Apparatus and method for estimating blood pressure, and sensor for estimating blood pressure

Abstract

Disclosed are a device and method for estimating blood pressure, and a sensor for estimating blood pressure. The device includes a sensor and a processor configured to estimate blood pressure based on a PPG signal and a contact pressure signal measured by the sensor. The sensor includes a transparent elastic body; a first polarizer disposed on a surface of the transparent elastic body and configured to contact an object; a light source disposed below the transparent elastic body and configured to emit light toward the object; a first detector disposed below the transparent elastic body and configured to detect light that has passed through the first polarizer after being emitted by the light source and scattered or reflected from the object, to measure a PPG signal; and a second detector disposed below the transparent elastic body and configured to detect light that has not passed through the first polarizer, to measure a contact pressure signal.

Description

[0001] This application claims priority from Korean Patent Application No. 10-2021-0185976 filed on December 23, 2021, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0002] The disclosed example embodiments relate to techniques for estimating blood pressure without the use of a cuff. Background Art

[0003] When observing blood movement on the body surface to identify cardiovascular characteristics, the following two methods are mainly used, including: a method of measuring blood pressure from the skin surface by using a pressure sensor; and a method of measuring changes in blood flow volume (or blood flow) under the skin by using light.

[0004] In the former method, vascular age or cardiovascular health can be estimated by analyzing the shape of the pressure distribution on the skin surface and calculating vascular compliance, etc.

[0005] In the latter method, oxygen saturation can be estimated by estimating the ratio between oxyhemoglobin and deoxyhemoglobin using two or more wavelengths.

[0006] The above two methods measure pressure and volume separately, and therefore are useful in providing information synchronized with the heartbeat. However, if the sensors used in these two methods are configured as a combined sensor, a difference occurs between the position for measuring pressure on the skin surface and the position for measuring blood volume changes, and it may be difficult to manufacture the sensor in a compact size. Summary of the Invention

[0007] According to an example embodiment, there is provided an apparatus for estimating blood pressure, the apparatus comprising: a sensor configured to measure a photoplethysmography (PPG) signal and a contact pressure signal from an object in contact with the sensor; and a processor configured to estimate the blood pressure based on the PPG signal and the contact pressure signal measured by the sensor, wherein the sensor comprises: a transparent elastic body; a first polarizer disposed on a surface of the transparent elastic body and configured to be in contact with the object; a light source disposed below the transparent elastic body and configured to emit light toward the object; a first detector disposed below the transparent elastic body and configured to detect light that passes through the first polarizer after being emitted by the light source and scattered or reflected from the object, to measure the PPG signal; and a second detector disposed below the transparent elastic body and configured to detect light that does not pass through the first polarizer, to measure the contact pressure signal.

[0008] The second detector may be further configured to detect light reflected from the transparent elastomer.

[0009] The sensor may further include a second polarizer disposed above the second detector and configured to block light passing through the first polarizer.

[0010] The polarization direction of the first polarizer may be perpendicular to the polarization direction of the second polarizer.

[0011] The polarization direction of the first polarizer may be a clockwise direction, and the polarization direction of the second polarizer may be a counterclockwise direction.

[0012] The light source, the first detector, the second detector, and the transparent elastic body may be spaced apart from each other by an air gap disposed therebetween.

[0013] The transparent elastomer may include at least one of silicone, styrenic block copolymer, or elastomer.

[0014] The transparent elastomer may have a thickness of 2 mm to 10 mm.

[0015] The processor may be further configured to convert the light intensity, which is measured by the second detector and changes according to the pressure applied to the transparent elastic body, into a contact pressure value.

[0016] The processor may be further configured to obtain an oscillometric waveform envelope based on the PPG signal and the contact pressure signal, and estimate the blood pressure by using the obtained oscillometric waveform envelope.

[0017] The processor can also be configured to obtain at least one characteristic value based on at least one of a first contact pressure value at a maximum amplitude point, a second contact pressure value at a point to the left of the maximum amplitude point having a preset ratio to the first contact pressure value in the oscillometric waveform envelope, or a third contact pressure value at a point to the right of the maximum amplitude point having a preset ratio to the first contact pressure value, and estimate blood pressure based on the at least one characteristic value obtained.

[0018] According to an example embodiment, a sensor is provided, comprising: a transparent elastic body; a first polarizer disposed on a surface of the transparent elastic body and configured to be in contact with an object; a light source disposed below the transparent elastic body and configured to emit light toward the object; a first detector disposed below the transparent elastic body and configured to detect light that passes through the first polarizer after being emitted by the light source and scattered or reflected from the object, to measure a photoplethysmography (PPG) signal; and a second detector disposed below the transparent elastic body and configured to detect light that does not pass through the first polarizer, to measure a contact pressure signal.

[0019] The second detector may be further configured to detect light reflected from the transparent elastomer.

[0020] The sensor may further include: a second polarizer disposed above the second detector and configured to block light passing through the first polarizer.

