Apparatus and method for measuring biological information

Abstract

According to one aspect, an apparatus for measuring biological information may include: a pulse wave sensor configured to have a circular contact surface protruding toward a contact surface of an object of interest and in contact with the object of interest, and measuring one or more pulse wave signals from the object in contact with the contact surface; a force sensor disposed below or on a side of the pulse wave sensor and configured to measure a contact force of the object; and a processor configured to estimate the biological information of the object based on the measured one or more pulse wave signals and the measured contact force.

Description

Technical Field

[0001] The following description relates to an apparatus and method for measuring biological information. Background Art

[0002] The pressurized cuff-based method is used for general blood pressure measurement. The pressurized cuff-based method is a discontinuous measurement method in which a cuff is used to tighten the blood vessel to the maximum blood pressure and is loosened to measure the blood pressure. The pressurized cuff-based method is not easily applied to portable devices due to the configuration of a pressurizing pump, etc.

[0003] Recently, a blood pressure measuring device for measuring blood pressure using a non-pressurized cuffless method without using a cuff has been studied. For example, there are blood pressure measuring devices based on pulse transit time (PTT) and blood pressure measuring devices based on pulse wave analysis (PWA). The inconvenience of the PTT method is that correction must be performed on each person for accurate measurement. In addition, since biological signals must be measured at two or more locations in order to measure the pulse wave velocity, it is difficult to construct a compact device. On the other hand, the PWA method estimates blood pressure only by analyzing the pulse waveform, so it is susceptible to noise and has limitations in accurate blood pressure measurement. Summary of the invention

[0004] Technical issues

[0005] The following description relates to an apparatus and method for measuring biological information.

[0006] Technical Solution

[0007] In one general aspect, an apparatus for measuring biological information includes: a pulse wave sensor configured to have a curved contact surface that protrudes toward a contact surface of an object of interest and contacts the object of interest, and to measure one or more pulse wave signals from the object in contact with the contact surface; a force sensor disposed below or on a side of the pulse wave sensor and configured to measure a contact force of the object; and a processor configured to estimate the biological information of the object based on the measured one or more pulse wave signals and the measured contact force.

[0008] The pulse wave sensor may include: a housing having a curved contact surface; and a pulse wave measurer installed in the housing and configured to measure the one or more pulse wave signals from an object in contact with the contact surface.

[0009] The housing may be formed in a semi-cylindrical shape, a semi-ellipsoidal shape, or a hemispherical shape.

[0010] The housing may be formed to have a size smaller than that of a finger.

[0011] The housing may be formed to have a size smaller than an average finger size of a plurality of users.

[0012] The housing may have a first radius of curvature R of not less than 2 mm and not more than 10 mm. 1 and not less than 0.5×R 1 And not more than 4×R 1 The second radius of curvature R 2 .

[0013] The housing may have a surface roughness of 1.6 μm or less.

[0014] The housing may have a stiffness of 0.5 GPa or greater.

[0015] The housing may be formed in a semi-cylindrical or semi-ellipsoidal shape having a length greater than 0 and equal to or less than 16 mm.

[0016] The pulse wave signal may be a photoplethysmography (PPG) signal.

[0017] The pulse wave measurer may include: one or more light sources configured to emit light to an object of interest; and a photodetector configured to receive light returned from the object and measure the one or more pulse wave signals.

[0018] The processor may acquire an oscillometric waveform using the one or more pulse wave signals and the contact force, and estimate bio-information by analyzing changes in the oscillometric waveform.

[0019] The processor may select one or more pulse wave signals from among the one or more pulse wave signals, and acquire an oscillometric waveform using the selected one or more pulse wave signals and the contact force.

[0020] The processor may select one or more pulse wave signals based on at least one of a maximum amplitude value of each pulse wave signal, an average amplitude value, and a difference between a maximum amplitude value and a minimum amplitude value of each pulse wave signal.

[0021] The processor may generate and provide contact pressure guidance information based on the measured contact force during the measurement of the plurality of pulse wave signals.

[0022] The biological information may be blood pressure.

[0023] The apparatus for measuring bio-information may not include a contact area sensor that measures a contact area with the object of interest.

[0024] In another general aspect, a method of measuring biological information includes: measuring one or more pulse wave signals from an object of interest in contact with a contact surface of a pulse wave sensor, wherein the contact surface of the pulse wave sensor is a curved surface convex toward a contact surface of the object of interest; measuring a contact force between the pulse wave sensor and the object; and estimating the biological information of the object based on the measured one or more pulse wave signals and the measured contact force.

[0025] The pulse wave signal may be a PPG signal.

[0026] The step of measuring the one or more pulse wave signals may include: emitting light to the subject; and measuring the one or more pulse wave signals by receiving light returned from the subject.

[0027] The step of estimating the bio-information may include: acquiring an oscillometric waveform using the one or more pulse wave signals and the contact force; and estimating the bio-information by analyzing a change in the oscillometric waveform.

[0028] The step of acquiring the oscillometric waveform may include: selecting one or more pulse wave signals from among the one or more pulse wave signals; and acquiring the oscillometric waveform using the selected one or more pulse wave signals and the contact force.

[0029] The step of selecting one or more pulse wave signals may include selecting the one or more pulse wave signals based on at least one of a maximum amplitude value, an average amplitude value, and a difference between a maximum amplitude value and a minimum amplitude value of each pulse wave signal.

[0030] The method may further include generating and providing contact pressure guide information based on the measured contact force during the measurement of the plurality of pulse wave signals.

[0031] The biological information may be blood pressure.

[0032] Beneficial Effects

[0033] By forming the contact surface of the pulse wave sensor into a curved surface, the pulse wave signal can be measured more accurately, thereby improving the accuracy of estimating biological information. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a diagram illustrating an apparatus for measuring biological information according to an embodiment of the present disclosure.

[0035] Figure 2 is a diagram showing one example of the structure of a housing.

[0036] Figure 3 is a diagram showing another example of the structure of the housing.

[0037] Figure 4 is a diagram showing still another example of the structure of the housing.

[0038] Figure 5 is a diagram for describing the dimensions of a housing.

[0039] Figure 6a is a diagram for describing the relationship between contact pressure and contact force when the pulse wave sensor is formed in a hemispherical shape.

[0040] Figure 6b is a diagram for describing the relationship between contact pressure and contact force when the pulse wave sensor is formed in a semi-cylindrical shape.

[0041] Figure 7a A graph showing an example of an oscillometric waveform is shown.

[0042] Figure 7b A graph showing an example of an oscillometric pulse wave signal and contact force is shown.

[0043] Figure 7c A graph showing that data regarding contact force values ​​and diastolic pressure values ​​acquired from a plurality of objects of interest are plotted as XY coordinates.

[0044] Figure 7d A graph in which data on contact force values ​​and systolic pressure values ​​acquired from a plurality of objects of interest are plotted as XY coordinates.

