# US 2019/0167124 A1 · Device for use in blood oxygen saturation measurement

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- Number: US 2019/0167124 A1
- Document ID: US20190167124A1
- Status: Published application
- Kind: A1
- Application number: 16/323,560
- Filed: 2017-08-07
- Published: 2019-06-06
- Earliest claimed: 2016-08-09
- Assignees: Koninklijke Philips N.V.
- Applicants: Koninklijke Philips N.V.
- Inventors: Willem VERKRUIJSSE; Simone Cornelia Maria Anna ORDELMAN; Cristian Nicolae PRESURA; Rick BEZEMER; Calina CIUHU
- Web page: https://patentgrep.com/patent/US20190167124A1

## CPC

- A61B 5/0261: {using optical means, e.g. infrared light}
- A61B 5/14552: {Details of sensors specially adapted therefor}
- A61B 5/6826: {Finger}
- A61B 5/7221: {Determining signal validity, reliability or quality (preventing, reducing or removing noise induced by motion artefacts A61B5/7207; noise originating from a therapeutic or surgical apparatus A61B5/7217)}
- G02B 27/48: Laser speckle optics
- A61B 5/7278: {Artificial waveform generation or derivation, e.g. synthesizing signals from measured signals}
- A61B 2560/0223: of calibration, e.g. protocols for calibrating sensors
- A61B 2562/0238: Optical sensor arrangements for performing transmission measurements on body tissue
- A61B 2562/0242: for varying or adjusting the optical path length in the tissue
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

The present invention relates to a device (10), system (1) and method (200) for use in blood oxygen saturation measurement of a subject. To enable blood oxygen saturation measurements with improved reliability, a processing device (10) is presented comprising an input (11) for receiving first and second detection data of a tissue region of the subject, said first detection data being data acquired over time by detecting radiation at a first wavelength (λ1) and at a second wavelength (λ2) received from said tissue region; said second detection data being data acquired over time by detecting radiation at the first wavelength and at the second wavelength received from said tissue region in response to coherent light at the first wavelength and coherent light at the second wavelength being emitted towards the tissue region; a PPG unit (12) for deriving, from said first detection data, a first PPG signal indicative of an absorption of light within the tissue region at the first wavelength, and a second PPG signal indicative of an absorption of light within the tissue region at the second wavelength; a flow unit (13) for deriving, from said second detection data, a first flow signal indicative of a flow of light scattering particles within the tissue region probed at the first wavelength, and a second flow signal indicative of a flow of light scattering particles within the tissue region probed at the second wavelength; and a processing unit (14) for correcting said PPG signals based on said flow signals and/or for providing a feedback signal based on a comparison of the first and second flow signals.

## Claims

### Claim 1

A processing device for use in blood oxygen saturation measurement of a subject, the processing device comprising:
an input for receiving first and second detection data of a tissue region of the subject, said first detection data being data acquired over time by detecting radiation at a first wavelength and at a second wavelength received from said tissue region; said second detection data being data acquired over time by detecting radiation at the first wavelength and at the second wavelength received from said tissue region in response to coherent light at the first wavelength and coherent light at the second wavelength being emitted towards the tissue region;
a PPG unit for deriving, from said first detection data, a first PPG signal indicative of an absorption of light within the tissue region at the first wavelength, and a second PPG signal indicative of an absorption of light within the tissue region at the second wavelength;
a flow unit for deriving, from said second detection data, a first flow signal indicative of a flow of light scattering particles within the tissue region probed at the first wavelength, and a second flow signal indicative of a flow of light scattering particles within the tissue region probed at the second wavelength; and
a processing unit for correcting said PPG signals based on said flow signals and/or for providing a feedback signal based on a comparison of the first and second flow signals.

### Claim 2 (depends on 1)

The processing device as claimed in claim 1, wherein the processing unit is configured to correct said PPG signals based on said flow signals and to provide an output indicative of a blood oxygen saturation of the subject based on said corrected PPG signals.