[0021] The polarization direction of the first polarizer may be perpendicular to the polarization direction of the second polarizer.

[0022] The polarization direction of the first polarizer may be a clockwise direction, and the polarization direction of the second polarizer may be a counterclockwise direction.

[0023] The light source, the first detector, the second detector, and the transparent elastic body may be spaced apart from each other by an air gap disposed therebetween.

[0024] The transparent elastomer may have a thickness of 2 mm to 10 mm.

[0025] According to an example embodiment, there is provided a method for estimating blood pressure by using a sensor, the sensor including a transparent elastomer, a first polarizer disposed on the transparent elastomer, a light source, a first detector, and a second detector, the method including: emitting light toward an object by using a light source disposed below the transparent elastomer; detecting light scattered or reflected from the object and passing through the first polarizer by using the first detector disposed below the transparent elastomer to measure a photoplethysmography (PPG) signal; detecting light that does not pass through the first polarizer by using the second detector disposed below the transparent elastomer to measure a contact pressure signal; and estimating the blood pressure based on the PPG signal and the contact pressure signal.

[0026] The estimating of the blood pressure may include obtaining an oscillometric waveform envelope based on the PPG signal and the contact pressure signal, and estimating the blood pressure by using the obtained oscillometric waveform envelope.

[0027] According to an aspect of example embodiments, there is provided a non-transitory computer-readable storage medium storing instructions that, when executed by a processor, configure the processor to perform a method of estimating blood pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and / or other aspects will become clearer and more readily understood from the following description of example embodiments with reference to the accompanying drawings, in which:

[0029] Figure 1 is a block diagram illustrating an apparatus for estimating blood pressure according to example embodiments.

[0030] Figures 2A to 2E is a diagram illustrating an example of a structure of a sensor in an apparatus for estimating blood pressure according to example embodiments.

[0031] Figure 3A and Figure 3B is a diagram explaining an example of estimating blood pressure based on the oscillometric method.

[0032] Figure 4 is a block diagram illustrating an apparatus for estimating blood pressure according to example embodiments.

[0033] Figure 5 is a flowchart illustrating a method of estimating blood pressure according to example embodiments.

[0034] Figure 6 、 Figure 7 and Figure 8 is a diagram illustrating an example of an electronic device including an apparatus for estimating blood pressure according to example embodiments. DETAILED DESCRIPTION

[0035] The following detailed description and accompanying drawings include details of other embodiments. The advantages and features disclosed herein, as well as the methods for implementing the disclosed embodiments, will be more clearly understood based on the embodiments described in detail below with reference to the accompanying drawings. Throughout the drawings and detailed description, unless otherwise indicated, like reference numerals will be understood to represent like elements, features, and structures. The relative sizes and depictions of these elements may be exaggerated for clarity, illustration, and convenience.

[0036] It should be understood that although the terms first, second, etc. can be used to describe various elements herein, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. Unless otherwise explicitly stated, any reference to the singular may include the plural. In addition, unless explicitly described to the contrary, expressions such as "comprising" or "including" will be understood to imply the inclusion of the elements stated but not to exclude any other elements. In addition, terms such as "unit" or "module" should be understood to be units for performing at least one function or operation and that can be implemented as hardware, software, or a combination thereof.

[0037] Hereinafter, embodiments of an apparatus and method for estimating blood pressure will be described in detail with reference to the accompanying drawings.

[0038] Figure 1 is a block diagram illustrating an apparatus for estimating blood pressure according to example embodiments. Figures 2A to 2E is a diagram illustrating an example of a structure of a sensor in an apparatus for estimating blood pressure according to example embodiments.

[0039] The apparatus 100 for estimating blood pressure can be installed in various devices (such as portable wearable devices, smart devices, etc.). For example, the various devices may include various types of wearable devices (such as smart watches worn on the wrist, smart wristband wearable devices, headphone-type wearable devices, headband-type wearable devices, etc.) and mobile devices (such as smartphones, tablet PCs, etc.), but the devices are not limited to these. The apparatus of this example embodiment can estimate blood pressure among the biometric information. The biometric information that can be estimated may include, for example, heart rate, vascular age, arterial stiffness, aortic pressure waveform, vascular compliance, pressure index, fatigue level, skin elasticity, skin age, etc., but is not limited to this.

[0040] Reference Figure 1 , an apparatus 100 for estimating blood pressure may include a sensor 110 and a processor 120 .

[0041] Sensor 110 may obtain data for estimating blood pressure from a subject, and processor 120 may estimate the subject's blood pressure using the data obtained by sensor 110. Processor 120 and sensor 110 may be electrically connected to each other, and processor 120 may control sensor 110 in response to a request to estimate blood pressure. The subject may be a body part that can be brought into contact with sensor 110, and may be, for example, a body part where a pulse wave can be easily measured using a photoplethysmography (PPG) signal. For example, the subject may be a finger where blood vessels are densely distributed, but is not limited thereto, and may be the surface of the wrist adjacent to the radial artery, the upper part of the wrist where veins or capillaries are located, or a peripheral part of the body (such as a toe).