[0045] Figure 8a is a diagram showing an example of a pulse wave measuring device.

[0046] Figure 8b is a diagram showing another example of the pulse wave measurement device.

[0047] Figure 8c is a diagram showing still another example of the pulse wave measuring device.

[0048] Figure 9a is a diagram showing an example of the arrangement of a light source and a photodetector when the pulse wave sensor is formed in a semi-cylindrical shape.

[0049] Figure 9b is a diagram showing an example of the arrangement of a light source and a photodetector when the pulse wave sensor is formed in a semi-ellipsoidal shape.

[0050] Fig.9c is a diagram showing an example of the arrangement of a light source and a photodetector when the pulse wave sensor is formed in a hemispherical shape.

[0051] Fig.10 is a diagram illustrating an apparatus for measuring biological information according to another embodiment of the present disclosure.

[0052] Fig.11 is a diagram showing an example to which a device for measuring biological information is applied.

[0053] Fig.12 is a diagram showing another example to which the apparatus for measuring biological information is applied.

[0054] Fig.13 is a diagram showing still another example to which the device for measuring biological information is applied.

[0055] Fig.14 is a diagram showing still another example to which the device for measuring biological information is applied.

[0056] Fig.15 is a diagram showing still another example to which the device for measuring biological information is applied.

[0057] Fig.16 is a diagram showing another example to which the apparatus for measuring biological information is applied.

[0058] Fig.17 is a diagram showing another example to which the apparatus for measuring biological information is applied.

[0059] Fig.18 is a flowchart illustrating a method of measuring biological information according to one embodiment of the present disclosure.

[0060] Throughout the drawings and detailed description, unless otherwise described, the same drawing reference numerals will be understood to refer to the same elements, features, and structures. For clarity, illustration, and convenience, the relative sizes and descriptions of these elements may be exaggerated. DETAILED DESCRIPTION

[0061] In the following description, the same reference numerals are used for the same elements even in different drawings. The matters defined in the description, such as detailed construction and elements, are provided to help fully understand the exemplary embodiments. However, it is clear that the exemplary embodiments can be practiced without those specifically defined matters.

[0062] It should be noted that in some alternative implementations, the functions / actions indicated in the blocks may not occur in the order indicated in the flow chart. For example, depending on the functions / actions involved, two blocks shown in succession may actually be performed substantially simultaneously, or these blocks may sometimes be performed in reverse order.

[0063] As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. It will also be understood that the terms "comprise" or "include" when used in this specification indicate the presence of the recited features, quantities, steps, operations, elements, components, or combinations thereof, but do not exclude the presence or addition of one or more other features, quantities, steps, operations, elements, components, or combinations thereof.

[0064] It will also be understood that the elements or components in the following description are distinguished according to their respective primary functions. In other words, two or more elements may be formed into one element, or one element may be divided into two or more elements, according to the subdivided functions. In addition, each element in the following description may perform part or all of the functions of another element as well as its primary function, and some of the primary functions of each element may be performed exclusively by other elements. Each element may be implemented in the form of a hardware component, a software component, and / or a combination thereof.

[0065] Figure 1 is a diagram illustrating an apparatus for measuring biological information according to an embodiment of the present disclosure. Figures 2 to 4 is a diagram showing an example of the structure of a housing. Figure 5 is a diagram used to describe the dimensions of the housing. Figure 6a and Figure 6b is a diagram for describing the relationship between contact pressure and contact force according to the structure of the pulse wave sensor. Figure 7a A graph showing an example of an oscillometric waveform is shown, Figure 7b A graph showing an example of a pulse wave signal and a contact force showing an oscillometric waveform, Figure 7c A graph showing that data regarding contact force values ​​and diastolic pressure values ​​acquired from a plurality of objects of interest are plotted as XY coordinates, Figure 7d A graph in which data on contact force values ​​and systolic pressure values ​​acquired from a plurality of objects of interest are plotted as XY coordinates. Figure 1 The apparatus 100 for measuring bio-information shown in the figure may be installed in an electronic device, an accessory of the electronic device (e.g., a protective case of the electronic device, etc.), a stylus, etc. In this case, the electronic device may include a mobile phone, a smart phone, a tablet terminal, a notebook computer, a personal digital assistant (PDA), a portable multimedia player (PMP), a navigation device, an MP3 player, a digital camera, a wearable device, etc., and the wearable device may include various types of wearable devices (such as a watch type, a wristband type, a belt type, a necklace type, an ankle band type, a thigh band type, a forearm band type, etc.). However, the electronic device is not limited to the above examples, and the wearable device is not limited to the above examples.

[0066] Reference Figure 1, the device 100 may include a pulse wave sensor 110 , a force sensor 120 , and a processor 130 .

[0067] The pulse wave sensor 110 may have a circular contact surface that contacts an object of interest, and measures one or more pulse wave signals from an object that contacts the contact surface. Here, the pulse wave signal may be a photoplethysmography (PPG) signal. When the pulse wave sensor 110 measures a plurality of pulse wave signals, the plurality of pulse wave signals may be measured using light of different wavelengths. Here, the object of interest may be an area of ​​a human body that may contact the pulse wave sensor 110, and from which a pulse wave signal may be easily measured. For example, the object may be a peripheral part of the body (such as a finger, a toe, etc.), or an area of ​​the wrist surface adjacent to the radial artery, which is an upper area of ​​the wrist through which capillary blood or venous blood passes. In the following, for ease of description, a finger will be described as an example of an object of interest.

[0068] The elasticity of the finger is affected by the rigidity and structure of the contact object. For example, when the same force is applied, a contact object having a curved surface deforms a deeper layer of the finger than a contact object having a flat surface. Therefore, the pulse wave sensor 110 according to one embodiment has a curved contact surface that contacts the finger, so that the same pressure can be applied to the finger using a smaller force than that applied to a flat contact surface.

[0069] The pulse wave sensor 110 may include a housing 111 and a pulse wave measurer 112 .

[0070] The housing 111 may have a curved contact surface that is convex toward a contact surface of a finger, and the curved contact surface contacts the finger in consideration of the elasticity and anatomical structure of the finger. According to one embodiment, the housing 111 may be formed as follows: Figure 2 The semi-cylindrical shape shown in Figure 3 The semi-ellipsoidal shape shown in Figure 4 In this case, the housing 111 may be formed as follows. Figure 5, the housing 111 may be formed to have a size smaller than the finger, so that the contact area between the finger and the housing 111 can be constant. For example, by considering the age and gender of the user, the type of finger to be used (e.g., thumb, index finger, middle finger, ring finger, or little finger), etc., the housing 111 may be formed to have a size smaller than the average size of the fingers of multiple users. For example, considering the maximum width / thickness of the finger and / or the size of the pulse wave sensor 110, the housing 111 may be formed to have a first radius of curvature R1 not less than 2 mm (millimeter) and not more than 10 mm and a second radius of curvature R2 not less than 0.5×R1 and not more than 4×R1. In addition, when the housing 111 is formed in a semi-cylindrical and / or semi-ellipsoidal shape, the length L of the housing 111 may be greater than 0 mm and equal to or less than 16 mm in consideration of the width of the finger. However, this is merely an example, and the length of the housing 111 is not limited thereto.

