NEW TETRAPOLAR METHOD USING MAGNETIC FIELD FOR

The tetrapolar circuit method has been used to detect physiological events as changes in electrical impedance[1J. However, it is still difficult to ob­ tain more meaningful imformation of local events be­ cause of the expanse of current distribution. In order to measure the local impedance change in the living tissue, we proposed a tetrapolar cir cuit method using magnetic field[2J. In this method, a constant current and eddy current are used. The eddy current is generated in the living t. iss ue by applying magnetic field. The current distribution can be restricted to a local part, by combining the eddy current with the constant current. We confirmed the effectiveness of this method by in-vivo measure­ ment of pulsatile waveforms due to the arterial blood flow in the forearm.