[0042] Reference Figures 2A to 2E The sensor 110 may include a transparent elastic body 21 , a first polarizer 22 , a light source 23 , a first detector 24 , a second detector 25 , and a second polarizer 26 .

[0043] The transparent elastomer 21 is pressed against the skin where the blood vessels are located (e.g., the wrist) and may include a material for expressing the curvature of the wrist skin. When a predetermined contact pressure is applied to the transparent elastomer 21, the appearance of the transparent elastomer 21 may be changed. For example, the transparent elastomer 21 may include silicone, styrene block copolymer, or thermoplastic elastomer. In addition, the transparent elastomer 21 is formed to be thinner so as to deform along the curvature on the skin surface of the object OBJ. For example, the transparent elastomer 21 may have a thickness of approximately 2 mm to 10 mm. In addition, the transparent elastomer 21 may be formed as a curved surface or a flat surface, but the shape of the transparent elastomer 21 is not limited thereto.

[0044] Reference Figure 2A, the transparent elastic body 21 is disposed above the light source 23, the first detector 24, and the second detector 25; and the light source 23, the first detector 24, the second detector 25, and the transparent elastic body 21 can be separated from each other by an air gap formed therebetween. Figure 2B , the transparent elastic body 21 may be formed in a single layer including the light source 23 , the first detector 24 , and the second detector 25 . For example, the light source 23 , the first detector 24 , and the second detector 25 may be provided in the transparent elastic body 21 .

[0045] The first polarizer 22 may be formed on the surface of the transparent elastic body 21 so as to contact the object OBJ, and the second polarizer 26 may be formed above the second detector 25. The first polarizer 22 and the second polarizer 26 may convert natural light that is incident while vibrating in various directions into polarized light that vibrates only in one direction. Examples of the first polarizer 22 and the second polarizer 26 may include an iodine-based polarizer, a dye-based polarizer, a phase difference polarizer, a transflective polarizer, etc., but the first polarizer and the second polarizer are not limited thereto.

[0046] By using the first polarizer 22 and the second polarizer 26, light that has passed through the first polarizer 22 can be blocked by the second polarizer 26. For example, the polarization direction of the first polarizer 22 is perpendicular to the polarization direction of the second polarizer 26, so that light that has passed through the first polarizer 22 can be blocked by the second polarizer 26. For example, the first polarizer 22 can polarize light at zero degrees, and the second polarizer 26 can polarize light at 90 degrees. Alternatively, the polarization direction of the first polarizer 22 can be clockwise, and the polarization direction of the second polarizer 26 can be counterclockwise, so that light that has passed through the first polarizer 22 can be blocked by the second polarizer 26. However, the disclosure is not limited to the above examples.

[0047] The light source 23 may be disposed below the transparent elastic body 21 to emit light toward the object OBJ. The light source 23 may include a light emitting diode (LED), a laser diode (LD), a phosphor, or the like, and may emit light in the near infrared (NIR) range or the mid-infrared (MIR) range. The wavelength range of the emitted light is not limited thereto.

[0048] The first detector 24 and the second detector 25 can measure the spectrum by detecting light. The first detector 24 and the second detector 25 may include one or more pixels, each of which may include a photodiode, a phototransistor (PTr), an image sensor (e.g., a complementary metal oxide semiconductor (CMOS) image sensor), etc., but is not limited thereto. In addition, the sensor 110 can be formed with an array of multiple light sources and / or an array of multiple detectors for measuring two or more biosignals (e.g., PPG signals). In this case, the multiple light sources may emit light of different wavelengths. Each light source may be placed at a different distance from the detector. For ease of explanation, a description will be given below of an example in which the sensor 110 includes one light source 23, the first detector 24, and the second detector 25.

[0049] When the light source 23 emits light toward the skin of the user as the object OBJ according to the control signal of the processor 120, the emitted light passes through the user's skin to reach the body tissue, and the light reaching the body tissue is scattered or reflected from the user's body tissue and returned through the skin.

[0050] The first detector 24 may measure a PPG signal by detecting light returning through the user's skin.

[0051] Reference Figure 2C When light source 23 emits light toward the user's skin as object OBJ, the emitted light may pass through the user's skin and reach body tissue (e.g., radial artery). The light reaching the body tissue is scattered or reflected from the user's body tissue and returns through the user's skin, where the light may return after passing through first polarizer 22 formed on the surface of transparent elastic body 21. In this case, first detector 24 may detect polarized light 27 that has passed through first polarizer 22 and measure a PPG signal using the detected polarized light 27.

[0052] The first detector 24 may also detect light reflected from the transparent elastic body 21. In this case, the processor 120 may remove the light reflected from the transparent elastic body 21 by performing preprocessing for removing noise, such as filtering (e.g., bandpass filtering), thereby minimizing the influence of light that does not include a biological signal.

