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BME 462Electrode selection, testing and
placement
Zexi Liu, Ashley Mulchrone, Yue Yin 09/30/2014
Electrode Selection
Dry-Contact and Noncontact Biopotential Electrodes:Methodological Review, Yu Mike Chi etc.
Wet Electrode• Reusable• Low-cost• Produce reliable signals in
different conditions• Adhesive material to lower skin
impedance, buffer electrode against mechanical motion
• Most common in clinical setting
Floating Electrode• Metal disk is recessed,
swimming in the electrolyte gel• It is not in contact with the skin• Reduces motion artifact
Dry Electrode
Flexible dry surface-electrodes for ECG long-term monitoring, Klaus-Peter Hoffmann and Roman Ruff
• Direct contact with skin• No electrolyte• Use moisture on skin• Work well for quick
measurement• Motion artifact
Ex. Polysiloxane framework with conductive nano-particle
Non-contact Electrode
Dry-Contact and Noncontact Biopotential Electrodes:Methodological Review, Yu Mike Chi etc.
• Gap between skin and sensor• No dielectric layer• Measure through hair, clothing
or air• A need to design amplifier to
acquire signals
Electrode Placement
• 3 Lead ECG
• Einthoven’s Triangle• 2 leads (3rd can be calculated)
• 4 electrodes
• Current Standard – any part of arms/legs below the shoulders and the gluteal fold• Shoulders and wrist are
approximately equal
Electrode Placement• Mason-Likar placement –
mainly used for exercise• Diminishes QRS complex• Rightward axial shifts
• Torso placement• Obscure myocardial infarction
(create or mask)
• Motion artifact – muscle noise• Bone• MuscleStandard Mason-Likar
http://pmj.bmj.com/content/81/952/122.full