Simple and non-quantitative electrochemistry can be done by power sources. This is not sufficient for the quantitative detection of substances or other more detailed investigations. A potentiostat allows a precise control of the voltage, or rather potential of one electrode - the working electrode. A voltage is applied between the working electrode and a reference electrode, whose potential is known. The current will flow between the working electrode and counter electrode; this ensures the reference electrode is current-free and does not change while the potentiostat is being used. The potentiostat will adjust the potential between the working and counter electrodes to make sure the required current will flow. This setup allows the study of reactions at one electrode and ignores the rest. An important note for electronic experts and electrochemists working together: while the electrochemist views the working electrode as the electrode with the flexible potential, the electronics experts know the working electrode is ground in the device. This is often a challenge for the communication.