Granted Patent B2

US 12,629,044 · App. 19/234,899 · Granted May 19, 2026

Inventor: Yakup Kilic (Hoofddrop, NL)

Assignee: Sonion Nederland B.V.

A61B5/0261A61B5/381A61B5/7278A61B5/7285

Abstract

Claims (43)

1 . A system for performing a laser Doppler flowmetry measurement of a blood perfused tissue, the system comprising:

a light source configured to emit coherent light to the blood perfused tissue;

a photodetector configured to receive a portion of the coherent light scattered by the blood perfused tissue and generate a photodetector output signal in response to receiving said portion; and

one or more processors configured to determine a selected frequency range (F selected ) for computing a laser Doppler flowmetry signal (LDF signal), wherein the determining the selected frequency range (F selected ) includes

computing a spectrum (S i (f)) of the photodetector output signal for a series of time intervals (t i ), thereby obtaining a series of spectra,

computing, for a number of different frequencies (f), a measure of an amount of physiological information (Q f ) in the spectra (S i (f)), and

determining the selected frequency range (F selected ) as a range of frequencies (f) for which the measure of the amount of physiological information (Q f ) fulfills a predetermined criterion,

wherein the one or more processors are further configured to compute the LDF signal using the selected frequency range, and to output the LDF signal,

wherein the measure of the amount of physiological information (Q f ) comprises a dispersion d(f) of the spectra, as a function of frequency (f), and

wherein the predetermined criterion includes a threshold criterion for the dispersion d(f), and the determining the selected frequency range (F selected ) includes

comparing the dispersion d(f) to a threshold λ,

determining a minimum frequency (f min ) of the selected frequency range (F selected ) as a first frequency where the threshold λ is crossed for a first time while the dispersion d(f) has a positive slope, such that the dispersion d(f) has a value that increases with increasing frequency across the first frequency while maintaining the positive slope across the first frequency, and

determining a maximum frequency (f max ) of the selected frequency range (F selected ) as a second frequency where the threshold λ is crossed for a first time while the dispersion d(f) has a negative slope, such that the dispersion d(f) has a value that decreases with increasing frequency across the second frequency while maintaining the negative slope across the second frequency.

2 . The system of claim 1 , wherein the determining the selected frequency range (F selected ) comprises:

obtaining a plurality of trigger signals, each trigger signal of the plurality of trigger signals indicative of a timing of a separate individual LDF pulse of individual LDF pulses of the LDF signal, the individual LDF pulses following a cadence of a cardiac cycle;

using the plurality of trigger signals, determining, from the spectra (S i (f)), a separate spectrogram for each separate individual LDF pulse of the individual LDF pulses to determine spectrograms of the individual LDF pulses; and

determining, from the spectrograms of the individual LDF pulses, an ensemble spectrogram (X E (f,t)), comprising a central tendency of the spectrograms of the individual LDF pulses,

wherein the dispersion d(f) is computed from the ensemble spectrogram (X E (f,t)).

3 . The system of claim 2 , wherein the plurality of trigger signals are obtained from at least one of:

an ECG sensor (electrocardiography sensor) generating ECG signals that follow the cadence of the cardiac cycle, such that the plurality of trigger signals are obtained based on the ECG signals, or

a PPG sensor (photoplethysmography sensor) generating PPG signals that follow the cadence of the cardiac cycle, such that the plurality of trigger signals are obtained based on the PPG signals.

4 . The system of claim 1 , comprising a wearable device comprising the light source and the photodetector.

5 . A computer-implemented method for computing a laser Doppler flowmetry signal (LDF signal), the computer-implemented method comprising:

receiving a photodetector output signal from an LDF system; and

determining a selected frequency range (F selected ) for computing the LDF signal, wherein the determining the selected frequency range (F selected ) includes

computing a spectrum (S i (f)) of the photodetector output signal for a series of time intervals (t i ), thereby obtaining a series of spectra,

computing, for a number of different frequencies (f), a measure of an amount of physiological information (Q f ) in the spectra (S i (f)), and

determining the selected frequency range (F selected ) as a range of frequencies (f) for which the measure of the amount of physiological information (Q f ) fulfills a predetermined criterion,

wherein the computer-implemented method further includes computing the LDF signal using the selected frequency range, and outputting the LDF signal,

wherein the measure of the amount of physiological information comprises a dispersion d(f) of the spectra, as a function of frequency (f), and

wherein the predetermined criterion includes a threshold criterion for the dispersion d(f), and the determining the selected frequency range (F selected ) includes

comparing the dispersion d(f) to a threshold λ,

determining a minimum frequency (f min ) of the selected frequency range (F selected ) as a first frequency where the threshold λ is crossed for a first time while the dispersion d(f) has a positive slope, such that the dispersion d(f) has a value that increases with increasing frequency across the first frequency while maintaining the positive slope across the first frequency, and

determining a maximum frequency (f max ) of the selected frequency range (F selected ) as a second frequency where the threshold λ is crossed for a first time while the dispersion d(f) has a negative slope, such that the dispersion d(f) has a value that decreases with increasing frequency across the second frequency while maintaining the negative slope across the second frequency.

6 . The computer-implemented method of claim 5 , wherein the determining the selected frequency range (F selected ) comprises:

obtaining a plurality of trigger signals, each trigger signal of the plurality of trigger signals indicative of a timing of a separate individual LDF pulse of individual LDF pulses of the LDF signal, the individual LDF pulses following a cadence of a cardiac cycle;

using the plurality of trigger signals, determining, from the spectra (S i (f)), a separate spectrogram for each separate individual LDF pulse of the individual LDF pulses to determine spectrograms of the individual LDF pulses; and

determining, from the spectrograms of the individual LDF pulses, an ensemble spectrogram (X E (f,t)), comprising a central tendency of the spectrograms of the individual LDF pulses,

wherein the dispersion d(f) is computed from the ensemble spectrogram (X E (f,t)).

7 . The computer-implemented method of claim 6 , wherein the plurality of trigger signals are obtained from at least one of:

an ECG sensor (electrocardiography sensor) generating ECG signals that follow the cadence of the cardiac cycle, such that the plurality of trigger signals are obtained based on the ECG signals, or

a PPG sensor (photoplethysmography sensor) generating PPG signals that follow the cadence of the cardiac cycle, such that the plurality of trigger signals are obtained based on the PPG signals.

8 . A non-transitory computer-readable medium storing a computer program, the computer program comprising instructions that, when executed by one or more processors, cause the one or more processors to execute the computer-implemented method according to claim 5 .

Assignments (1)

Priority Claims (1)

Continuity (1)

References Cited (22)