Patent ID: 8089283

Claim:
An apparatus for determining individual electrode impedance values for all electrodes of a bioelectric signal-monitoring system including a differential amplifier and only two signal electrodes which connect between a subject and inputs of the amplifier and a ground or common electrode which connects between the subject and a common or ground point in the system, without interruption of any of said electrode connections, the apparatus comprising: a signal source outputting a voltage signal; a first switching arrangement, including inputs electrically connected with the signal source through known impedances for receiving the voltage signal, outputs electrically connected with the signal electrodes, and switches between the inputs and the outputs; and a second switching arrangement, including inputs electrically connected with the signal electrodes, outputs electrically connected with the ground or common point in the system, and switches between the inputs and the outputs; and a controller in communication with the first and second switching arrangements for establishing a plurality of signal paths, wherein each signal path corresponds to a predetermined mathematical equation expressing an electrode impedance in terms of an equivalent signal path impedance and a voltage output of the differential amplifier; and the controller further comprising an algorithm for solving a plurality of mathematical equations corresponding to the plurality of signal paths to determine the electrode impedances.