Biosensor

Abstract

A ring-shaped biosensor (2) comprises a main unit (21) that is ring-shaped to be strapped around a finger or a wrist, a sensor unit (22) that is provided in the main unit (21) and detects biological data including a blood pressure, an acceleration sensor (25) that is provided in the main unit (21) and detects the acceleration of the main unit (21) and the inclination of the main unit (21) with respect to a vertical direction, and a control unit (24) that determines whether a user is sleeping or not on the basis of the acceleration of the main unit (21), estimates the measurement posture of the user from the inclination of the main unit (21) with respect to the vertical direction, determines whether a height difference between the main unit (21) and the heart of the user is within a predetermined range, and performs processing on the biological data including a blood pressure on the basis of the result of determination on whether the user is sleeping or not and the result of determination on the measurement posture of the user.

Description

Technical Field

[0001] The present invention relates to a biosensor, and more particularly to a biosensor that acquires biological data including blood pressure whose measured value is affected by the difference between the height of the measurement site and the height of the heart (i.e., affected by hydrostatic pressure).

Background Art

[0002] When the blood pressure measurement site is at a position higher than the heart, the measured value of the blood pressure is lowered by the pressure difference of the hydrostatic pressure in the blood vessel due to gravity. Conversely, when the blood pressure measurement site is at a position lower than the heart, the measured value of the blood pressure is increased by the pressure difference of the hydrostatic pressure in the blood vessel. More specifically, when the blood pressure measurement site is about 1 cm above or below the height of the heart, the blood pressure (measured value) changes by about 0.7 mmHg.

[0003] Here, Patent Document 1 discloses a blood pressure measurement device that can measure accurate blood pressure even when the user is in an arbitrary posture. More specifically, in this blood pressure measurement device, in addition to a blood pressure sensor that detects the user's blood pressure, one or more sensors are attached to one or more body parts of the user, and based on the sensor information from each sensor, posture information of the user to whom the sensor is attached is acquired, and height information of the blood pressure sensor is acquired. Then, the blood pressure measurement value measured by the blood pressure sensor is corrected from the user's posture information and the height information of the blood pressure sensor.

[0004] Further, Patent Document 1 describes that when it can be determined that the user is in bed because the time zone and / or the acceleration do not vary so much, since each sensor is fixed to the user's body, it is possible to determine which direction the user is facing with respect to the direction of gravity.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the blood pressure measuring device disclosed in Patent Document 1, in addition to the blood pressure sensor for measuring blood pressure, it is necessary to attach one or more sensors for acquiring the posture information of the user and the height information of the blood pressure sensor to one or more body parts of the user. Therefore, the handling is complicated, and measurement errors (that is, errors caused by handling), such as displacement of the sensor mounting position, are likely to occur.

[0007] The present invention has been made to solve the above problems, and is a biological sensor that acquires biological data including blood pressure, the measurement value of which is affected by the difference between the height of the measurement site and the height of the heart (that is, affected by hydrostatic pressure) during sleep, and is easy to handle and less likely to cause errors due to handling.

Means for Solving the Problems

[0008] The biological sensor according to the present invention includes a main body portion formed in a ring shape so as to be attachable to a finger or a wrist of a hand, a sensor portion provided in the main body portion for detecting biological data including blood pressure, an acceleration sensor provided in the main body portion for detecting the acceleration of the main body portion and the inclination with respect to the vertical direction, determining whether the user is asleep from the acceleration of the main body portion, and estimating the measurement posture of the user from the inclination of the main body portion with respect to the vertical direction to determine whether the difference in height between the main body portion and the user's heart is within a predetermined range, and based on the determination result of whether the user is asleep and the determination result of the user's measurement posture, a control unit that performs detection of biological data including blood pressure by the sensor unit and processing of the detected biological data including blood pressure.

[0009] According to the biological sensor of the present invention, it is determined whether the user is asleep based on the acceleration of the main body portion formed in a ring shape so as to be wearable on a finger or wrist of the hand, and the measurement posture of the user is estimated from the inclination of the main body portion with respect to the vertical direction, and it is determined whether the height difference between the main body portion and the user's heart is within a predetermined range. Based on the determination result of whether the user is asleep and the determination result of the measurement posture of the user, detection of biological data including blood pressure using the sensor unit and processing of the detected biological data including blood pressure are performed. Therefore, by simply wearing the biological sensor according to the present invention on a finger or wrist of the hand, it is automatically determined whether the user is asleep, and considering the measurement posture (sleeping posture) at that time, that is, the height difference between the main body portion and the user's heart, biological data including blood pressure can be processed and acquired. Thus, for example, it is not necessary to wear one or more sensors for acquiring the posture information of the user and the height information of the blood pressure sensor on one or more body parts of the user separately from the blood pressure sensor, so that the handling becomes simple and errors caused by handling are less likely to occur.

Advantages of the Invention

[0010] According to the present invention, in a biological sensor that acquires biological data including blood pressure whose measured value is affected by the difference in height between the measurement site and the heart (i.e., affected by hydrostatic pressure) during sleep, it is possible to simplify the handling and make it difficult to cause errors due to handling.

Brief Description of the Drawings

[0011]

Figure 1

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Mode for Carrying Out the Invention

[0012] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts will be denoted by the same reference numerals. Also, in each figure, the same elements will be denoted by the same reference numerals and redundant explanations will be omitted. Here, the case where the annular biosensor 2 (corresponding to the biosensor described in the claims) according to the embodiment is used as a biological data measurement system 1 together with the portable control unit 3 will be described as an example. Note that the annular biosensor 2 can also be used alone.