[0071] The structure of the housing is such that pressure can be well transmitted into the finger using a smaller force than that applied to a flat surface, so when measuring blood pressure using an oscillometric technique, it is possible to easily reach the maximum pulse pressure. In addition, by allowing the device 100 for measuring biological information to be accurately positioned at a position close to a target (e.g., blood vessel, etc.) from which biological information is to be obtained, the device 100 can easily obtain information inside the finger (e.g., blood vessels and blood under the skin).

[0072] When a finger contacts an object, the force of the finger generates friction due to the anatomical structure of the finger bones and the adhesive properties and elasticity of the finger skin. Since the friction varies according to the shape and material of the surface in contact with the finger, even when a predetermined pressure is applied to the finger, the pressure applied to the finger from the outside may not be completely transmitted to the inside of the finger due to the loss of friction with the contact object. Therefore, it is necessary to appropriately select the material and / or structure of the housing 111 so that the influence of the friction can be minimized.

[0073] When the stiffness of the contact object is lower than or similar to the stiffness of the finger, when the finger applies a force to the contact object, the contact object is deformed together with the finger, and thus the force causing the contact object to deform may be lost and may not be transmitted to the finger. Therefore, the stiffness of the housing 111 should be much greater than the stiffness of the finger so that the housing 111 is not deformed by the applied force. In addition, the housing 111 may be formed of a material that is stronger than rubber or polyethylene. For example, the housing 111 may be formed of a material having a stiffness of 0.5 GPa (gigaPascal) or more (e.g., carbon fiber, high-strength plastic, metal, etc.).

[0074] Since a contact object with high surface roughness has large contact friction and adhesion when contacting a finger, the housing 111 may be formed of a material having a smooth surface with a roughness less than a predetermined level. For example, the housing 111 may be formed of a material having a surface roughness of 1.6 μm (micrometer) or less.

[0075] The pulse wave measurer 112 may be installed in the housing 111 and measure one or more pulse wave signals from a finger in contact with the curved surface of the housing 111. When the pulse wave measurer 112 measures a plurality of pulse wave signals, the plurality of pulse wave signals may be measured using light of different wavelengths. According to one embodiment, the pulse wave measurer 112 may include one or more light sources configured to emit light to an object of interest in contact with the curved surface of the housing 111 and a photodetector configured to receive light returned from the object of interest.

[0076] The force sensor 120 may measure the contact force between the object of interest and the pulse wave sensor 110. The force sensor 120 may be disposed below or at the side of the pulse wave sensor 110, but is not limited thereto. According to one embodiment, the force sensor 120 may measure the force applied to the force sensor 120 due to the contact between the object of interest and the pulse wave sensor 110. According to one embodiment, the force sensor 120 may include a resistive force sensor, an ultrasonic force sensor, a load cell sensor, a capacitive force sensor, a thermoelectric force sensor, a strain gauge force sensor, an electrochemical force sensor, an optical force sensor, a magnetic force sensor, and the like.

[0077] Figure 6a and Figure 6b is a diagram for describing the relationship between contact pressure and contact force according to the structure of the pulse wave sensor. More specifically, Figure 6a is a diagram for describing the relationship between contact pressure and contact force when the pulse wave sensor is formed into a hemispherical shape, Figure 6b is a diagram for describing the relationship between contact pressure and contact force when the pulse wave sensor is formed in a semi-cylindrical shape.

[0078] Reference Figure 6a , when the radius R 1 A sphere with radius R 2 When the spheres of the contact area are in contact, the contact area may appear as a circle with a radius a. In this case, the radius a of the contact area may be expressed as Equation 1, and the maximum contact pressure P occurring at the center of the contact area max It can be expressed as Equation 2.

[0079] [Equation 1]

[0080]

[0081] [Equation 2]

[0082]

[0083] Here, E 1 and E 2 can be represented by the radius R 1 The elastic modulus of a sphere with radius R 2 The elastic modulus of the sphere, v 1 and v 2 can be represented by the radius R 1 The Poisson's ratio of a sphere with radius R 2 Poisson's ratio of a sphere, and F can be expressed as the external force applied to a sphere with radius R 1 The force on the sphere.

[0084] As shown in Equation 2, when the radius R 1 A sphere with radius R 2 When the spheres come into contact, the maximum contact pressure P of the two objects max The contact area 2πa 2 and applied externally to a 1 Therefore, when the housing 111 is implemented to have a size smaller than the finger size of the hand, it has a fixed contact area 2πa that is independent of the size of the finger. 2 It is possible to calculate the contact pressure between the object of interest and the housing 111 using only the force sensor 120 without the need for a separate contact area sensor.

[0085] Reference Figure 6b , when the radius R 1 The cylinder with radius R 2 When the semi-cylinder contacts, the contact area may appear as a rectangle with a width of 2b and a length of L. In this case, the half-width b of the contact area may be expressed as Equation 3, and the maximum contact pressure P occurring at the center line of the contact area is max It can be expressed as Equation 4.

[0086] [Equation 3]

[0087]

[0088] [Equation 4]

[0089]

[0090] Here, E 1 and E 2 can be represented by the radius R 1 The elastic modulus of a cylinder with radius R 2The elastic modulus of the semi-cylinder, v 1 and v 2 can be represented by the radius R 1 The Poisson's ratio of a cylinder with radius R 2 The Poisson's ratio of a half cylinder, F, can be expressed as the external force applied to a half cylinder with radius R. 1 The force on the cylinder, and L can represent the contact length.

[0091] As shown in Equation 4, when the radius R 1 The cylinder with radius R 2 When the semi-cylinders are in contact, the maximum contact pressure P of the two objects max The contact area πbL and the external surface are applied to the 1 Therefore, when the housing 111 is implemented to have a size smaller than the size of the object of interest (e.g., a finger), it is possible to have a fixed contact area πbL that is independent of the size of the object of interest (e.g., a finger), and it is possible to calculate the contact pressure between the object of interest and the housing 111 using only the force sensor 120 without the need for a separate contact area sensor.

[0092] The processor 130 may control the overall operation of the apparatus 100 for measuring bio-information.

[0093] The processor 130 may control the pulse wave sensor 110 to measure one or more pulse wave signals required for measuring biological information. When a request for measuring biological information is received from a user, the processor 130 may generate a pulse wave sensor control signal to control the pulse wave sensor 110. Conditions for driving the pulse wave sensor may be pre-stored in a storage device. When a request for measuring biological information is received, the processor 130 may control the pulse wave sensor 110 by referring to the sensor driving conditions stored in the storage device. In this case, the sensor driving conditions may include an emission time of each light source, a driving order, a current intensity, a pulse duration, etc.

