Optical vital signs sensor

• US 10,034,639 B2
• Filed: 10/19/2016
• Issued: 07/31/2018
• Est. Priority Date: 01/16/2015
• Status: Active Grant

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips N.V.
• Inventors: van Dinther, Cornelus Hendricus Bertus Arnoldus, Roovers, David Antoine Christian Marie
• Primary Examiner(s): CHAO, ELMER M
• Application Number:
  US15/297,861
• Publication Number:
  US 20170035362A1
• Time in Patent Office: 650 Days
• CPC Class Codes: A61B 2560/0209 adapted for power saving
• CPC Class Codes: A61B 2562/0238 Optical sensor arrangements for performing transmission measurements on body tissue
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/02433 for infrared radiation
• 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 5/1116 Determining posture transitions
• CPC Class Codes: A61B 5/1118 Determining activity level
• 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

Abstract

An optical vital signs sensor is provided which comprises at least one light source with a primary and a secondary light unit and a photo detector, a motion sensor configured to detect a motion of a user, a periodicity metric unit to analyze an output signal of the at least one motion sensor to detect a periodicity in its output signal and a control unit configured to control an operation of the at least one primary and secondary light unit and to activate the at least one secondary light unit in addition to the at least one primary light unit when the periodicity metric unit does not detect a periodicity in the output signal of the motion sensor.

Claims

1. An optical vital signs sensor, comprising:

at least one light source having at least one primary and at least one secondary light unit each being configured to generate light, which is directed towards a skin of a user, said primary light unit being activated when the optical vital signs sensor is switched on, wherein the primary light unit emits light of a first color and the secondary light unit emits light of a second color different from the first color,

at least one photo detector unit having at least one photo diode configured to detect light which is indicative of a transmission or reflection of the light from the at least one primary and at least one secondary light unit in or from the skin of the user, wherein the at least one photodetector unit produces a detected light signal,

at least one motion sensor configured to detect a motion of the optical vital signs sensor,

a periodicity metric unit configured to analyze an output signal of the at least one motion sensor to determine whether or not the motion of the optical vital signs sensor is periodic,

a switching unit configured to control an operation of the at least one primary and secondary light unit, wherein the switching unit is configured to;

activate the at least one secondary light unit in addition to the at least one primary light unit when the periodicity metric unit determines that the motion is not periodic,

deactivate the at least one secondary light unit when the periodicity metric unit determines that the motion is periodic,

wherein the at least one primary light operates regardless of whether or not the motion is periodic, and

a motion artifact removal unit configured to remove motion artifacts from the detected light signal of the photo detector unit based on;

the output signal of the at least one motion sensor when the motion is determined to be periodic, and

the detected light signal including detected light of the second color from the at least one secondary light unit when the at least one secondary light unit is activated.

2. Optical vital signs sensor according to claim 1, wherein the at least one primary light unit emits green light and/or the at least one secondary light unit emits red, yellow or infrared light.

3. An optical vital signs sensor according to claim 1, wherein the switching unit is configured to deactivate the at least one secondary light unit with a predetettnined delay, if the periodicity metric unit has detettnined that the motion is periodic.

4. An optical vital signs sensor according to claim 1, wherein the periodicity metric unit is configured to detect a resting of a user of the optical vital signs sensor based on the output signal of the photo detector unit, wherein the switching unit is configured to deactivate the at least one secondary light unit if a resting of the user is determined.

5. An optical vital signs sensor according to claim 4, further comprising

a motion artifact removal unit which is configured to remove motion artifacts from the output signal of the photo detector unit, and

the switching unit is configured to deactivate the motion artifact removal unit if the periodicity metric unit has determined that a person is at rest.

6. Method of operating an optical vital signs sensor having at least one light source having at least one primary and at least one secondary light unit, at least one photo detector unit having at least one photo diode and a motion sensor, comprising the steps of:

activating a primary light unit to direct its light towards a skin of a user, when the optical vital signs sensor is switched on, wherein the primary light unit emits light of a first color and the secondary light unit emits light of a second color different from the first color,

detecting a light which is indicative of a transmission or reflection of the light from the at least one primary and/or at least one secondary light unit in or from the skin of the user,

detecting a motion of the optical vital signs sensor by a motion sensor,

analyzing an output signal of the at least one motion sensor to determine whether or not the motion of the optical vital signs sensor is periodic,

controlling an operation of the at least one primary light unit regardless of whether the motion is periodic,

activating the at least one secondary light unit in addition to the at least one primary light unit when the motion is determined to not be periodic;

deactivating the at least one secondary light unit when the motion is determined to be periodic; and

removing motion artifacts from the output signal based on the output signal of the motion sensor when the motion is determined to be periodic, and based on the detected light including detected light of the second color from the at secondary light unit when the at least one secondary light unit is activated.

7. The method according to claim 6, wherein the at least one primary light unit emits green light and/or the at least one secondary light unit emits red, yellow or infrared light.

8. The method according to claim 6, wherein the activating comprises deactivating the at least one secondary light unit with a predetermined delay, if motion is periodic.

9. The method according to claim 6, further comprising:

detecting a resting of a user of based on the detected light; and

deactivating the at least one secondary light unit if a resting of the user is determined.

10. The method according to claim 9, further comprising:

removing motion artifacts from the output signal of the photo detector unit, and

wherein the removing is omitted if the person is determined to be at rest.

11. A non-transitory machine-readable storage medium comprising instructions for execution by a processor, the medium comprising:

instructions for activating a primary light unit to direct its light towards a skin of a user, when the optical vital signs sensor is switched on, wherein the primary light unit emits light of a first color and a secondary light unit emits light of a second color different from the first color,

instructions for detecting a light which is indicative of a transmission or reflection of the light from the at least one primary and/or at least one secondary light unit in or from the skin of the user,

instructions for detecting a motion of the optical vital signs sensor by a motion sensor,

instructions for analyzing an output signal of the at least one motion sensor to determine whether or not the motion of the user is periodic,

instructions for controlling an operation of the at least one primary light unit regardless of whether the motion is periodic,

instructions for activating the at least one secondary light unit in addition to the at least one primary light unit when the motion is determined to not be periodic;

instructions for deactivating the at least one secondary light unit when the motion is determined to be periodic; and

instructions for removing motion artifacts from the output signal based on the output signal of the motion sensor when the motion is determined to be periodic, and based on the detected light including detected light of the second color from the at secondary light unit when the at least one secondary light unit is activated.

12. The non-transitory machine-readable storage medium according to claim 11, wherein the at least one primary light unit emits green light and/or the at least one secondary light unit emits red, yellow or infrared light.

13. The non-transitory machine-readable storage medium according to claim 11, wherein the instructions for activating comprise instructions for deactivating the at least one secondary light unit with a predetermined delay, if motion is periodic.

14. The non-transitory machine-readable storage medium according to claim 11, further comprising:

instructions for detecting a resting of a user of based on the detected light; and

instructions for deactivating the at least one secondary light unit if a resting of the user is determined.

15. The non-transitory machine-readable storage medium according to claim 14, further comprising:

instructions for removing motion artifacts from the output signal of the photo detector unit, and

wherein the instructions for removing are configured to not be executed if the person is determined to be at rest.