Placement and fixation of the sensor

After the sensor location has been determined and marked, the electrodes need to be placed and fixed around the marked location. When placing and fixing electrodes, the inter electrode distance, the orientation, the fixation method and the location of the reference electrode have to be chosen. 'Inter electrode distance' is defined as the centre to centre distance between the conductive area's of 2 bipolar electrodes. The influence of the inter electrode distance on the pick-up area and crosstalk is a relevant item in literature. 'Orientation' is defined as the position of the line between the 2 bipolar electrodes with respect to the direction of the muscle fibres. It is know from literature that the orientation of electrodes has an important effect on the recorded SEMG. The reference electrode need to be placed at a location in which the risk for a large common mode disturbance signal will be minimal. It is generally accepted that reference electrodes need to be placed on electrical inactive tissue. A number of reference electrode locations are preferred in literature, depending on the muscles from which the SEMG is recorded.

SENIAM recommendations for placement and fixation of the sensor

The SENIAM recommendations for electrode placement and fixation consist of recommendations for the:

Inter electrode distance
'Inter electrode distance' is defined as the centre to centre distance between the conductive area's of 2 bipolar electrodes.
SENIAM recommends to apply the bipolar SEMG electrodes around the recommended sensor location with an inter electrode distance of 20 mm. When bipolar electrodes are being applied on relatively small muscles the inter electrode distance should not exceed 1/4 of the muscle fibre length. In this way unstable recordings, due to tendon and motor endplate effects can be avoided.

Orientation of electrodes
'Electrode orientation' is defined as the position of the line between the 2 bipolar electrodes with respect to the direction of the muscle fibres.
SENIAM recommends that the bipolar SEMG electrodes should be placed around the recommended sensor location with the orientation parallel to the muscle fibres.

Fixation on the skin
SENIAM recommends to use elastic band or (double sided) tape / rings for the fixation of the electrodes(construction) and cables to the skin in such a way that the electrodes are properly fixed to the skin, movement is not hindered and cables are not pulling the electrodes(construction).

Location of the reference electrode
Depending on the application SENIAM recommends to use the wrist, the proc. spin. of C7 or the ankle as the standard location of the reference electrode.

The recommendations for sensor locations for individual muscles include for each individual muscle a recommendation for the inter electrode distance, orientation of the bipolar SEMG electrodes and the location of the reference electrode. These recommendations can be found at another part of this website:
Recommendations for sensor locations on individual muscles.