Method for detecting at least one of a heart rate and a respiratory rate of a subject

Patent metadata

Field	Value
Publication number	US-2017172425-A1
Application number	US-201615373322-A
Country	US
Kind code	A1
Filing date	Dec 8, 2016
Priority date	Dec 21, 2015
Publication date	Jun 22, 2017
Grant date	—

Abstract

A method for detecting at least one of a heart rate and a respiratory rate of a subject is disclosed. In one aspect, the method includes transmitting a radio frequency signal towards the subject and receiving a reflected signal from the subject, the reflected signal being Doppler-shifted due to at least one of the heart rate and the respiratory rate. The method also includes providing the reflected signal to a first input of a phase comparator and generating an adjustable reference signal by a reference signal generator. The method further includes providing the reference signal to a second input of the phase comparator and generating an output signal by the phase comparator based on the reflected signal and the reference signal. The method includes varying, by the reference signal generator, at least one of a phase and a frequency of the adjustable reference signal based on the output signal of the phase comparator to track a phase of the reflected signal.

First claim

What is claimed is:

1 . A method for detecting at least one of a heart rate and a respiratory rate of a subject, comprising:
transmitting a radio frequency signal towards the subject; receiving a reflected signal from the subject, the reflected signal being Doppler-shifted due to at least one of the heart rate and the respiratory rate; providing the reflected signal to a first input of a phase comparator; generating an adjustable reference signal by a reference signal generator and providing the reference signal to a second input of the phase comparator; generating an output signal by the phase comparator based on the reflected signal and the reference signal; and varying, by the reference signal generator, at least one of a phase and a frequency of the adjustable reference signal based on the output signal of the phase comparator to track a phase of the reflected signal.

2 . The method according to claim 1 , further comprising determining at least one of a heart rate and a respiratory rate by performing a frequency analysis of the output signal of the phase comparator.

3 . The method according to claim 1 , further comprising integrating the output signal from the phase comparator.

4 . The method according to claim 3 , further comprising determining at least one of a heart rate and a respiratory rate by performing a frequency analysis of the integrated output.

5 . The method according to claim 3 , further comprising estimating a magnitude of the motion of the subject's tissue by determining an amplitude of a frequency component of the integrated output.

6 . The method according to claim 1 , wherein the phase comparator includes a mixer.

7 . The method according to claim 1 , wherein the reference signal generator includes a voltage controlled oscillator.

8 . The method according to claim 1 , wherein the reference signal generator includes an oscillator and a phase modulator.

9 . The method according to claim 8 , further comprising integrating the output signal of the phase comparator and providing the integrated output signal to the phase modulator.

10 . The method according to claim 1 , wherein the adjustable reference signal is generated with a phase which is correlated to a phase of the transmitted signal.

11 . The method according to claim 1 , wherein the radio frequency signal transmitted towards the subject is a fixed-frequency signal.

12 . A system for detecting at least one of a heart rate and a respiratory rate of a subject, the system comprising:
a transmitter adapted to transmit a radio frequency signal towards the subject; a receiver adapted to receive a reflected signal from the subject, the reflected signal being Doppler-shifted due to at least one of the heart rate and the respiratory rate a phase comparator adapted to receive the reflected signal at a first input of the phase comparator and to receive an adjustable reference signal at a second input of the phase comparator, the phase comparator adapted to provide an output signal based on the reflected signal and the adjustable reference signal; and a reference signal generator adapted to output the adjustable reference signal, wherein the reference signal generator is adapted to vary at least one of a phase and a frequency of the adjustable reference signal based on the output signal of the phase comparator to track a phase of the reflected signal.

13 . The system of claim 1 , wherein the phase comparator and the reference signal generator form part of a phase-locked loop of the system which tracks the phase of the reflected signal.

14 . The system of claim 1 , further comprising a loop filter adapted to filter the output signal from the phase comparator.

15 . The system of claim 14 , wherein the filtered output signal is provided as a feedback signal to the reference signal generator, and wherein the reference signal generator is adapted to vary at least one of the phase and the frequency of the adjustable reference signal based on the filtered output signal.

16 . The system of claim 1 , further comprising a processing unit adapted to determine at least one of the heart rate and the respiratory rate by performing a frequency analysis of the output signal from the phase comparator.

17 . The system of claim 1 , further comprising an integrator adapted to integrate the output signal from the phase comparator.

18 . The system of claim 1 , wherein the adjustable reference signal is generated with a phase which is correlated to a phase of the transmitted signal.

Assignees

• Imec Vzw
• Stichting Imec Nederland

Inventors

• Liu Yao-Hong
• Mercuri Marco

Classifications

• A61B5/7228

  Signal modulation applied to the input signal sent to patient or subject; Demodulation to recover the physiological signal · CPC title

• A61B5/0507

  using microwaves or terahertz waves · CPC title

• A61B5/7278

  Artificial waveform generation or derivation, e.g. synthesizing signals from measured signals · CPC title

• A61B5/0816

  Measuring devices for examining respiratory frequency (measuring frequency of electric signals G01R23/00) · CPC title

• A61B5/0205 Primary

  Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition · CPC title