Remote-sensing method and device

• US 7,272,431 B2
• Filed: 08/01/2003
• Issued: 09/18/2007
• Est. Priority Date: 08/01/2002
• Status: Active Grant

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: McGrath, William R.
• Primary Examiner(s): Manuel; George
• Assistant Examiner(s): Flory; Christopher A.
• Application Number:
  US10/632,347
• Publication Number:
  US 20040123667A1
• Time in Patent Office: 1,509 Days
• Field of Search: 600/407, 600/509
• US Class Current: 600/509
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/0507 using microwaves or terahertz waves
• CPC Class Codes: A61B 5/08 Detecting, measuring or recording devices for evaluating the respiratory organs A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/24 Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
• CPC Class Codes: A61B 5/389 Electromyography [EMG]

Abstract

Apparatus and methods for performing remote detection of physiological activity are described. One aspect of the invention involves obtaining information concerning respiration and heart function. In one embodiment, the invention includes a source containing an oscillator configured to illuminate the subject with electromagnetic signal beam and a receiver configured to observe changes in the amplitude of the electromagnetic signal reflected by the subject.

Claims

1. A remote-detection system for monitoring changes in complex impedance associated with physiological activity of a subject that is free to move, comprising:

a source containing an oscillator configured to illuminate tissue of the subject with an electromagnetic signal beam;

a receiver configured to receive reflections of the electromagnetic signal beam from the subject, where the reflections include amplitude variations indicative of motion of the subject and amplitude variations indicative of time dependent variations in the complex impedance of the illuminated tissue associated with electrical activity of the subject'"'"'s heart; and

a detector connected to the receiver and configured to extract from the reflected signal beam the variations in amplitude indicative of time dependent variations in the complex impedance of the illuminated tissue associated with the electrical activity of the subject'"'"'s heart.

2. The remote-detection system of claim 1, wherein:

the source also includes a first antenna portion; and

the receiver includes a second antenna portion connected to the detector.

3. The remote-detection system in claim 2, wherein the source and the receiver are directionally coupled to a single antenna that acts as the first and second antenna portions.

4. The remote-detection system of claim 1, wherein:

the subject has a beating heart;

the complex impedance of the illuminated tissue of the subject changes as the heart beats;

the amplitude of the reflected electromagnetic signal beam changes as the complex impedance of the illuminated the tissue changes; and

the detector is configured to extract from the reflected electromagnetic signal beam variations in amplitude associated with the changes in the complex impedance of the illuminated tissue.

5. The remote-detection system of claim 4, further comprises signal processing circuitry connected to the filter and configured to extract an electrocardiographic waveform from the reflected electromagnetic signal beam.

6. The remote-detection system of claim 5, wherein the signal processing circuitry comprises an analog to digital converter and a microprocessor.

7. The remote-detection system of claim 1, wherein:

the source is configured to generate an electromagnetic signal beam at a predetermined frequency;

the receiver is configured to amplify the predetermined frequency of the received reflections; and

the receiver is configured to filter the amplified signal to remove noise.

8. A remote-detection system for monitoring the physiological activity of a subject, comprising:

means for illuminating at tissue of the subject with an electromagnetic signal;

means for detecting reflections of the electromagnetic signal, where the reflections include amplitude variations indicative of motion of the subject and amplitude variations indicative of time dependent variations in the complex impedance of the illuminated tissue with respect to the electrical activity of the subject'"'"'s heart; and

means for extracting a signal indicative of the changes in the amplitude of the electromagnetic signal reflected by the subject that are associated with time dependent changes in the complex impedance of the illuminated tissue with respect to the electrical activity of the subject'"'"'s heart.

9. A method of observing changes in the complex impedance of a subject associated with physiological activity, comprising:

illuminating tissue of the subject with an electromagnetic signal beam;

receiving reflections of the electromagnetic signal beam that include amplitude variations indicative of motion of the subject and amplitude variations indicative of time dependent variations in the complex impedance of the illuminated tissue associated with electrical activity of the subject'"'"'s heart; and

extracting from the reflected signal a signal indicative of the changes in the amplitude of the electromagnetic signal associated with time dependent changes in the complex impedance of the illuminated tissue associated with the electrical activity of the subject'"'"'s heart.

10. The method of claim 9, further comprising observing the electromagnetic signal reflected by changes in the complex impedance of the illuminated tissue of the subject.

11. The method of claim 10, further comprising filtering the observed electromagnetic signal to remove components of the reflected signal associated with movement of the subject.

12. The method of claim 9, further comprising producing an electrocardiographic waveform from the extracted signal.