JP2018121704A - Wearable pulse wave sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wearable pulse wave sensor which can be attached to a nail to measure a pulse wave which is biological information. SOLUTION: A mounting portion 10 attached to the surface of a claw N and a light irradiation portion 11 provided on the mounting portion 10 so that a light emitting surface faces the claw N with the mounting portion 10 attached to the claw N. The light receiving unit 12 is provided on the mounting unit 10 so that the light receiving surface faces the claw with the mounting unit 10 attached to the claw, and outputs an electric signal corresponding to the amount of light received by the light receiving surface. And a sensor main body 2 including a control unit 13 that is electrically connected to the light irradiation unit 11 and controls the operation of both, and the control unit 13 has a function of amplifying an electric signal from which the offset has been removed. It is characterized in that the offset is calculated based on the electric signal output by the light receiving unit 12. [Selection diagram] Fig. 1

Description

  The present invention relates to a wearable pulse wave sensor. More specifically, the present invention relates to a wearable pulse wave sensor that can be attached to a human nail and measure a pulse wave.

  Currently, many sensors have been developed that are attached to a person's body and measure a person's motion state, pulse, and the like. For example, a device that is worn on a person's arm and measures the movement of the arm or the whole body of the person, or a device that measures a pulse or the like has been developed.

  If such a wearable sensor is used, the movement of a person can be monitored without using a large-scale device, and a person's condition such as a pulse wave and a body temperature that can only be measured in a stationary state can be measured even during exercise. In addition, if it is worn by an elderly person, there is an advantage that it can be used for safety confirmation and watching of the elderly person.

  On the other hand, wearable sensors have become smaller and lighter in recent years, and the feeling of discomfort due to wearing has been reduced. However, the sense of wearing a special device has not yet been dismissed. The reason is that many wearable sensors have a form attached to the body surface. Since there are many sweat glands and sensory nerves on the body surface, it is difficult to completely eliminate the sensation that a foreign object is in contact with the body surface even with a small sensor.

  On the other hand, since there are no sweat glands and sensory nerves in the nail, there is a possibility that a feeling of incongruity due to wearing may be eliminated if a sensor is attached to the nail. Examples of attaching a sensor to a nail include Patent Documents 1 and 2. The purpose of these techniques is to obtain a tactile information based on the distortion of a nail when a strain gauge is attached to the nail and a finger touches an object.

Japanese Patent No. 5108485 JP 2001-265522 A

Ishii et al., “Development of a reflective photoelectric pulse wave circuit for artificial nail type pulse wave meter”, 55th Japan Society for Biomedical Engineering, 2016.

  The techniques of Patent Documents 1 and 2 described above are merely techniques for measuring distortion of the nail, and are not techniques for attaching a sensor for measuring biological information to the nail.

  At present, development of a wearable sensor that is attached to a nail and measures a pulse wave, which is biological information, has been attempted, and it has been shown that the pulse wave can be measured (Non-patent Document 1, etc.). However, when a person performs daily activities, it has not been realized to accurately grasp biological information from the obtained information.

  In view of the above circumstances, an object of the present invention is to provide a wearable pulse wave sensor that can be attached to a nail and can measure a pulse wave that is biological information.

The wearable pulse wave sensor according to the first aspect of the present invention includes an attachment portion attached to the surface of the nail, and a light irradiation portion provided in the attachment portion so that the light emission surface faces the nail in a state where the attachment portion is attached to the nail. A light receiving portion that is provided on the attachment portion so that the light receiving surface faces the nail in a state where the attachment portion is attached to the nail, and that outputs an electric signal corresponding to the amount of light received by the light receiving surface; And a control body that is electrically connected to the light irradiation section and controls the operation of the two, and the control section is based on the electrical signal output by the light receiving section. It has a function of calculating an offset and amplifying the electric signal from which the offset is removed.
A wearable pulse wave sensor according to a second aspect of the present invention includes, in the first aspect of the present invention, a plurality of the sensor bodies and an analysis unit that transmits signals from the control units of the plurality of sensor bodies. The pulse wave is measured by comparing signals transmitted from the control units of the plurality of sensor bodies.
The wearable pulse wave sensor according to a third aspect of the present invention is the wearable pulse wave sensor according to the second aspect, wherein the control unit is provided in the attachment unit, and includes a wireless unit that wirelessly transmits a signal calculated by the control unit to an external device. Features.
A wearable pulse wave sensor according to a fourth aspect of the present invention is the first, second or third aspect of the invention, and further includes a power source that supplies power to the light irradiation unit, the light receiving unit, the control unit, and the radio unit. The attachment part is a circuit board, and the light irradiation part, the light receiving part, the control part, the wireless part, and the power source are attached to the circuit board.