[0094] The processor 130 may generate contact pressure guide information for guiding the user to increase or decrease the pressure applied to the pulse wave sensor 110 during the measurement of the pulse wave signal, and provide the contact pressure guide information to the user. The processor 130 may provide the contact pressure guide information by visually displaying the contact pressure guide information or using a non-visual method such as sound or vibration. As described above, the contact pressure may be calculated from the value measured by the force sensor 120.

[0095] The contact pressure guide information may be provided before, after, or simultaneously with the start of the pulse wave signal measurement by the pulse wave sensor 110. The contact pressure guide information may be continuously provided to the user while the pulse wave sensor 110 measures the pulse wave signal from the object of interest. The contact pressure guide information may be preset for each user based on user characteristics such as the user's age, gender, health status, contact area of ​​the object, etc. The contact pressure guide information may be a pressure value to be increased or decreased by the user in the pulse wave sensor 110, but is not limited thereto, and may include the user's motion information for guiding the change of the pressure applied to the pulse wave sensor 110 by the object of interest.

[0096] When receiving a request to measure bio-information, the processor 130 may generate a control signal for controlling the force sensor 120 to measure the contact force.

[0097] The processor 130 may continuously receive contact force measurement values ​​from the force sensor 120, calculate contact pressure values ​​based on the received contact force measurement values, and generate and provide contact pressure guidance information using the calculated contact pressure values. For example, the processor 130 may provide contact pressure guidance information based on the difference between the contact pressure value obtained in a specific situation and the contact pressure value applied to the pulse wave sensor 110 by the user in the specific situation.

[0098] The processor 130 may obtain an oscillometric waveform using one or more pulse wave signals obtained by the pulse wave sensor 110 and the contact force obtained by the force sensor 120. In this case, Figure 7a As shown in , the oscillometric waveform may represent changes in the pulse wave signal according to changes in contact pressure.

[0099] According to one embodiment, the processor 130 may select one or more pulse wave signals from among the pulse wave signals acquired from the pulse wave sensor 110 according to a predetermined criterion, and acquire an oscillometric waveform using a combination of the selected pulse wave signals and the contact pressure calculated based on the contact force acquired from the force sensor 120. In this case, the predetermined criterion may include at least one of a maximum amplitude value, an average amplitude value, and a difference between a maximum amplitude value and a minimum amplitude value of each pulse wave signal. However, the embodiment is not limited thereto, and a pulse wave signal measured using light of a predetermined wavelength may be selected and used from among the acquired pulse wave signals. For example, the processor 130 may select one pulse wave signal having the largest difference between a maximum amplitude value and a minimum amplitude value, and acquire an oscillometric waveform using the selected pulse wave signal and the contact pressure.

[0100] The processor 130 may estimate the bio-information by analyzing the change of the oscillometric waveform according to the change of the contact pressure. In this case, the bio-information may include, but is not limited to, blood pressure, blood sugar level, cholesterol level, vascular age, arterial stiffness, aortic pressure waveform, stress index, fatigue level, etc. However, for ease of description, hereinafter, blood pressure will be described as an example of bio-information.

[0101] Blood pressure may include diastolic blood pressure (DBP), systolic blood pressure (SBP), and mean arterial pressure (MAP), and the contact pressure applied to the finger may act as an external pressure applied to the blood vessel. When the contact pressure is less than MAP, the elastic restoring force of the tissue acts in the direction of compressing the blood vessel, so the amplitude of the oscillometric waveform becomes smaller. When the contact pressure is equal to MAP, the elastic restoring force of the tissue becomes zero, so the blood vessel is not affected, thereby maximizing the amplitude of the oscillometric waveform. In addition, when the contact pressure is greater than MAP, the elastic restoring force of the tissue acts in the direction of expanding the blood vessel, so the amplitude of the oscillometric waveform becomes smaller. Therefore, the processor 130 may analyze the change of the oscillometric waveform according to the contact pressure, and use the contact pressure at the point where the amplitude of the oscillometric waveform is the largest to estimate MAP. In addition, the processor 130 may estimate DBP using the contact pressure at the point where the amplitude corresponds to the first ratio (e.g., 0.7) relative to the maximum amplitude of the oscillometric waveform, and may estimate SBP using the contact pressure at the point where the amplitude corresponds to the second ratio (e.g., 0.6) relative to the maximum amplitude of the oscillometric waveform. In this case, the relationship between MAP and the contact pressure when the amplitude of the oscillometric waveform is maximum, the relationship between SBP and the contact pressure at a point where the amplitude is a first proportion to the maximum amplitude, and the relationship between DBP and the contact pressure at a point where the amplitude is a second proportion to the maximum amplitude can be pre-defined experimentally.

[0102] To measure blood pressure, the user may bring his / her finger into contact with the housing 111 of the apparatus 100 for measuring bio-information, and then gradually increase the force applied to the housing 111. In this case, the pulse wave sensor 110 of the apparatus 100 may output a signal such as Figure 7b The pulse wave signal in the oscillometric waveform shown in the upper part of FIG. 1 , and the force sensor 120 may output as Figure 7b The contact force signal increasing over time is shown in the lower part.

[0103] When using the apparatus 100 for measuring biological information having the above-described structure, a change in the contact area between the finger and the sensor may occur in the initial stage when the user first brings his / her finger into contact with the housing 111 and increases the force. However, during the period of time when pulse wave information meaningful for estimating blood pressure is acquired, the change in the contact area may be negligible or zero. Therefore, when measuring blood pressure by the apparatus 100 for measuring biological information, it may be considered that the contact area between the user's finger and the housing 111 is fixed. For example, in Figure 7b In the pulse wave signal shown in the upper part of FIG. 1 , at the time point t from when the user first brings his / her finger into contact with the housing 111, 0 At the time point when the contact force increases, a During the interval of t, the contact area between the finger and the housing 111 may increase. However, at time point t a In the interval thereafter, the contact area rarely changes, and the pulse wave signal required for blood pressure estimation can be included in the interval.

[0104] Therefore, the processor 130 does not calculate the contact pressure value, but estimates the user's blood pressure using a blood pressure estimation function that uses the contact force value obtained from the force sensor 120 as an input parameter. The blood pressure estimation function may be stored in an internal or external memory of the processor 130, and there may be a DBP estimation function and an SBP estimation function that are independent of each other. The blood pressure estimation function may be obtained in advance from experiments on a plurality of subjects of interest.

[0105] Hereinafter, a method of acquiring a blood pressure estimation function will be described in detail.

