Versatile Bio Sensor Guide: ExG

Understanding the ExG (EMG, ECG, EOG) sensor on the Versatile Bio


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). 

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. 

Connect as many electrode channels as required via the labeled 2.5 mm ExG connectors on the Versatile Bio amplifier. 

Note:  All ExG setups require a ground electrode, connected to the GND input. 

How to clean:

The electrode itself is disposable.  Clean the leads with mild soap and water. Avoid getting the connectors wet.  Allow the sensors and all wiring to dry completely before use.  The adhesive electrodes themselves are disposable. 

Autoclave is not recommended.

Connector on Versatile Bio:

ExG

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