Motion detection for physiological applications
AssigneeSouthwest Research Institute
InventorsLarry D. Canady, Kevin S. Honeyager, Jerome A. Helffrich, David A. Tong
Life of this patent
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Abstract
A method and system for physiological monitoring using a microprocessor-enhanced magnetic field sensor to measure the mechanical effects of body motion is described. The measurements may be used for a variety of applications, such as detection of respiration, cardiac rhythms, and blood pressure. The source or detector may be made sufficiently small so as to be implantable. The system is sufficiently sensitive to provide output data for very small movements.
Claims43
A method of measuring mechanical activity associated with physiological motion of a living body, comprising the steps of:
- locating at least one magnetic field sensor on or in an area of the body, such that the sensor measures magnetic field changes caused by motion of that area of the body relative to an ambient magnetic field;
- detecting a signal from the sensor, the signal having time varying characteristics representative of the motion;
- and
- analyzing the signal to determine characteristics of the motion as indicated by the signal.
A method of measuring mechanical activity associated with a physiological motion of a living body, comprising the steps of:
- locating a magnetized material on or in an area of the body;
- sensing the magnetic field resulting from the motion of the magnetized material, using a magnetic field sensor;
- nulling the ambient magnetic field surrounding the body, by generating a nulling magnetic field in the area of the sensor and that is sensed by the sensor, the nulling magnetic field being substantially equal and opposite to that of the ambient magnetic field;
- detecting a signal from the magnetic field sensor, the signal having time varying characteristics representative of the motion;
- and
- analyzing the signal to determine characteristics of the motion as indicated by the signal.
A method of measuring mechanical activity associated with a physiological motion of a living body, comprising the steps of:
- locating a magnetized material on the skin over a blood vessel;
- sensing the magnetic field resulting from the motion of the magnetized material, using a magnetic field sensor;
- detecting a signal from the magnetic field sensor, the signal having time varying characteristics representative of the motion;
- analyzing the signal to determine characteristics of the motion as indicated by the signal and nulling the ambient magnetic field surrounding the body, by generating a nulling magnetic field in the area of the sensor, the nulling magnetic field being substantially equal and opposite to that of the ambient magnetic field.
A method of measuring mechanical activity associated with a physiological motion of a living body, comprising the steps of:
- affixing a magnetized material to a lead implanted in the body;
- sensing the magnetic field resulting from the motion of the magnetized material, using a magnetic field sensor;
- nulling the magnetic field surrounding the body, by generating a nulling magnetic field in the area of the sensor and that is sensed by the sensor, the nulling magnetic field being substantially equal and opposite that of the ambient magnetic field;
- detecting a signal from the magnetic field sensor, the signal having time varying characteristics representative of the motion;
- analyzing the signal to determine characteristics of the motion as indicated by the signal.
A method of measuring mechanical activity of the heart associated with a physiological motion of the heart, comprising the steps of:
- locating a magnetized material over the heart;
- sensing the magnetic field resulting from the motion of the magnetized material, using a magnetic field sensor;
- detecting a signal from the magnetic field sensor, the signal having time varying characteristics representative of the motion;
- analyzing the signal to determine heart motion as indicated by the signal.
A sensor system for measuring motion associated with a living body, comprising:
- a magnetic field sensor, the magnetic field sensor having a nulling coil;
- an AC excitation source for providing an excitation signal to the magnetic field sensor;
- a signal conditioning circuit for amplifying a signal provided by the magnetic field sensor;
- a detection unit for demodulating the filtered signal from the signal conditioning circuit;
- an analog to digital converter for converting the demodulated signal to a digital signal;
- a controller for calculating a nulling signal value;
- and
- a digital to analog converter for providing a nulling signal to the nulling coil.
Dependencies are inferred from the claim text.