IP Library › Granted Patent US 12667307

Granted Patent B2

US 12667307 · App. 18/317,435 · Granted Jun 30, 2026

Hydration measurement using optical sensors

Inventors: Ammar Al-Ali (San Juan Capistrano, CA); Walter M. Weber (Laguna Hills, CA); Sean Devlin (Irvine, CA)

Assignee: Masimo Corporation

A61B5/4875 A61B5/6802 A61B5/7435 A61B2562/0238

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Quick Facts

Patent No.: US 12667307
App. No.: 18/317,435
Granted: Jun 30, 2026
Kind: B2

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Abstract

The present disclosure provides a physiological monitoring system that can include a hardware processor. The hardware processor can access first optical data corresponding to a water-dependent radiation wavelength attenuated through a medium and detected at a detector. The hardware processor can access second optical data corresponding to a water-independent radiation wavelength attenuated through the medium and detected at the detector. The hardware processor can determine a hydration index of the medium based on the first and second optical data.

Claims (66)

1 . A physiological monitoring system for non-invasively monitoring a subject's hydration, the physiological monitoring system comprising:

a wearable device configured to secure to a subject, the wearable device comprising:

one or more optical emitters configured to emit optical radiation toward a tissue of the subject, wherein the optical radiation includes a water-dependent wavelength and a water-independent wavelength, wherein the water-dependent wavelength is between 900 nm and 1400 nm, wherein the water-independent wavelength is between 600 nm and 700 nm; and

one or more optical detectors configured to:

detect the optical radiation emitted by the one or more optical emitters after attenuation through the tissue of the subject; and

generate optical data in response to detecting the optical radiation; and

one or more hardware computer processors configured to:

access the optical data;

determine a water-dependent optical parameter based on the optical data corresponding to the water-dependent wavelength;

determine a water-independent optical parameter based on the optical data corresponding to the water-independent wavelength;

determine a hydration index of the subject based on normalizing the water-dependent optical parameter with the water-independent optical parameter; and

generate user interface data for rendering an indication of the hydration index on a display.

2 . The physiological monitoring system of claim 1 , wherein normalizing the water-dependent optical parameter with the water-independent optical parameter includes dividing the water-dependent optical parameter by the water-independent optical parameter.

3 . The physiological monitoring system of claim 1 , wherein normalizing the water-dependent optical parameter with the water-independent optical parameter includes subtracting the water-independent optical parameter from the water-dependent optical parameter.

4 . The physiological monitoring system of claim 1 , wherein the water-dependent optical parameter corresponds to an optical intensity of the water-dependent wavelength of the optical radiation detected by the one or more optical detectors, and wherein the water-independent optical parameter corresponds to an optical intensity of the water-independent wavelength of the optical radiation detected by the one or more optical detectors.

5 . The physiological monitoring system of claim 1 , wherein the water-dependent optical parameter corresponds to an absorption of the water-dependent wavelength of the optical radiation by the tissue, and wherein the water-independent optical parameter corresponds to an absorption of the water-independent wavelength of the optical radiation by the tissue.

6 . The physiological monitoring system of claim 1 , wherein the water-dependent wavelength of the optical radiation is sensitive to absorption by water, and wherein absorption of the water-independent wavelength of the optical radiation is substantially unaffected by water.

7 . The physiological monitoring system of claim 1 , wherein the one or more hardware computer processors is further configured to:

access reference optical data corresponding to other radiation attenuated through a reference medium, wherein the other radiation includes the water-dependent wavelength and water-independent wavelength;

determine the water-dependent optical parameter based on normalizing the optical data corresponding to the water-dependent wavelength with the reference optical data corresponding to the water-dependent wavelength; and

determine the water-independent optical parameter based on normalizing the optical data corresponding to the water-independent wavelength with the reference optical data corresponding to the water-independent wavelength.

8 . The physiological monitoring system of claim 7 , wherein the optical data corresponds to an optical density of the tissue, and wherein the reference optical data corresponds to an optical density of the reference medium.

