JP4714179B2 - Biological information measuring device and method for controlling biological information measuring device - Google Patents

Description

  The present invention relates to a biological information measuring apparatus that measures blood flow and pulse of a living body using scattered light from the living body.

With the aging of society, there is an increasing interest in blood flow meters that can measure blood circulation deeply associated with adult diseases. In particular, laser blood flow meters are attracting attention because they have much higher resolution than ultrasonic blood flow meters and can measure blood flow in capillaries in peripheral tissues, which was difficult with ultrasonic blood flow meters. ing. As a conventional laser blood flow meter, for example, there is a technique disclosed in Non-Patent Document 1.
Dennis Watkins and G. Allen Holloway, Jr. , An Instrument to measure cutaneous blood flowing the Doppler shift of laser light, IEEE TRANSACTIONS ON BIOMEDAL ENGINNERING. BME-25, No. 1, January 28-33 (1978)

  Here, since the blood flow information includes a pulse component that varies in synchronization with the heartbeat, it is possible to estimate the pulse rate and the pulse interval from the variation in the blood flow. Since the pulse rate and pulse interval obtained by such an estimation method are not obtained by measuring the pulse, there is a problem that information such as fine fluctuations cannot be obtained accurately. In order to obtain an accurate pulse, it is necessary to provide a photoelectric sensor that combines a light-emitting diode (LED) and a photodiode (PD) that have been conventionally used in photoelectric pulse wave measurement. Low power consumption is difficult, and it cannot be adopted as a portable blood flow meter.

  An object of the present invention is to provide a biological information measuring device that is small in size, consumes less power, and can measure blood flow and pulse, and a control method for the biological information measuring device.

  When the present inventors measured the photoelectric pulse wave using the scattered light from the living body as it is, the output of the light receiving element is disturbed due to speckle interference of the laser oscillation light, and it is difficult to measure the pulse. When it was weak, light was spontaneously emitted without laser oscillation, and it was found that the pulse can be measured as in the case of using an LED, and the present invention was completed.

Specifically, the biological information measuring apparatus according to the present invention outputs a photocurrent by receiving a light source that emits outgoing light toward the living body, and scattered light generated in the living body by the outgoing light from the light source. A biological information measuring device comprising: a light receiving element that drives the light source; and a drive measurement circuit that measures the blood flow of the living body and the pulse of the living body by the photocurrent from the light receiving element, Switches the laser oscillation light and the spontaneous emission light by changing the modulation intensity and emits the emitted light as the emission light, and the drive measurement circuit detects the blood flow of the living body when the light source emits the laser oscillation light. The pulse of the living body is measured when the light source emits the spontaneous emission light.

  The biological information measuring device is small and has low power consumption, and can measure blood flow and pulse.

In the biological information measuring apparatus according to the present invention, the drive measuring circuit, by intensity modulation in the outgoing light pulsed at a low frequency so that it contains the lasing threshold of the laser oscillation light of the light source intensity modulation region The light source is preferably switched between laser oscillation light and spontaneous emission light .

  The biological information measuring device can measure blood flow and pulse at substantially the same time.

In the biological information measuring apparatus according to the present invention, the drive measurement circuit performs intensity modulation of the emitted light in a sine wave shape at a high frequency so that the intensity modulation region includes the oscillation threshold value of the laser oscillation light of the light source , The light source is preferably switched between laser oscillation light and spontaneous emission light .

  The biological information measuring device can measure blood flow and pulse at substantially the same time.

  In the biological information measuring apparatus according to the present invention, the drive measurement circuit intensity-modulates the emitted light at a frequency other than the Doppler shift frequency used for blood flow measurement, and the time change of the intensity peak of the line spectrum in the frequency spectrum region Preferably, the pulse information of the living body is measured.

  The biological information measuring device can increase the measurement accuracy of the pulse rate without affecting the blood flow measurement.