According to the first aspect of the invention, if light is emitted from the light emitting unit toward the nail, the light receiving unit receives the light reflected by the blood vessel of the fingertip. Therefore, the pulse wave is acquired based on the variation in the amount of received light. can do. In addition, since the offset is calculated based on the electrical signal output from the light receiving unit, even if the amount of light emitted from the light irradiation unit or the hemodynamics of the finger changes, the offset corresponding to the change in the amount of light is removed from the electrical signal. it can. Therefore, the accuracy of measuring the pulse wave can be increased.
According to the second aspect of the present invention, even when a force is applied from the outside and a state where accurate measurement cannot be performed with some nails or some fingers, measurement can be continued with the sensor main body provided on the other nails. Therefore, the pulse wave can be measured stably.
According to the third aspect of the present invention, usability can be improved compared to the case where the control unit is provided at a place other than the nail.
According to the fourth aspect of the invention, since all the components are provided on the same substrate, the handleability can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic explanatory drawing of the wearable pulse wave sensor 1 of this embodiment, (A) is explanatory drawing of the state which attached the sensor main body 2 to the nail | claw N, (B) is a block diagram of the wearable pulse wave sensor 1. is there. It is a figure explaining the transmission signal formation process by the control part. It is the figure which showed the principle of the pulse wave measurement by reflected light.

The wearable pulse wave sensor 1 of this embodiment is a device that detects a human pulse wave, and is characterized in that it is attached to a nail to detect a pulse wave.
Hereinafter, the wearable pulse wave sensor 1 of the present embodiment will be described based on the drawings.

(Sensor body 2)
In FIG. 1, the code | symbol 2 has shown the sensor main body 2 of the wearable pulse wave sensor 1 of this embodiment. The sensor body 2 is attached to the surface of a human nail N. The sensor body 2 is provided with a light emitting unit 11, a light receiving unit 12, a control unit 13, a radio unit 14, and an attachment unit 10 to which a power supply unit 15 is attached.

(Analysis unit 20)
As shown in FIG. 1, the wearable pulse wave sensor 1 of the present embodiment includes an analysis unit 20 provided separately from the sensor body 2. The analysis unit 20 is configured to transmit a signal (transmission signal described later) including information on the detected pulse wave from the sensor body 2, and extract the pulse wave from the transmitted signal (transmission signal described later). It has a function to do. The analysis unit 20 is, for example, a personal computer in which software for extracting a pulse wave from a transmission signal is installed. The analysis unit 20 can receive a transmission signal transmitted from the sensor body 2 and extract a pulse wave from the transmission signal. There is no particular limitation as long as it has.

  Further, the analyzing unit 20 is not provided with a function for receiving a transmission signal, but the transmission signal is received and stored in another storage medium, and the information stored in the storage medium is supplied to the analyzing unit 20. Also good. In this case, the storage medium does not necessarily need to be separated from the sensor main body 2, and a storage medium connected to the sensor main body 2 by wire or the like may be used. For example, a storage medium may be provided in a wristband or the like, and the storage medium and the sensor body 2 may be connected by a conductive wire.

  Furthermore, the analysis unit 20 itself may be connected to the sensor main body 2 by wire or the like. For example, the analysis unit 20 may be provided in a wristband or the like, and the analysis unit 20 and the sensor main body 2 may be connected by a conductive wire.

(Detailed description of sensor body 2)
Hereinafter, the configuration of the sensor body 2 will be described in detail.

