Real-time periodic artifact extraction from a physiological signal

Patent metadata

Field	Value
Publication number	US-11717229-B2
Application number	US-202017109475-A
Country	US
Kind code	B2
Filing date	Dec 2, 2020
Priority date	Dec 9, 2019
Publication date	Aug 8, 2023
Grant date	Aug 8, 2023

Abstract

A physiological activity detection system comprises a signal acquisition module configured for non-invasively acquiring a signal from an anatomical structure of a user, the acquired signal having a physiological-encoded component and a periodic artifact component that dominates the physiological-encoded component. The physiological activity detection system further comprises a phase-locked loop (PLL) component configured for estimating a phase of the periodic artifact component of the acquired signal, and generating a periodic reference signal having a phase representative of the estimated phase of the periodic artifact component of the acquired signal.

First claim

What is claimed is:

1. A physiological activity detection system, comprising:
a signal acquisition module configured for non-invasively acquiring a signal from an anatomical structure of a user, the acquired signal having a physiological-encoded component and a periodic artifact component that dominates the physiological-encoded component;
a phase-locked loop (PLL) component configured for estimating a phase of the periodic artifact component of the acquired signal, and generating a periodic reference signal having a phase representative of the estimated phase of the periodic artifact component of the acquired signal; and
an artifact cancellation component configured for generating an estimated periodic artifact component by scaling and offsetting the periodic reference signal to the periodic artifact component in the acquired signal, and filtering the periodic artifact component from the acquired signal based on the estimated periodic component, thereby yielding a reduced-artifact signal.

2. The physiological activity detection system of claim 1 , wherein the anatomical structure of the user is a brain, and wherein the physiological-encoded component is a neurological-encoded component.

3. The physiological activity detection system of claim 2 , wherein the periodic artifact component is a cardiac artifact component.

4. The physiological activity detection system of claim 2 , wherein the acquired signal comprises signal light.

5. The physiological activity detection system of claim 4 , wherein the signal acquisition module is configured for non-invasively acquiring the signal light from the brain of the user via functional near-infrared spectroscopy (fNIRS).

6. The physiological activity detection system of claim 1 , wherein the periodic reference signal varies in accordance with a sine wave.

7. The physiological activity detection system of claim 1 , wherein the signal acquisition module is configured for digitizing the acquired signal into acquired data, and wherein the PLL component is configured for estimating the phase of the periodic artifact component in the acquired data, and generating periodic reference data having a phase representative of the estimated phase of the periodic artifact component in the acquired data.

8. The physiological activity detection system of claim 7 , wherein the acquired data comprises a time-series of data samples, and the PLL component is configured for respectively estimating phases of the periodic artifact component in the acquired data samples, and generating periodic reference data samples respectively having phases representative of the estimated phases of the periodic artifact component in the acquired data samples.

9. The physiological activity detection system of claim 1 , wherein the PLL component comprises:
a phase comparator; and
a voltage-controlled oscillator (VCO) arranged in a closed feedback loop with the phase comparator;
wherein the phase comparator is configured for computing a difference between the phase of the periodic artifact component of the acquired signal and the phase of the periodic reference signal, thereby respectively generating a phase error signal; and
wherein the VCO is configured for generating the periodic reference signal, and varying the frequency of the periodic reference signal in accordance with the phase error signal, thereby varying the phase of the periodic reference signal.

10. The physiological activity detection system of claim 1 , further comprising a frequency computation component configured for computing a frequency of the periodic artifact component.

11. The physiological activity detection system of claim 10 , wherein the periodic artifact component is a cardiac artifact component, the frequency computation component is a heart rate (HR) computation component, and the computed frequency of the cardiac artifact component is a heart rate (HR) of the user.

12. The physiological activity detection system of claim 1 , wherein the artifact cancellation component is configured for filtering the periodic artifact component from the acquired signal by subtracting the estimated periodic artifact component from the acquired signal, thereby yielding the reduced-artifact signal.

13. The physiological activity detection system of claim 1 , wherein the physiological-encoded component dominates the periodic artifact component in the reduced-artifact signal.

14. The physiological activity detection system of claim 1 , wherein the periodic artifact component is substantially eliminated from the reduced-artifact signal.

15. The physiological activity detection system of claim 1 , further comprising a signal processor configured for determining an existence of physiological activity in the user based on the reduced-artifact signal.

16. The physiological activity detection system of claim 15 , wherein the anatomical structure of the user is a brain, the physiological-encoded component is neurological-encoded component, and the physiological activity is neural activity.

17. The physiological activity detection system of claim 16 , wherein the neural activity is within cortical region of the brain of the user, wherein the periodic artifact component is a cardiac artifact component, and the physiological activity detection system further comprises a heart rate (HR) computation component configured for computing a heart rate (HR) of the user based on the phase of the periodic reference signal, wherein the signal processor is configured for determining an existence of neural activity in subcortical region of the brain of the user based on the computed HR of the user.

18. The physiological activity detection system of claim 1 , wherein the artifact cancellation component comprises:
a first signal comparator;
an adaptive filter arranged in a feedback loop with the first signal comparator; and
a second signal comparator;
wherein the first signal comparator is configured for computing a difference between a magnitude of the estimated periodic artifact component and a magnitude of the periodic reference signal, thereby generating a magnitude error signal;
wherein the adaptive filter is configured for varying a transfer function in response to the magnitude error signal, and filtering the acquired signal in accordance with the varied transfer function, thereby generating the estimated periodic artifact component;
wherein the second signal comparator is configured for computing the difference between a magnitude of the acquired signal and a magnitude of the estimated periodic artifact component to yield the reduced-artifact signal.

19. The physiological activity detection system of claim 1 , wherein the artifact cancellation component comprises:
a signal comparator;
an adaptive filter arranged in a feedback loop with the first signal comparator;
wherein the signal comparator is configured for computing a difference between a magnitude of the acquired signal and a magnitude of the estimated periodic artifact component, thereby generating a magnitude error signal representative of the reduced-artifact signal;
wherein the adaptive filter is configured for varying a transfer function in response to the magnitude error signal, and filtering the periodic reference signal in accordance with the varied transfer function, thereby generating the estimated periodic artifact component.

20. The physiological activity detection system of claim 1 , wherein the artifact cancellation component is configured for utilizing a recursive least squares (RLS) algorithm to

Assignees

• Hi Llc

Inventors

• Ojeda Alejandro
• Katnani Husam

Classifications

• A61B5/7214 Primary

  using signal cancellation, e.g. based on input of two identical physiological sensors spaced apart, or based on two signals derived from the same sensor, for different optical wavelengths · CPC title

• A61B5/0075

  by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy (A61B5/0071 takes precedence) · CPC title

• A61B5/0082

  adapted for particular medical purposes · CPC title

• A61B5/024

  Measuring pulse rate or heart rate · CPC title

• A61B5/725

  using specific filters therefor, e.g. Kalman or adaptive filters (specific diagnostics methods using using bioelectric or biomagnetic signals A61B5/316) · CPC title