Oxygen saturation estimation system using a PPG signal sensing ring

Abstract

An oxygen saturation estimation system using a photoplethysmogram (PPG) signal sensing ring is provided, the system includes a server, the server includes a signal quality classification component configured to classify the quality of a first wavelength PPG signal and a second wavelength PPG signal into good and bad, and an oxygen saturation estimation component configured to estimate an oxygen saturation from the first wavelength PPG signal and the second wavelength PPG signal, the PPG signal sensing ring includes a plurality of sensors at different positions, each of the plurality of sensors configured to measure the first wavelength PPG signal and the second wavelength PPG signal, each of the plurality of sensors includes a first wavelength light source, a second wavelength light source, and a photoelectric conversion device, and the terminal also includes a sensor selection component configured to select a sensor that measures a combination of the first wavelength test PPG signal and the second wavelength test PPG signal having the highest signal quality from a plurality of first wavelength test PPG signals and a plurality of second wavelength test PPG signals among the plurality of sensors, as a sensor for measuring the first wavelength PPG signal and the second wavelength PPG signal.

Description

[Technical Field]

[0001] The present invention relates to an oxygen saturation estimation system, and more particularly to an oxygen saturation estimation system using a photoplethysmography (PPG) signal sensing ring. [Background technology]

[0002] Oxygen saturation indicates the ratio of hemoglobin bound to oxygen and saturated to the total hemoglobin in the body. It generally ranges from 95 to 100%, and if it is below 90%, it is called hypoxemia, and if it is below 80%, various tissues in the body will suffer serious damage. There is a need for a method that allows people to easily measure oxygen saturation in their daily lives and check their health status without visiting a hospital. Summary of the Invention [Problem to be solved by the invention]

[0003] The problem to be solved by the present disclosure is to provide an oxygen saturation estimation system that uses a PPG (photoplethysmography) signal sensing ring. [Means for solving the problem]

[0004] In order to solve the above-mentioned problems, an oxygen saturation estimation system using a PPG signal sensing ring according to an embodiment of the present disclosure includes a server, the server including a signal quality classification component configured to classify the quality of a first-wavelength PPG signal and a second-wavelength PPG signal into good or bad, and an oxygen saturation estimation component configured to estimate oxygen saturation from the first-wavelength PPG signal and the second-wavelength PPG signal, the first-wavelength PPG signal and the second-wavelength PPG signal being measured using the PPG signal sensing ring, the server receiving the first-wavelength PPG signal and the second-wavelength PPG signal from the PPG signal sensing ring via a terminal, The PPG signal sensing ring includes a plurality of sensors at different positions, each configured to measure a first-wavelength PPG signal and a second-wavelength PPG signal, and each of the plurality of sensors includes a first-wavelength light source, a second-wavelength light source, and a photoelectric conversion device. The terminal also includes a sensor selection component configured to select, among the plurality of sensors, a sensor that measures a combination of a first-wavelength test PPG signal and a second-wavelength test PPG signal having the highest signal quality, as a sensor for measuring the first-wavelength PPG signal and the second-wavelength PPG signal.

[0005] In some embodiments, the signal quality of the plurality of test PPG signals may be evaluated by at least one of acceleration signal magnitude, signal-to-noise ratio, and alternating current (AC) component magnitude to direct current (DC) component magnitude ratio.

[0006] In some embodiments, the server further includes an oxygen saturation index calculation component configured to calculate an oxygen saturation index, and the oxygen saturation index may be defined by the ratio of a time during which the signal quality classification component classifies the quality of the first wavelength PPG signal and the second wavelength PPG signal as good and the oxygen saturation is outside a normal range to a time during which the signal quality classification component classifies the quality of the first wavelength PPG signal and the second wavelength PPG signal as good.

[0007] In some embodiments, the terminal device further includes a light source control component configured to control the first wavelength light source and the second wavelength light source of each of the plurality of sensors so that a DC component of each of the plurality of first wavelength test PPG signals measured using the plurality of sensors is within a first predetermined range and a DC component of each of the plurality of second wavelength test PPG signals measured using the plurality of sensors is within a second predetermined range.

[0008] In some embodiments, the control of the first wavelength light source and the second wavelength light source by the light source control component and the sensor selection by the sensor selection component may be performed sequentially, and the control of the first wavelength light source and the second wavelength light source by the light source control component and the sensor selection by the sensor selection component may be performed cyclically.