(Mounting part 10)
The attachment unit 10 is a general circuit board, and is attached in a state where the light irradiation unit 11, the light receiving unit 12, the control unit 13, the wireless unit 14, and the power supply unit 15 are electrically connected. Note that the attachment portion 10 may be formed of a plurality of circuit boards. In this case, the light irradiation unit 11, the light receiving unit 12, the control unit 13, the radio unit 14, and the power supply unit 15 do not necessarily have to be provided on the same circuit board. Moreover, the attachment part 10 is not restricted to a circuit board, A simple plate may be sufficient. In this case, each part may be connected by a conducting wire or the like. However, if the mounting part 10 is formed by a single circuit board and the light irradiation part 11, the light receiving part 12, the control part 13, the wireless part 14 and the power supply part 15 are all provided on the same circuit board, the sensor body 2 The advantage of being compact and thin can be obtained.

(Light irradiation unit 11)
The light irradiation unit 11 has a function of irradiating the nail N with light. For example, an LED (light emitting diode), an organic EL, or the like can be used as the light irradiation unit 11. The wavelength of the light irradiated by the light irradiation unit 11 is not particularly limited. For example, red or green visible light or infrared light can be used.

(Light receiving unit 12)
The light receiving unit 12 is capable of receiving light supplied from the nail N side and transmitting an electric signal (for example, a voltage value or a current value) corresponding to the light amount of the received light. In other words, the function of receiving the reflected light reflected by the blood vessel V of the fingertip from the light irradiated from the light irradiation unit 11 toward the nail N and transmitting an electrical signal corresponding to the received light amount (that is, the amount of reflected light). The light receiving section 12 has (see FIG. 3). For example, a photodiode or a phototransistor can be used as the light receiving unit 12.

(Control unit 13)
The control unit 13 is electrically connected to the light irradiation unit 11 and the light receiving unit 12 described above. The control unit 13 has a function of controlling the operation of the light irradiation unit 11 and the light receiving unit 12. For the control unit 13, a commercially available microminiature wireless module (for example, SEDK-PAN-D14580 manufactured by TDK) or the like can be used. That is, the operation control of the light irradiation unit 11 and the light receiving unit 12 can be realized by a function of a commercially available microminiature wireless module or the like.

For example, the control unit 13 has a function of turning on the light irradiation unit 11 intermittently, and controls the timing at which the light irradiation unit 11 is turned on, its emission intensity, and the like.
Information such as the timing at which the light irradiation unit 11 is turned on and the light emission intensity thereof may be stored in the control unit 13 in advance or supplied from the outside via the wireless unit 14 described later. Also good.
In addition, the light irradiation unit 11 may be continuously lit without being intermittently lit. However, if the light irradiation unit 11 is lit intermittently, power consumption can be suppressed, so that the sensor body 2 can be operated for a long time. It becomes.

(Transmission signal generation)
Further, the control unit 13 has a function of receiving an electrical signal transmitted from the light receiving unit 12 and converting the electrical signal into a transmission signal for transmitting to the analysis unit 20. Since the electrical signal transmitted by the light receiving unit 12 is a weak signal, when the signal is transmitted to the analyzing unit 20 as it is, if noise or the like is added to the signal during the transmission process, the change in the amount of light received by the light receiving unit 12 in the analyzing unit 20 is electrically detected. It may become impossible to extract from the signal. Therefore, the control unit 13 converts the electrical signal into a transmission signal so that the change in the amount of light received by the light receiving unit 12 can be extracted from the electrical signal by the analysis unit 20. Specifically, the control unit 13 converts the electrical signal supplied from the light receiving unit 12 into a transmission signal by the following method.

  When the light irradiation unit 11 is intermittently turned on as shown in FIG. 2B, the electrical signal transmitted from the light receiving unit 12 is in a state in which an offset is added to the amount of reflected light (FIG. 2 ( B)). That is, the electrical signal transmitted by the light receiving unit 12 is a signal in which an offset caused by blood existing in the artery in the diastole of the vein or heart is added to the signal corresponding to the amount of reflected light (variable component). It has become.

  For the electrical signal transmitted by the light receiving unit 12 described above, the control unit 13 amplifies the electrical signal and generates a primary amplified signal so that the maximum value of the electrical signal becomes the maximum value of the transmission signal (primary amplification processing, (FIG. 2 (C))).

  In the primary amplified signal, not only the fluctuation component but also the offset is amplified. Therefore, an offset is removed from the primary amplified signal by estimating the offset from the primary amplified signal. Then, a fluctuation signal in which only the fluctuation component is extracted from the primary amplification signal is formed (FIG. 2D). The offset is estimated based on the average value of a plurality of signals when the light source of the light irradiation unit 11 is intermittently turned on.

  When the fluctuation signal is formed, the fluctuation signal is amplified so that the maximum value of the fluctuation signal becomes the maximum value of the transmission signal. Then, a transmission signal transmitted to the analysis unit 20 is generated (secondary amplification process, FIG. 2E).

  Since the control unit 13 generates a transmission signal from the electrical signal transmitted from the light receiving unit 12 by performing the above-described processing, even when the offset fluctuates due to noise due to disturbance, the control unit 13 can cope with the expansion and contraction of the blood vessel V. It is possible to properly grasp the change in the amount of light.

(Radio unit 14)
As illustrated in FIG. 1B, the wireless unit 14 has a function of transmitting the transmission signal generated by the control unit 13 to the analysis unit 20. By providing the wireless unit 14, it is not necessary to provide a storage function in the sensor body 2, so that the sensor body 2 can be reduced in size and weight. Moreover, by analyzing the transmitted signal at any time by the analysis unit 20, the activity state and biological information of the person wearing the sensor body 2 can be confirmed even at a remote place.

  In addition, when the control unit 13 has a communication function like the above-described micro wireless module, a transmission signal can be transmitted to the analysis unit 20 using the communication function of the control unit 13. In this case, the wireless unit 14 may not be provided specially.

(Power supply unit 15)
The power supply unit 15 supplies power to each unit provided in the sensor body 2, and a small button battery or the like can be used. The power supply unit 15 may have a terminal that can be electrically connected to the outside. In that case, since the power supply unit 15 can be charged by connecting the power supply unit 15 to an external commercial power supply or the like, the sensor body 2 can be used for a long period of time or repeatedly.

(Description of use of wearable pulse wave sensor 1 of this embodiment)
The wearable pulse wave sensor 1 having the above-described configuration is used as follows.

  First, the sensor body 2 of the wearable pulse wave sensor 1 is attached to the surface of the nail N. A method for attaching the sensor body 2 to the surface of the nail N is not particularly limited. It is only necessary that the light irradiated from the light irradiation unit 11 and reflected by the blood vessel V can be received by the light receiving unit 12. For example, the nail N and the sensor body 2 can be fixed with a known adhesive that transmits light. Further, while the nail N and the sensor main body 2 are in direct contact with each other (that is, in a state in which no other substance is interposed between them), the sensor main body 2 can be covered and fixed by gel or the like ( (See FIG. 1A).

  If the sensor body 2 is attached to the surface of a person's nail N, the sensor body 2 is operated. The method for operating the sensor body 2 is not particularly limited, and a switch may be provided in the sensor body 2 or the sensor body 2 may be operated by receiving a signal from the analysis unit 20. Alternatively, the sensor body 2 may be attached to the surface of the nail N after the sensor body 2 is operated.

  When the sensor body 2 is activated, light is irradiated from the light irradiation unit 11 toward the nail N, and the light transmitted through the nail N is reflected by the blood vessel V in the nail bed (see FIG. 3). The reflected light is received by the light receiving unit 12, and an electrical signal corresponding to the intensity of the received light is transmitted to the control unit 13. Then, the control unit 13 generates a transmission signal from the electrical signal as described above, and the generated transmission signal is transmitted to the analysis unit 20 by the wireless unit 14. Then, the analysis unit 20 can extract the pulse wave of the person wearing the sensor body 2 based on the transmitted transmission signal.

  The sensor body 2 may be covered with resin or the like so as to be sealed from the outside. For example, when the sensor body 2 is waterproof, it is possible to take a bath or perform water work such as cooking and washing while the sensor body 2 is attached to the surface of the person's nail N. . Then, the activity and biological information of the person who attached the sensor main body 2 can be acquired at any time.

(When multiple sensor bodies 2 are mounted)
As described above, the analysis unit 20 can extract the pulse wave of the person wearing the sensor main body 2 based on the transmitted pulse wave signal. However, blood flow is hindered in a state where the fingertip is being pressed, such as when a person grabs an object. Then, since the fluctuation amount when the blood vessel V expands and contracts corresponding to the pulse wave becomes small, it becomes difficult to grasp the pulsation. In addition, when the object is grabbed, the offset value changes due to a change in hemodynamics. Then, the signal processing by the control unit 13 described above cannot follow the change in the offset value, and an erroneous transmission signal may be formed. If such a state occurs, there is a possibility that the pulse wave of the person wearing the sensor body 2 cannot be properly grasped.

  On the other hand, the pulse wave shows the same time variation even though there is a difference in amplitude depending on the body part. That is, although the thickness and blood flow volume of the blood vessel V are different depending on the nail N to which the sensor body 2 is attached, the heart rate extracted from the transmission signal subjected to the signal processing described above is substantially the same. Then, if the sensor main body 2 is attached to the plurality of nails N, the pulse wave can be properly grasped at a portion other than the finger that grasps an object or the like.

  In the wearable pulse wave sensor 1 of the present embodiment, the sensor main body 2 is attached to the nail N, so that a maximum of ten pieces can be attached by hand alone. Considering even the toenails, up to 20 sensors can be attached to one person. Then, since there is a high possibility that measurement is performed in a normal state in any one of the sensor bodies 2, by comparing the transmission signals transmitted from the plurality of sensor bodies 2, which transmission signal is an abnormal signal That is, it is possible to grasp whether the transmission signal is from the fingernail N holding the object. In other words, since a normal transmission signal from which a pulse wave can be appropriately extracted can be grasped, the pulse wave of the person wearing the sensor main body 2 can be grasped appropriately.

  Therefore, in the wearable pulse wave sensor 1 of the present embodiment, if the plurality of sensor bodies 2 are attached to the plurality of claws N, even if a person wearing the sensor body 2 is performing daily life, the sensor body 2 Appropriately grasp the pulse wave of the person wearing.

  In addition, when an abnormal signal is detected from all the sensor main bodies 2, there is a high possibility that an abnormality has occurred in the person wearing the sensor main body 2. That is, in the wearable pulse wave sensor 1 of the present embodiment, if a plurality of sensor main bodies 2 are attached to a plurality of claws N, an abnormality of a person wearing the sensor main body 2 can be quickly detected. There is also a possibility of improvement.

  The wearable pulse wave sensor of the present invention is suitable as a device for monitoring the activities of patients who receive home medical care, patients in hospitals, and elderly people.

DESCRIPTION OF SYMBOLS 1 Wearable pulse wave sensor 2 Sensor main body 10 Board | substrate 11 Light irradiation part 12 Light receiving part 13 Control part 14 Radio | wireless part 15 Power supply part 20 Analysis part N nail V Blood vessel

Claims (4)

A mounting portion to be attached to the surface of the nail;
A light irradiating portion provided on the mounting portion so that the light emitting surface faces the nail in a state where the mounting portion is mounted on the nail;
A light receiving portion that outputs an electrical signal corresponding to the amount of light received by the light receiving surface, provided on the mounting portion so that the light receiving surface faces the nail in a state where the mounting portion is attached to the nail
A control unit electrically connected to the light receiving unit and the light irradiating unit, and controlling the operation of both;
The control unit
A wearable pulse wave sensor having a function of calculating an offset based on an electrical signal output from the light receiving unit and amplifying the electrical signal from which the offset has been removed. A plurality of the sensor bodies;
An analysis unit that transmits signals from the control units of the plurality of sensor bodies,
The analysis unit
The wearable pulse wave sensor according to claim 1, wherein a pulse wave is extracted by comparing signals transmitted from control units of the plurality of sensor bodies. The control part is provided in the attachment part;
The wearable pulse wave sensor according to claim 1 or 2, further comprising a wireless unit that wirelessly transmits a signal calculated by the control unit to an external device. A power supply for supplying power to the light irradiation unit, the light receiving unit, the control unit and the radio unit;
The mounting portion is a circuit board;
4. The wearable pulse wave sensor according to claim 3, wherein the light irradiation unit, the light receiving unit, the control unit, the radio unit, and the power source are attached to the circuit board.

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