The Impedance Properties of Needle Electrodes for Electromyography

Abstract

Needle electrodes are extensively used in electromyography. The impedance properties of these electrodes are an important parameter for the design of the associated recording equipment and for the interpretation of the results obtained. It was therefore decided to investigate theoretically the factors which determine the impedance of the electrode for a.c. signals and its frequency dependence. The conclusions obtained were then verified experimentally. Though the primary objective was electromyography, it is assumed that the results may prove useful for other applications e.g. metal microelectrodes, pacemaker electrodes, etc.