[0013] First, with reference to FIGS. 1 to 3 together, the configuration of the annular biosensor 2 according to the embodiment and the biological data measurement system 1 including the annular biosensor 2 will be described. FIG. 1 is a diagram showing the overall configuration of the annular biosensor 2 and the biological data measurement system 1 including the annular biosensor 2. FIG. 2 is a block diagram showing the functional configuration of the annular biosensor 2 and the biological data measurement system 1 including the annular biosensor 2. FIG. 3 is a diagram showing an example when the annular biosensor 2 is made asymmetric, and (a) shows an example when it is left - right asymmetric, and (b) shows an example when it is up - down - left - right asymmetric.

[0014] The annular biological sensor 2 and the portable control unit 3 that constitute the biological data measurement system 1 are communicably connected to each other via wireless communication. In particular, the annular biological sensor 2 is a biological sensor that acquires biological data including blood pressure whose measured value is affected by the difference between the height of the measurement site and the height of the heart (i.e., affected by hydrostatic pressure) during sleep (while sleeping), and has a function that enables easy handling and makes it difficult to cause errors due to handling.

[0015] The annular biological sensor 2 mainly includes a main body 21 formed in an annular shape (ring type or wristband type) that can be worn on a finger or wrist of a hand, a sensor unit 22 provided on the inner surface of the main body 21 that measures (detects) at least blood pressure, an acceleration sensor 25 provided on the main body 21 that detects the acceleration (body movement) and inclination with respect to the vertical direction of the main body 21, a sensor-side communication unit 23 that transmits and receives data (measurement data, control data, etc.) between the portable control unit 3, determines whether the user is sleeping based on the acceleration of the main body 21, estimates the measurement posture of the user from the inclination of the main body 21 with respect to the vertical direction, and determines whether the difference in height between the main body 21 and the user's heart is within a predetermined range, and based on the determination result of whether the user is sleeping and the determination result of the user's measurement posture, a control unit 24 that detects biological data including blood pressure by the sensor unit 22 and processes the detected biological data including blood pressure.

[0016] Here, the control unit 24 mainly includes a microprocessor that performs calculations, an EEPROM that stores programs and the like for causing the microprocessor to execute each process, a RAM that temporarily stores data, and an input / output interface (I / F), etc. Each function of the control unit 24 is realized by a program stored in the EEPROM or the like being executed by the microprocessor. Further, the annular biological sensor 2 preferably has a temperature sensor that detects body surface temperature.

[0017] The main body 21 of the annular biosensor 2 is formed in an annular (ring-shaped) manner so as to be wearable on a finger of a hand. Alternatively, the main body 21 is formed in an annular (wristband-shaped) manner so as to be wearable on the wrist. In this embodiment, as the annular biosensor 2, a ring-shaped biosensor worn on a finger of a hand will be described as an example. The annular biosensor 2 is worn on, for example, the index finger of one hand. However, the finger on which the annular biosensor 2 is worn may be the middle finger, ring finger, little finger, or thumb.

[0018] The sensor unit 22 includes, for example, a light-emitting element (light-emitting unit) 221 and a light-receiving element (light-receiving unit) 222, and is a photoelectric plethysmogram sensor that detects a photoelectric plethysmogram signal. The photoelectric plethysmogram sensor optically measures a pulse or the like by utilizing the light absorption characteristics of hemoglobin in the blood. Hereinafter, the sensor unit 22 may also be referred to as the photoelectric plethysmogram sensor 22. The sensor unit (photoelectric plethysmogram sensor) 22 is provided on the inner surface of the main body 21.

[0019] Further, the sensor unit (photoelectric plethysmogram sensor) 22 is preferably arranged on the main body 21 so as to come to (be located at) the ventral side of the finger when the annular biosensor 2 is worn on the user's finger. This is because in a plethysmogram sensor including the photoelectric plethysmogram sensor 22, it is easier to acquire a biological signal from the ventral side of the finger than from the dorsal side of the finger.

[0020] The sensor unit 22 measures (detects) at least blood pressure. In this embodiment, a blood pressure sensor that estimates blood pressure from a photoelectric plethysmogram waveform will be described as an example. As a method for estimating blood pressure from a photoelectric plethysmogram waveform, a known method (for example, refer to Japanese Patent Application Laid-Open No. 2016-16295, etc.) can be used. That is, the annular biosensor 2 is a so-called cuffless blood pressure monitor that does not use a cuff. In addition, other blood pressure estimation techniques (methods) using pulse wave transit time may also be utilized.

[0021] However, with any method, the obtained blood pressure measurement value may be inaccurate due to the influence of hydrostatic pressure. To avoid the influence of hydrostatic pressure, blood pressure measurement needs to be performed at or near the height of the user's heart. If blood pressure measurement is performed above the height of the heart, the measurement result will be too low. If blood pressure measurement is performed below the height of the heart, the measurement result will be too high. A difference of 10 cm between the blood pressure measurement position and the height of the heart will result in an error of 7-8 mmHg in the blood pressure measurement value. That is, when blood pressure measurement is performed with a finger in a state where the arm is hanging down, a height difference of about 50 cm occurs, resulting in an error of 35-40 mmHg. When a general user who has not received training like medical staff performs blood pressure measurement, blood pressure measurement is often performed at a height quite different from the height of the user's heart, resulting in an error in the blood pressure measurement value. Even in the method of estimating blood pressure from the photoelectric plethysmogram waveform measured with a finger, it is necessary to minimize or eliminate the influence of hydrostatic pressure in order to perform accurate blood pressure measurement.

