Method and apparatus to measure bioelectric impedance of patient tissue

摘要

A device to measure tissue impedance comprises drive circuitry coupled to calibration circuitry, such that a calibration signal from the calibration circuitry corresponds to the current delivered through the tissue. Measurement circuitry can be coupled to measurement electrodes and the calibration circuitry, such that the tissue impedance can be determined in response to the measured calibration signal from the calibration circuitry and the measured tissue impedance signal from the measurement electrodes. Processor circuitry comprising a tangible medium can be configured to determine a complex tissue impedance in response to the calibration signal and the tissue impedance signal. The processor can be configured to select a frequency for the drive current, and the amount of drive current at increased frequencies may exceed a safety threshold for the drive current at lower frequencies.

主权项

1. A device for measuring an impedance of a tissue of a patient, the device comprising:
an adhesive patch that includes at least four electrodes configured to couple to the tissue of the patient, the at least four electrodes comprising two measurement electrodes and two drive electrodes; and an electronics module comprising circuitry coupled to the at least four electrodes, the circuitry including drive circuitry coupled to the two drive electrodes to pass a current through the two drive electrodes, and sensing circuitry coupled to the two measurement electrodes to measure a signal generated across the two measurement electrodes as a result of the current through the drive electrodes, and a processor programmed to receive and process the signal measured from the two measurement electrodes to determine a tissue impedance of the patient; wherein the adhesive patch and the electronics module are separable.