The control method of the biological information measuring apparatus according to the present invention includes a light source that emits outgoing light toward a living body, a light receiving element that receives scattered light generated in the living body by the outgoing light from the light source and outputs a photocurrent , and the driving of the light source, a control method of the biological information measuring apparatus having a drive measuring circuit for measuring the pulse of the blood flow and the biological of the living body by the photocurrent from the light receiving element, said light source An emission step in which laser oscillation light and spontaneous emission light are switched by changing the modulation intensity and emitted as the emission light; and the living body when the light source emits the laser oscillation light to the drive measurement circuit And measuring step of measuring the pulse of the living body when the light source emits the spontaneous emission light.

  The control method of the biological information measuring device can realize the biological information measuring device that is small in size, has low power consumption, and can measure blood flow and pulse.

In the control method of the biological information measuring device according to the present invention, the emission step includes emitting the emitted light at a low frequency so that the drive measurement circuit includes an oscillation threshold value of the laser oscillation light of the light source in the intensity modulation region. It is preferable to cause the light source to switch between laser oscillation light and spontaneous emission light by modulating the intensity in pulses.

  The biological information measuring device control method can cause the biological information measuring device to measure blood flow and pulse at substantially the same time.

In the control method of the biological information measuring apparatus according to the present invention, the emission step sine the emission light at a high frequency so that the drive measurement circuit includes an oscillation threshold value of the laser oscillation light of the light source in the intensity modulation region. It is preferable to cause the light source to switch between laser oscillation light and spontaneous emission light by modulating the intensity in a wave shape.

  The biological information measuring device control method can cause the biological information measuring device to measure blood flow and pulse at substantially the same time.

  In the control method of the biological information measuring device according to the present invention, the emission step causes the drive measurement circuit to intensity-modulate the emitted light at a frequency other than a Doppler shift frequency used for blood flow measurement, and the measurement step includes It is preferable that the drive measurement circuit measures the pulse information of the living body from the time change of the intensity peak of the line spectrum in the frequency spectrum region.

  The biological information measuring device control method can increase the pulse rate measurement accuracy of the biological information measuring device without affecting the blood flow measurement.

  INDUSTRIAL APPLICABILITY The present invention can provide a biological information measuring device that is small in size, consumes low power, and can measure blood flow and pulse and a method for controlling the biological information measuring device.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiment described below is an example of the configuration of the present invention, and the present invention is not limited to the following embodiment. Moreover, in the figure which shows the structure of the biological information measuring device which concerns on each embodiment, the part which can be implement | achieved by normal techniques, such as a power supply or a control part which controls the whole operation | movement, is not shown in figure.

  FIG. 1 shows a schematic diagram of a biological information measuring apparatus according to the present embodiment. The biological information measuring apparatus 100 according to this embodiment includes a light source 110 that emits emitted light toward the living body 99, and a light reception that receives scattered light generated in the living body 99 by the emitted light from the light source 110 and outputs a photocurrent. The biological information measuring apparatus 100 includes an element 120 and a drive measurement circuit 130 that measures the blood flow of the living body 99 and the pulse of the living body 99 by the photocurrent from the light receiving element 120, and the light source 110 includes laser oscillation light and The spontaneous emission light is switched and emitted as outgoing light. The drive measurement circuit 130 measures the blood flow of the living body 99 when the light source 110 emits laser oscillation light, and the living body when the light source 110 emits spontaneous emission light. Measure 99 pulses. The living body 99 is, for example, a person or an animal. Examples of the light source 110 include a distributed feedback (DFB) semiconductor laser light source. An example of the light receiving element 120 is a photodiode. Details of the biological information measuring apparatus 100 will be described below with reference to specific examples.

  FIG. 2 shows a first form of the biological information measuring apparatus according to the present embodiment. The biological information measuring apparatus 100 in FIG. 2 includes a sensor 112 and a drive measurement circuit 130. The sensor 112 includes a sensor chip 114 and an amplifier 116. The drive measurement circuit 130 includes an analog-digital converter 131, a switching unit 132, a digital signal processor 133, a pulse analysis unit 134, a blood flow signal output terminal 135, a pulse signal output terminal 136, an LD driver 137, and a control circuit 138. .