[0053] The second detector 25 may be disposed under the transparent elastic body 21 and may measure a contact pressure signal by detecting light passing through the first polarizing plate 22 .

[0054] Reference Figure 2DWhen the light source 23 emits light toward the skin of a user serving as object OBJ, the emitted light passes through the user's skin and reaches the body tissue. The light reaching the body tissue may be scattered or reflected from the user's body tissue and return through the user's skin, wherein the light may return after passing through the first polarizer 22 formed on the surface of the transparent elastic body 21. In this case, the light 28 that has passed through the first polarizer 22 may be blocked by the second polarizer 26 formed above the second detector 25. For example, the polarization direction of the first polarizer 22 may be perpendicular to the polarization direction of the second polarizer 26, or the polarization direction of the first polarizer 22 may be clockwise, and the polarization direction of the second polarizer 26 may be counterclockwise. In this arrangement, the light 28 including the biosignal may be blocked by the second polarizer 26 and, therefore, not detected by the second detector 25.

[0055] The second detector 25 can detect light 29 reflected from the transparent elastic body 21. For example, the light 29 emitted by the light source 23 and reflected from the transparent elastic body 21 passes through the second polarizing plate 26 formed above the second detector 25. Therefore, the second detector 25 can detect the polarized light 29 that passed through the second polarizing plate 26 and can measure the contact pressure signal by using the detected polarized light 29.

[0056] Figure 2E is a diagram showing the structure of the sensor 110 when pressure is applied to the transparent elastic body 21 .

[0057] Figure 2D shows a state where the object OBJ is in contact with the transparent elastic body 21, and Figure 2E An example is shown in which the object OBJ applies downward pressure so that the transparent elastic body 21 becomes convex downward.

[0058] Reference Figure 2D and Figure 2E ,exist Figure 2E The optical path length of the light reflected from the transparent elastic body 21 and detected by the second detector 25 is shorter than that in Figure 2D The corresponding optical path length of the light in . Therefore, it can be seen that Figure 2E The intensity of the light detected by the second detector 25 is greater than that in Figure 2D The intensity of light detected by the second detector 25 is measured. That is, the transparent elastic body 21 is deformed by the change in pressure applied to the transparent elastic body 21, and the second detector 25 can measure the change in light intensity according to the change in pressure, and can measure the change in contact pressure based on the change in the intensity of light detected by the second detector 25.

[0059] In the related art, blood pressure is typically measured using an optical sensor and a pressure sensor. In this case, compact manufacturing is difficult, and the sensors are spaced apart from each other, making it impossible to measure a biosignal and a pressure signal at the same location. To address this issue, example embodiments provide a compact device that includes only an optical sensor without a separate pressure sensor, and that simultaneously measures a biosignal and a pressure signal at the same location.

[0060] Return to reference Figure 1 , the processor 120 may estimate the blood pressure by using the PPG signal and the contact pressure signal measured by the sensor 110 .

[0061] For example, the processor 120 may obtain an oscillometric waveform envelope based on the PPG signal and the contact pressure signal, and may estimate blood pressure by using the obtained oscillometric waveform envelope.

[0062] Figure 3A and Figure 3B is a diagram explaining an example of estimating blood pressure based on the oscillometric method.

[0063] Figure 3A is a diagram showing changes in the amplitude of a PPG signal when an object placed on the sensor 110 gradually increases pressing force. Figure 3B is a diagram showing an oscillometric waveform envelope OW indicating the relationship between changes in contact pressure and the amplitude of a PPG signal. In this case, the contact pressure may be a value obtained by converting the light intensity, which is measured by the second detector 25 and changes according to the pressure applied to the transparent elastic body 21, into a contact pressure value using a predefined conversion equation.

[0064] For example, the processor 120 may extract the peak-to-peak point by subtracting the negative (-) amplitude value in3 from the positive (+) amplitude value in2 of the waveform envelope in1 of the pulse wave signal at each measurement time point. Furthermore, the processor 120 may obtain the oscillometric waveform envelope OW by plotting the peak-to-peak amplitude at each measurement time point against the contact pressure value at the corresponding time point and performing, for example, polynomial curve fitting.

[0065] The processor 120 can estimate, for example, blood pressure using the generated oscillometric waveform envelope OW. The processor 120 can estimate mean arterial pressure (MAP) based on the contact pressure value MP at the maximum point MA of the pulse wave in the waveform graph. For example, the processor 120 can determine the contact pressure value MP at the maximum point MA of the pulse wave itself as the MAP, or can obtain the MAP from the contact pressure value MP using a predefined MAP estimation equation. In this case, the MAP estimation equation can be expressed in the form of various linear or nonlinear combination functions (e.g., addition, subtraction, division, multiplication, logarithm, regression equation, etc.), without particular limitation.