[0022] In addition, a method for estimating blood glucose levels from a photoelectric pulse wave form can also use a known method (see, for example, Japanese Patent Application No. 2017-506158, etc.). However, since the photoelectric pulse wave form is also affected by the blood pressure value at that time, it also affects the estimated blood glucose level. Therefore, it is necessary to take an appropriate measurement posture even with a blood glucose sensor to limit the influence of blood pressure. Also, in a posture where the abdomen is compressed like a hunched forward position, the blood pressure may increase, but depending on the posture, the pulse and breathing may also change, and it may be necessary to take an appropriate measurement posture. The photoelectric pulse wave form also contains information on vascular resistance. When obtaining vascular resistance, since the photoelectric pulse wave form is affected by blood pressure, the variation can be reduced by measuring at the height of the heart. Although vascular resistance is cited as an example, the same applies when estimating blood flow rate, blood glucose level, and degree of arteriosclerosis from the waveform. Also, since the measurement posture affects the pulse rate, blood flow rate, body surface temperature, and breathing itself, the measurement variation can be reduced by performing the measurement in a fixed posture. Here, as the biological data (biological information) to be measured, in addition to blood pressure, for example, sleep state, pulse wave, pulse, oxygen saturation, blood glucose level, body surface temperature, activity level, vascular resistance, blood flow rate, degree of arteriosclerosis, and breathing, etc. may be included. In this way, by simultaneously measuring a plurality of biological data (information), it becomes possible to estimate the state of health and signs of diseases, etc.

[0023] In addition, there are also various other factors that affect blood pressure. For example, diet, alcohol consumption, caffeine intake, smoking, etc. are known to affect blood pressure. Also, for example, exercise, walking, physical work (such as cleaning), taking a bath, conversation, mental stress, an environment with noise or vibration, a cold environment, etc. also affect blood pressure. These events occur frequently during wakefulness, and it is difficult to determine at which timing they occur. During sleep, since the influence of the above-mentioned events can be reduced, it is suitable for stably measuring blood pressure. By determining whether it is during sleep, for example, from the activity level, body surface temperature, pulse rate, etc., the wakeful state and the sleep state can be distinguished, and the measurement accuracy can be improved.

[0024] Furthermore, in the waking state (while awake), compared to the sleeping state (while sleeping), there are more types of postures that can be taken, and it is difficult to infer the posture of the trunk only from information such as the inclination of the hand. However, by limiting it to the sleeping time, it becomes easier to infer the posture of the trunk only from hand information, and the estimation accuracy of the height from the heart can be improved. For example, in a state where the forearm is placed on the armrest of a chair in a sitting position or in a state where the arm is placed on the backrest of a large sofa, the wrist and fingers are almost horizontal, there is no significant body movement, and it is difficult to distinguish the lying position with a single sensor. On the other hand, in the sleeping state, since the arm often goes limp and hangs down in a sitting position, it becomes easier to distinguish.

[0025] Also, generally, blood pressure during sleep is lower than during waking (dipper type). However, in cases where it is almost the same (non-dipper type), increases (riser type), or becomes excessively low (extreme dipper type), it is known that the risk of cerebrovascular disease increases. Measuring blood pressure during sleep is also useful in that it can detect such nocturnal blood pressure.

[0026] Therefore, the control unit 24 determines whether the user is sleeping or not from the acceleration of the main body unit 21. For example, when the acceleration exceeds a predetermined value, the control unit 24 determines it as body movement, and when the number of body movements within a predetermined time is below a predetermined threshold, it determines that the user is sleeping. Although the acceleration may suddenly increase during sleep due to turning over or the like, the frequency is lower compared to the waking state. The fingers move more frequently during waking compared to the waist, chest, wrist, etc. Therefore, it may be determined that the user is sleeping simply when the average value of the acceleration over a predetermined time is below a predetermined threshold. Also, it is preferable to utilize the fact that the temperature of the fingers rises during sleep to estimate the circadian rhythm from the surface body temperature of the fingers and improve the accuracy of sleep determination in combination with the acceleration. Also, since the pulse rate decreases during sleep and respiratory variations are more likely to occur in the pulse rate, the accuracy of sleep determination may be improved by adding the trend of the pulse rate. When it is determined that the user is in the sleeping state, sleep state information is transmitted.

[0027] Even during sleep, there are body movements such as turning over. It is also known that body movements increase during REM sleep. In addition, body movements may be involved in sleep disorders. Furthermore, body movements are also involved in periodic limb movement disorder (PLMD), restless legs syndrome (RLS), sleep apnea syndrome, etc. When there is body movement, blood pressure temporarily rises, so it is necessary to wait until the blood pressure stabilizes before measuring. Generally, it can be considered at rest after about 5 minutes, but it takes even longer to reach a resting state after intense movement. Therefore, the control unit 24 determines that it is in a resting state (or has become a resting state) when acceleration (body movement) above a predetermined value is not detected for a predetermined time or more. The predetermined time (determination time) may be, for example, 5 minutes and may be changed according to the magnitude of the acceleration (intensity of body movement) detected most recently. When it is determined that it is in a resting state, resting state information is transmitted. In this way, the measurement accuracy can be improved by performing the resting state determination.

[0028] Here, it should be noted that it takes several minutes or more to execute each of the sleep determination and the resting state determination. During that time, if a temporary body movement such as turning over occurs, the sleep determination may continue, while the resting state determination is reset. The sleep determination is performed based on criteria such as body movement where the acceleration exceeds the first threshold value not more than m times in 15 minutes or not more than n times in 90 minutes, while the resting state determination is performed based on criteria such as body movement where the acceleration exceeds the second threshold value has not occurred for 5 minutes since the previous occurrence. Note that the first threshold value and the second threshold value do not have to be the same.