The sensor chip 114 has a light emitting element and a light receiving element integrated on a semiconductor substrate (see, for example, Patent Document 1), and has a function as a light source and a light receiving element. The amplifier 116 amplifies scattered light from the living body received by the light receiving element of the sensor chip 114. The living body information measuring apparatus 100 of FIG. 2 can integrate a light source and a light receiving element as a sensor 112, can be reduced in size and power consumption, and can have a shape that can be easily attached to a living body.
JP 2002-330936 A

  The LD driver 137 drives the sensor 112 and causes the sensor 112 to emit outgoing light. The analog-to-digital converter 131 performs analog-to-digital conversion on scattered light from a living body (not shown) received by the sensor 112 and outputs a signal. The switching unit 132 switches the signal from the analog-digital converter 131 to either the digital signal processor 133 or the pulse analysis unit 134 and outputs it. The digital signal processor 133 performs a calculation for obtaining a blood flow from the received signal, and outputs the result to the blood flow signal output terminal 135. Here, the digital signal processor 133 may measure blood flow such as blood flow volume, blood volume, and blood flow velocity. The pulse analysis unit 134 performs a calculation for obtaining a pulse from the received signal, and outputs the result to the pulse signal output terminal 136. The control circuit 138 controls the LD driver 137 to cause the sensor 112 to emit either laser oscillation light or spontaneous emission light as emission light. The control circuit 138 switches the switching unit 132 to the digital signal processor 133 when the sensor 112 emits laser oscillation light. On the other hand, the control circuit 138 switches the switching unit 132 to the pulse analysis unit 134 when the sensor 112 emits spontaneous emission light. The biometric information measuring apparatus 100 of FIG. 2 can mount the entire drive measurement circuit 130 on one LSI (Large Scale Integration Circuit), and can be downsized.

  The blood flow signal output terminal 135 may be connected to a display or a printer to display or print the blood flow (not shown). The pulse signal output terminal 136 may be connected to a display or a printer to display or print the pulse (not shown).

  2 has a sensor head (not shown) of a sensor 112, and scattered light (blood) from scattered light from a living body and red blood cells (scattered particles) moving through capillaries in the living body. Scattered light that has undergone Doppler shift Δf according to the flow velocity) is detected, for example, heterodyne detection. In the biological information measuring apparatus 100, the interference component of the scattered light is amplified in the amplification unit 116 of the sensor 112. In the biological information measuring apparatus 100, when the sensor 112 emits laser oscillation light, the digital signal processor 133 performs frequency analysis of the interference component of the scattered light. Here, the frequency of the interference component of the scattered light corresponds to the blood flow velocity, and the intensity of the scattered light corresponds to the blood flow rate. On the other hand, in the biological information measuring apparatus 100, when the sensor 112 emits spontaneously emitted light, the pulse analysis unit 134 measures the pulse. Here, the biological information measuring apparatus 100 can obtain a pulse wave by the amplitude fluctuation of the photocurrent from the sensor 112. As described above, the biological information measuring apparatus 100 can measure blood flow and pulse.

  FIG. 3 shows a second form of the biological information measuring apparatus according to this embodiment. FIG. 3 shows the biological information measuring device 100 in an exploded state for ease of explanation. 3 includes a light source 110, a light receiving element 120, a substrate 140, an optical waveguide 150, and a light shielding block 160. A driving measurement circuit (not shown) is mounted on the substrate 140, and the light source 110 and the light receiving element 120 are mounted thereon. The optical waveguide 150 turns emitted light emitted from the light source 110 into divergent light or focused light and directs it toward a living body (not shown). The light blocking block 160 blocks the outgoing light emitted from the light source 110 so that it does not directly enter the light receiving element 120. 3 can mount the light source 110 and the light receiving element 120 on the substrate 140. Therefore, the biological information measuring apparatus 100 can be miniaturized, and the output of the light receiving element 120 can be disturbed because it is not necessary to handle the optical fiber. Absent.

