ECG Instrumentation
In order to record the ECG, we need a transducer capable of converting the ionic potentials generated within the body into electronic potentials which can be measured by conventional electronic instrumentation. Such a transducer consists of a pair of electrodes, which measure the ionic potential difference between their respective points of application on the body surface. Electrodes may be classified either as polarisable, in which case they behave as capacitors, or non−polarisable, in which case they behave as resistors. Common electrodes have characteristics that lie between these extremes; the silver−silver chloride electrode discussed below approximates more closely to a non−polarisable electrode.
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