[0009] According to an embodiment of the present disclosure, a method for estimating oxygen saturation using a PPG signal sensing ring includes the steps of receiving a first wavelength PPG signal and a second wavelength PPG signal from the PPG signal sensing ring via a terminal, classifying the quality of the first wavelength PPG signal and the second wavelength PPG signal into good and bad, and estimating oxygen saturation from the first wavelength PPG signal and the second wavelength PPG signal. The PPG signal sensing ring includes a plurality of sensors at different positions, each of the plurality of sensors configured to measure the first wavelength PPG signal and the second wavelength PPG signal, and each of the plurality of sensors including a first wavelength light source, a second wavelength light source, and a photoelectric conversion device. The terminal also includes a sensor selection component configured to select, from the plurality of sensors, a sensor that measures a combination of a first wavelength test PPG signal and a second wavelength test PPG signal having the highest signal quality, as a sensor for measuring the first wavelength PPG signal and the second wavelength PPG signal.

[0010] In some embodiments, the signal quality of the plurality of test PPG signals may be assessed by at least one of acceleration signal magnitude, signal-to-noise ratio, and AC component magnitude to DC component magnitude ratio.

[0011] In some embodiments, the method further includes calculating an oxygen saturation index, wherein the oxygen saturation index may be defined as a ratio of a time during which the signal quality classification component classifies the quality of the first wavelength PPG signal and the second wavelength PPG signal as good and the oxygen saturation is outside a normal range to a time during which the signal quality classification component classifies the quality of the first wavelength PPG signal and the second wavelength PPG signal as good.

[0012] In some embodiments, the terminal device further includes a light source control component configured to control the first wavelength light source and the second wavelength light source of each of the plurality of sensors so that a DC component of each of the plurality of first wavelength test PPG signals measured using the plurality of sensors is within a first predetermined range and a DC component of each of the plurality of second wavelength test PPG signals measured using the plurality of sensors is within a second predetermined range.

[0013] In some embodiments, the control of the first wavelength light source and the second wavelength light source by the light source control component and the sensor selection by the sensor selection component may be performed sequentially, and the control of the first wavelength light source and the second wavelength light source by the light source control component and the sensor selection by the sensor selection component may be performed cyclically. [Effects of the Invention]

[0014] An oxygen saturation estimation system using a PPG (photoplethysmography) signal sensing ring is provided. According to the present invention, oxygen saturation can be continuously and easily monitored in daily life. According to the present invention, the PPG signal sensing ring includes a plurality of sensors at different positions. Among the plurality of sensors, a sensor that provides excellent signal quality for a first-wavelength PPG signal and a second-wavelength PPG signal can be selected. Therefore, a sensor can be selected to suit the position and shape of blood vessels, which vary for each user. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a three-dimensional view of a PPG signal sensing ring according to one embodiment of the present disclosure. [Figure 2] FIG. 1 is an exploded three-dimensional view of a PPG signal sensing ring according to one embodiment of the present disclosure. [Figure 3] FIG. 1 is a block diagram of an oxygen saturation estimation system utilizing a PPG signal sensing ring, according to one embodiment of the present disclosure. [Figure 4]10 is a flowchart showing a method for estimating oxygen saturation using a PPG signal sensing ring. [Figure 5] 10 is a flowchart showing a method for setting a sensor of a PPG signal sensing ring. DETAILED DESCRIPTION OF THE INVENTION

[0016] Figure 1 is a three-dimensional view of a photoplethysmography (PPG) signal sensing ring 100 according to one embodiment of the present disclosure. Figure 2 is an exploded three-dimensional view of the PPG signal sensing ring 100 according to one embodiment of the present disclosure.

[0017] Referring to FIGS. 1 and 2, the PPG signal sensing ring 100 also includes an outer electrode 130 , an inner electrode 140 , an insulating unit 150 , a top cover 110 , an operation indicating unit 120 , and a plurality of sensors 160 .

[0018] The external electrode 130 may have an arc shape. The external electrode 130 may be made of a conductor and may function as an electrode for measuring an electrocardiogram (ECG). The external electrode 130 also forms the exterior of the PPG signal sensing ring 100, and the external electrode 130 may be in contact with the user's body.

[0019] The internal electrode 140 may have a ring shape and may have multiple openings 145 for multiple sensors 160. The internal electrode 140 may be made of a conductor and may function as an electrode for measuring an electrocardiogram. The internal electrode 140 also forms the interior of the PPG signal sensing ring 100, and the internal electrode 140 may be in contact with a user's finger.

[0020] The insulating unit 150 may be disposed between the outer electrode 130 and the inner electrode 140. The insulating unit 150 may enable electrical insulation between the outer electrode 130 and the inner electrode 140.

[0021] The top cover 110 may have an arc shape and may form a ring shape together with the external electrode 130. The top cover 110 may form the outer appearance of the PPG signal sensing ring 100.