[0029] In addition, the control unit 24 determines whether the annular biological sensor 2 is worn on the finger (or wrist) of the hand. If the posture determination (details will be described later) is performed when the annular biological sensor 2 is not worn, there is a risk of misjudging as appropriate even though it is not in an appropriate posture. However, such a problem can be avoided by performing the posture determination only when the annular biological sensor 2 is worn.

[0030] Here, as a method for determining whether the annular biological sensor 2 is worn, it is desirable to determine based on whether a pulse wave is detected by the photoelectric pulse wave sensor 22. This is because the possibility of misjudgment, such as determining that it is worn even though it is not worn on the finger, is low. However, since it is necessary to measure for two or more beats to determine that it is a pulse wave, it may take more than 3 seconds. Therefore, it may also be determined based on whether the received light amount by the photoelectric pulse wave sensor 22 exceeds a threshold value. When the photoelectric pulse wave sensor 22 is a reflection type, since the received light amount becomes low when it is not worn, it is considered not to be worn when the threshold value is not exceeded. When the photoelectric pulse wave sensor 22 is a transmission type, since the received light amount becomes high when it is not worn, it is considered not to be worn when the threshold value is exceeded. According to this method, determination can be made in a short time. However, no matter what blocks the light and is inserted into the annular biological sensor 2, there is a possibility that it may be determined to be worn (that is, misjudged). Therefore, when no movement is detected by the acceleration sensor 25, gyro sensor, etc., a method of determining that the annular biological sensor 2 is not worn, or a temperature sensor for detecting the body surface temperature is provided, and when the detected temperature is below a predetermined value, it is determined that the annular biological sensor 2 is not worn. It may also be configured to determine whether the annular biological sensor 2 is worn on the finger in combination with other methods.

[0031] When the control unit 24 determines that the annular biological sensor 2 is not worn on the finger or wrist of the hand, it does not perform a determination as to whether the user is sleeping (sleep determination), a determination as to whether the user is in a resting state (resting state determination), or a determination of the measurement posture of the user (posture determination).

[0032] When the control unit 24 determines that the user is in a resting state, it estimates the measurement posture of the user from the inclination of the annular biological sensor 2 (main body unit 21) with respect to the vertical direction, and determines whether the height difference between the annular biological sensor 2 (main body unit 21) and the user's heart is within a predetermined range. Then, the control unit 24 performs detection of biological data including blood pressure by the sensor unit and processing of the detected biological data including blood pressure based on the determination result as to whether the user is sleeping and the determination result of the measurement posture of the user.

[0033] Here, a method for estimating the difference in height between the annular biosensor 2 and the heart will be described. Note that the concept is the same even for a wristwatch-type or wristband-type annular biosensor worn on the wrist. The control unit 24 estimates the difference in height between the annular biosensor 2 and the user's heart based on the inclination of the central axis of the annular biosensor 2 with respect to the vertical direction. More specifically, when the inclination of the central axis of the annular biosensor 2, that is, the axis in the longitudinal direction of the finger (or wrist) on which the annular biosensor 2 is worn, from the vertical direction is near 90°, it is estimated that the user is in a lying position (supine position, prone position, lateral lying position) (see Fig. 6). In this case, the difference in height between the annular biosensor 2 and the heart is small, and it is determined that correction is possible.

[0034] On the other hand, when the inclination of the central axis of the annular biosensor 2, that is, the axis in the longitudinal direction of the finger (or wrist) on which the annular biosensor 2 is worn, from the vertical direction is near 0° (the finger is in the vertical direction), it means that the forearm is facing the vertical direction, and it is estimated that the user is in a sitting position or a state (posture) where the arm protrudes from the bed and hangs down due to gravity (see Fig. 7). In this case, the difference in height between the annular biosensor 2 and the heart is large, and it is determined that correction is impossible. When the inclination is near 0° (the finger is in the vertical direction), since it is determined that the posture has a large difference in height from the heart, measurement of biological data (such as blood pressure) that is greatly affected by the deviation in height from the heart is not performed.

[0035] The range near 90° is preferably 40 - 90° for the ring-type annular biosensor 2 (see Fig. 6) and 70 - 90° for the wristwatch-type or wristband-type annular biosensor. In the case of the ring-type, it is worn on the phalanx. However, due to the bending of the palm with respect to the wrist and the bending of the phalanx with respect to the palm, even if the wrist is approximately 90°, the phalanx may bend about 0 - 30° with respect to the wrist, so the range for the ring-type is widened. The range near 0° is preferably 0 - 40° for the ring-type (see Fig. 7) and 0 - 70° for the wristwatch-type or wristband-type.

[0036] Also, during sleep, when the hand is placed on the floor (bedding), the height of the hand is lower than the height of the heart in any of the supine, prone, or lateral positions. Since the heart is approximately in the center of the chest, in the supine and prone positions, it is lower by approximately half of the chest thickness. In the lateral position, it is lower by approximately half of the chest width. Therefore, the measured value may be corrected by the difference in height. Here, according to the "AIST Human Dimension Database 1991 - 1992", the average value of the chest width (transverse chest diameter) is 288.7 mm, and half of it is 144.4 mm. Also, the average value of the chest thickness (anteroposterior chest diameter) is 211.8 mm, and half of it is 105.9 mm. Therefore, the difference is 38.5 mm, which corresponds to a deviation of approximately 3 mmHg in blood pressure value. Although this deviation in blood pressure value is within an acceptable range, it is possible to reduce the deviation by obtaining data on the deviation from the heart height at the measurement position and acceleration data for many people and performing machine learning.

