Remote-sensing method and device

• US 7,811,234 B2
• Filed: 08/30/2007
• Issued: 10/12/2010
• 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): Wieland; Robert N
• Application Number:
  US11/897,884
• Publication Number:
  US 20080045832A1
• Time in Patent Office: 1,139 Days
• Field of Search: 600/407, 600/425, 600/426, 600/427, 600/429, 600/430, 600/428, 600/595, 600/534, 600/547, 600/508, 324/638, 324/642, 324/644, 702/20, 702/57, 435/6, 435/7.1, 606/33
• US Class Current: 600/508
• 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 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 5/726 using Wavelet transforms

Abstract

A remote-detection system is provided for monitoring changes in permittivity associated with physiological activity of a subject that is free to move. The system includes a source containing an oscillator configured to illuminate tissue of the subject with an electromagnetic signal beam. The system further includes a receiver configured to receive reflections of the electromagnetic signal beam from the subject. The reflections include amplitude variations indicative of motion of the illuminated tissue and amplitude variations indicative of time dependent variations in the permittivity of the illuminated tissue associated with electrical activity of the subject'"'"'s heart. The system further includes a detector connected to the receiver and configured to extract from the reflected signal beam the variations in amplitude indicative of motion of the illuminated tissue or indicative of time dependent variations in the permittivity of the illuminated tissue associated with the electrical activity of the subject'"'"'s heart.

Claims

1. A non-imaging remote-detection system for monitoring changes in permittivity associated with cardiac-related activity of a subject having a body 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 illuminated tissue and amplitude variations indicative of time dependent variations in a reflection coefficient at an air-tissue interface of the subject'"'"'s body resulting from variations in the permittivity 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 reflection coefficient.

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 antenna portion and the second antenna portion.

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

the subject has a beating heart;

the permittivity of the illuminated tissue changes in response to the beating heart;

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

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

5. The remote-detection system of claim 1, wherein the detector is further configured to extract from the reflected signal beam the variations in amplitude indicative of motion of the illuminated tissue.

6. The remote-detection system of claim 5, wherein:

the detector is configured to extract from the reflected signal beam the variations in amplitude indicative of motion of the illuminated tissue as correlates with heart sounds or a phonocardiogram of the subject.

7. A non-imaging remote-detection system for monitoring the cardiac-related activity of a subject having a body, comprising:

means for illuminating 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 illuminated tissue and amplitude variations indicative of time dependent variations in a reflection coefficient at an air-tissue interface of the subject'"'"'s body resulting from variations in the permittivity of the illuminated tissue associated with electrical activity of the subject'"'"'s heart; and

means for extracting a signal indicative of the amplitude variations of the electromagnetic signal reflected by the illuminated tissue that are associated with motion of the illuminated tissue and the amplitude variations of the electromagnetic signal reflected by the illuminated tissue that are associated with time dependent changes in the reflection coefficient.

8. The remote-detection system as claimed in claim 7, further comprising:

means for extracting a signal indicative of the changes in the amplitude of the electromagnetic signal reflected by the illuminated tissue that are associated with motion of the illuminated tissue as correlates with heart sounds or a phonocardiogram of the subject.

9. A non-imaging method of observing changes in the permittivity of a body of a subject associated with cardiac-related 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 illuminated tissue and amplitude variations indicative of time dependent variations in a reflection coefficient at an air-tissue interface of the subject'"'"'s body resulting from variations in the permittivity of the illuminated tissue associated with electrical activity of the subject'"'"'s heart; and

extracting from the reflected signal a signal indicative of the amplitude variations of the electromagnetic signal associated with motion of the illuminated tissue and the amplitude variations of the electromagnetic signal associated with time dependent changes in the reflection coefficient.

10. The method of claim 9, further comprising:

extracting from the reflected signal a signal indicative of the changes in the amplitude of the electromagnetic signal associated with motion of the illuminated tissue as correlates with heart sounds or a phonocardiogram of the subject.

