Fabrication of suction-cup electrodes for electromyography.

Many kinds of surface electrodes are used today in EMG, the small silver and gold cup being the standard electrode in the United States. A suction-cup surface electrode is rarely used but several years of experience with many kinds of electrodes in our laboratory have led us to the conclusion that this electrode has many practical qualities. The suction-cup electrode has several advantages over other kinds of surface electrodes. It can be placed on the skin very quickly and easily by a mere pinch of the fingers. No adhesives or tapes are necessary to hold it in place or to insure contact with the skin to which it adheres without slipping during movements. It can be placed on the exact reference point marked on the skin. If suction is lost, the electrode can quickly be relubricated (Cardeez electrode jelly) and replaced exactly on the same spot. Suction can be maintained from one to several hours, depending upon the size of the suction-cup and its electrode, and the amount of electrode jelly used. Because of the slight suction created, continuous contact between the electrode and the skin is insured. Shaving of body hair is not necessary unless the subject is heavily endowed with hair. One precaution is the prolonged use of the electrode on flexor surfaces of the body such as the chest or abdomen. Some individuals are more susceptible to the development of petechiae in these areas. The cost is negligible, amounting to a few cents per pair. A dozen sets can be fabricated in a few hours using simple tools. If proper care is taken, these electrodes will last several years.