[0066] Furthermore, processor 120 may obtain at least one of the following as a characteristic value: a contact pressure value at the maximum amplitude point in the oscillometric waveform envelope, and contact pressure values ​​at points to the left and right of the maximum amplitude point that have a preset ratio to the contact pressure value at the maximum amplitude point, and may estimate blood pressure based on the obtained characteristic value. For example, processor 120 may estimate diastolic and systolic pressures using contact pressure values ​​DP and SP, respectively, located at points to the left and right of the maximum point MA of the pulse wave and corresponding to amplitude values ​​that have a preset ratio (e.g., 0.5 to 0.7) to the amplitude value at the maximum point MA of the pulse wave. Processor 120 may determine contact pressure values ​​DP and SP as diastolic and systolic pressures, respectively, or may estimate diastolic and systolic pressures from the corresponding contact pressure values ​​DP and SP using predefined diastolic and systolic pressure estimation equations.

[0067] Figure 4 is a block diagram illustrating an apparatus for estimating blood pressure according to example embodiments.

[0068] Reference Figure 4 , the apparatus 400 for estimating blood pressure may include a sensor 410, a processor 420, an output interface 430, a storage device 440, and a communication interface 450. The sensor 410 and the processor 420 are connected to Figure 1 The sensor 110 and the processor 120 in the embodiment are the same, so their detailed description will be omitted.

[0069] The output interface 430 may provide the user with the processing result of the processor 420. For example, the output interface 430 may display the estimated blood pressure value of the processor 420 on a display. In this case, if the estimated blood pressure value falls outside the normal range, the output interface 430 may provide a warning message to the user by changing the color, line width, etc. or displaying the abnormal value together with the normal range, so that the user can easily identify the abnormal value. In addition, together with or without visual output, the output interface 430 may use an audio output module (such as a speaker) or a tactile module to provide the user with the estimated blood pressure value in a non-visual manner through voice, vibration, touch, etc.

[0070] In addition, the output interface 430 can visually display the blood pressure estimation process and the results of the blood pressure estimation process performed by the processor 420 in a manner such as a graph. In addition, if the measured blood pressure is of poor quality (e.g., has low reliability), the output interface 430 can guide the user to remeasure the blood pressure, additionally measure the blood pressure, or terminate the blood pressure estimation.

[0071] The storage device 440 may store information related to the estimated blood pressure. For example, the storage device 440 may store the PPG signal acquired by the sensor 410, the processing result of the processor 420 (eg, the estimated blood pressure value), the contact pressure conversion model, etc.

[0072] The storage device 440 may include at least one storage medium selected from the group consisting of a flash memory, a hard disk memory, a multimedia card micro memory, a card-type memory (for example, an SD memory, an XD memory, etc.), a random access memory (RAM), a static random access memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a programmable read-only memory (PROM), a magnetic memory, a magnetic disk, and an optical disk, but is not limited thereto.

[0073] The communication interface 450 can communicate with an external device to transmit and receive various data related to the estimated blood pressure to and from the external device. The external device may include an information processing device (such as a smartphone, tablet PC, desktop computer, laptop computer, etc.). For example, the communication interface 450 can transmit the blood pressure estimation results to an external device (such as a user's smartphone), allowing the user to manage and monitor the estimation results using a relatively high-performance device. In addition, if the external device includes a sensor for measuring blood pressure, the communication interface 450 can receive a PPG signal from the external device.

[0074] The communication interface 450 may communicate with an external device by using various wired or wireless communication technologies, such as Bluetooth communication, Bluetooth Low Energy (BLE) communication, near field communication (NFC), WLAN communication, Zigbee communication, infrared data association (IrDA) communication, Wi-Fi Direct (WFD) communication, ultra-wideband (UWB) communication, Ant+ communication, WIFI communication, radio frequency identification (RFID) communication, 3G communication, 4G communication, and 5G communication, etc. However, this is merely an example and is not intended to be limiting.

[0075] Figure 5 is a flowchart illustrating a method of estimating blood pressure according to example embodiments.

[0076] Figure 5 The method can be based on Figure 1 and Figure 4

[0046] The present invention provides an example of a method of estimating blood pressure performed by the apparatuses 100 and 400 for estimating blood pressure according to the embodiments of the present invention. Various embodiments thereof have been described in detail above, and thus, will be briefly described below.

[0077] First, in 510, the apparatus for estimating blood pressure may emit light toward a subject using a light source disposed below a transparent elastomer. For example, the transparent elastomer may be disposed above the light source, a first detector, and a second detector; and the light source, the first detector, the second detector, and the transparent elastomer may be separated from each other by an air gap formed therebetween. Furthermore, the transparent elastomer may include at least one of silicone, a styrenic block copolymer, and a thermoplastic elastomer, and may have a thickness of 2 mm to 10 mm. Furthermore, the transparent elastomer may have a curved surface or a flat surface. The shape of the transparent elastomer is not limited thereto.

[0078] Then, in 520 , the apparatus for estimating blood pressure may measure a PPG signal by detecting light scattered or reflected from the object and passing through the first polarizer using a first detector disposed under the transparent elastic body.