[0106] A device for estimating biological information can be used to acquire pulse wave signals and contact force signals in oscillometric waveforms from a plurality of objects of interest, the device having a reference Figures 1 to 5 The pulse wave signal and contact force signal acquired from each object of interest may have the same Figure 7b . In addition, a separate blood pressure measurement device (such as a cuff sphygmomanometer) may be used to measure the DBP and SBP of the subject of interest. In this case, the blood pressure of the subject of interest may be measured at a time point that is not significantly different from the actual blood pressure of the subject of interest at the time when the pulse wave signal and the contact force signal are measured using the device for measuring biological information. For example, the blood pressure of the subject of interest may be measured during the measurement of the pulse wave signal and the contact force signal of the subject of interest using the device for measuring biological information. Optionally, the blood pressure of the subject of interest may be measured immediately before or after the measurement of the pulse wave signal and the contact force signal of the subject of interest using the device for measuring biological information.

[0107] The pulse wave signal, contact force signal, and blood pressure value obtained through the above process can be used to derive a blood pressure estimation function. For example, assuming that Figure 7b The pulse wave signal in the oscillographic waveform shown in the upper part of the graph can be seen at the time point t where the amplitude of the pulse wave signal is the largest. r Among the multiple pulse waves shown on the left side, select the one with the largest amplitude A relative to max The first ratio corresponds to the amplitude of the pulse wave at the time point t 1 At the selected time t 1 Get the contact force value f obtained by the force sensor 1 The contact force value f can be obtained 1 The DBP value of the corresponding object of interest is mapped and stored. The above process can be performed for multiple objects, so that multiple contact force values ​​and DBP values ​​corresponding to each contact force value can be obtained.

[0108] Figure 7c A graph showing data on contact force values ​​and DBP values ​​acquired from a plurality of objects of interest is plotted as XY coordinates. The DBP candidate function 720 may be acquired through regression analysis of the data set 710. More specifically, the relationship between the contact force and the DBP may be derived through regression analysis in which the contact force values ​​of the data set 710 are used as independent variables and the DBP values ​​are used as dependent variables, and the relationship may be used as the DBP candidate function 720. In this case, other mathematical techniques besides regression analysis may be used. When the DBP candidate function 720 is used as a DBP estimation function, the first scale used to acquire the data set 710 may be used as a condition for acquiring the contact force value as an input parameter.

[0109] When Figure 7b When the first ratio is changed in 1 can be changed. If the first scale is set to X 1 To obtain Figure 7c The data set 710 in the example above can be obtained by adjusting the first scale to X 2 , X 3 The DBP candidate function for each of the plurality of data sets may be derived, and each DBP candidate function may output an expected DBP value when the contact force value of the data set is used as input. The average error between the DBP value obtained by each DBP candidate function and the actual DBP value included in the data set may be calculated, and the DBP candidate function with the smallest average error may be selected and used as the DBP estimation function.

[0110] The finally decided DBP estimation function and the first ratio corresponding to the DBP estimation function may be stored in an internal or external memory of the processor 130 of the apparatus 100 for measuring bio-information, and may be used when the processor 130 calculates the DBP of the user.

[0111] An example of the DBP estimation function acquired through the above process can be expressed as Equation 5.

[0112] [Equation 5]

[0113] BP DBP (f n ) = af n +b

[0114] Even when DBP is estimated using Equation 5, the user may bring his / her finger into contact with the apparatus 100 for measuring biological information and then gradually increase the pressing force. The pulse wave signal and the contact force signal in the oscillometric waveform acquired accordingly have the same Figure 7b If you obtain Figure 7b The signal shown in 1 The contact force value f at 1 This corresponds to f in Equation 5. n , at time point t 1 , with respect to the maximum amplitude A max The first ratio corresponds to the amplitude A 1 The pulse wave appears at the time point t where the amplitude of the pulse wave signal is the largest in the curve. r Among the multiple pulse waves shown on the left side of . In Equation 5, a and b are constants and can be determined according to the characteristics of the sensor to be used or the characteristics of the group of objects of interest.

[0115] In a similar manner to the above-mentioned DBP estimation function, the SBP estimation function can be obtained. Figure 7b , a pulse wave signal measured from an oscillometric waveform of an object of interest can be plotted at a time point t where the pulse wave signal has a maximum amplitude. r Among the pulse waves shown on the right, select the one with the maximum amplitude A relative to max The second ratio corresponds to the amplitude of the pulse wave at the time point t 2 . You can get the value at the selected time point t 2 The contact force value f obtained by the force sensor at 2 The contact force value f can be obtained 2 The SBP value of the corresponding object of interest measured previously is mapped and stored. The above process can be performed for each of the multiple objects of interest, so that multiple contact force values ​​and the SBP value corresponding to each contact force value can be obtained.

[0116] Figure 7d The data about the contact force values ​​and SBP values ​​obtained from a plurality of objects of interest are plotted as a curve graph of XY coordinates. The SBP candidate function 740 can be obtained by regression analysis of the data set 730. More specifically, the relationship between the contact force and the SBP can be derived by regression analysis, in which the contact force values ​​of the data set 730 are used as independent variables and the SBP values ​​are used as dependent variables, and the relationship can be used as the SBP candidate function 740. In this case, other mathematical techniques besides regression analysis can be used. When the SBP candidate function 740 is used as an SBP estimation function, the second ratio used to obtain the data set 730 can be used as a condition for obtaining the contact force value as an input parameter.

[0117] When Figure 7b When the second ratio is changed in 2 can be changed. If the second scale is set to Y 1 To obtain Figure 7d The data set 730 in the example above can be obtained by adjusting the second scale to Y 2 , Y 3 The method can be used to obtain other data sets consisting of changed contact force values ​​and corresponding SBP values ​​by deriving an SBP candidate function for each of the multiple data sets, and each SBP candidate function can output an SBP value expected when the contact force value of the data set is used as input. The average error between the SBP value obtained by each SBP candidate function and the actual SBP value included in the data set can be calculated, and the SBP candidate function with the smallest average error can be selected and used as the SBP estimation function.

[0118] The finally decided SBP estimation function and the second ratio corresponding to the SBP estimation function may be stored in an internal or external memory of the processor 130 of the apparatus 100 for measuring bio-information, and may be used when the processor 130 calculates the SBP of the user.

[0119] An example of the SBP estimation function obtained through the above process can be expressed as Equation 6.

[0120] [Equation 6]

[0121] BP SBP (f m ) = cf m +d

[0122] Even when the SBP is estimated using Equation 6, the user may bring his / her finger into contact with the apparatus 100 for measuring biological information and then gradually increase the pressing force. The pulse wave signal and the contact force signal in the oscillometric waveform acquired accordingly have the same Figure 7bIf you obtain Figure 7b The signal shown in 2 The contact force value f at 2 This corresponds to f in Equation 6 m , at time point t 2 , with respect to the maximum amplitude A max The second ratio corresponds to the amplitude A 2 The pulse wave appears at the time point t where the amplitude of the pulse wave signal is the largest in the curve. r Among the multiple pulse waves shown on the right side of . In Equation 6, c and d are constants and can be determined according to the characteristics of the sensor to be used or the characteristics of the group of objects of interest.

