Fig. 1. The custom-built concentric surface electrode. The design of this planar concentric electrode was previously described. Central cathode (diameter 0.5 mm) and external anode ring (diameter 6 mm) were assembled. A medical engineering company (Hurev Co. Ltd., Wonju, Korea) contractually produced the first sample electrode according. Then we tested and confirmed final production. This custom-built electrode use conventional carbon wire cable and socket that fits well with a portable electromyography system.