[0079] In 530, the apparatus for estimating blood pressure can measure a contact pressure signal by detecting light that has not passed through the first polarizer using a second detector disposed below the transparent elastic body. For example, by using a second polarizer formed above the second detector, the apparatus for estimating blood pressure can block light that has passed through the first polarizer and detect light reflected from the transparent elastic body using the second detector. For example, the polarization direction of the first polarizer can be perpendicular to the polarization direction of the second polarizer, or the polarization direction of the first polarizer can be clockwise and the polarization direction of the second polarizer can be counterclockwise, so that light that has passed through the first polarizer can be blocked by the second polarizer 26. The transparent elastic body deforms in response to changes in pressure applied to the transparent elastic body, and the second detector can measure changes in light intensity in response to the changes in pressure. Changes in contact pressure can be measured based on changes in the intensity of light detected by the second detector.

[0080] Next, at 540, the apparatus for estimating blood pressure may estimate the blood pressure based on the measured PPG signal and the contact pressure signal. For example, the apparatus for estimating blood pressure may obtain an oscillometric waveform envelope based on the PPG signal and the contact pressure signal, and estimate the blood pressure using the obtained oscillometric waveform envelope. In this case, the contact pressure may be a value obtained by converting the light intensity, which is measured by the second detector and changes according to the pressure applied to the transparent elastic body, into a contact pressure value using a predefined conversion equation.

[0081] The device for estimating blood pressure can obtain at least one of the following as characteristic values: the contact pressure value at the maximum amplitude point in the oscillometric waveform envelope, and the contact pressure values ​​at the left and right points of the maximum amplitude point that have a preset ratio to the contact pressure value at the maximum amplitude point, and can estimate the blood pressure based on the obtained characteristic values.

[0082] Figures 6 to 8 is a diagram illustrating an example of an electronic device including an apparatus for estimating blood pressure according to example embodiments.

[0083] Figure 6 is a diagram illustrating a wearable device according to an example embodiment. The aforementioned embodiments of the apparatuses 100 and 400 for estimating blood pressure may be installed in the wearable device.

[0084] Reference Figure 6 , the wearable device 600 may include a main body 610 and a band 630.

[0085] The strap 630 can be connected to both ends of the body 610 and can be flexible so as to wrap around the user's wrist. The strap 630 can include a first strap and a second strap that are separate from each other. One end of the first strap and the second strap are connected to the body 610, and the other ends of the first strap and the second strap can be connected to each other via a fastening device. The fastening device can include, but is not limited to, magnetic fastening, Velcro fastening, pin fastening, etc. Furthermore, the strap 630 is not limited to this and can be integrally formed as a non-detachable strap.

[0086] In this case, air may be injected into the band 630 , or the band 630 may be provided with an air bag so as to have elasticity according to a change in pressure applied to the wrist, and the change in pressure of the wrist may be transmitted to the body 610 .

[0087] A battery may be embedded in the body 610 or the band 630 to supply power to the wearable device 600 .

[0088] Furthermore, sensor 620 may be mounted on one side of body 610. When an object is placed on sensor 620, sensor 620 may measure a PPG signal and a contact pressure signal. Sensor 620 may include a transparent elastic body, a first polarizer formed on a surface of the transparent elastic body and in contact with the object, a light source disposed below the transparent elastic body and emitting light from the object, a first detector disposed below the transparent elastic body and detecting light emitted by the light source and scattered or reflected from the object to measure the PPG signal, and a second detector disposed below the transparent elastic body and detecting light that has not passed through the first polarizer to measure the contact pressure signal.

[0089] The processor may be installed in the body 610. The processor may be electrically connected to the components installed in the wearable device 600. As described above, the processor may estimate the blood pressure by using the PPG signal and the contact pressure signal measured by the sensor 620. For example, the processor may obtain an oscillometric waveform envelope based on the PPG signal and the contact pressure signal, and estimate the blood pressure by using the obtained oscillometric waveform envelope. In this case, the processor may obtain at least one of the following as a characteristic value: a contact pressure value at a maximum amplitude point in the oscillometric waveform envelope, and contact pressure values ​​at points to the left and right of the maximum amplitude point having a preset ratio to the contact pressure value at the maximum amplitude point, and may estimate the blood pressure based on the obtained characteristic value.

[0090] The memory may be included in the body 610 and may store reference information for estimating blood pressure and for performing various functions of the wearable device 600 , as well as information processed by various components.

[0091] In addition, the wearable device 600 may include a manipulator 640, which is installed on one side of the body 610 and is configured to receive a user's control command and send the received control command to the processor. The manipulator 640 may have a function of inputting a command for turning the wearable device 600 on / off.

[0092] A display for outputting information to the user may be provided on the front surface of the main body 610. The display may include a touch screen for receiving touch input. The display may receive the user's touch input and send the touch input to the processor, and may display the processing result of the processor.

[0093] In addition, the wearable device 600 may include a communication interface for communicating with an external device. The communication interface may transmit the blood pressure estimation result to the external device (eg, the user's smartphone).