[0123] In the foregoing description, the DBP estimation function and the SBP estimation function are described as linear functions, respectively, however, this is only an example. The blood pressure estimation function may be a multi-order function, or may be a function of a different type. In addition, a lookup table consisting of contact force values ​​and estimated blood pressure values ​​may be used instead of a function.

[0124] Figures 8a to 8c is a diagram showing an example of a pulse wave measurement device. Figures 8a to 8c Can show Figure 1 An example of a pulse wave measuring device 112. Figures 8a to 8c Various embodiments of configurations of a pulse wave measurer that measures a plurality of pulse wave signals from a subject of interest are described.

[0125] Reference Figure 8a According to one embodiment, the pulse wave meter 810 may be formed as an array of pulse wave meters for measuring a plurality of pulse wave signals. Figure 8a As shown in FIG. 8 , the pulse wave measurer 810 may include a first pulse wave measurer 811 and a second pulse wave measurer 812. However, the number of pulse wave measurers constituting the array of the pulse wave measurer is not particularly limited.

[0126] The first pulse wave measurer 811 may include a first light source 811a for emitting light of a first wavelength to the object of interest. In addition, the first pulse wave measurer 811 may include a first photodetector 811b for receiving light of the first wavelength returned from the object irradiated by the first light source 811a and measuring a first pulse wave signal.

[0127] The second pulse wave measurer 812 may include a second light source 812a that emits light of a second wavelength to the object of interest. In addition, the second pulse wave measurer 812 may include a second photodetector 812b that receives light of a second wavelength returned from the object irradiated by the second light source 812a and measures a second pulse wave signal. In this case, the first wavelength may be different from the second wavelength.

[0128] Here, the first light source 811a and the second light source 812a may include a light emitting diode (LED), a laser diode, and a phosphor, but are not limited thereto. In addition, the first photodetector 811b and the second photodetector 812b may include a photodiode, a phototransistor, or an image sensor (e.g., a charge coupled device (CCD), a complementary metal oxide semiconductor (CMOS)), but are not limited thereto.

[0129] Reference Figure 8b According to another embodiment, a pulse wave measurer 820 may include a light source unit 821 including a plurality of light sources 821a and 821b and a photodetector 822. Figure 8b In the figure, for the convenience of description, two light sources are shown in the light source unit 821, but the embodiment is not particularly limited to the number of light sources.

[0130] The first light source 821a emits light of a first wavelength toward the object of interest, and the second light source 821b emits light of a second wavelength toward the object. Here, the first wavelength may be different from the second wavelength.

[0131] For example, the first light source 821a and the second light source 821b may be driven in a time-division manner according to the control of the processor, and may emit light to the object of interest sequentially or simultaneously. In this case, the light source driving conditions (such as the emission time, driving order, current intensity, and pulse duration of each of the first light source 821a and the second light source 821b) may be set in advance. The processor may control the driving of each light source 821a and 821b by referring to the light source driving conditions.

[0132] The photodetector 822 may sequentially or simultaneously detect light of the first wavelength and light of the second wavelength returned from the object of interest continuously or simultaneously illuminated by the respective first and second light sources 821a and 821b and measure the first and second pulse wave signals.

[0133] Reference Figure 8c According to another embodiment, the pulse wave measurement device 830 may include a single light source 831 and a photodetector unit 832. The photodetector unit 832 may include a first photodetector 832a and a second photodetector 832b. However, for ease of description, Figure 8c Two photodetectors in the photodetector unit 832 are shown, but embodiments are not specifically limited to that number of photodetectors.

[0134] The single light source 831 may emit light of a specific wavelength toward the object of interest. In this case, the single light source 831 may be formed to emit light of a wide wavelength range including visible wavelengths.

[0135] The photodetector unit 832 may receive light of a specific wavelength returned from the subject and measure a plurality of pulse wave signals. To this end, the photodetector 832 may be formed to have a plurality of different response characteristics.

[0136] For example, the first photodetector 832a and the second photodetector 832b may be formed using photodiodes having different measurement ranges to respond to light of different wavelengths returned from the object of interest. Alternatively, one of the first photodetector 832a and the second photodetector 832b may have a color filter mounted on its front surface, or each of the first photodetector 832a and the second photodetector 832b may have different color filters mounted on their front surfaces to respond to light of different wavelengths. Alternatively, the first photodetector 832a and the second photodetector 832b may be disposed at different distances from the single light source 831. In this case, the photodetector disposed at a relatively short distance from the single light source 831 may detect light of a short wavelength band, and the other photodetector disposed at a relatively long distance from the single light source 831 may detect light of a long wavelength band.

[0137] Refer to above Figures 8a to 8c An example of a pulse wave meter that measures a plurality of pulse wave signals is described. However, the embodiments are not limited to the examples set forth herein, and the number and arrangement of light sources and photodetectors may vary depending on the application purpose of the pulse wave meter and the size and shape of an electronic device on which the pulse wave meter is installed.

[0138] Figures 9a to 9c is a diagram showing an example of the arrangement of a light source and a photodetector. More specifically, Figure 9a is a diagram showing an example of arrangement of a light source and a photodetector when the pulse wave sensor is formed in a semi-cylindrical shape, Figure 9b is a diagram showing an example of the arrangement of a light source and a photodetector when the pulse wave sensor is formed into a semi-ellipsoidal shape, and Fig.9c is a diagram showing an example of the arrangement of a light source and a photodetector when the pulse wave sensor is formed in a hemispherical shape. Figures 9a to 9c Two light sources 910 a and 910 b and one photodetector 920 are shown, but these are provided only for convenience of description, and the number of light sources and photodetectors is not particularly limited.

[0139] Reference Figures 9a to 9c , the pulse wave sensor 110 may include two light sources 910 a and 910 b and one photodetector 920 .

[0140] The photodetector 920 may be disposed at the center of the curved surface as the contact surface, and the two light sources 910a and 910b may be arranged symmetrically with respect to the photodetector 920 along the length direction of the pulse wave sensor 110 or the tangent direction of the curved surface. In this case, the two light sources 910a and 910b may be disposed inside the edge portion (e.g., 0.1L to 0.9L; L is the length of the pulse wave sensor) to reduce the influence of the edge on pressure or force.

