Basic functionality

The potentiostat is an important tool in electrochemical research. It applies and/or measures potentials and currents in a three-electrode configuration, where the electrodes consist of a working electrode (WE), reference electrode (RE) and counter electrode (CE). Potentials are measured between the working electrode and the reference electrode, with practically zero current flowing, while currents are applied between the working electrode and the counter electrode.

In potentiostatic mode, the device allows control over the potential between the working and reference electrodes, and it achieves this by sinking or sourcing current between the working electrode and the counter electrode. It draws essentially no current from the reference electrode. The amount of current between WE and CE is determined by a feedback loop which compares the desired potential with the measured potential.

This basic functionality is illustrated in the figure below.

In galvanostatic mode, the device allows control over the current between WE and CE. This can be achieved by taking feedback from the measured current instead of from the measured potential.

The figure below shows the basic block diagram of the potentiostat/galvanostat. The control amplifier takes a setpoint from the digital-to-analog convertor, and compares this to the feedback signal which can be switched to either the measured potential (in potentiostatic mode) or the measured current (in galvanostatic mode). An analog-to-digital convertor allows acquisition of the measured potential and the measured current.