[0022] The operation indicator unit 120 may be coupled to the top cover 110. The operation indicator unit 120 may also include a plurality of LEDs (light-emitting diodes), for example, green and red LEDs. The operation indicator unit 120 may use the plurality of LEDs to indicate the operation of the PPG signal sensing ring 100. For example, the green LED may be turned on for two seconds to indicate the start of measurement, and the green LED may be turned on for one second to indicate the end of measurement. Furthermore, the red LED may flash repeatedly at one-second intervals to indicate a malfunction.

[0023] The sensors 160 may be arranged to contact a user's finger. The sensors 160 may be respectively positioned within the openings 145 of the internal electrode 140 and protrude from the surface of the internal electrode 140. The sensors 160 may be configured to acquire a plurality of first-wavelength PPG signals and a plurality of second-wavelength PPG signals at different positions. Each sensor 160 also includes a first-wavelength light source and a second-wavelength light source having different wavelengths, and a photoelectric conversion device.

[0024] In some embodiments, although not shown in FIGS. 1 and 2, the PPG signal sensing ring 100 also includes an acceleration sensor disposed between the outer electrode 130 and the inner electrode 140.

[0025] FIG. 3 is a block diagram of an oxygen saturation estimation system 1000 using a PPG signal sensing ring, according to one embodiment of the present disclosure.

[0026] Referring to FIG. 3, the oxygen saturation estimation system 1000 using the PPG signal detecting ring includes the PPG signal detecting ring 100, a first terminal 200, a server 300, and a second terminal 400.

[0027] The PPG signal sensing ring 100 also includes multiple sensors, for example, a first sensor 160A and a second sensor 160B. Although Fig. 3 illustrates the PPG signal sensing ring 100 as including two sensors, the number of sensors included in the PPG signal sensing ring 100 is not limited to two. In some embodiments, the PPG signal sensing ring 100 also includes an acceleration sensor, although not shown in Fig. 3.

[0028] The first sensor 160A may include a first-wavelength light source 161A, a second-wavelength light source 162A, and a photoelectric conversion device 164A. The first sensor 160A may sense a first-wavelength PPG signal using the first-wavelength light source 161A and the photoelectric conversion device 164A. The first sensor 160A may sense a second-wavelength PPG signal using the second-wavelength light source 162A and the photoelectric conversion device 164A. The first-wavelength light source 161A may include, for example, a red LED, the second-wavelength light source 162A may include, for example, an infrared LED, and the photoelectric conversion device 164A may include a photodiode.

[0029] The second sensor 160B may include a first-wavelength light source 161B, a second-wavelength light source 162B, and a photoelectric conversion device 164B. The second sensor 160B may sense a first-wavelength PPG signal using the first-wavelength light source 161B and the photoelectric conversion device 164B. The second sensor 160B may sense a second-wavelength PPG signal using the second-wavelength light source 162B and the photoelectric conversion device 164B. The first-wavelength light source 161B may include, for example, a red LED, the second-wavelength light source 162B may include, for example, an infrared LED, and the photoelectric conversion device 164B may include a photodiode.

[0030] The acceleration sensor may sense the movement of the user by measuring the acceleration of the PPG signal sensing ring 100 .

[0031] The first terminal 200 may be used by a user. The first terminal 200 may include, for example, a smartphone or a tablet PC (personal computer). The first terminal 200 may be connected to the PPG signal sensing ring 100 by wire or wirelessly. For example, the first terminal 200 may be connected to the PPG signal sensing ring 100 using Bluetooth or Wi-Fi (wireless fidelity). The first terminal 200 may be connected to the server 300 by wire or wirelessly. For example, the first terminal 200 may be connected to the server 300 by Wi-Fi (wireless fidelity) or, for example, 3G (3G). rd generation), LTE (long term evolution), 5G (5 th The server 300 may be connected to the server 300 via a mobile telecommunication technology such as a mobile phone generation (MPU).

[0032] The first terminal 200 also includes a light source control component 210, a sensor selection component 220, a measurement control component 230, and a display component 240. An application may be installed on the first terminal 200. The light source control component 210, the sensor selection component 220, the measurement control component 230, and the display component 240 may be implemented by the application. Alternatively, the first terminal 200 may connect to a website, and the light source control component 210, the sensor selection component 220, the measurement control component 230, and the display component 240 may be implemented on the website.

[0033] The light source control component 210 may control the first wavelength light source 161A and the second wavelength light source 162A of the first sensor 160A, and the first wavelength light source 161B and the second wavelength light source 162B of the second sensor 160B so that the DC (direct current) components of each of the two first wavelength test PPG signals received from the first sensor 160A and the second sensor 160B are within a first predetermined range, and the DC components of each of the two second wavelength test PPG signals received from the first sensor 160A and the second sensor 160B are within a second predetermined range.

