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 headgear for placing sensors on a subject's head includes a centerpiece; a plurality of arms attached to and radiating outward and generally downward from the centerpiece; and sensor tips attached to the dorsal ends of at least some of the arms. At least one of the plurality of arms is a lower arm that is elastic and/or spring-like. When the headgear is placed on a subject's head, the at least one lower arm is so disposed in relation to the maximum circumference of the subject's head that the at least one lower arm must be bent outward for placement of the headgear on the subject's head and thereby provide a reactive force toward the head that causes the at least one lower arm to grasp at least a portion of the head that is at and/or below the maximum circumference of the head.

Abstract: A headgear for placing sensors on a subject's head includes a centerpiece; a plurality of arms attached to and radiating outward and generally downward from the centerpiece; and sensor tips attached to the dorsal ends of at least some of the arms. At least one of the plurality of arms is a lower arm that is elastic and/or spring-like. When the headgear is placed on a subject's head, the at least one lower arm is so disposed in relation to the maximum circumference of the subject's head that the at least one lower arm must be bent outward for placement of the headgear on the subject's head and thereby provide a reactive force toward the head that causes the at least one lower arm to grasp at least a portion of the head that is at and/or below the maximum circumference of the head.

Abstract: A wireless data acquisition system includes a data acquisition unit including a data sensor; a first wireless data link and a second wireless timing link with predicable or low latency. Stimulus and time markers come from a trigger generator. Data signals from the data sensor are transmitted across the wireless data link and timing information of the data acquisition unit is transmitted across the wireless timing link. A receiving host receives the transmitted data and timing information for logging and/or processing.

Abstract: Electrode impedances on a body of a subject are measured by connecting a sense electrode, a reference electrode and a return electrode to the body, using the sense electrode to deliver a test current from a current source to the body of the subject, and measuring the potential difference between the sense electrode and the reference electrode. The impedance of the sense electrode on the body is measured in accordance with the measurement of the potential difference between the sense electrode and the reference electrode.

Abstract: A headgear for placing sensors on a subject's head includes a centerpiece; a plurality of arms attached to and radiating generally downward from the centerpiece; and sensor tips attached to the dorsal ends of at least some of the arms. At least one of the plurality of arms is a lower arm that is elastic and/or spring-like. When the headgear is placed on a subject's head, the at least one lower arm is so disposed in relation to the maximum circumference of the subject's head that the at least one lower arm must be bent outward for placement of the headgear on the subject's head and thereby provide a reactive force toward the head that causes the at least one lower arm to grasp at least a portion of the head that is at and/or below the maximum circumference of the head.

Abstract: An electric field sensor includes one or more sensing electrodes connected to an integrated amplifier that bootstraps all parasitic capacitances at the sensor input to provide for a very high input impedance without the need for neutralization or other adjustments and calibration. The integrated amplifier for the electric field sensor further includes low-noise ESD/biasing structures to stabilize the DC-potential of the sensor with a minimum amount of added noise, leakage and parasitic capacitance.

Abstract: Electrode impedances on a body of a subject are measured by connecting a sense electrode, a reference electrode and a return electrode to the body, using the sense electrode to deliver a test current from a current source to the body of the subject, and measuring the potential difference between the sense electrode and the reference electrode. The impedance of the sense electrode on the body is measured in accordance with the measurement of the potential difference between the sense electrode and the reference electrode.

Abstract: A transducer assembly including a support terminal and at least one probe extending from the support terminal is adapted to enable a transducer to penetrate and slide through patches of hair covering a subject area of a person. The probe includes at least one leg structure supporting a transducer disposed at the distal end of the leg structure for sensing or stimulating the state of a particular property of a selected subject area when the transducer is applied by the leg structure to the selected subject area. The leg structure is so disposed in relation to the support terminal as to be disposed at a non-perpendicular angle to the subject area when the transducer assembly is applied to the selected subject area. The leg structure is adapted to flex when the transducer is applied under pressure to the selected subject area to thereby cause the transducer to slide on the subject area.

Abstract: A wireless data acquisition system includes a data acquisition unit including a data sensor; a first wireless data link and a second wireless timing link with predicable or low latency. Stimulus and time markers come from a trigger generator. Data signals from the data sensor are transmitted across the wireless data link and timing information of the data acquisition unit is transmitted across the wireless timing link. A receiving host receives the transmitted data and timing information for logging and/or processing.

Abstract: A transducer assembly including a support terminal and at least one probe extending from the support terminal is adapted to enable a transducer to penetrate and slide through patches of hair covering a subject area of a person. The probe includes at least one leg structure supporting a transducer disposed at the distal end of the leg structure for sensing or stimulating the state of a particular property of a selected subject area when the transducer is applied by the leg structure to the selected subject area. The leg structure is so disposed in relation to the support terminal as to be disposed at a non-perpendicular angle to the subject area when the transducer assembly is applied to the selected subject area. The leg structure is adapted to flex when the transducer is applied under pressure to the selected subject area to thereby cause the transducer to slide on the subject area.

Abstract: An electric field sensor includes one or more sensing electrodes connected to an integrated amplifier that bootstraps all parasitic capacitances at the sensor input to provide for a very high input impedance without the need for neutralization or other adjustments and calibration. The integrated amplifier for the electric field sensor further includes low-noise ESD/biasing structures to stabilize the DC-potential of the sensor with a minimum amount of added noise, leakage and parasitic capacitance.

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 electric field sensor includes one or more sensing electrodes connected to an integrated amplifier that bootstraps all parasitic capacitances at the sensor input to provide for a very high input impedance without the need for neutralization or other adjustments and calibration. The integrated amplifier for the electric field sensor further includes low-noise ESD/biasing structures to stabilize the DC-potential of the sensor with a minimum amount of added noise, leakage and parasitic capacitance.

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.