Abstract: In a biopotential-physiological-phenomena sensing system, an impedance measurement circuit for measuring the impedance of a channel electrode that is applied to a subject's body for sensing a physiological phenomenon includes: an amplifier, a DC-biased power supply with an AC component and a conductive element. The amplifier has a signal input coupled to a channel electrode that is applied to a subject's body and a signal output for providing an output voltage that is representative of a voltage provided at the signal input in accordance with an amplification of the amplifier. The conductive element is coupled between the power supply and the signal input of the amplifier. The AC component of the DC-biased power supply causes a known test current to flow through the channel electrode thereby causing a voltage drop proportional to the impedance of the channel electrode at the input of the amplifier. The impedance of the channel electrode is measured in accordance with the amplifier's output voltage.

Abstract: A biopotential electrode for transferring electrical signals with a subject that includes an electrical conductor, a membrane selectively permeable to ionic conduction for presenting a dry surface to the subject, and a conductive medium positioned in communication with a portion of the electrical conductor and a portion of the membrane. The electrical potentials are coupled from the subject across the membrane into the conductive medium and then transferred from the subject to the electrical conductor. In other embodiments, the electrical potentials may be transferred from the external conductor to the subject through the conductive medium across the membrane into the subject. Other embodiments include systems and methods for using the biopotential electrodes.

Abstract: An assembly for reducing motion artifacts that includes an opening on the face of the assembly, an elastic material at least partially covering the opening for suspending objects above the opening, and a sensor attached to the elastic material wherein the sensor is suspended over the opening so that the sensor may be moved in the direction of the opening so that it at least partially recesses into the opening when the sensor is positioned against a subject. The tension on the elastic material generates a force on the sensor directed towards the subject as the elastic material is stretched. Methods and systems of reducing motion artifacts including methods and systems using the assembly are also claimed.