[0034] After light source control component 210 controls first-wavelength light source 161A and second-wavelength light source 162A of first sensor 160A and first-wavelength light source 161B and second-wavelength light source 162B of second sensor 160B, sensor selection component 220 may select one of first sensor 160A and second sensor 160B as a sensor for subsequently measuring the first-wavelength PPG signal and the second-wavelength PPG signal. Sensor selection component 220 may select one of first sensor 160A and second sensor 160B that measured the combination of the first-wavelength test PPG signal and the second-wavelength test PPG signal with the highest signal quality from the two first-wavelength test PPG signals and the two second-wavelength test PPG signals from first sensor 160A and second sensor 160B. For example, the sensor that measured the combination of the first-wavelength test PPG signal and the second-wavelength test PPG signal with the highest average signal quality may be selected from among the two first-wavelength test PPG signals and the two second-wavelength test PPG signals. The signal quality may be evaluated by at least one of the magnitude of the acceleration signal, the signal-to-noise ratio (SNR), and the ratio of the alternating current (AC) component magnitude to the DC component magnitude. The smaller the magnitude of the acceleration signal, the higher the SNR, and the higher the ratio of the AC component magnitude to the DC component magnitude, the higher the signal quality. Then, the first-wavelength PPG signal and the second-wavelength PPG signal may be measured using the sensor selected by the sensor selection component 220.

[0035] The control of first wavelength light source 161A and second wavelength light source 162A of first sensor 160A and first wavelength light source 161B and second wavelength light source 162B of second sensor 160B by light source control component 210 and the sensor selection by sensor selection component 220 may be performed sequentially. That is, after light source control component 210 controls first wavelength light source 161A and second wavelength light source 162A of first sensor 160A and first wavelength light source 161B and second wavelength light source 162B of second sensor 160B, sensor selection component 220 may select a sensor.

[0036] Control of first wavelength light source 161A and second wavelength light source 162A of first sensor 160A and first wavelength light source 161B and second wavelength light source 162B of second sensor 160B by light source control component 210 and sensor selection by sensor selection component 220 may occur periodically. As PPG signal sensing ring 100 may move or rotate relative to the finger, light source control component 210 may periodically control first wavelength light source 161A and second wavelength light source 162A of first sensor 160A and first wavelength light source 161B and second wavelength light source 162B of second sensor 160B, and sensor selection component 220 may periodically select a sensor.

[0037] The measurement control component 230 may select a measurement mode or start or end a measurement based on user input. For example, a user may use the measurement control component 230 to select a measurement mode between a self-check mode and a background mode. In the self-check mode, the user may use the measurement control component 230 to start and end a measurement. In the background mode, a measurement begins and continues regardless of user input. In the background mode, the user may set or change the measurement period. In some embodiments, the measurement control component 230 may be included in the PPG signal sensing ring 100. That is, a user may use the measurement control component 230 of the PPG signal sensing ring 100 to select a measurement mode or start or end a measurement. In some embodiments, the measurement control component 230 may also be included in the server 300. That is, a service provider may use the measurement control component 230 of the server 300 to select a measurement mode or start or end a measurement.

[0038] The display component 240 may display at least one of the first wavelength PPG signal and the second wavelength PPG signal measured by the PPG signal sensing ring 100 and stored in the PPG signal storage component 381 of the server 300, the measurement date and time of the first wavelength PPG signal and the second wavelength PPG signal stored in the PPG signal storage component 381 of the server 300, the signal quality classification result classified by the signal quality classification component 320 of the server 300 and stored in the oxygen saturation storage component 382 of the server 300, the oxygen saturation estimated by the oxygen saturation estimation component 350 of the server 300 and stored in the oxygen saturation storage component 382 of the server 300, and the oxygen saturation index calculated by the oxygen saturation index calculation component 360 of the server 300 and stored in the oxygen saturation index storage component 383.

[0039] The server 300 also includes a PPG signal pre-processing component 310, a signal quality classification component 320, an oxygen saturation estimation component 350, a PPG signal storage component 381, and an oxygen saturation storage component 382. In some embodiments, the server 300 also includes an oxygen saturation index calculation component 360 and an oxygen saturation index storage component 383. In some embodiments, the server 300 also includes an alarm component 370.

[0040] The PPG signal preprocessing component 310 may preprocess the first wavelength PPG signal and the second wavelength PPG signal received by the server 300 via the first terminal 200 from a selected sensor of the PPG signal sensing ring 100. For example, a low-pass filter, a high-pass filter, and normalization may be used to preprocess the first wavelength PPG signal and the second wavelength PPG signal. In some embodiments, the PPG signal preprocessing component 310 may preprocess the acceleration signal received by the server 300 via the first terminal 200 from an acceleration sensor of the PPG signal sensing ring 100.

