METHOD AND SYSTEM FOR CARRYING OUT PHOTOPLETHYSMOGRAPHY

• US 20120197137A1
• Filed: 10/04/2010
• Published: 08/02/2012
• Est. Priority Date: 10/06/2009
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Jeanne, Vincent, Cennini, Giovanni, Kirenko, Ihor Olehovych
• Granted Patent: US 10,271,746 B2
• Time in Patent Office: Days
• US Class Current: 600/479
• CPC Class Codes: A61B 5/02028 Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/7214 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

Abstract

A method of photoplethysmography includes processing a signal (46;56) based on at least one signal (35;50) from at least one sensor (5;18-20;26;63) arranged to capture light from a living subject to extract information on a characteristic of a periodic biological phenomenon. At least one of the signals (35;50) from at least one sensor (5;18-20;26;63) is obtained by using at least one of a light sensor (1;11-13) and a filter (6;17;64) placed before the at least one sensor (5;18-20;26;63) tuned to a peak in an absorption spectrum of water.

Claims

1. Method of photoplethysmography, including:

processing a signal (46;

56) based on at least one signal (35;

50) from at least one sensor (5;

18-20;

26;

63) arranged to capture light from a living subject to extract information on a characteristic of a periodic biological phenomenon,

wherein at least one of the signals (35;

50) from at least one sensor (5;

18-20;

26;

63) is obtained by using at least one of a light source (1;

11-13) and a filter (6;

17;

64) placed before the at least one sensor (5;

18,19,20;

26;

63) tuned to a peak in an absorption spectrum of water.

2. Method according to claim 1, wherein the peak is in a range corresponding to a range of wavelengths of electromagnetic radiation in air of above 750 nm.

3. Method according to claim 2, wherein the peak is in a range corresponding to a range of wavelengths smaller than 1100 nm.

4. Method according to claim 1, including directing polarized light onto the living subject and capturing light from the living subject through a polarization dependent filter (6;

17).

5. Method according to claim 1, wherein the signal obtained by using at least one of a light source and a filter placed before the at least one sensor tuned to a peak in the absorption spectrum of water is obtained from a first sensor (63) and a second signal is obtained from a second sensor (67), arranged to capture light from the living subject in a different wavelength range than the first sensor (63).

6. Method according to claim 5, including using a beam splitting arrangement (62) to split light from the living subject into a beam directed onto the first sensor (63) and a beam directed onto the second sensor (67).

7. Method according to claim 5, including subtracting a signal at least based on only the second of the first and second signals from a signal at least based on only the first of the first and second signals.

8. Method according to claim 5, including, prior to using the sensors (63,67) to capture light from the living subject, using the sensors (63,67) to capture light from a calibration surface and adjusting parameters affecting at least one of the capture of light and a provision of signals at least based on the signals from the sensors (63,67), so as to adjust at least one of amplitude and phase of the respective signals at least based on the signals from the first and second sensors (63,67) to each other.

9. System for carrying out photoplethysmography, including:

at least one sensor (5;

18-20;

26;

63) for capturing light from a living subject;

a signal processing system (7;

21;

25;

67) arranged to process a signal (46;

56) based on at least one signal (35;

50) from the at least one sensor (5;

18-20;

26;

63) to extract information on a characteristic of a periodic biological phenomenon; and

at least one of a light source (1;

11-13) and a filter (6;

17;

64) placed before at least one of the sensors (5;

18-20;

26;

63) tuned to a peak in an absorption spectrum of water.

10. (canceled)