[0094] Figure 7 is a diagram illustrating a smart device according to an exemplary embodiment. In this case, the smart device may include a smart phone, a tablet PC, etc. The smart device may have the functions of the aforementioned apparatuses 100 and 400 for estimating biometric information.

[0095] Reference Figure 7 , the smart device 700 includes a main body 710 and a sensor 730 mounted on one surface of the main body 710. For example, the sensor 730 may include one or more light sources 732 disposed at predetermined locations thereof. The one or more light sources 732 may emit light of different wavelengths. Furthermore, in order to measure pulse wave signals at multiple points on a subject, a plurality of light receivers 731 may be positioned at predetermined distances from the light sources 732. However, this is merely an example, and the sensor 730 may be arranged in various shapes, as described above.

[0096] Furthermore, when an object is placed on the sensor 730, the sensor 730 can measure a PPG signal and a contact pressure signal. The sensor 730 may include a transparent elastic body, a first polarizer formed on a surface of the transparent elastic body and in contact with the object, a light source disposed below the transparent elastic body and emitting light to the object, a first detector disposed below the transparent elastic body and detecting light emitted by the light source and scattered or reflected from the object to measure the PPG signal, and a second detector disposed below the transparent elastic body and detecting light that has not passed through the first polarizer to measure the contact pressure signal.

[0097] In addition, a display may be mounted on the front surface of the body 710. The display may visually output blood pressure estimation results, health status assessment results, etc. The display may include a touch screen, and may receive information input through the touch screen and transmit the information to the processor.

[0098] The body 710 may include Figure 7 . The image sensor 720 can capture various images, and when a user's object (e.g., a finger) approaches the sensor 730, the image sensor 720 can capture an image of the finger. In the case where a contact image sensor (CIS image sensor) is installed in the light receiver 731 of the sensor 730, the image sensor 720 can be omitted.

[0099] As described above, the processor may estimate bio-information based on the PPG signal and the contact pressure signal measured by the sensor 730. A detailed description thereof will be omitted.

[0100] In addition, when the user sends a request for estimating blood pressure by executing an application installed in the smart device 700, the smart device 700 can obtain data by using the sensor 730, and can estimate the blood pressure and provide the estimated value to the user as an image and / or sound by using the processor in the smart device 700.

[0101] Figure 8 is a diagram illustrating an electronic device according to an example embodiment. Figure 8 , the electronic device can be implemented as a combination of a wristwatch-type wearable device 810 and a smart phone 800. For example, a processor for estimating blood pressure can be installed in the body of the smart phone 800. Upon receiving a request to estimate blood pressure, the processor of the smart phone 800 can communicate with a communication interface installed in the body of the wearable device 810 to obtain data through the communication interface. In addition, upon receiving data (such as a PPG signal, a contact pressure signal, etc.) from the wearable device 810, the processor of the smart phone 800 can estimate the blood pressure and can output the estimation result to the display of the smart phone 800 through the output interface, as shown here. In this case, in response to the user's request, the processor can display not only the current estimated blood pressure value on the display, but also the continuous estimated blood pressure values ​​over time on the display to provide the values ​​to the user.

[0102] The disclosure is implemented as computer-readable codes written on a computer-readable recording medium. The computer-readable recording medium may be any type of recording device that stores data in a computer-readable manner.

[0103] Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage device, and carrier wave (e.g., data transmission via the Internet). Computer-readable recording media can be distributed across multiple computer systems connected to a network so that computer-readable code can be written therein and executed therefrom in a decentralized manner. Programmers having ordinary skill in the art can easily derive the functional programs, codes, and code segments required to implement the disclosed exemplary embodiments.

[0104] According to example embodiments, at least one of the components, elements, modules, and units (collectively referred to as "components" in this paragraph) represented by the blocks in the accompanying drawings may be implemented as various numbers of hardware, software, and / or firmware structures that perform the corresponding functions described above. According to example embodiments, at least one of these components may use a direct circuit structure (such as a memory, a processor, a logic circuit, a lookup table, etc.) that can be controlled by one or more microprocessors or other control devices to perform the corresponding functions. In addition, at least one of these components may be specifically implemented by a module, a program, or a portion of code that contains one or more executable instructions for performing a specific logical function and is executed by one or more microprocessors or other control devices. In addition, at least one of these components may include a processor (such as a central processing unit (CPU), a microprocessor, etc. that performs the corresponding functions) or may be implemented by a processor (such as a central processing unit (CPU), a microprocessor, etc. that performs the corresponding functions). Two or more of these components may be combined into a single component that performs all the operations or functions of the combined two or more components. In addition, at least a portion of the functions of at least one of these components may be performed by another of these components. The functional aspects of the above example embodiments may be implemented in an algorithm that is executed on one or more processors. Furthermore, components represented by blocks or processing steps may employ any number of related techniques for electronics configuration, signal processing and / or control, data processing and the like.