  The biological information measuring apparatus 100 can be controlled as follows. FIG. 4 shows a flow of a control method of the biological information measuring apparatus according to the present embodiment. The control method of the biological information measuring apparatus according to the present embodiment includes a light source that emits outgoing light toward the living body, a light receiving element that receives scattered light generated in the living body by the outgoing light from the light source and outputs a photocurrent, and A method for controlling a biological information measuring apparatus having a driving measurement circuit for measuring a blood flow and a pulse of a living body by a photocurrent from a light receiving element, wherein the light source switches between laser oscillation light and spontaneous emission light. An emission step S110 for emitting light, and a measurement step for causing the drive measurement circuit to measure the blood flow of the living body when the light source emits laser oscillation light and to measure the pulse of the living body when the light source emits spontaneous emission light. S120 in order. As described above, the biological information measuring device control method according to this embodiment can realize a biological information measuring device that is small in size, consumes low power, and can measure blood flow and pulse.

  The biological information measuring device 100 shown in FIG. 3 may include a switch (not shown) that allows the user to switch between laser oscillation light and spontaneous emission light. At this time, the biological information measuring apparatus 100 can measure the blood flow or the pulse according to the user's request. On the other hand, the biological information measuring apparatus 100 may alternately repeat the emission of the laser transmission light and the spontaneous emission light. At this time, the biological information measuring apparatus 100 can alternately measure the blood flow and the pulse. Hereinafter, it will be described in detail that the biological information measuring apparatus 100 alternately measures blood flow and pulse.

  FIG. 5 shows a relationship diagram between the received light intensity of the light receiving element and time when the intensity of the emitted light is modulated in a pulse shape at a low frequency. FIG. 5 shows the time when the light source emits laser oscillation light, that is, the time when the biological information measuring device measures blood flow, and the time when the light source emits spontaneous emission light, ie, the biological information measuring device is pulsed. The time for measuring is indicated by symbol b. In the biological information measuring apparatus according to the present embodiment, the drive measurement circuit preferably modulates the intensity of the emitted light in a pulsed manner at a low frequency so that the intensity modulation region includes the oscillation threshold value of the laser oscillation light of the light source. Further, in the control method of the biological information measuring apparatus according to the present embodiment, in the emission step, the drive measurement circuit pulses the emitted light at a low frequency so that the intensity modulation region includes the oscillation threshold value of the laser oscillation light of the light source. It is preferable to modulate the intensity in a shape. In FIG. 5, for example, the intensity modulation is performed at a cycle of 5 times per second. If the laser injection current is weak and the modulation intensity does not exceed the oscillation threshold, the light source emits spontaneous emission light. On the other hand, if the laser injection current of the light source is increased and the modulation intensity exceeds the oscillation threshold, the light source emits laser oscillation light. Exit. That is, if intensity modulation is performed so that the intensity modulation region includes the oscillation threshold value of the laser oscillation light from the light source, the light source emits laser oscillation light and spontaneous emission light alternately. Thereby, the biological information measuring device can alternately measure the blood flow and the pulse. If this intensity modulation is performed at high speed, blood flow and pulse can be measured substantially simultaneously.

  FIG. 6 shows a relationship between the light receiving intensity of the light receiving element and time when the intensity of the emitted light is sinusoidally modulated at a high frequency. In the biological information measuring apparatus according to the present embodiment, it is preferable that the drive measurement circuit intensity-modulates the emitted light at a high frequency in a sinusoidal manner so that the intensity modulation region includes the oscillation threshold value of the laser oscillation light of the light source. Further, in the control method of the biological information measuring apparatus according to the present embodiment, in the emission step, the emitted light is sinusoidally shaped at a high frequency so that the drive measurement circuit includes the oscillation threshold value of the laser oscillation light of the light source in the intensity modulation region. It is preferable to modulate the intensity. Similar to the case of FIG. 5, the biological information measuring apparatus can measure the blood flow and the pulse almost simultaneously.

