Placement of Reference Electrodes (dry vs. gel)

Each channel of the Explore Pro is recorded against a unipolar reference electrode (marked in blue with a “REF” or “0” label). Accurate placement of the reference electrode (REF or 0) is critical for high-quality EEG and ExG recordings. Each active channel is measured against the reference, so poor placement or unstable contact can degrade the entire dataset.

General Principles

  • Every Explore amplifier requires a reference electrode in addition to the recording channels.

  • Reference should be placed on areas with good skin contact, low hair density, and minimal muscle activity.

Recommended Reference Electrode Positions

  • For most EEG applications, the REF electrode should be placed on the mastoid (TP9 or TP10). This placement helps minimize artifacts from non-relevant brain activity, EMG, and ECG activity.

  • Earlobes – alternative position if mastoids are not accessible.

  • Other ExG applications (ECG, EMG, EOG) – reference placement may vary; follow protocol guidelines.