[0105] The disclosure has been described herein with reference to example embodiments. However, it will be apparent to those skilled in the art that various changes and modifications may be made without altering the technical concepts and essential features of the disclosure. Therefore, it is clear that the above-described embodiments are illustrative in all respects and are not intended to limit the disclosure.

Claims

1. A device for estimating blood pressure, the device comprising: a sensor configured to: measure a photoplethysmographic signal and a contact pressure signal from an object in contact with the sensor; as well as a processor configured to estimate blood pressure based on the photoplethysmographic signal and the contact pressure signal measured by the sensor, The sensors include: Transparent elastomer; a first polarizer disposed on a surface of the transparent elastic body and configured to be in contact with the object; a light source disposed below the transparent elastic body and configured to emit light toward the object; a first detector disposed below the transparent elastic body and configured to: detect light that has passed through the first polarizer after being emitted by the light source and scattered or reflected from the object to measure a photoplethysmographic signal; a second polarizer configured to block light passing through the first polarizer; and The second detector is disposed below the transparent elastic body and is configured to detect the light that has not passed through the first polarizer to measure a contact pressure signal.

2. The device according to claim 1, wherein The second detector is further configured to detect light reflected from the transparent elastomer.

3. The device according to claim 1, wherein The second polarizer is disposed above the second detector.

4. The device according to claim 3, wherein The polarization direction of the first polarizer is perpendicular to the polarization direction of the second polarizer.

5. The apparatus according to claim 3, wherein The polarization direction of the first polarizer is clockwise, and the polarization direction of the second polarizer is counterclockwise.

6. The apparatus according to claim 1, wherein The light source, the first detector, the second detector, and the transparent elastic body are spaced apart from each other by an air gap disposed therebetween.

7. The apparatus according to claim 1, wherein The transparent elastomer includes at least one of silicone resin, styrenic block copolymer, and thermoplastic elastomer.

8. The apparatus according to claim 1, wherein The transparent elastic body has a thickness of 2 mm to 10 mm.

9. The device according to any one of claims 1 to 8, wherein: The processor is further configured to convert the light intensity, which is measured by the second detector and changes according to the pressure applied to the transparent elastic body, into a contact pressure value.

10. The apparatus according to any one of claims 1 to 8, wherein: The processor is further configured to obtain an oscillometric waveform envelope based on the photoplethysmographic signal and the contact pressure signal, and estimate the blood pressure by using the obtained oscillometric waveform envelope.

11. The apparatus according to claim 10, wherein The processor is also configured to obtain at least one characteristic value based on at least one of a first contact pressure value at a maximum amplitude point, a second contact pressure value at a left point of the maximum amplitude point having a preset ratio to the first contact pressure value in the oscillometric waveform envelope, and a third contact pressure value at a right point of the maximum amplitude point having a preset ratio to the first contact pressure value, and estimate blood pressure based on the at least one obtained characteristic value.

12. A sensor comprising: Transparent elastomer; a first polarizer disposed on a surface of the transparent elastic body and configured to be in contact with the object; a light source disposed below the transparent elastic body and configured to emit light toward the object; a first detector disposed below the transparent elastic body and configured to: detect light that has passed through the first polarizer after being emitted by the light source and scattered or reflected from the object to measure a photoplethysmographic signal; a second polarizer configured to block light passing through the first polarizer; as well as The second detector is disposed below the transparent elastic body and is configured to detect the light that has not passed through the first polarizer to measure a contact pressure signal.

13. The sensor according to claim 12, wherein The second detector is further configured to detect light reflected from the transparent elastomer.

14. The sensor according to claim 12, wherein The second polarizer is disposed above the second detector.

15. The sensor according to claim 14, wherein The polarization direction of the first polarizer is perpendicular to the polarization direction of the second polarizer.

16. The sensor according to claim 14, wherein The polarization direction of the first polarizer is clockwise, and the polarization direction of the second polarizer is counterclockwise.

17. The sensor according to claim 12, wherein The light source, the first detector, the second detector, and the transparent elastic body are spaced apart from each other by an air gap disposed therebetween.

18. The sensor according to claim 12, wherein The transparent elastic body has a thickness of 2 mm to 10 mm.

19. A method for estimating blood pressure by using a sensor, the sensor comprising a transparent elastic body, a first polarizer disposed on the transparent elastic body, a light source, a first detector, a second polarizer, and a second detector, the method comprising: emitting light toward the object by using a light source disposed below the transparent elastic body; measuring a photoplethysmographic signal by detecting light scattered or reflected from the object and passing through the first polarizer using a first detector disposed below the transparent elastic body; blocking light passing through the first polarizer by using a second polarizer; measuring a contact pressure signal by detecting light that has not passed through the first polarizer using a second detector disposed below the transparent elastic body; as well as Blood pressure is estimated based on the photoplethysmographic signal and the contact pressure signal.

20. The method according to claim 19, wherein The step of estimating the blood pressure includes obtaining an oscillometric waveform envelope based on the photoplethysmography signal and the contact pressure signal, and estimating the blood pressure by using the obtained oscillometric waveform envelope.

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