System and methods for physiological monitoring

• US 9,649,055 B2
• Filed: 03/30/2012
• Issued: 05/16/2017
• Est. Priority Date: 03/30/2012
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Todorovic, Milos, Ashe, Jeffrey Michael, Yazdanfar, Siavash, Yakimov, Aharon
• Primary Examiner(s): Winakur, Eric
• Assistant Examiner(s): Liu, Chu Chuan (JJ)
• Application Number:
  US13/435,966
• Publication Number:
  US 20130261415A1
• Time in Patent Office: 1,873 Days
• Field of Search: 600310-344, 600473, 600476, 356 41
• CPC Class Codes: A61B 5/02427 Details of sensor
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence
• CPC Class Codes: A61B 5/08 Detecting, measuring or recording devices for evaluating the respiratory organs A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor

Abstract

Embodiments of devices, methods, and non-transitory computer readable media for monitoring a subject are presented. The monitoring device includes at least one sensor configured to monitor one or more physiological parameters of a subject and a processing unit operatively coupled to the sensor. The sensor comprises a plurality of radiation sources and detectors disposed on a flexible substrate in a designated physical arrangement. The processing unit is configured to dynamically configure an operational geometry of the sensor by controlling the intensity of one or more of the radiation sources and the gain of one or more of the detectors so as to satisfy at least one quality metric associated with one or more physiological parameters of the subject.

Claims

1. A monitoring device, comprising:

at least one sensor configured to monitor one or more physiological parameters of a subject, wherein the sensor comprises a plurality of radiation sources and detectors disposed on a flexible substrate in a designated physical arrangement;

a processing unit operatively coupled to the sensor, wherein the processing unit is configured to;

dynamically configure an initial operational geometry of the sensor for an initial wavelength by controlling the intensity of one or more of the radiation sources and the gain of one or more of the detectors until a threshold value of at least one quality metric associated with one or more physiological parameters of the subject is satisfied;

determine a revised configuration of operational geometry of the sensor for each of plural additional wavelengths using Monte Carlo simulations at each of the plural additional wavelengths, wherein the processing unit is configured to perform the Monte Carlo simulations to determine resulting signal quality based on placement of the radiation sources and detectors for plural configurations and to select the revised configuration based on the determined resulting signal quality; and

obtain measurements of the one or more physiological parameters at each of the plural additional wavelengths using the corresponding revised configuration for each of the plural additional wavelengths, without physically moving the sensor to a different measurement position.

2. The monitoring device of claim 1, wherein the operational geometry of the sensor comprises a subset of one or more radiation sources and detectors selected from the plurality of radiation sources and detectors disposed on the flexible substrate, which when operational, provide desired location and intensity characteristics, and wherein at least one of the revised configurations uses a subset that is symmetric with a subset used for the initial operational geometry.

3. The monitoring device of claim 1 being a multi-wavelength photoplethysmograph device.

4. The monitoring device of claim 1 being a multi-source multi-detector arrayed photoplethysmograph device.

5. The monitoring device of claim 1, wherein the plurality of radiation sources and detectors are disposed on the flexible substrate using a roll-to-roll assembly technique.

6. The monitoring device of claim 1, wherein the substrate is a flexible polyimide substrate.

7. The monitoring device of claim 1, wherein the sensor comprises a pixelated optical transducer comprising the plurality of radiation sources and detectors arranged in an array on the flexible substrate.

8. The monitoring device of claim 1, wherein the radiation sources are disposed on the flexible substrate at a plurality of distances from the detectors to allow different depths of light penetration into a region of interest of the subject.

9. The monitoring device of claim 1, wherein the radiation sources comprise sources configured to generate radiation at a plurality of wavelengths.

10. The monitoring device of claim 9, wherein the radiation sources comprise one or more light emitting diodes, one or more organic light emitting diodes, one or more laser diodes, or combinations thereof.

11. The monitoring device of claim 1, wherein the detectors comprise organic photodetectors.

12. The monitoring device of claim 1, wherein a response curve of the detectors covers a spectrum band of interest.

13. The monitoring device of claim 1, wherein the quality metric comprises signal-to-noise ratio, an amplitude or an alternating current-to-direct current ratio of an output signal measured at a particular wavelength.

14. The monitoring device of claim 1, wherein one or more physiological parameters comprise one or more hemoglobin fractions.

15. The monitoring device of claim 1, wherein one or more physiological parameters comprise one or more of oxygen saturation, blood flow, blood volume, carboxyhemoglobin, methemoglobin, total hemoglobin, heart rate, cardiac output, respiration, or combinations thereof.

16. The monitoring device of claim 1, wherein the processing unit is configured to dynamically configure the operational geometry of the sensor by selectively operating one or more of the radiation sources and one or more of the detectors to improve the optical path between the one or more radiation sources and one or more of the detectors to improve the signal-to-noise ratio of the one or more physiological parameters of the subject.

17. The monitoring device of claim 1, wherein the processing unit is configured to dynamically configure the operational geometry of the sensor by selectively operating one or more of the radiation sources and one or more of the detectors that minimize effects of large blood vessels or static absorbers.

18. The monitoring device of claim 1, wherein the processing unit is configured to dynamically configure the operational geometry of the sensor by selectively operating one or more of the radiation sources and one or more of the detectors that minimize power consumption.

19. The monitoring device of claim 1, wherein the processing unit is configured to dynamically configure the operational geometry of the sensor using a photon transport model.

20. The monitoring device of claim 1, wherein the processing unit comprises a geometry controller configured to selectively operate one or more of the radiation sources and one or more of the detectors, wherein the geometry controller comprises one or more switching subsystems.