[0037] In the ring-shaped biological sensor 2, the height of the measurement position is approximately the same whether the palm is facing down or up. Depending on whether the measurement point is the fingertip, the back, or the side of the finger, and whether it is a reflection-type photoplethysmogram sensor or a transmission-type photoplethysmogram sensor, a height deviation of about the thickness of one finger occurs. This deviation may be tolerated or corrected for improved accuracy. In a wristwatch-type or wristband-type ring-shaped biological sensor, for example, when a reflection-type photoplethysmogram sensor is placed on the back of the wrist, it is higher by the thickness of the wrist when the palm is facing down compared to when it is facing up.

[0038] By using the inclination of the ring-shaped biological sensor 2 attached to the finger (or wrist) from the vertical direction of the width axis and the thickness axis, the difference in height between the ring-shaped biological sensor 2 and the heart can be estimated more accurately.

[0039] In the case of the ring-shaped biological sensor 2, when the palm is facing down and in contact with the floor (bedding) (see Fig. 4(a)), and when the back of the hand is in contact with the bedding (see Fig. 4(b)), there is no significant difference in the height of the measurement site (about the thickness of one finger), but when neither the palm nor the back of the hand is in contact with the bedding (the palm is facing in a substantially horizontal direction) (see Figs. 5(a) and 5(b)), the height of the measurement site often becomes higher (in the case of wearing on the index finger, about three times the thickness of the finger). Therefore, by further considering the inclination of the axis perpendicular to the central axis of the ring-shaped biological sensor 2 with respect to the vertical direction (for example, the inclination of the X-axis or the Y-axis when the central axis is the Z-axis), and estimating the difference in height between the ring-shaped biological sensor 2 and the height of the user's heart, the estimation accuracy of the difference in height from the heart can be improved. By using the statistical quantity of the width from the index finger (second finger) to the little finger (fifth finger), it is possible to estimate how much higher it is when neither the palm nor the back of the hand is in contact with the bedding (the palm is facing in a substantially horizontal direction) compared to the case when the palm is facing down and in contact with the floor (bedding). For example, it can be estimated that it is higher by the total of the proximal joint widths from the index finger (second finger) to the ring finger (fourth finger) compared to the case when the palm is facing down.

[0040] In the case of a wristwatch-type or wristband-type ring-shaped biological sensor, the height of the measurement site is different when the palm is in contact with the bedding, when the back of the hand is in contact with the bedding, and when neither the palm nor the back of the hand is in contact with the bedding (the palm is facing in a substantially horizontal direction). For example, in the case of a ring-shaped biological sensor measured at the center of the back of the wrist, when the palm is in contact with the bedding, it can be estimated that it is at a position higher by the statistical quantity of the wrist thickness compared to the case when the back of the hand is in contact with the bedding. When the palm is facing in a substantially horizontal direction, it can be estimated that it is at a position higher by half of the statistical quantity of the wrist width. By combining with the inclination of the longitudinal axis of the finger (or wrist) from the vertical direction, the estimation accuracy of the difference in height from the heart can be improved.

[0041] In the case of the ring-shaped biological sensor 2, when the palm is facing in a substantially horizontal direction, if (1) the finger on which the ring-shaped biological sensor 2 is fitted and (2) the direction in which the ring-shaped biological sensor 2 is fitted cannot be specified, the accuracy of height estimation may deteriorate. The height estimation result varies depending on whether the hand on which the ring-shaped biological sensor 2 is fitted is the right hand or the left hand and which finger of the five fingers it is. There may be a deviation in the estimated height for about three fingers. Therefore, the control unit 24 acquires information specifying the mounting site of the ring-shaped biological sensor 2 (main body unit 21), and estimates the difference between the height of the ring-shaped biological sensor 2 and the height of the user's heart in consideration of the mounting site. By doing so, it is possible to specify which finger of which hand on the left or right the ring-shaped biological sensor 2 is mounted, and thus the accuracy of height estimation can be improved.

[0042] More specifically, the user is asked to input into the portable control unit 3 the finger on which the ring-shaped biological sensor 2 is fitted, and to move the hand on which it is fitted around the elbow. Then, a method of specifying the orientation (front and back) of the ring-shaped biological sensor 2 from the data of the acceleration sensor 25 (or gyro sensor) at that time (since the mounting orientation (front and back) is unknown only from which finger it is, it is necessary to specify the orientation), a method of having the hand on which the ring-shaped biological sensor 2 is fitted photographed by the imaging unit 31 (camera) of the portable control unit 3, and automatically recognizing and specifying the hand and the ring-shaped biological sensor 2 from the image, etc. can be mentioned. In this case, as a method of specifying the orientation, it may be configured to determine from the image, or as described above, the hand on which the ring-shaped biological sensor 2 is fitted may be moved around the elbow, and the orientation (front and back) of the ring-shaped biological sensor 2 may be specified from the data of the acceleration sensor 25 (or gyro sensor) at that time.

[0043] Also, it is preferable to configure the annular biosensor 2 to have a structure (shape) that can only be fitted onto a specific finger. For example, by forming the main body 21 asymmetric with respect to a plane including the central axis or asymmetric with respect to a plane orthogonal to the central axis (rotationally asymmetric / left-right asymmetric in side view), it can be made difficult to wear on fingers other than the index finger or little finger (see Fig. 3(a)). Note that, depending on the hole diameter of the ring, it is possible to distinguish whether it is for wearing on the index finger or the little finger. In the shape shown in Fig. 3(a), since the wider side is on the thumb side, by determining whether it is upward or downward with the acceleration sensor (tilt sensor) 25, it is possible to determine whether the thumb side is upward or downward. In this case, it can be estimated in the same way regardless of which hand (left or right) it is worn on. Also, as shown in Fig. 3(b), by making it asymmetric in the vertical (front-back) direction as well, it may be configured to have a shape that can only be worn on a specific finger (in the example of Fig. 3(b), it can only be worn on the index finger of the right hand).

