Methods and apparatus for physiological measurement using color band photoplethysmographic sensor

Patent metadata

Field	Value
Publication number	US-10028669-B2
Application number	US-201514677869-A
Country	US
Kind code	B2
Filing date	Apr 2, 2015
Priority date	Apr 2, 2014
Publication date	Jul 24, 2018
Grant date	Jul 24, 2018

Abstract

In illustrative implementations of this invention, a photoplethysmographic device measures variations of light that is reflected from, or transmitted through, human skin. In some implementations, the device includes a camera that takes the measurements remotely. In others, the device touches the skin during the measurements. The device includes a camera or other light sensor, which includes at least orange, green and cyan color channels. In some cases, such as a contact device, the device includes three or more colors of active light sources, including at least orange, green and cyan light sources. A computer analyzes the sensor data, in order to estimate a cardiac blood volume pulse wave. For each cardiac pulse, a computer detects the systolic peak and diastolic inflection of the wave, by calculating a second derivative of the wave. From the estimated wave, a computer estimates heart rate, heart rate variability and respiration rate.

First claim

What is claimed is:

1. Apparatus comprising a photoplethysmograph, which photoplethysmograph includes at least five color channels, which color channels include an orange color channel, a green color channel and a cyan color channel.

2. The apparatus of claim 1 , wherein the color channels further include a red color channel and a blue color channel.

3. The apparatus of claim 1 , wherein each of the color channels comprises a set of pixels in a video camera.

4. The apparatus of claim 1 , wherein the photoplethysmograph is housed in a housing, which housing is configured to touch tissue while a camera in the photoplethysmograph captures light that reflects from, or is transmitted through, the tissue.

5. The apparatus of claim 4 , wherein the photoplethysmograph includes at least three light sources, including an orange light source, a green light source, and a cyan light source.

6. The apparatus of claim 1 , wherein the photoplethysmograph includes at least three light sources, including an orange light source, a green light source, and a cyan light source.

7. A method comprising, in combination:
(a) taking measurements of light that reflects from, or is transmitted through, tissue of a mammal; and
(b) taking, as input, data indicative of the measurements, and estimating a blood pulse volume wave; wherein the measurements are taken by at least five color channels of a light sensor, which color channels include an orange color channel, a green color channel and a cyan color channel.

8. The method of claim 7 , wherein the measurements are taken by at least five color channels of the light sensor, which at least five color channels include at least an orange color channel, a green color channel, a cyan color channel, a red color channel and a blue color channel.

9. The method of claim 7 , further comprising estimating a time interval between a systolic peak and a diastolic inflection, which peak and inflection occur during a single heartbeat of the blood pulse volume wave.

10. The method of claim 9 , further comprising calculating a second derivative of the blood pulse volume wave.

11. The method of claim 7 , wherein the light sensor comprises a digital video camera.

12. The method of claim 11 , wherein the camera is positioned more than a meter from the tissue while the measurements are taken.

13. The method of claim 7 , wherein the light sensor is housed in a housing, which housing does not touch the tissue while the measurements are taken.

14. The method of claim 7 , further comprising calculating a heart rate of the mammal.

15. Apparatus comprising, in combination:
(a) a set of light sensors for taking measurements of light that reflects from, or is transmitted through, tissue of a mammal; and
(b) one or more computer that are programmed to take, as input, data indicative of the measurements, and to estimate a blood pulse volume wave; wherein the light sensors include at least five color channels, which color channels include an orange color channel, a green color channel and a cyan color channel.

16. The apparatus of claim 15 , wherein the light sensors comprise pixels in a digital video camera.

17. The apparatus of claim 15 , wherein the color channels further include a red color channel and a blue color channel.

18. The apparatus of claim 15 , wherein the light sensors are housed in a housing, which housing is configured to touch tissue while the light sensors capture light that reflects from, or is transmitted through, the tissue.

19. The apparatus of claim 18 , wherein the housing also houses at least three light sources, including an orange light source, a green light source, and a cyan light source.

Assignees

• Mcduff Daniel
• Picard Rosalind
• Gontarek Sarah
• Massachusetts Inst Technology

Inventors

• Mcduff Daniel
• Picard Rosalind
• Gontarek Sarah

Classifications

• G16H30/40

  for processing medical images, e.g. editing · CPC title

• A61B5/0077

  Devices for viewing the surface of the body, e.g. camera, magnifying lens · CPC title

• A61B5/02427 Primary

  Details of sensor · CPC title

• A61B5/02405

  Determining heart rate variability · CPC title

• A61B5/7203

  for noise prevention, reduction or removal · CPC title