Question

Please give a clear explanation as to why an electrolyte is needed in the recording of a biosignal.

Answer 1

In bio-signal recordings, the initial elements (electrodes) are biopotential sources into electrical signals which are used to convert those biopotential signals.

An electrode paste or an electrolyte gel is generally used as an interface that separates the surface of the source of the event and the electrode in order to obtain a low contact impedance (clearly established contact) and to avoid movement artefacts.

The gel carries free chloride ions in such a way that the charge can be transmitted through the electrolyte. Thus, the electrolyte can be admitted as conductive for ion current such as human tissues. Therefore, the current is facilitated to pass from the human tissues to the electrode.