SYSTEMS AND METHODS FOR NON-PULSATILE BLOOD VOLUME MEASUREMENTS

• US 20170325698A1
• Filed: 05/10/2017
• Published: 11/16/2017
• Est. Priority Date: 05/10/2016
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: ALLEC, Nicholas Paul Joseph, PETERSON, Rui, BLOCK, Ueyn L., VENUGOPAL, Vivek
• Granted Patent: US 10,687,718 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 2562/0238 Optical sensor arrangements for performing transmission measurements on body tissue
• CPC Class Codes: A61B 2562/046 in a matrix array
• CPC Class Codes: A61B 2562/146 for optical coupling
• CPC Class Codes: A61B 2562/185 Optical shielding, e.g. baffles
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/02427 Details of sensor
• CPC Class Codes: A61B 5/02433 for infrared radiation
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/0295 using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
• CPC Class Codes: A61B 5/11 Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb for measuring pulse A61B5/02 ;A61B5/1038 takes precedence; motion detection to correct for motion artifacts in physiological signals A61B5/721
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61B 5/6843 Monitoring or controlling sensor contact pressure
• CPC Class Codes: A61B 5/6898 Portable consumer electronic devices, e.g. music players, telephones, tablet computers
• CPC Class Codes: A61B 5/721 using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured
• 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
• CPC Class Codes: A61B 5/7264 Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00

Abstract

This relates to systems and methods for determining one or more of a user'"'"'s physiological signals. The one or more of the user'"'"'s physiological signals can be determined by measuring pulsatile blood volume changes. Motion artifacts included in the signals can be canceled or reduced by measuring non-pulsatile blood volume changes and adjusting the signal to account for the non-pulsatile blood information. Non-pulsatile blood volume changes can be measured using at least one set of light emitter-light sensor. The light emitter can be located in close proximity (e.g., less than or equal to 1 mm away) to the light sensor, thereby limiting light emitted by the light emitter to blood volume without interacting with one or more blood vessels and/or arterioles. In some examples, the systems can further include an accelerometer configured to measure the user'"'"'s acceleration, and the acceleration signal can be additionally be used for compensating for motion artifacts.

Claims

1. An electronic device comprising:

one or more first light emitters configured to generate a first light;

one or more first light sensors configured to detect a reflection of the first light and configured to generate a first signal indicative of the reflection of the first light, the first signal including non-pulsatile blood information; and

logic coupled to the one or more first light sensors, the logic configured to;

receive the first signal, and

determine at least a portion of a physiological signal from the first signal.

2. The electronic device of claim 1, further comprising:

one or more second light sensors configured to detect a reflection of a second light and configured to generate a second signal indicative of the reflection of the second light, the second light generated by the one or more first light emitters and the second signal including pulsatile blood information,

wherein the logic is further coupled to the one or more second light sensors, and

further configured to receive the second signal and include the second signal in the determination of the physiological signal.

3. The electronic device of claim 2, wherein the one or more first light emitters, one or more first light sensors, and one or more second light sensors are located along a common optical axis.

4. The electronic device of claim 1, further comprising:

one or more second light emitters configured to generate a second light, wherein the one or more first light sensors are further configured to generate a second signal indicative of the reflection of the second light, the second signal including pulsatile blood information,

wherein the logic is further configured to receive the second signal and include the second signal in the determination of the physiological signal.

5. The electronic device of claim 1, further comprising:

one or more second light emitters configured to generate a second light; and

one or more second light sensors configured to detect a reflection of the second light and configured to generate a second signal indicative of the reflection of the second light, the second signal including pulsatile blood information,

wherein logic is further coupled to the one or more second light sensors and is further configured to receive the second signal and include the second signal in the determination of the physiological signal.

6. The electronic device of claim 5, wherein the one or more second light emitters and the one or more second light sensors are located in different cavities.

7. The electronic device of claim 5, further comprising:

one or more third light emitters configured to generate a third light, wherein the one or more second light sensors are further configured to detect a reflection of the third light and configured to generate a third signal indicative of the reflection of the third light, the third signal including pulsatile blood information,

wherein logic is further configured to receive the third signal and include the third signal in the determination of the physiological signal.

8. The electronic device of claim 5, wherein the first light includes light with a wavelength between 570-750 nm, the second light includes light with a wavelength between 495-570 nm, and the third light includes light with a wavelength between 750-1400 nm.

9. The electronic device of claim 1, wherein at least one of the one or more first light emitters is spaced less than 1 mm from at least one of the one or more first light sensors.

10. The electronic device of claim 1, further comprising:

an isolation configured to optically isolate at least one of the one or more first light emitters from at least one of the one or more first light sensors.

11. The electronic device of claim 10, further comprising:

a window optically coupled to at least one of the one or more first light emitters, wherein an end of the isolation contacts an inner surface of the window, the inner surface located closer to the one or more first light emitters than an outer surface of the window.

12. The electronic device of claim 10, further comprising:

a window optically coupled to at least one of the one or more first light emitters, wherein a first end of the isolation contacts an outer surface of the window, the outer surface located further from the one or more first light emitters than an inner surface of the window.

13. The electronic device of claim 12, wherein the isolation includes a continuous section disposed between the first end and a second end, the second end located proximate to the at least one of the one or more first light emitters.

14. The electronic device of claim 12, wherein the isolation comprises:

a first section disposed between the first end and a third end, the third end located at the inner surface of the window, and

a second section disposed between the third end and a second end, the second end located proximate to the at least one of the one or more first light emitters.

15. The electronic device of claim 10, further comprising:

a second isolation, wherein a first end of the isolation is laterally spaced a first distance away from the second isolation and a second end of the isolation is laterally spaced a second distance, different from the first distance, away from the second isolation.

16. A method for determining a physiological signal, the method comprising:

emitting a first light at a user;

detecting a reflection of the first light;

generating a first signal indicative of the detected reflection of the first light, the first signal including non-pulsatile blood information;

emitting a second light at the user;

detecting a reflection of the second light;

generating a second signal indicative of the detected reflection of the second light, the second signal including pulsatile blood information;

adjusting the second signal to compensate for information included in the first signal; and

determining the physiological signal based on the adjusted second signal.

17. The method of claim 16, wherein the first light is emitted at a first portion of the user and the second light is emitted at a second portion, different from the first portion, of the user.

18. The method of claim 16, further comprising:

determining one or more peaks included in the first and second signals; and

determining one or more locations of the one or more peaks, wherein adjusting the second signal includes scaling the second signal at the one or more locations.

19. The method of claim 16, further comprising:

detecting an acceleration of the user; and

generating a third signal indicative of the acceleration,

wherein adjusting the second signal further includes information included in the third signal.

20. The method of claim 16, further comprising:

detecting an acceleration of the user;

generating a third signal indicative of the acceleration;

comparing the third signal to a threshold value, wherein the second light is emitted at the user when the third signal is greater than or equal to the threshold value.