[0041] The signal quality classification component 320 may classify the signal quality of the first wavelength PPG signal and the second wavelength PPG signal as good or bad. In some embodiments, the signal quality classification component 320 may reference the acceleration signal to classify the signal quality of the first wavelength PPG signal and the second wavelength PPG signal as good or bad.

[0042] The oxygen saturation estimated from the first and second wavelength PPG signals classified as having poor quality is determined to be unreliable and is not displayed by the display component 240 of the first terminal 200. The oxygen saturation estimated from the first and second wavelength PPG signals classified as having good quality is determined to be reliable and may be displayed by the display component 240 of the first terminal 200. In an alternative embodiment, the oxygen saturation estimated from the first and second wavelength PPG signals may be displayed by the display component 240 of the first terminal 200 together with the signal quality classification result, regardless of the signal quality classification result. Furthermore, the oxygen saturation estimated from the first and second wavelength PPG signals may be displayed by the display component 420 of the second terminal 400 together with the signal quality classification result, regardless of the signal quality classification result.

[0043] In some embodiments, the signal quality classification component 320 may utilize a deep learning model to classify the quality of the PPG signal as good or bad. The deep learning model used in the signal quality classification component 320 may include a convolution neural network (CNN), a long short-term memory (LSTM), a fully connected network (FCN), an encoder, a decoder, or a combination thereof. The method for classifying the signal quality is not limited to the methods described herein.

[0044] The oxygen saturation estimation component 350 can estimate the oxygen saturation from the first wavelength PPG signal and the second wavelength PPG signal. Various methods can be used to estimate the oxygen saturation.

[0045] For example, the R value may be first calculated using Equation 1 as follows:

[0046]

number

[0047] where AC R is the magnitude of the AC component of the first wavelength PPG signal, and DC R is the magnitude of the DC component of the first wavelength PPG signal, and AC IR is the magnitude of the AC component of the second wavelength PPG signal, and DC IR is the magnitude of the DC component of the second wavelength PPG signal.

[0048] The oxygen saturation can then be calculated from the R value using Equation 2 as follows:

[0049]

number

[0050] C0 and C1 are constants that can be determined using linear regression.

[0051] In Equation 2, the oxygen saturation is described as being expressed by a linear equation with respect to the R value, but the oxygen saturation may also be expressed by a polynomial of a degree greater than 1, for example, a quadratic or cubic equation with respect to the R value. The method for estimating the oxygen saturation is not limited to the method described in this specification.

[0052] The oxygen saturation index calculation component 360 may calculate an oxygen saturation index. The oxygen saturation index may be defined based on the time during which the signal quality classification component 320 classifies the first and second wavelength PPG signals as having good quality and the time during which the signal quality classification component 320 classifies the first and second wavelength PPG signals as having good quality and the oxygen saturation estimated by the oxygen saturation estimation component 350 is outside of a normal range. For example, the oxygen saturation index may be defined as a ratio of the time during which the signal quality classification component 320 classifies the first and second wavelength PPG signals as having good quality and the oxygen saturation estimated by the oxygen saturation estimation component 350 is outside of a normal range to the time during which the signal quality classification component 320 classifies the first and second wavelength PPG signals as having good quality. That is, the oxygen saturation index may refer to the proportion of time that the oxygen saturation is outside the normal range relative to the time during which a reliable oxygen saturation is available.

[0053] The alarm component 370 may transmit an alarm to at least one of the first terminal 200 and the second terminal 400 if at least one of the oxygen saturation estimated by the oxygen saturation estimation component 350 and the oxygen saturation index calculated by the oxygen saturation index calculation component 360 satisfies the alarm conditions set by the alarm condition setting component 410 of the second terminal 400.

[0054] The PPG signal storage component 381 may store the first wavelength PPG signal and the second wavelength PPG signal received by the server 300 via the first terminal 200 from a selected sensor of the PPG signal sensing ring 100. The PPG signal storage component 381 may further store the measurement date and time of the first wavelength PPG signal and the second wavelength PPG signal. The PPG signal storage component 381 may further store the first wavelength PPG signal and the second wavelength PPG signal preprocessed by the PPG signal preprocessing component 310. The PPG signal storage component 381 may further store the acceleration signal received by the server 300 via the first terminal 200 from the acceleration sensor of the PPG signal sensing ring 100. The oxygen saturation storage component 382 may store the oxygen saturation estimated by the oxygen saturation estimation component 350. The oxygen saturation storage component 382 may further store the signal quality classification result classified by the signal quality classification component 320. The oxygen saturation index storage component 383 can store the oxygen saturation index calculated by the oxygen saturation index calculation component 360 .