11. A non-imaging remote sensing system for providing cardiac-related data of a subject having a body, comprising:

a transmitter for transmitting a microwave signal to illuminate tissue of the subject;

a receiver for receiving a reflected microwave signal, the reflected microwave signal being a reflection of the microwave signal from illuminated tissue of the subject; and

a processor for processing the reflected microwave signal;

wherein the processor is configured to analyze an amplitude of the reflected microwave signal to determine changes in a reflection coefficient at an air-tissue interface of the subject'"'"'s body resulting from changes in permittivity of the illuminated tissue of the subject, the changes in permittivity containing a static component and a time-varying component, the processor being configured to process the time-varying component to provide cardiographic related data of the subject.

12. The remote sensing system as claimed in claim 11, wherein:

the transmitter includes an RF oscillator coupled to a circulator and an antenna coupled to the circulator;

the receiver includes the antenna coupled to the circulator; and

the processor includes an amplifier, a direct detector, and a computer.

13. The remote sensing system as claimed in claim 11, wherein the microwave signal has a frequency between 100 MHz and 200 GHz.

14. A remote sensing system for providing cardiac-related data of a subject, comprising:

a transmitter for transmitting a microwave signal to illuminate tissue of the subject;

a receiver for receiving a reflected microwave signal, the reflected microwave signal being a reflection of the microwave signal from illuminated tissue of the subject; and

a processor for processing the reflected microwave signal;

wherein the processor is configured to analyze an amplitude of the reflected microwave signal to determine changes in permittivity of the illuminated tissue of the subject, the changes in permittivity containing a static component and a time-varying component, the processor being configured to process the time-varying component to provide cardiographic related data of the subject;

wherein the cardiographic related data correlate with an electrocardiogram or an impedance cardiogram.

15. A remote sensing system for providing cardiac-related data of a subject, comprising:

a transmitter for transmitting a microwave signal to illuminate tissue of the subject;

a receiver for receiving a reflected microwave signal, the reflected microwave signal being a reflection of the microwave signal from illuminated tissue of the subject; and

a processor for processing the reflected microwave signal;

wherein the processor is configured to analyze an amplitude of the reflected microwave signal to determine changes in permittivity of the illuminated tissue of the subject, the changes in permittivity containing a static component and a time-varying component, the processor being configured to process the time-varying component to provide cardiographic related data of the subject;

wherein the processor is further configured to process the time-varying component to provide a respiratory pattern or a pulse rate of the subject.

16. A non-imaging method of remotely sensing cardiac-related data of a subject, comprising:

transmitting a microwave signal to illuminate tissue of the subject;

receiving a reflected microwave signal, the reflected microwave signal being a reflection of the microwave signal from illuminated tissue of the subject;

processing the reflected microwave signal and analyzing an amplitude of the reflected microwave signal to determine changes in a reflection coefficient at an air-tissue interface of the subject'"'"'s body resulting from changes in permittivity of the illuminated tissue of the subject, the changes in permittivity containing a static component and a time-varying component; and

processing the time-varying component to provide cardiographic related data of the subject.

17. The method as claimed in claim 16, further comprising:

A method of remotely sensing cardiac-related data of a subject, comprising;

transmitting a microwave signal to illuminate tissue of the subject;

receiving a reflected microwave signal, the reflected microwave signal being a reflection of the microwave signal from illuminated tissue of the subject;

processing the reflected microwave signal and analyzing an amplitude of the reflected microwave signal to determine changes in permittivity of the illuminated tissue of the subject, the changes in permittivity containing a static component and a time-varying component; and

processing the time-varying component to provide cardiographic related data of the subject;

providing a respiratory pattern or a pulse rate from the time-varying component.

18. The method as claimed in claim 16, wherein the microwave signal has a frequency between 100 MHz and 200 GHz.

19. A method of remotely sensing cardiac-related data of a subject, comprising:

transmitting a microwave signal to illuminate tissue of the subject;

receiving a reflected microwave signal, the reflected microwave signal being a reflection of the microwave signal from illuminated tissue of the subject;

processing the reflected microwave signal and analyzing an amplitude of the reflected microwave signal to determine changes in permittivity of the illuminated tissue of the subject, the changes in permittivity containing a static component and a time-varying component; and

processing the time-varying component to provide cardiographic related data of the subject;

providing the cardiographic related data as correlated with an electrocardiogram or an impedance cardiogram.