[0044] In this way, by making the annular biosensor 2 have a shape that is not symmetric between the thumb side and the little finger side, the wearing orientation can be limited when worn on the right hand and when worn on the left hand. When the palm is facing in a substantially horizontal direction, the height of the measurement site changes depending on whether the thumb side is downward or upward, but by limiting the wearing orientation, it is possible to distinguish between the case where the thumb side is downward and the case where the thumb side is upward, thus improving the estimation accuracy of the difference from the height of the heart.

[0045] Also, if it is configured to display characters or the like on the side surface, even if the shape is symmetric left and right, by setting the direction in which the characters or the like can be read in the circumferential direction (90° sideways), the direction of the thumb side can be specified. Such a form can be realized by providing a display or indicator in an annular biosensor in the form of a wristwatch or a wristband. When the palm is facing in a substantially horizontal direction, the height of the measurement site changes depending on whether the thumb side is downward (Fig. 5(b)) or upward (Fig. 5(a)), but by limiting the wearing orientation by the method described above, it is possible to distinguish between the case where the thumb side is downward and the case where the thumb side is upward, thus improving the estimation accuracy of the difference from the height of the heart.

[0046] The above-described method illustrates an example of estimating heart height from the average value of statistical quantities. However, the estimation accuracy can be improved by using the user's physical information. The user's physical information can be read from a memory or server that the user has previously entered into the portable control unit 3, or from health checkup data stored on a server. While height alone is sufficient, it is preferable to also include actual measurements of the user's weight and other data (such as chest thickness). In practice, actual measurements other than height and weight are often unavailable, so in such cases, estimation is performed from statistical quantities. For example, the average value of the statistical quantities is μ and the standard deviation is σ, and the user's height can be expressed using the height statistics μ and σ as shown in the following equation (1). The user's chest thickness can then be estimated from the calculated coefficient a and the chest thickness statistics. User measurement value = μ i +a×σ i ···(1)

[0047] That is, the control unit 24 acquires pre-stored physical information of the user and estimates the height of the user's heart in consideration of the physical information. In this way, the chest thickness and chest width can be estimated from the height (and weight), improving the accuracy of determining whether the annular biosensor 2 is at the height of the heart.

[0048] As mentioned above, it is important to measure blood pressure at heart height while the user is at rest, and accurate blood pressure values cannot be obtained unless the user is in the proper position. However, measuring at heart height limits the user's measurement position, which can be difficult when continuous or periodic data is required. Therefore, it is important to calculate the reliability of the measurement value and correct it so that it is approximately equivalent to the blood pressure value obtained in the proper measurement position. The more the user deviates from the proper position, the more inaccurate the blood pressure value becomes. Therefore, by calculating the reliability of the measurement value according to the deviation from the proper position, the user can handle the measurement value while taking into account the risk that the blood pressure measurement value may deviate from the true value.

[0049] Therefore, based on the determination result of the user's measurement posture (posture determination result), the control unit 24 calculates the reliability of the biological data including the acquired blood pressure. By calculating the reliability, the measured blood pressure value can be handled in consideration of the risk that the blood pressure measurement value deviates from the true value.

[0050] In addition, by correcting the measured blood pressure value to be approximately equal to the blood pressure value in the case of an appropriate measurement posture, it becomes more convenient for the user. The control unit 24 may correct biological data such as blood pressure based on the determination result of the user's measurement posture.

[0051] If the difference in height between the annular biological sensor 2 and the heart can be estimated, the blood pressure value can be corrected. However, the blood pressure estimation accuracy is improved when the annular biological sensor 2 is set to the (vertical) height of the heart for measurement. That is, measuring at the height of the heart each time results in more stable blood pressure accuracy than measuring at a position lower or higher than the heart. However, measuring at the height of the heart limits the user's measurement posture, so it may be difficult when continuous data or periodic data is required (there is a risk of causing pain to the user). Therefore, by correcting the measured blood pressure value to be approximately equal to the blood pressure value in the case of an appropriate measurement posture, it becomes possible to acquire continuous data and periodic data.

[0052] Note that when the portable control unit 3 configured to be mutually communicable is being operated, the control unit 24 determines that the user is not sleeping (awake). When performing sleep determination based only on acceleration data, there is a risk of misjudgment that the user is awake but has little movement. By determining that the user is awake when the portable control unit 3 is being operated, the probability of misjudgment can be reduced. In particular, it is difficult to determine whether the user is in a sleeping state or an awake state during a middle-of-the-night awakening or waking up, but the determination accuracy can be improved by adding whether the portable control unit 3 is being operated as a determination criterion. However, this method is applicable only when the annular biological sensor 2 and the portable control unit 3 are in a one-to-one correspondence. That is, it is applicable to a system in which only one annular biological sensor 2 can be paired with one portable control unit 3, or a system in which a plurality of annular biological sensors 2 can be paired with one portable control unit 3, and only one annular biological sensor 2 is connected. This is because when a plurality of annular biological sensors 2 are connected, there is a possibility that a plurality of users share the portable control unit 3. However, if the user operating the portable control unit 3 can be determined by the login ID of the portable control unit 3 or the like and can be determined to be the same as the user wearing the annular biological sensor 2, it is also applicable when a plurality of annular biological sensors 2 are connected.

[0053] The sensor-side communication unit 23 transmits and receives data (measurement data, operation / control data, etc.) to and from the portable control unit 3. Here, in the present embodiment, Bluetooth (registered trademark) is adopted as the wireless communication standard. That is, the sensor-side communication unit 23 has a transmission function and a reception function based on Bluetooth (registered trademark). Note that the wireless communication standard to be used is not limited to Bluetooth (registered trademark), and other standards may be used. More specifically, the sensor-side communication unit 23 transmits the wearing state information, sleep state information, rest state information, etc. of the annular biological sensor 2 to the portable control unit 3. In addition, the sensor-side communication unit 23 transmits the acquired biological data such as blood pressure to the portable control unit 3 at a predetermined timing (or cycle).