[0055] The second terminal 400 may be connected to the server 300 via a wired or wireless connection. For example, the second terminal 400 may be connected via a Wi-Fi (wireless fidelity) or a 3G (3G) network. rd generation), LTE (long term evolution), 5G (5 th The second terminal 400 may be connected to the server 300 via a mobile telecommunication technology such as a mobile phone (mobile phone) generation (M2D) or a mobile device (device). The second terminal 400 may be used by a doctor. The second terminal 400 may include, for example, a smartphone, a tablet PC, a computer, or a laptop.

[0056] The second terminal 400 also includes an alarm condition setting component 410 and a display component 420. The second terminal 400 may be connected to a website or have an application installed thereon. The alarm condition setting component 410 and the display component 420 may be implemented using the website or the application.

[0057] Using the alarm condition setting component 410, a physician may set alarm conditions, for example, an alarm may be set to sound if oxygen saturation remains below 90% for 10 minutes or more.

[0058] The display component 420 may display at least one of the first wavelength PPG signal and the second wavelength PPG signal from the PPG signal storage component 381, the measurement date and time of the first wavelength PPG signal and the second wavelength PPG signal from the PPG signal storage component 381, the preprocessed first wavelength PPG signal and the second wavelength PPG signal stored in the PPG signal storage component 381, the signal quality classification result from the oxygen saturation storage component 382, ​​the oxygen saturation from the oxygen saturation storage component 382, ​​and the oxygen saturation index from the oxygen saturation index storage component 383.

[0059] FIG. 4 is a flowchart showing a method (2000) for estimating oxygen saturation using a PPG signal sensing ring.

[0060] 3 and 4 , the server 300 may receive a first wavelength PPG signal and a second wavelength PPG signal from a selected sensor of the PPG signal sensing ring 100 via the first terminal 200 (S2050). Next, the PPG signal pre-processing component 310 may pre-process the first wavelength PPG signal and the second wavelength PPG signal (S2100). For example, a low-pass filter, a high-pass filter, and normalization may be used to pre-process the first wavelength PPG signal and the second wavelength PPG signal. In some embodiments, the PPG signal pre-processing component 310 may further pre-process the acceleration signal received by the server 300 via the first terminal 200 from the acceleration sensor of the PPG signal sensing ring 100.

[0061] Next, the signal quality classification component 320 may classify the signal quality of the first and second wavelength PPG signals as good or bad (S2200). The signal quality classification component 320 may refer to the acceleration signal to classify the signal quality of the first and second wavelength PPG signals as good or bad. The oxygen saturation estimated from the first and second wavelength PPG signals classified as having poor quality is determined to be unreliable and is not displayed by the display component 240 of the first terminal 200. The oxygen saturation estimated from the first and second wavelength PPG signals classified as having good quality is determined to be reliable and may be displayed by the display component 240 of the first terminal 200. In an alternative embodiment, the oxygen saturation estimated from the first and second wavelength PPG signals may be displayed by the display component 240 of the first terminal 200 together with the signal quality classification result, regardless of the signal quality classification result. Furthermore, regardless of the signal quality classification result, the oxygen saturation estimated from the first wavelength PPG signal and the second wavelength PPG signal can be displayed by the display component 420 of the second terminal 400 together with the signal quality classification result.

[0062] In some embodiments, a deep learning model may be used in the signal quality classification component 320. The deep learning model used in the signal quality classification component 320 may include a convolutional neural network (CNN), a long short-term memory (LSTM), a fully connected neural network (FCN), an encoder, a decoder, or a combination thereof. The method for classifying signal quality is not limited to the methods described herein.

[0063] Next, the oxygen saturation estimation component 350 may estimate the oxygen saturation from the first wavelength PPG signal and the second wavelength PPG signal (S2500). The method for estimating the oxygen saturation is as described above with reference to FIG. 3.

[0064] Next, the first wavelength PPG signal, the second wavelength PPG signal, the signal quality classification result, and the oxygen saturation level may be stored (S2570). The first wavelength PPG signal and the second wavelength PPG signal may be stored in a PPG signal storage component 381. In some embodiments, the pre-processed first wavelength PPG signal and the pre-processed second wavelength PPG signal may be further stored in the PPG signal storage component 381. In some embodiments, the acceleration signal may be further stored in the PPG signal storage component 381. In some embodiments, the pre-processed acceleration signal may be further stored in the PPG signal storage component 381. The signal quality classification result and the oxygen saturation level may be stored in an oxygen saturation storage component 382.

[0065] Next, the steps of receiving the first wavelength PPG signal and the second wavelength PPG signal (S2050), pre-processing the first wavelength PPG signal and the second wavelength PPG signal (S2100), classifying the quality of the first wavelength PPG signal and the second wavelength PPG signal (S2220), estimating the oxygen saturation (S2500), and storing (S2570) may be repeated.

