EMS (Electrical muscle stimulation) and any of its variants (FES, TENS, etc) utilize two electrodes connected to a muscle and let current pass through the skin, nerves and muscle tissue. This means current is passing through your body. This current is not enough to harm you in any way (it will usually be around 10 times less than inside a 9V battery) if you follow the safety procedures described by clinicians and experts.
Golden Rule 1: Never place two electrodes across the heart.
Golden Rule 2: Never place electrodes from the same channel on different sides of the body (because it can pass through the heart). This means no electrodes on each shoulder, no electrodes on each hand, on each feet, etc. If you are placing two electrodes, make sure they are in the same side of your body and very close to each other.
Golden Rule 3: Never place two electrodes more than a few centimeters away. If you are doing that, something is wrong with your electrode placement, stop.
Golden Rule 4: Do not allow other circuits that you do not understand to interfere with EMS device. Do not interrupt the path and modulate it with some circuit you found somewhere.
Golden Rule 5: Use only medically compliant hardware. This means your stimulator should come from a reliable and approved source, and be legal and aligned with the regulations of your country.
Golden Rule 6: Use only EMS electrodes (pre-gelled, sticky). If you are making your own electrodes, stop.
Golden Rule 7: Check electrode placement charts before you place any electrodes. Are you sure the muscle you want to stimulate is there? If you are not sure, stop and check anatomy guides before.
Golden Rule 8: Do not put electrodes close to your chest, back, neck, face. If you are not a physician, just use the muscles provided in the guides (arms, legs).
Golden Rule 9: Go read all our tutorials and watch our videos before.
Please refer to the liability waiver (in documentation/liability_waiver.md).
Please refer to the license (in /license.md)