21. The monitoring device of claim 1, wherein the processing unit is configured to operate the monitoring device in transmission mode by selectively operating one or more of the radiation sources and one or more of the detectors such that the radiation sources and the detectors are disposed on opposite sides of a region of interest of the subject.

22. The monitoring device of claim 1, wherein the processing unit is configured to operate the monitoring device in reflectance mode by selectively operating one or more of the radiation sources and one or more of the detectors such that the radiation sources and the detectors are disposed on the same side of a region of interest of the subject.

23. The monitoring device of claim 1, wherein the processing unit is configured to operate the monitoring device in a combined mode by selectively operating one or more of the radiation sources and one or more of the detectors such that the radiation sources and the detectors are disposed on at least two sides of a region of interest of the subject to simultaneously measure reflectance and transmission signals.

24. The monitoring device of claim 1, wherein the processing unit is configured to generate an audio output, a visual output, an alert message, or combinations thereof, if the quality metric associated with a physiological parameter is outside a corresponding designated threshold.

25. The monitoring device of claim 24, wherein the processing unit is configured to terminate the audio output, the visual output, the alert message, or combinations

thereof, if the quality metric associated with a physiological parameter is within a corresponding designated threshold.

26. The monitoring device of claim 1, wherein the processing unit is further configured to:

select the one or more other wavelengths that minimize an effect of a wavelength shift in one or more of the radiation sources during multi-analyte measurements corresponding to the one or more physiological parameters;

determine optical path length data corresponding to each of the one or more other selected wavelengths, wherein the determined optical path length data accounts for non-linearity of photon transport through a target tissue of the subject while performing the multi-analyte measurements;

determine the configuration of the operational geometry of the sensor for the one or more other wavelengths based on die determined optical path length data and the baseline operating configuration; and

operate one or more of the radiation sources and detectors as large area devices, distributed devices, or a combination thereof, in the determined configuration, wherein the determined configuration maximizes optical generation and light capture efficiency, while reducing tissue motion artifacts.

27. A method for monitoring a subject, comprising:

selecting an initial set of one or more radiation sources and one or more detectors for an initial wavelength from a plurality of radiation sources and detectors disposed on a flexible substrate in a sensor in a designated physical arrangement;

determining an initial value of one or more physiological parameters of a subject by evaluating a region of interest of the subject using the initial set of radiation sources and detectors and the initial wavelength;

estimating a quality metric associated with the initial value of the physiological parameters; and

dynamically configuring an initial operational geometry of the sensor for the initial wavelength by controlling intensity of one or more of the radiation sources, gain of one or more of the detectors, or a combination thereof, until a threshold value of to satisfy at least one quality metric associated with the one or more physiological parameters of the subject is satisfied;

determining a revised configuration of operational geometry of the sensor for each of plural additional wavelengths that maximizes the quality metric using Monte Carlo simulations at each of the plural additional wavelengths, wherein the processing unit is configured to perform the Monte Carlo simulations to determine resulting signal quality based on placement of the radiation sources and detectors for plural configurations and to select the revised configuration based on the determined resulting signal quality; and

obtaining multiple measurements of the one or more physiological parameters at each of the plural additional wavelengths using the corresponding revised determined configuration for each of the plural additional wavelengths, without physically moving the sensor to a different measurement position.

28. The method of claim 27, wherein dynamically configuring the operational geometry of the sensor comprises:

iteratively selecting the one or more further radiation sources and detectors from the plurality of radiation sources and the one or more detectors;

determining corresponding values of one or more physiological parameters by evaluating the region of interest of the subject using the one or more further radiation sources and detectors for each iteration;

estimating the quality metric associated with the values of the physiological parameters determined using the one or more further radiation sources and detectors; and

adaptively reconfiguring the operational geometry of the sensor until the quality metric associated with the values of the physiological parameters determined in a particular iteration is within a designated threshold.

29. The method of claim 28, further comprising:

continuously monitoring the one or more physiological parameters of the subject using the radiation sources and detectors used in the particular iteration

periodically estimating the quality metric associated with the values of the physiological parameters; and

adaptively configuring the operational geometry of the sensor until the quality metric associated with the values of the physiological parameters is within the designated threshold.

30. A non-transitory computer readable medium that stores instructions executable by one or more processors to perform a method for monitoring a subject, comprising:

selecting an initial set of one or more radiation sources and one or more detectors for an initial wavelength from a plurality of radiation sources and detectors disposed on a flexible substrate in a sensor in a designated physical arrangement;

determining an initial value of one or more physiological parameters of a subject by evaluating a region of interest of the subject using the initial set of radiation sources and detectors and the initial wavelength;

estimating a quality metric associated with the initial value of the physiological parameters; and

dynamically configuring an initial operational geometry of the sensor for the initial wavelength by controlling intensity of one or more of the radiation sources, gain of one or more of the detectors, or a combination thereof, until a threshold value of to satisfy at least one quality metric associated with the one or more physiological parameters of the subject is satisfied;

determining a revised configuration of operational geometry of the sensor for each of plural additional wavelengths that maximizes the quality metric using Monte Carlo simulations at each of the plural additional wavelengths, wherein the processing unit is configured to perform the Monte Carlo simulations to determine resulting signal quality based on placement of the radiation sources and detectors for plural configurations and to select the revised configuration based on the determined resulting signal quality; and

obtaining multiple measurements of the one or more physiological parameters at each of the plural additional wavelengths using the corresponding revised determined configuration for each of the plural additional wavelengths, without physically moving the sensor to a different measurement position.