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ExG Sensor Guide for Versatile 32 and 64

Guide to using the EOG, EMG and ECG sensors on the Versatile 32 and Versatile 64 EEG systems

What it measures:

The ExG sensors are used to measure electrical activity between a pair of sensors (differential).  They are typically used for one of these measurements:

EMG:  Electromyogram, a way of measuring the electrical activity produced by skeletal muscles during contraction.

ECG:  Electrocardiogram (also called "EKG"), a measure of the electrical activity of the heart vs time.

EOG:  Electrooculogram, a measure of potential between the front and back of the eyeball as a way of determining relative orientation of the eye.

Research Applications:

Sports, rehabilitation, kinesiology, psychology, biomechanics, neuromarketing, human factors, etc.

How to use:

Connect the sensors to the participant using standard adhesive disposable electrodes like the Aqua-Tac (pictured here). 

Skintact

Electrode locations depend on the application (EMG, EOG, ECG).  ExG electrodes are bipolar, requiring one electrode positioned on either side of the area to be measured.  Consult standard practices for the electrode positions for ECG, EMG, EOG, etc. 

The Versatile 32 EEG system has 2 bipolar ExG leads.
The Versatile 64 EEG system has 4 bipolar ExG leads

In both cases, ground is provided by the ground channel 0 in the EEG cap. 

For information about collecting ExG data via the Versatile Bio platform, click here.

How to clean:

Clinell Universal Wipes can be used to clean the ExG leads and electrodes.

  •  The adhesive electrodes themselves are disposable.
  • Avoid getting the connectors wet. 
  • Allow the sensors and all wiring to dry completely before use.
  • Autoclave is not recommended.

Visualization filters:

Right-click on wave view in Bitbrain Device Viewer to view data-visualization filter settings.

Under "Notch-Filter" we recommend setting this to the preset matching your country's AC frequency (presets exist for USA/Japan at 60 Hz, and Europe at 50 Hz).

Under "Other Filter" click "enabled"
Set filter type to "Bandpass"

For ECG and EOG detection:
Set Low (Hz) to 0.5 Hz
Set High (Hz) to 30 Hz

For EMG detection:
Set Low (Hz) to 1 Hz
Set High (Hz) to 100 Hz

Type is "Butterworth"
Order set to 4

Data file:

Output: ExG data output is reported in µV
Data Range:  ±420 mV
Data Noise:  <4 µVRMS (0.5-30Hz)
Output Type:  Bipolar analog