[0141] Fig.10 is a diagram illustrating an apparatus for measuring biological information according to another embodiment of the present disclosure. Fig.10 The apparatus 1000 for measuring bio-information may be installed in an electronic device, an accessory of the electronic device (e.g., a protective case of the electronic device, etc.), a stylus, etc. In this case, the electronic device may include a mobile phone, a smart phone, a tablet terminal, a notebook computer, a PDA, a PMP, a navigation device, an MP3 player, a digital camera, a wearable device, etc., and the wearable device may include various types of wearable devices (such as a watch type, a wristband type, a belt type, a necklace type, an ankle band type, a thigh band type, a forearm band type, etc.). However, the electronic device is not limited to the above examples, and the wearable device is not limited to the above examples.

[0142] Reference Fig.10 , the device 1000 may include a pulse wave sensor 110, a force sensor 120, a processor 130, an input interface 1010, a memory 1020, a communication interface 1030, and an output interface 1040. In this case, the pulse wave sensor 110, the force sensor 120, and the processor 130 are similar to the reference Figures 1 to 9c Those described are similar, so their detailed descriptions will be omitted.

[0143] The input interface 1010 may receive various operation signals input by the user. According to one embodiment, the input interface 1010 may include a keyboard, a dome switch, a touch pad (resistance / capacitance), a scroll wheel, a rocker switch, a hardware button, etc. In particular, when the touch pad has a layered structure with a display, the structure may be referred to as a touch screen.

[0144] Programs or instructions for the operation of the apparatus 1000 for measuring bio-information may be stored in the memory 1020, and data input to and output from the apparatus 1000 may also be stored in the memory 1020. In addition, the memory 1020 may store data processed by the apparatus 1000 and information required for the apparatus 1000 to process the data.

[0145] The memory 1020 may include at least one type of storage medium (such as flash memory, hard disk type memory, multimedia card micro memory, card type memory (e.g., SD memory or XD memory), random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), magnetic memory, magnetic disk, and optical disk). In addition, the device 1000 may operate an external storage medium (such as a network storage) that provides a storage function of the memory 1020.

[0146] The communication interface 1030 can communicate with an external device. For example, the communication interface 1030 can transmit data processed by the apparatus 1000 or processing result data of the apparatus 1000 to an external device, or can receive various data necessary or useful for measuring a pulse wave signal and contact force and / or estimating bio-information.

[0147] Here, the external device may be a medical device that uses data processed by the apparatus 1000 or processing result data of the apparatus 1000, or may be a printer or display device for outputting results. In addition, the external device may include, but is not limited to, a digital TV, a desktop computer, a mobile phone, a smart phone, a tablet computer, a notebook computer, a PDA, a PMP, a navigation terminal, an MP3 player, a digital camera, a wearable device, and the like.

[0148] The communication interface 1030 may communicate with an external device using various communication technologies such as Bluetooth, Bluetooth Low Energy (BLE), Near Field Communication (NFC), Wireless Local Area Network (WLAN) communication, ZigBee communication, Infrared Data Association (IrDA) communication, Wi-Fi Direct (WFD) communication, Ultra Wideband (UWB) communication, Ant+ communication, Wi-Fi communication, RFID communication, 3G communication, 4G communication, 5G communication, etc. However, these are merely examples, and embodiments are not limited thereto.

[0149] The output interface 1040 may output data processed by the device 1000, processing result data of the device 1000, etc. According to one embodiment, the output interface 1040 may output data processed by the device 1000, processing result data of the device 1000, etc. in at least one of a visual manner, an auditory manner, and a tactile manner. To this end, the output interface 1040 may include a display, a speaker, a vibrator, etc.

[0150] Figures 11 to 17 is a diagram showing an embodiment of an apparatus for measuring biological information.

[0151] The apparatus 100 or 1000 for measuring biometric information may be applied to the edge of a smartphone (see Fig.11), side buttons of smartphones (see Fig.12 ), the home button of a smartphone (see Fig.13 ), buttons or frames on the stylus (see Fig.14 ), the edge of the smartphone case (see Fig.15 ), a joystick button or edge (see Fig.16 ) and the edge or band of a watch-type wearable device (see Fig.17 ).

[0152] at the same time, Figures 11 to 17 That is, the device 100 or 1000 can be applied without limitation as long as it is applied to a curved surface or button of an electronic device, an accessory of an electronic device (eg, a protective case of an electronic device), a stylus pen, a joystick, etc.

[0153] Fig.18 is a flowchart illustrating a method of measuring biological information according to one embodiment of the present disclosure. Fig.18 The method shown in Figure 1 The device 100 for measuring biological information and Fig.10 The method is performed by the apparatus 1000 for measuring biological information.

[0154] Reference Fig.18 , the device for measuring bio-information may measure one or more pulse wave signals from an object of interest in contact with a circular contact surface of a pulse wave sensor (1810). In this case, the pulse wave signal may be a PPG signal. When the device for measuring bio-information measures a plurality of pulse wave signals, the plurality of pulse wave signals may be measured using light of different wavelengths. According to one embodiment, the device may emit light to an object of interest in contact with a circular contact surface of the device, and receive light returned from the object to measure one or more pulse wave signals.

[0155] The apparatus for measuring bio-information may measure contact force between the object and the pulse wave sensor (1820). According to one embodiment, the apparatus for measuring bio-information may measure force applied to a force sensor disposed under or on a side of the pulse wave sensor due to contact between the object and the pulse wave sensor.

[0156] The device may estimate biological information of the object of interest based on the measured one or more pulse wave signals and the measured contact force (1830). The device may use the pulse signal and the contact force to obtain an oscillometric waveform. For example, the device may select one or more pulse wave signals from the measured one or more pulse wave signals according to a predetermined standard, and calculate the contact pressure using the measured contact force. In addition, the device may use a combination of one or more selected pulse wave signals and contact force to obtain an oscillometric waveform. In this case, the predetermined standard may include at least one of the maximum amplitude value, the average amplitude value, and the difference between the maximum amplitude value and the minimum amplitude value of each pulse wave signal. However, the embodiment is not limited thereto, and a pulse wave signal measured using light of a predetermined wavelength may be selected from the acquired pulse wave signals. The device may estimate biological information by analyzing changes in the oscillometric waveform according to changes in the contact pressure. In this case, the biological information may include, but is not limited to, blood pressure, blood sugar level, cholesterol level, vascular age, arterial stiffness, aortic pressure waveform, pressure index, fatigue level, etc.

[0157] Blood pressure may include DBP, SBP and MAP, and the contact pressure applied to the object of interest may act as an external pressure applied to the blood vessel. When the contact pressure is less than MAP, the elastic restoring force of the tissue acts in the direction of compressing the blood vessel, so the amplitude of the oscillometric waveform becomes smaller. When the contact pressure is equal to MAP, the elastic restoring force of the tissue becomes zero, so the blood vessel is not affected, so that the amplitude of the oscillometric waveform is the largest. In addition, when the contact pressure is greater than MAP, the elastic restoring force of the tissue acts in the direction of dilating the blood vessel, so the amplitude of the oscillometric waveform becomes smaller. Therefore, the device for measuring biological information can analyze the change of the oscillometric waveform according to the contact pressure, and use the contact pressure at the point where the amplitude of the oscillometric waveform is the largest to estimate MAP. In addition, the device for measuring biological information can estimate SBP using the contact pressure at the point where the amplitude is a first ratio (e.g., 0.6) relative to the maximum amplitude, and estimate DBP using the contact pressure at the point where the amplitude is a second ratio (e.g., 0.7) relative to the maximum amplitude.