[0054] On one hand, the portable control unit 3 mainly includes an imaging unit (camera) 31 that captures an image (a still image or a moving image), a display unit 32 composed of an LCD display or the like, which displays the image, information, etc. captured by the imaging unit 31, a unit-side communication unit 33 that transmits and receives data (operation / control data, measurement data, etc.) to and from the annular biosensor 2, and an operation unit 34 that receives operations from the user. As the portable control unit 3 which is a control terminal, for example, a portable terminal such as a smartphone can be preferably used. In this embodiment, a smartphone is used as the portable control unit 3.

[0055] The portable control unit 3, for example, receives from the user the input of the wearing site (wearing position) information of the annular biosensor 2, or captures the wearing site (wearing position) of the annular biosensor 2, identifies the wearing site (wearing position) by image analysis or the like, and as a result, that is, transmits the wearing site (wearing position) information of the annular biosensor 2 to the annular biosensor 2.

[0056] Next, with reference to FIG. 8, the operation of the annular biosensor 2 will be described. FIG. 8 is a flowchart showing the processing procedure of blood pressure measurement processing and the like by the annular biosensor 2. The processing shown in FIG. 8 is mainly repeatedly executed by the annular biosensor 2 at a predetermined timing.

[0057] In step S100, it is determined whether or not it is connected to the portable control unit 3 via Bluetooth (registered trademark). Here, if it is not connected to the portable control unit 3, the process exits temporarily from this process. On the other hand, when it is connected to the portable control unit 3, the process proceeds to step S102.

[0058] In step S102, a photoelectric pulse wave signal is acquired. Then, in step S104, based on the photoelectric pulse wave signal acquired in step S102, a determination is made as to whether the annular biological sensor 2 is attached to a finger. Here, if the annular biological sensor 2 is not attached to the finger, the process exits temporarily from this processing. On the other hand, if the annular biological sensor 2 is attached to the finger, the process proceeds to step S106.

[0059] In step S106, information indicating that the annular biological sensor 2 is attached to the finger (attachment state information) is transmitted to the portable control unit 3. In the subsequent step S108, acceleration data (body movement data) is acquired.

[0060] Then, in step S110, based on the acquired acceleration data (body movement data), a determination is made as to whether the user is sleeping. Note that the method for determining whether the user is sleeping is as described above, so detailed description is omitted here. Also, this determination does not need to be performed continuously and may be performed, for example, at 10 - minute intervals. Here, if it is determined that the user is not sleeping (awake), the process exits temporarily from this processing. On the other hand, if it is determined that the user is sleeping, the process proceeds to step S112.

[0061] In step S112, a determination is made as to whether the user is in a resting state. Note that the method for determining whether the user is in a resting state is as described above, so detailed description is omitted here. Here, if it is determined that the user is not in a resting state, in step S114, after the sleep state information is transmitted to the portable control unit 3, the process exits temporarily from this processing. On the other hand, if it is determined that the user is in a resting state, the process proceeds to step S116.

[0062] In step S116, sleep state information and rest state information are transmitted to the portable control unit 3. Next, in step S118, based on the inclination of the main body 21 with respect to the vertical direction, a determination is made as to whether the measurement posture of the user is appropriate. Here, if the measurement posture of the user is not appropriate, the process exits temporarily. On the other hand, if the measurement posture of the user is appropriate, the process proceeds to step S120.

[0063] In step S120, photoelectric pulse wave data (blood pressure data) and acceleration data (body movement data) are acquired. Then, in step S122, the photoelectric pulse wave data (blood pressure data) and acceleration data (body movement data) acquired in step S120 are transmitted to the portable control unit 3. Thereafter, the process exits temporarily.

[0064] As described in detail above, according to the present embodiment, it is determined whether the user is asleep based on the acceleration of the main body 21 formed in a ring shape so as to be wearable on a finger (or wrist) of the hand, and the measurement posture of the user is estimated from the inclination of the main body 21 with respect to the vertical direction, and it is determined whether the height difference between the annular biological sensor 2 (main body 21) and the user's heart is within a predetermined range. Based on the determination result of whether the user is asleep and the determination result of the user's measurement posture, detection of biological data including blood pressure using the sensor unit 22 and processing of the detected biological data including blood pressure are performed. Therefore, by simply wearing the annular biological sensor 2 on a finger (or wrist) of the hand, it is possible to automatically determine whether the user is asleep, and considering the measurement posture (sleeping posture) at that time, that is, the height difference between the annular biological sensor 2 (main body 21) and the user's heart, biological data including blood pressure can be processed and acquired. Thus, for example, there is no need to wear one or more sensors for acquiring the posture information of the user and the height information of the blood pressure sensor on one or more body parts of the user separately from the blood pressure sensor, so that handling becomes simple and errors caused by handling are less likely to occur.

[0065] As a result, according to this embodiment, in a biological sensor that acquires biological data including blood pressure affected by the difference between the measured value and the height of the measurement site and the height of the heart (i.e., affected by hydrostatic pressure) during sleep, handling can be simplified, and it is possible to make it difficult to cause errors due to handling.

