DEVICE, SYSTEM AND METHOD FOR EXTRACTING PHYSIOLOGICAL INFORMATION

• US 20160120482A1
• Filed: 08/20/2015
• Published: 05/05/2016
• Est. Priority Date: 10/30/2014
• Status: Active Grant

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips N.V.
• Inventors: KIRENKO, Ihor Olehovych, BRESCH, Erik, ROCQUE, Mukul Julius
• Granted Patent: US 9,770,213 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 5/0077 Devices for viewing the surface of the body, e.g. camera, magnifying lens
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/02427 Details of sensor
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence

Abstract

The present invention relates to a device, system and a method for extracting physiological information indicative of at least one vital sign of a subject from detected electromagnetic radiation reflected from the subject. The device comprises an input interface for receiving a data stream of detection data derived from detected electromagnetic radiation reflected from a skin region of a subject, wherein the detected electromagnetic radiation is detected by a polarized radiation detector, while the polarization angle of the polarized radiation detector is changed, a PPG extraction unit for extracting a photoplethysmographic, PPG, signal from said detection data, a signal quality determination unit for determining quality metrics from said PPG signal for different settings of the polarization angle of the polarized radiation detector, a selection unit for selecting the optimum quality metric value from the determined quality metrics and for generating polarization control information for use by said polarized radiation detector for setting the polarization angle to an angle value, at which said optimum quality metric value was obtained, for subsequent detection of radiation, and a processor for deriving physiological information indicative of at least one vital sign from the PPG signal.

Claims

1. A device for extracting physiological information indicative of at least one vital sign of a subject from detected electromagnetic radiation reflected from the subject, said device comprising:

an input interface for receiving a data stream of detection data derived from detected electromagnetic radiation reflected from a skin region of a subject, wherein the detected electromagnetic radiation is detected by a polarized radiation detector while the polarization angle of the polarized radiation detector is changed,

a PPG extraction unit for extracting a photoplethysmographic, PPG, signal from said detection data,

a signal quality determination unit for determining quality metrics from said PPG signal for different settings of the polarization angle of the polarized radiation detector,

a selection unit for selecting the optimum quality metric value from the determined quality metrics and for generating polarization control information for use by said polarized radiation detector for setting the polarization angle to an angle value, at which said optimum quality metric value was obtained, for subsequent detection of radiation, and

a processor for deriving physiological information indicative of at least one vital sign from the PPG signal.

2. The device as claimed in claim 1,

wherein said PPG extraction unit is configured to extract two or more PPG signals from detection data derived from detected electromagnetic radiation reflected from two or more different skin regions of the subject,

wherein said signal quality determination unit is configured to determine quality metrics from each of said two or more PPG signals, and

wherein said selection unit is configured to separately select the optimum quality metric value from the calculated quality metrics for each of said two or more PPG signals and to generate a polarization control information for use by said polarized radiation detector for setting the polarization angle to angle values, at which said optimum quality metric value was obtained for the respective PPG signal, for subsequent detection of radiation from the respective skin region.

3. The device as claimed in claim 1,

wherein said PPG extraction unit, said signal quality determination unit and said selection unit are configured to regularly, continuously or from time to time perform their functions to regularly, continuously or from time to time adjust the polarization angle setting.

4. The device as claimed in claim 1,

wherein said PPG extraction unit is configured to extract two or more PPG signals from different frequency components of said detection data,

wherein said signal quality determination unit is configured to determine quality metrics from each of said two or more PPG signals, and

wherein said selection unit is configured to separately select the optimum quality metric value from the calculated quality metrics for each of said two or more PPG signals and to generate a polarization control information for use by said polarized radiation detector for setting the polarization angle to angle values, at which said optimum quality metric value was obtained for the respective PPG signal, for subsequent detection of radiation in the respective frequency range.

5. The device as claimed in claim 1,

wherein said signal quality determination unit is configured to determine pulsatility, signal-to-noise ratio and/or shape information as quality metrics from said PPG signal for different settings of the polarization angle of the polarized radiation detector.

6. The device as claimed in claim 1,

wherein said signal quality determination unit is configured to determine pulsatility as quality metrics from said PPG signal for different settings of the polarization angle of the polarized radiation detector and wherein said selection unit is configured to select the maximum pulsatility value from the determined pulsatility values and for generating a polarization control information for use by said polarized radiation detector for setting the polarization angle to an angle value, at which said maximum pulsatility value was obtained, for subsequent detection of radiation.

7. The device as claimed in claim 1,

wherein said input interface is configured to receive a polarization angle information indicating the setting of the polarization angle of the polarized radiation detector during the detection of the electromagnetic radiation or wherein said signal quality determination unit is configured to determine the polarization angle information from the detected electromagnetic radiation.

8. A system for extracting physiological information indicative of at least one vital sign of a subject from detected electromagnetic radiation reflected from the subject, said system comprising:

a device as claimed in claim 1 and

a polarized radiation detector for detecting electromagnetic radiation reflected from a skin region of a subject and for deriving detection data from the detected electromagnetic radiation, wherein said polarized radiation detector is configured to change the polarization angle during the detection of the electromagnetic radiation either to different angle values to find the optimum angle value or to an optimum angle value in response to polarization control information received from said device.

9. The system as claimed in claim 8,

wherein said detector comprises a mechanically or electrically controllable polarizer, whose polarization angle can be mechanically or electrically changed.

10. The system as claimed in claim 8,

wherein said detector comprises a rotatable polarizer, whose polarization angle can be changed by rotation of the polarizer, arranged in front of the detector input, at which the electromagnetic radiation is received.

11. The system as claimed in claim 8,

wherein said detector comprises an optical structure, whose polarization angle can be electrically controlled, arranged in front of the detector input, at which the electromagnetic radiation is received.

12. The system as claimed in claim 8,

further comprising a non-polarized radiation detector for detecting electromagnetic radiation reflected from the same skin region of the subject as the polarized radiation detector and for deriving additional detection data from the detected electromagnetic radiation,

wherein said device is configured to use said additional detection data as reference data used for selecting the optimum quality metric value from the determined quality metrics and for generating said polarization control information.

13. The system as claimed in claim 12,

wherein said non-polarized radiation detector comprises a plethysmography sensor configured for being mounted to a skin portion of the subject for acquiring photo-plethysmography signals and/or an imaging unit for acquiring a sequence of image frames of the subject over time, from which photo-plethysmography signals for use as reference data can be derived.

14. A method for extracting physiological information indicative of at least one vital sign of a subject from detected electromagnetic radiation reflected from the subject, said method comprising:

receiving a data stream of detection data derived from detected electromagnetic radiation reflected from a skin region of a subject, wherein the detected electromagnetic radiation is detected by a polarized radiation detector while the polarization angle of the polarized radiation detector is changed,

extracting a photoplethysmographic, PPG, signal from said detection data,

determining quality metrics from said PPG signal for different settings of the polarization angle of the polarized radiation detector,

selecting the optimum quality metric value from the calculated quality metrics,

generating polarization control information for use by said polarized radiation detector for setting the polarization angle to an angle value, at which said optimum quality metric value was obtained, for subsequent detection of radiation, and

deriving physiological information indicative of at least one vital sign from the PPG signal.

15. 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 the computer.