[0158] For example, the apparatus for measuring bio-information may estimate blood pressure using the measured contact force value and the blood pressure calculation equation shown in Equation 5 and Equation 6 described above.

[0159] Meanwhile, the operation 1810 of measuring a pulse wave signal and the operation 1820 of measuring a contact force may not be performed in the above order, and may be performed simultaneously within a predetermined time length.

[0160] According to an additional embodiment, the apparatus may generate contact pressure guide information based on the calculated contact pressure during the measurement of the pulse wave signal, and provide the generated contact pressure guide information to the user.

[0161] The current embodiment can be implemented as a computer-readable code in a computer-readable recording medium. The code and code segments constituting the computer program can be easily inferred by a computer programmer skilled in the art. The computer-readable recording medium includes all types of recording media storing computer-readable data. Examples of computer-readable recording media include: ROM, RAM, CD-ROM, magnetic tape, floppy disk, and optical data storage. In addition, the recording medium can be implemented in the form of a carrier wave (such as, Internet transmission). In addition, the computer-readable recording medium can be distributed to computer systems on a network, where the computer-readable code can be stored and executed in a distributed manner.

Claims

1. A device for measuring biological information, comprising: a pulse wave sensor configured to have a circular contact surface protruding toward a contact surface of an object of interest and in contact with the object of interest, and to measure one or more pulse wave signals from the object in contact with the contact surface; a force sensor disposed below or on a side of the pulse wave sensor and configured to measure a contact force of the object; and a processor configured to estimate biological information of the subject based on the measured one or more pulse wave signals and the measured contact force, The pulse wave sensor comprises: a housing having a curved contact surface; The housing has a first curvature radius R1 of not less than 2 mm and not more than 10 mm and a second curvature radius R2 of not less than 0.5×R1 and not more than 4×R1. Among them, the pulse wave signal is a photoplethysmography (PPG) signal, The pulse wave sensor also includes a pulse wave measuring device installed in the housing. The pulse wave measurer includes: two light sources configured to emit light to the object of interest; and a photodetector configured to receive light returned from the object and measure the one or more pulse wave signals. wherein the photodetector is disposed at the center of the curved surface as a circular contact surface, and The two light sources are symmetrically arranged relative to the photodetector along the length direction of the pulse wave sensor or the tangent direction of the curved surface, and are arranged inside the edge portion to be arranged at 0.1L to 0.9L, where L is the length of the pulse wave sensor.

2. The device according to claim 1, wherein The housing is formed in a semi-cylindrical shape, a semi-ellipsoidal shape, or a hemispherical shape.

3. The device according to claim 1, wherein: The housing is formed to have a size smaller than that of a finger.

4. The device according to claim 3, wherein: The housing is formed to have a size smaller than an average finger size of a plurality of users.

5. The device according to claim 1, wherein: The housing is formed in a semi-cylindrical or semi-ellipsoidal shape having a length greater than 0 and equal to or less than 16 mm.

6. The device according to claim 1, wherein: The housing has a surface roughness of 1.6 μm or less.

7. The device according to claim 1, wherein: The outer shell has a rigidity of 0.5 GPa or more.

8. The device according to claim 1, wherein: The processor is configured to acquire an oscillometric waveform using the one or more pulse wave signals and the contact force, and estimate bio-information by analyzing changes in the oscillometric waveform.

9. The device according to claim 8, wherein: The processor is configured to select one or more pulse wave signals from among the one or more pulse wave signals, and acquire an oscillometric waveform using the selected one or more pulse wave signals and the contact force.

10. The device according to claim 9, wherein: The processor is configured to select one or more pulse wave signals based on at least one of a maximum amplitude value of each pulse wave signal, an average amplitude value, and a difference between a maximum amplitude value and a minimum amplitude value of each pulse wave signal.

11. The device according to claim 1, wherein: The processor is configured to generate and provide contact pressure guidance information based on the measured contact force during the measurement of the pulse wave signal.

12. The device according to claim 1, wherein: The biological information is blood pressure.

13. The apparatus according to claim 1, wherein: The device does not include a contact area sensor to measure the contact area with the object of interest.

14. A method for measuring biological information, comprising: measuring one or more pulse wave signals from an object of interest in contact with a contact surface of the pulse wave sensor, the contact surface of the pulse wave sensor being a curved surface convex toward a contact surface of the object of interest; measuring the contact force between the pulse wave sensor and the object; and estimating biological information of the subject based on the measured one or more pulse wave signals and the measured contact force, The pulse wave sensor comprises: a housing having a curved contact surface; The housing has a first curvature radius R1 of not less than 2 mm and not more than 10 mm and a second curvature radius R2 of not less than 0.5×R1 and not more than 4×R1. Among them, the pulse wave signal is a photoplethysmography (PPG) signal, The pulse wave sensor also includes a pulse wave measuring device installed in the housing. The pulse wave measurer includes: two light sources configured to emit light to the object of interest; and a photodetector configured to receive light returned from the object and measure the one or more pulse wave signals. wherein the photodetector is disposed at the center of the curved surface as a circular contact surface, and The two light sources are symmetrically arranged relative to the photodetector along the length direction of the pulse wave sensor or the tangent direction of the curved surface, and are arranged inside the edge portion to be arranged at 0.1L to 0.9L, where L is the length of the pulse wave sensor.

15. The method according to claim 14, wherein: The step of measuring the one or more pulse wave signals includes: emitting light to the subject; and measuring the one or more pulse wave signals by receiving light returned from the subject.

16. The method according to claim 14, wherein: The step of estimating the biological information includes: acquiring an oscillometric waveform using the one or more pulse wave signals and the contact force; and estimating the biological information by analyzing a change in the oscillometric waveform.

17. The method according to claim 16, wherein: The step of acquiring the oscillometric waveform includes: selecting one or more pulse wave signals from among the one or more pulse wave signals; and acquiring the oscillometric waveform using the selected one or more pulse wave signals and the contact force.

18. The method according to claim 17, wherein: The step of selecting one or more pulse wave signals includes selecting one or more pulse wave signals based on at least one of a maximum amplitude value, an average amplitude value, and a difference between a maximum amplitude value and a minimum amplitude value of each pulse wave signal.

19. The method according to claim 14, further comprising: Contact pressure guidance information is generated and provided based on the measured contact force during the measurement of the pulse wave signal.

20. The method according to claim 14, wherein: The biological information is blood pressure.

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