[0066] Next, the oxygen saturation index calculation component 360 may calculate an oxygen saturation index (S2600). The oxygen saturation index may be defined based on the time during which the signal quality classification component 320 classifies the quality of the first and second wavelength PPG signals as good and the time during which the signal quality classification component 320 classifies the quality of the first and second wavelength PPG signals as good and the oxygen saturation estimated by the oxygen saturation estimation component 350 is outside a normal range. For example, the oxygen saturation index may be defined as a ratio of the time during which the signal quality classification component 320 classifies the quality of the first and second wavelength PPG signals as good and the oxygen saturation estimated by the oxygen saturation estimation component 350 is outside a normal range to the time during which the signal quality classification component 320 classifies the quality of the first and second wavelength PPG signals as good. That is, the oxygen saturation index may refer to the proportion of time that the oxygen saturation is outside the normal range relative to the time during which a reliable oxygen saturation is available.

[0067] The oxygen saturation index may then be stored in the oxygen saturation index storage component 383 (S2700).

[0068] FIG. 5 is a flow chart illustrating a method (3000) for configuring a sensor in a PPG signal sensing ring.

[0069] Referring to Figures 5 and 3, the light source control component 210 may control the first wavelength light source 161A and the second wavelength light source 162A of the first sensor 160A and the first wavelength light source 161B and the second wavelength light source 162B of the second sensor 160B so that the DC components of each of the two first wavelength test PPG signals received from the first sensor 160A and the second sensor 160B are within a first predetermined range, and the DC components of each of the two second wavelength test PPG signals received from the first sensor 160A and the second sensor 160B are within a second predetermined range (S3100).

[0070] After light source control component 210 controls first wavelength light source 161A and second wavelength light source 162A of first sensor 160A and first wavelength light source 161B and second wavelength light source 162B of second sensor 160B, sensor selection component 220 may select one of first sensor 160A and second sensor 160B as a sensor for subsequently measuring the first wavelength PPG signal and the second wavelength PPG signal (S3200). Sensor selection component 220 may select one of first sensor 160A and second sensor 160B that measured the combination of the first wavelength test PPG signal and the second wavelength test PPG signal with the highest signal quality from the two first wavelength test PPG signals and the two second wavelength test PPG signals from first sensor 160A and second sensor 160B. For example, the sensor that measured the combination of the first-wavelength test PPG signal and the second-wavelength test PPG signal with the highest average signal quality may be selected from among the two first-wavelength test PPG signals and the two second-wavelength test PPG signals. The signal quality may be evaluated based on at least one of the magnitude of the acceleration signal, the signal-to-noise ratio (SNR), and the ratio of the AC component magnitude to the DC component magnitude. The smaller the magnitude of the acceleration signal, the higher the SNR, and the higher the ratio of the AC component magnitude to the DC component magnitude, the higher the signal quality. Then, the first-wavelength PPG signal and the second-wavelength PPG signal measured by the sensor selected by the sensor selection component 220 may be transmitted to the server 300 via the first terminal 200.

[0071] The step of controlling first wavelength light source 161A and second wavelength light source 162A of first sensor 160A and first wavelength light source 161B and second wavelength light source 162B of second sensor 160B by light source control component 210 (S3100) and the step of selecting a sensor by sensor selection component 220 (S3200) may be performed sequentially. That is, after light source control component 210 controls first wavelength light source 161A and second wavelength light source 162A of first sensor 160A and first wavelength light source 161B and second wavelength light source 162B of second sensor 160B, sensor selection component 220 may select a sensor.

[0072] The step of controlling the first wavelength light source 161A and the second wavelength light source 162A of the first sensor 160A and the first wavelength light source 161B and the second wavelength light source 162B of the second sensor 160B by the light source control component 210 (S3100) and the step of selecting a sensor by the sensor selection component 220 (S3200) may be performed periodically. Because the PPG signal sensing ring 100 may move or rotate with respect to the finger, the light source control component 210 may periodically control the first wavelength light source 161A and the second wavelength light source 162A of the first sensor 160A and the first wavelength light source 161B and the second wavelength light source 162B of the second sensor 160B, and the sensor selection component 220 may periodically select a sensor.

[0073] The embodiments disclosed in this disclosure are intended to illustrate, not limit, the technical idea of ​​the disclosure, and such embodiments do not limit the scope of the technical idea of ​​the disclosure. The scope of protection of the disclosure should be interpreted by the following claims, and all technical ideas within the equivalent range should be interpreted as being included in the scope of rights of the disclosure.

