US-12616399-B2 - Combination of reflective and transmissive sensors with characteristic wavelengths for physiological monitoring

US12616399B2US 12616399 B2US12616399 B2US 12616399B2US-12616399-B2

Abstract

A light sensing device includes a first light source configured to emit light within a first wavelength range, a second light source configured to emit light within a second wavelength range, detector circuitry, a first photodetector in the detector circuitry configured to detect the light within the first wavelength range, and a second photodetector in the detector circuitry configured to detect the light within the second wavelength range. The first photodetector and the second photodetector are in parallel in the detector circuitry such that the detector circuitry sums electrical signals outputted by the first photodetector and the second photodetector.

Inventors

DEREK L. MOODY
Jacob D. DOVE
Paul S. Addison
Rakesh K. Sethi
Peter M. Galen
Linden Reustle

Assignees

COVIDIEN LP
HEMEX HEALTH, INC.

Dates

Publication Date: 20260505
Application Date: 20230120

Claims (16)

1 . A light sensing system comprising: a first light source configured to emit light within a first wavelength range; a second light source configured to emit light within a second wavelength range; a first pair of photodetectors located in a reflective position with respect to the first and second light sources, the first pair of photodetectors comprising a first photodetector and a second photodetector having different responsivities to wavelengths of light, wherein the first photodetector is configured to detect the light within the first wavelength range and the second photodetector is configured to detect the light within the second wavelength range; a second pair of photodetectors located in a transmission position with respect to the first and second light sources, the second pair of photodetectors comprising a third photodetector and a fourth photodetector having different responsivities to wavelengths of light, wherein the third photodetector is configured to detect the light within the first wavelength range and the fourth photodetector is configured to detect the light within the second wavelength range, wherein the first photodetector and the second photodetector are in parallel with each other and wherein the third and fourth photodetectors are in parallel with each other; and detector circuitry configured to: sum electrical signals outputted by the first photodetector and the second photodetector; sum electrical signals outputted by the third photodetector and the fourth photodetector; and output the summed signals to a regional oximetry device.
2 . The light sensing system of claim 1 , wherein the first photodetector comprises a first output node and the second photodetector comprises a second output node, wherein the first photodetector and the second photodetector being in parallel comprises the first output node and the second output node being electrically connected to one another at a common node, and wherein the detector circuitry configured to sum the electrical signals outputted by the first photodetector and the second photodetector is further configured to perform at least one of receiving or outputting a summed electrical signal from the common node.
3 . The light sensing system of claim 1 , wherein: the first light source is a near ultraviolet light emitting light source; and the second light source is an infrared light emitting light source.
4 . The light sensing system of claim 1 , wherein: the first wavelength range is between about 300 nanometers (nm) and about 550 nm; and the second wavelength range is between about 1300 nm and 1500 nm.
5 . The light sensing system of claim 1 , wherein, relative to each other: the reflective position comprises a shorter optical path length in the light sensing system; and the transmission position comprises a longer optical path length in the light sensing system.
6 . The light sensing system of claim 1 , wherein the first light source and the second light source are switched on separately according to a sequential pattern.
7 . A method comprising: emitting, by a first light source of a light sensing device, light within a first wavelength range; emitting, by a second light source of the light sensing device, light within a second wavelength range; detecting, by a first pair of photodetectors, the light within the first wavelength range and the light within the second wavelength range through a reflective optical path, wherein detecting by the first pair of photodetectors comprises generating a first electrical signal that corresponds to light within the first wavelength range and generating a second electrical signal that corresponds to light within the second wavelength range; detecting, by a second pair of photodetectors, the light within the first wavelength range and the light within the second wavelength range through a transmission optical path, wherein the transmission optical path is longer than the reflective optical path, and wherein detecting by the second pair of photodetectors comprises generating a third electrical signal that corresponds to light within the first wavelength range and generating a fourth electrical signal that corresponds to light within the second wavelength range; summing, by the light sensing device, the first electrical signal and the second electrical signal; summing, by the light sensing device, the third electrical signal and the fourth electrical signal; and outputting, by the light sensing device, the summed signals to a regional oximetry device.
8 . The method of claim 7 , wherein the first pair of photodetectors comprises a first photodetector and a second photodetector in parallel and wherein the second pair of photodetectors comprises a third photodetector and a fourth photodetector in parallel.
9 . The method of claim 7 , wherein: the first light source is a near ultraviolet light emitting light source; and the second light source is an infrared light emitting light source.
10 . The method of claim 7 , wherein: the first wavelength range is between about 300 nanometers (nm) and about 550 nm; and the second wavelength range is between about 1300 nm and 1500 nm.
11 . The method of claim 7 , wherein emitting, by the first light source of the light sensing device, the light within the first wavelength range and emitting, by the second light source of the light sensing device, the light within the second wavelength range further comprises separately emitting the light within the first wirelength range and the light within the second wirelength range according to a sequential pattern.
12 . The method of claim 7 , wherein the first pair of photodetectors comprises first and second photodetectors and the second pair of photodetectors comprises third and fourth photodetectors, and wherein the first photodetector has a wavelength responsivity that differs from the second photodetector, and wherein the third photodetector has a wavelength responsivity that differs from the fourth photodetector.
13 . The method of claim 12 , wherein the first and third photodetectors are responsive to the light within the first wavelength range, and wherein the second and fourth photodetectors are responsive to the light within the second wavelength range.
14 . The method of claim 7 , further comprising determining, by the regional oximetry device, a physiological parameter of the patient based on the summed signals.
15 . The method of claim 14 , wherein the physiological parameter comprises oxygen saturation.
16 . The method of claim 14 , wherein the physiological parameter comprises hemoglobin concentration.