### Claim 3 (depends on 1)

The processing device as claimed in claim 1, wherein the processing unit is configured to provide said feedback signal based on said flow signals, said feedback signal being indicative of a quality of the PPG signals and derived from a mismatch between the first flow signal at the first wavelength and the second flow signal at the second wavelength.

### Claim 4 (depends on 1)

The processing device as claimed in claim 1, wherein the PPG unit is configured to determine the first and the second PPG signal based on an average of the detected radiation at the first wavelength and at the second wavelength.

### Claim 5 (depends on 1)

The processing device as claimed in claim 1, wherein the flow unit is configured to derive the first and second flow signal based on a laser Doppler and/or laser speckle technique.

### Claim 6 (depends on 1)

The processing device as claimed in claim 1, wherein the flow unit is configured to determine the first and the second flow signal based on a standard deviation of the detected radiation at the first wavelength and at the second wavelength.

### Claim 7 (depends on 1)

The processing device as claimed in claim 1, wherein the flow unit is configured to determine the first and the second flow signals based on a speckle contrast at the first wavelength and the second wavelength.

### Claim 8 (depends on 1)

The processing device as claimed in claim 1, wherein the processing unit is configured to correct the first and the second PPG signal based on a temporal modulation of the first and the second flow signal at the first wavelength and the second wavelength.

### Claim 9 (depends on 1)

The processing device as claimed in claim 1, wherein the processing unit is configured to correct the PPG signals by scaling amplitudes of the first and the second PPG signal at the first wavelength and the second wavelength based on amplitudes of the first and the second flow signal at the first wavelength and the second wavelength.

### Claim 10 (depends on 1)

The processing device as claimed in claim 1, wherein the processing unit is configured to determine a ratio of ratios of the PPG signals and to correct said ratio of ratios of the PPG signals based on a ratio of ratios of the flow signals.

### Claim 11

(canceled)

### Claim 12 (depends on 1)

A system for use in blood oxygen saturation measurement of a subject, the system comprising:
a coherent light source arranged to emit coherent light at a first wavelength and at a second wavelength towards a tissue region of the subject
a detector for acquiring first and second detection data of the tissue region of the subject, said first detection data being acquired over time by detecting radiation at a first wavelength and at a second wavelength received from said tissue region; said second detection data being acquired over time by detecting radiation at the first wavelength and at the second wavelength received from said tissue region in response to the coherent light at the first wavelength and coherent light at the second wavelength being emitted towards the tissue region; and
the processing device as claimed in claim 1 for processing said first and said second detection data of the tissue region of the subject.

### Claim 13 (depends on 12)

The system as claimed in claim 12, arranged as a remote PPG system, in particular comprising a camera as the detector.

### Claim 14

A method for use in blood oxygen saturation measurement of a subject, the method comprising the steps of:
receiving first and second detection data of a tissue region of the subject, said first detection data being data acquired over time by detecting radiation at a first wavelength and at a second wavelength received from said tissue region; said second detection data being data acquired over time by detecting radiation at the first wavelength and at the second wavelength received from said tissue region in response to coherent light at the first wavelength and coherent light at the second wavelength being emitted towards the tissue region;
deriving, from said first detection data, a first PPG signal indicative of an absorption of light within the tissue region at the first wavelength, and a second PPG signal indicative of an absorption of light within the tissue region at the second wavelength;
deriving, from said second detection data, a first flow signal indicative of a flow of light scattering particles within the tissue region probed at the first wavelength, and a second flow signal indicative of a flow of light scattering particles within the tissue region probed at the second wavelength; and
correcting said PPG signals based on said flow signals and/or providing a feedback signal based on a comparison of the first and second flow signals.

### Claim 15 (depends on 14)

A computer program comprising program code means for causing a computer to carry out the steps of the method as claimed in claim 14 when said computer program is carried out on a computer.