9 . The physiological monitoring system of claim 1 , wherein the one or more hardware computer processors is further configured to:

determine a second water-dependent optical parameter based on a second water-dependent wavelength of the optical radiation;

determine a second water-independent optical parameter based on a second water-independent wavelength of the optical radiation; and

determine the hydration index based on normalizing a difference between the water-dependent optical parameter and the second water-dependent optical parameter with a difference between the water-independent optical parameter and the second water-independent optical parameter.

10 . The physiological monitoring system of claim 9 , wherein the second water-dependent wavelength of the optical radiation is between 900 nm and 1000 nm.

11 . The physiological monitoring system of claim 9 , wherein the second water-independent wavelength of the optical radiation is between 600 nm and 700 nm.

12 . The physiological monitoring system of claim 9 , wherein the water-dependent optical parameter corresponds to an estimated area integrated under an absorption curve between the water-dependent wavelength and the second water-dependent wavelength.

13 . The physiological monitoring system of claim 9 , wherein the water-independent optical parameter corresponds to an estimated area integrated under an absorption curve between the water-independent wavelength and the second water-independent wavelength.

14 . The physiological monitoring system of claim 1 , wherein the one or more hardware computer processors is further configured to:

access reference optical data corresponding to other radiation attenuated through a reference medium, wherein the other radiation includes the water-dependent wavelength, a second water-dependent wavelength, the water-independent wavelength, and a second water-independent wavelength, wherein the optical radiation includes the second water-dependent wavelength and the second water-independent wavelength;

determine a second water-dependent optical parameter based on normalizing the optical data corresponding to the second water-dependent wavelength with the reference optical data corresponding to the second water-dependent wavelength;

determine a second water-independent optical parameter based on normalizing the optical data corresponding to the second water-independent wavelength with the reference optical data corresponding to the second water-independent wavelength; and

determine the hydration index of the tissue based on normalizing a difference between the water-dependent optical parameter and the second water-dependent optical parameter with a difference between the water-independent optical parameter and the second water-independent optical parameter.

15 . The physiological monitoring system of claim 14 , wherein the water-dependent wavelength of the optical radiation is 970 nm, wherein the second water-dependent wavelength of the optical radiation is 905 nm, wherein the water-independent wavelength of the optical radiation is 620 nm, and wherein the second water-independent wavelength of the optical radiation is 660 nm.

16 . A method of non-invasively monitoring a subject's hydration, the method comprising:

emitting, by one or more optical emitters, optical radiation toward a tissue of a subject, wherein the optical radiation includes a water-dependent wavelength and a water-independent wavelength, wherein the water-dependent wavelength is between 900 nm and 1400 nm, wherein the water-independent wavelength is between 600 nm and 700 nm;

detecting, by one or more optical detectors, the optical radiation emitted after attenuation through the tissue of the subject;

generating optical data in response to detecting the optical radiation;

determining a water-dependent optical parameter based on the optical data corresponding to the water-dependent wavelength;

determining a water-independent optical parameter based on the optical data corresponding to the water-independent wavelength;

determining a hydration index of the subject based on normalizing the water-dependent optical parameter with the water-independent optical parameter;

generating user interface data for rendering an indication of the hydration index on a display; and

displaying, via the display, the indication of the hydration index.

17 . The method of claim 16 further comprising:

determining a second water-dependent optical parameter based on a second water-dependent wavelength of the optical radiation;

determining a second water-independent optical parameter based on a second water-independent wavelength of the optical radiation; and

determining the hydration index based on normalizing a difference between the water-dependent optical parameter and the second water-dependent optical parameter with a difference between the water-independent optical parameter and the second water-independent optical parameter.

18 . The method of claim 17 , wherein the second water-dependent wavelength of the optical radiation is between 900 nm and 1000 nm.

19 . Non-transitory computer-readable media including computer-executable instructions that, when executed by a computing system, cause the computing system to perform operations comprising: