Selective recording of thin muscular layers with improved Ag-AgCI electrodes

An electrode assembly has been developed to record in vivo in the animal, simultaneously from both sides of the device, the electromyogram (EMG) of different muscular layers of the intestinal wall. The transducer is composed of two opposite active electrodes, and is surrounded by a ring electrode which is used as reference and avoids recording of interfering signals. An improved chlorination technique of silver electrodes, using a partial electrolytic removal of the chloride, is presented : it decreases the electrodes impedance and lowers their ageing degradation. Techniques of evaluating the performance of electrodes by measurement of their complex impedance are critically discussed.