Claims

1. An oxygen saturation estimation system using a photoplethysmogram (PPG) signal sensing ring, the system including the PPG signal sensing ring, a terminal, and a server, the server comprising: a signal quality classification component configured to classify the quality of the first wavelength PPG signal and the second wavelength PPG signal as good or bad; an oxygen saturation estimation component configured to estimate oxygen saturation from the first wavelength PPG signal and the second wavelength PPG signal; the first wavelength PPG signal and the second wavelength PPG signal are measured using the PPG signal sensing ring, and the server receives the first wavelength PPG signal and the second wavelength PPG signal from the PPG signal sensing ring via the terminal; the PPG signal sensing ring includes a plurality of sensors at different positions; each of the plurality of sensors configured to measure a first wavelength PPG signal and a second wavelength PPG signal; each of the plurality of sensors includes a first wavelength light source, a second wavelength light source, and a photoelectric conversion device; the terminal includes a sensor selection component configured to select a sensor that measures a combination of a plurality of first wavelength test PPG signals and a plurality of second wavelength test PPG signals having the highest signal quality as a sensor for measuring the first wavelength PPG signal and the second wavelength PPG signal, among the plurality of sensors; the server further includes an oxygen saturation index calculation component configured to calculate an oxygen saturation index; the signal quality classification component classifies the quality of the first wavelength PPG signal and the second wavelength PPG signal as good, and the oxygen saturation index is defined by a ratio of a time during which the oxygen saturation is outside a normal range to a time during which the signal quality classification component classifies the quality of the first wavelength PPG signal and the second wavelength PPG signal as good.

2. 2. The oxygen saturation estimation system using a PPG signal sensing ring according to claim 1, wherein the signal quality of the plurality of test PPG signals is evaluated by at least one of a magnitude of an acceleration signal, a signal-to-noise ratio, and an AC component magnitude to DC component magnitude ratio.

3. 2. The oxygen saturation estimation system of claim 1, wherein the terminal further comprises a light source control component configured to control the first wavelength light source and the second wavelength light source of each of the plurality of sensors so that a DC (direct current) component of each of the plurality of first wavelength test PPG signals measured using the plurality of sensors is within a first predetermined range and a DC component of each of the plurality of second wavelength test PPG signals measured using the plurality of sensors is within a second predetermined range.

4. the control of the first wavelength light source and the second wavelength light source by the light source control component and the selection of a sensor by the sensor selection component are performed sequentially; 4. The oxygen saturation estimation system using a PPG signal sensing ring according to claim 3, wherein the control of the first wavelength light source and the second wavelength light source by the light source control component and the sensor selection by the sensor selection component are performed periodically.

5. receiving a first wavelength PPG signal and a second wavelength PPG signal from a PPG (photoplethysmography) signal sensing device via a terminal; classifying the quality of the first wavelength PPG signal and the second wavelength PPG signal into good or bad; estimating oxygen saturation from the first wavelength PPG signal and the second wavelength PPG signal; calculating an oxygen saturation index; the PPG signal sensing ring includes a plurality of sensors at different positions; each of the plurality of sensors configured to measure a first wavelength PPG signal and a second wavelength PPG signal; each of the plurality of sensors includes a first wavelength light source, a second wavelength light source, and a photoelectric conversion device; the terminal includes a sensor selection component configured to select a sensor that measures a combination of a plurality of first wavelength test PPG signals and a plurality of second wavelength test PPG signals having the highest signal quality as a sensor for measuring the first wavelength PPG signal and the second wavelength PPG signal, among the plurality of sensors; The oxygen saturation index is defined by the ratio of the time during which the quality of the first wavelength PPG signal and the second wavelength PPG signal is classified as good and the oxygen saturation is outside a normal range to the time during which the quality of the first wavelength PPG signal and the second wavelength PPG signal is classified as good. A method for estimating oxygen saturation using a PPG signal sensing ring.

6. 6. The method of claim 5, wherein the signal quality of the plurality of test PPG signals is evaluated based on at least one of a magnitude of an acceleration signal, a signal-to-noise ratio, and an AC component magnitude to DC component magnitude ratio.

7. 6. The method of claim 5, wherein the terminal further comprises a light source control component configured to control the first wavelength light source and the second wavelength light source of each of the plurality of sensors so that a DC (direct current) component of each of the plurality of first wavelength test PPG signals measured using the plurality of sensors is within a first predetermined range and a DC component of each of the plurality of second wavelength test PPG signals measured using the plurality of sensors is within a second predetermined range.

8. the control of the first wavelength light source and the second wavelength light source by the light source control component and the selection of a sensor by the sensor selection component are performed sequentially; 8. The method of claim 7, wherein the control of the first wavelength light source and the second wavelength light source by the light source control component and the sensor selection by the sensor selection component are performed periodically.

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