Mask & Electrodes
PiEEG XR has two parts that attach to your headset:
- A silicone face mask with built-in electrodes. It replaces (or sits inside) the headset's facial interface and touches your forehead and temples.
- A BCI box, connected to the mask by a cable and held by the head strap. It holds the amplifier and the Bluetooth controller.
Electrodes
The mask has 10 flat dry silver / silver-chloride (Ag/AgCl) electrodes. They pick up biosignals without gel, and also work with a little gel when you need a steadier signal.
| Electrode | Count | Purpose |
|---|---|---|
| Channels 1–8 | 8 | Signal electrodes on the forehead and temples |
| Reference | 1 | The common 0 µV point for all channels, centre-left of the forehead |
| Bias | 1 | Cancels common-mode noise such as mains hum, centre-right of the forehead |
Electrode layout
The electrodes sit in 10 holes (1 mm) around the top of the mask:
| Position on the mask (as drawn) | Electrodes | Picks up |
|---|---|---|
| Left side, lower and upper | Ch1, Ch2 | Temple: eye movement, jaw and temple muscles |
| Left forehead | Ch3, Ch4 | Frontal EEG, blinks |
| Centre forehead | Ref, Bias | Reference and bias |
| Right forehead | Ch5, Ch6 | Frontal EEG, blinks |
| Right side, upper and lower | Ch7, Ch8 | Temple: eye movement, jaw and temple muscles |
Because all electrodes are on the front of the head, PiEEG XR is strongest at frontal EEG, blinks, eye movements and facial expressions. The classic eyes-closed alpha test needs electrodes at the back of the head, which only the academic version has.
Attaching to the headset
The mask clips into the headset with four buckles, two at the back and two at the front. See How to Start.
Or keep your own mask: take out only the silicone insert and fit it into the headset's original facial interface.
The BCI box sits against the back of the headset, held in place by the head strap.
Getting good contact
A stable, well-positioned mask is the single biggest factor in clean signal quality.
- Clean the skin with an alcohol pad and let it dry. Oil, sweat and make-up raise the contact resistance.
- Tighten the strap so the mask presses evenly. No gaps, no bending.
- Check the silicone insert is seated all the way round. If the soft part has shifted or fallen out, push it back into place.
- Add a little gel or saline to the electrodes if the signal is unsteady, especially when you move.
- Clean the electrodes with an alcohol pad after each use.