[0066] Although blood pressure values may be different even in the same posture between the sleeping state and the waking state, according to this embodiment, by determining whether it is the sleeping state (during sleep), the sleeping state and the waking state can be distinguished and the accuracy can be improved. Also, when awake, there are more types of postures that can be taken compared to during sleep, and it is difficult to estimate the posture of the trunk only from information such as the inclination of the hand. However, by limiting it to the sleeping state, it becomes easier to estimate the posture of the trunk from only the hand information, so the estimation accuracy of the height from the heart can be improved. Furthermore, by determining the difference between the height of the annular biological sensor 2 and the heart from the inclination of the annular biological sensor 2, it becomes possible to estimate how much the measured blood pressure value deviates from the true value.

[0067] As described above, the embodiments of the present invention have been explained, but the present invention is not limited to the above embodiments and various modifications are possible. For example, in the above embodiment, the configuration is such that data such as measured blood pressure (measurement data) is sequentially transmitted to the portable control unit 3, but the measurement data may be stored in the EEPROM or RAM of the annular biological sensor 2 and read later (after measurement). In the above embodiment, the biological data processing, sleep determination, resting state determination, and wearing determination are performed by the control unit 24 of the annular biological sensor 2, but they may also be performed by the portable control unit 3.

[0068] In the above embodiment, a photoelectric plethysmogram sensor is used as the annular biological sensor 2 (sensor unit 22), but the annular biological sensor 2 (sensor unit 22) is not limited to the photoelectric plethysmogram sensor.

[0069] In the above-described embodiment, Bluetooth (registered trademark) is adopted as the wireless communication standard for transmitting and receiving data (control data (commands), measurement data, etc.) between the annular biological sensor 2 and the portable control unit 3. However, for example, BLE (Bluetooth (registered trademark) Low Energy) or the like may be adopted instead of Bluetooth (registered trademark).

Explanation of Reference Numerals

[0070] 1 Biological data measurement system 2 Annular biological sensor 21 Main body part 22 Sensor part (photoelectric pulse wave sensor) 221 Light emitting element (light emitting part) 222 Light receiving element (light receiving part) 23 Sensor-side communication unit (BT module) 24 Control unit 25 Acceleration sensor 3 Portable control unit 31 Imaging unit 32 Display unit 33 Unit-side communication unit (BT module) 34 Operation unit

Claims

1. A main body portion annularly formed so as to be attachable to a finger or wrist of a hand, A sensor unit provided on the main body portion for detecting biological data including blood pressure, An acceleration sensor provided on the main body portion for detecting the acceleration of the main body portion and the inclination with respect to the vertical direction, Determining whether the user is sleeping from the acceleration of the main body portion, estimating the measurement posture of the user from the inclination of the main body portion with respect to the vertical direction, and determining whether the height difference between the main body portion and the user's heart is within a predetermined range, and based on the determination result of whether the user is sleeping and the determination result of the measurement posture of the user, a control unit that performs detection of biological data including blood pressure by the sensor unit and processing of the detected biological data including blood pressure, The control unit determines that the user is not sleeping when a portable control unit configured to be communicable with each other is operated, and does not detect the biological data. A biosensor characterized by that.

2. A main body portion annularly formed so as to be attachable to a finger or wrist of a hand, A sensor unit provided on the main body portion for detecting biological data including blood pressure, An acceleration sensor provided on the main body portion for detecting the acceleration of the main body portion and the inclination with respect to the vertical direction, Determining whether the user is sleeping from the acceleration of the main body portion, estimating the measurement posture of the user from the inclination of the main body portion with respect to the vertical direction, and determining whether the height difference between the main body portion and the user's heart is within a predetermined range, and based on the determination result of whether the user is sleeping and the determination result of the measurement posture of the user, a control unit that performs detection of biological data including blood pressure by the sensor unit and processing of the detected biological data including blood pressure, A biosensor comprising: The control unit acquires information for specifying the wearing site of the biosensor, and determines the height difference between the biosensor and the user's heart in consideration of the wearing site. A biosensor characterized by that.

3. The control unit determines that the user is in a resting state when an acceleration equal to or greater than a predetermined value is not detected for a predetermined time or more, and when it is determined that the user is in a resting state, estimates the measurement posture of the user and determines whether the height difference between the main body portion and the user's heart is within a predetermined range. The biosensor according to claim 1 or 2, characterized by that.

4. The control unit determines whether the biosensor is attached to a finger or wrist of the hand. When it is determined that the biosensor is not attached to a finger or wrist of the hand, the determination of whether the user is sleeping, the determination of whether the user is in a resting state, and the determination of the measurement posture of the user are not performed. The biosensor according to claim 3, characterized in that.

5. The control unit estimates the difference in height between the biosensor and the user's heart based on the inclination of the central axis of the biosensor with respect to the vertical direction. The biosensor according to any one of claims 1 to 4, characterized in that.

6. The control unit further estimates the difference in height between the biosensor and the user's heart in consideration of the inclination of the axis orthogonal to the central axis of the biosensor with respect to the vertical direction. The biosensor according to claim 5, characterized in that.

7. The main body portion is formed asymmetrically with respect to a plane including the central axis or asymmetrically with respect to a plane orthogonal to the central axis. The biosensor according to any one of claims 1 to 6, characterized in that.

8. The control unit acquires the user's body information stored in advance and estimates the height of the user's heart in consideration of the body information. The biosensor according to any one of claims 1 to 7, characterized in that.

9. The biological data includes at least one of blood glucose level, pulse, respiration, pulse wave, oxygen saturation, body surface temperature, activity level, and sleep state in addition to blood pressure. The biosensor according to any one of claims 1 to 8, characterized in that.

10. The control unit calculates the reliability of the biological data including the acquired blood pressure based on the determination result of the measurement posture of the user. The biosensor according to any one of claims 1 to 9, characterized in that.

11. The control unit corrects the biological data including blood pressure based on the determination result of the measurement posture of the user. The biosensor according to any one of claims 1 to 10, characterized in that.

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