Description

This application claims the benefit of U.S. Provisional Patent Application No. 63/301,814, filed 21 Jan. 2022, the entire contents of which is incorporated herein by reference. BACKGROUND Hemoglobin disorders such as anemia, sickle cell, sickle cell trait, and beta thalassemia, are rare blood conditions that affect a person's hemoglobin, which is the protein in the blood that carries oxygen. Such hemoglobin disorders can be inherited conditions that may change the shape or amount of red blood cells in the body. SUMMARY The present disclosure describes example devices, systems, and techniques for non-invasive physiological monitoring using a light sensing device having photodetectors with ranges of wavelengths. Examples of the physiological monitoring are described with respect to sensing of hemoglobin disorders for purposes of illustration, but the example techniques are not limited to hemoglobin disorders. A light sensing device may emit various wavelengths of light that are collected by photodetectors of the light sensing device at various locations of a subject (e.g., various locations of a finger of the subject) to find the total hemoglobin of the subject, which may be used to determine whether the subject has a hemoglobin disorder. The light sensing device may sense multiple wavelengths of light to determine information that can be used to understand the water content of the arterial blood of a subject and the hemoglobin type of the subject. Such wavelengths of light may be at characteristic wavelengths for hemoglobin deficiencies, and can be used to determine disease states of such deficiencies. For example, the light sensing device may emit light at ultraviolet (UV) or near-UV wavelengths, which are characteristic wavelengths that are around the global maxima or minima of the hemoglobin absorption spectra. The signals from such wavelengths may be used to compare water absorption to hemoglobin absorption for a total hemoglobin measurement. Additionally, the signals from such wavelengths may also be used to sense changes to the pH or hypoxia in the blood of the subject, which may be due to certain hemoglobinopathies like sickle cell anemia. These changes in the absorption spectra of hemoglobin and may be sensed using these shorter wavelengths. Shorter wavelengths present a higher noise based on pigmentation because of the absorption spectrum of melanin. As such, the light sensing device may also emit light at infrared (IR) wavelengths, which can be used to reduce the effect of skin pigmentation on the signal as the absorption spectra of melanin is lower at longer wavelengths. In addition, water may dominate the absorption at these longer wavelengths, so the IR wavelengths may be used to compare the absorption of water versus hemoglobin to create a total hemoglobin measurement. The light sensing device may concurrently measure the transmission and reflectance of the wavelengths of light using a set of detectors that are in parallel. Specifically, the light sensing device may use multiple photodetectors with different responsivities. The multiple photodetectors may be placed in parallel in the same circuit to allow multiple photodetectors with different responsivities to add current to the same circuit, and the current outputted by the multiple photodetectors can be sent for amplification. For example, the output nodes of the multiple photodetectors may be connected together at a common node. The current at the common node may be equivalent to the sum of the current outputted by the multiple photodetectors since the output nodes of the multiple photodetectors are connected at the common node. In some examples, photodetectors are located at multiple locations in the light sensing device. Specifically, one or more photodetectors may be located in in a shorter optical path length reflective position of the light sensing device, and one or more photodetectors may be placed in a longer optical path length transmission position of the light sensing device. The difference in these long and short optical path lengths may be used to improve the signal quality of the signals outputted by the photodetectors and to remove noise factors from such signals. For example, the signals outputted by the one or more photodetectors in the shorter path length reflective position could be used to characterize the superficial tissue and to account for pigmentation, interstitial fluid, or other potential confounders, while the signals outputted by the one or more photodetectors in the longer path length transmission position may be used to generate the final measurement after accounting for such noise factors. In some aspects, the techniques described herein relate to a light sensing system including: a first light source configured to emit light within a first wavelength range; a second light source configured to emit light within a second wavelength range; a first photodetector configured to detect the light within the first wa