counter Electrode - A current-carrying electrode that completes the cell circuit

This system functions by maintaining the potential of the working electrode at a constant level with respect to the reference electrode by adjusting the current at an auxiliary electrode. It consists of an electric circuit which is usually described in terms of simple amps.

A potentiostat needs a low-impedance reference electrode. Potentiostats are less forgiving of high-impedance reference electrodes than pH meters.

A potentiostat is comprised of three primary components:

  • Control amplifier - Supplies power to maintain the controlled potential between the working and reference electrodes
  • Electrometer - Measures the potential difference between the reference and working electrodes
  • Current-to-voltage converter - Measures the current between the working and counter electrodes

The controlled variable in a potentiostat is the cell potential and the measured variable is the cell current. In voltammetry, electric current in amps is plotted against electric potential in voltage.

Limiting factors include:

  • Size of the electrodes
  • Potentiostat's limited range of operation
  • Cost

Modern potentiostats are operated through automated software packages. This software allows the user to rapidly shift between experiments and experimental conditions. Modern potentiostats are analyzed more effectively/accurately and rapidly than historic methods.

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