  FIG. 7 shows the relationship between the frequency and the received light intensity when the intensity of the emitted light is modulated in a sinusoidal shape at a high frequency. In FIG. 7, for example, a line spectrum corresponding to a frequency of 25 kHz appears, and the time change of the intensity peak is indicated by a symbol c. In the biological information measuring apparatus according to the present embodiment, the drive measurement circuit intensity-modulates the emitted light at a frequency other than the Doppler shift frequency used for blood flow measurement, and the time change c of the intensity peak of the line spectrum in the frequency spectrum region c. It is preferable to measure the pulse information of the living body. Further, in the control method of the biological information measuring device according to the present embodiment, the emission step causes the drive measurement circuit to intensity-modulate the emitted light at a frequency other than the Doppler shift frequency used for blood flow measurement, and the measurement step includes: It is preferable to cause the drive measurement circuit to measure the pulse information of the living body from the time change c of the intensity peak of the line spectrum in the frequency spectrum region.

  The frequency other than the Doppler shift frequency used for blood flow measurement is a frequency of 4 Hz to 25 Hz, or a frequency of 20 kHz to 40 kHz, preferably a frequency of 10 Hz to 20 Hz, or 20 kHz to 30 kHz. .

  By using a frequency other than the Doppler shift frequency used for blood flow measurement, the biological information measurement device can increase the measurement accuracy of the pulse rate without affecting the measurement of blood flow. In addition, since the time change of the intensity peak of the line spectrum in the frequency spectrum region can be easily obtained, the biological information measuring device can easily measure the pulse information of the living body. Furthermore, the biological information measuring apparatus can reduce power consumption by performing intensity modulation in a pulse shape or a sine wave shape as compared with the case where the light source continuously emits the emitted light.

  The biological information measuring device according to the present invention can be used for a portable laser blood flow meter because of low power consumption. Moreover, the control method of the biological information measuring device according to the present invention can be used for controlling the biological information measuring device.

It is a schematic diagram of a living body information measuring device concerning this embodiment. It is a figure showing the 1st form of the living body information measuring device concerning this embodiment. It is a figure which shows the 2nd form of the biological information measuring device which concerns on this embodiment. It is a flow of the control method of the biological information measuring device concerning this embodiment. FIG. 6 is a relationship diagram between light reception intensity of a light receiving element and time when intensity of emitted light is modulated in pulses at a low frequency. FIG. 4 is a relationship diagram between the light receiving intensity of a light receiving element and time when intensity of outgoing light is modulated in a sinusoidal shape at a high frequency. FIG. 6 is a relationship diagram between frequency and received light intensity when emitted light is intensity-modulated in a sinusoidal shape at a high frequency.

Explanation of symbols

99 Living body 100 Biological information measuring device 110 Light source 112 Sensor 114 Sensor chip 116 Amplifier 120 Light receiving element 130 Drive measurement circuit 131 Analog to digital converter 132 Switching unit 133 Digital signal processor 134 Pulse analysis unit 135 Blood flow signal output terminal 136 Pulse signal output terminal 137 LD driver 138 Control circuit 140 Substrate 150 Optical waveguide 160 Shading block S110 Emission step S120 Measurement step a Time when the light source emits laser oscillation light b Time when the light source emits spontaneous emission c Time change of intensity peak of the line spectrum

Claims (8)

A light source that emits emitted light toward a living body;
A light receiving element that receives scattered light generated in the living body by the emitted light from the light source and outputs a photocurrent; and
A biological information measuring device comprising: a driving measurement circuit that drives the light source and measures the blood flow of the living body and the pulse of the living body by the photocurrent from the light receiving element;
The light source switches the laser oscillation light and the spontaneous emission light by changing the modulation intensity and emits it as the emission light,
The drive measurement circuit measures the blood flow of the living body when the light source emits the laser oscillation light, and measures the pulse of the living body when the light source emits the spontaneous emission light. Biological information measuring device. The drive measurement circuit modulates the intensity of the emitted light in a pulsed manner at a low frequency so that the intensity modulation region includes the oscillation threshold of the laser oscillation light of the light source, so that the laser oscillation light and spontaneous emission are emitted to the light source. The biological information measuring device according to claim 1, wherein light is switched . The drive measurement circuit modulates the intensity of the emitted light in a sinusoidal shape at a high frequency so that the intensity modulation region includes the oscillation threshold value of the laser oscillation light of the light source, thereby causing the light source to emit laser oscillation light and spontaneous emission light. The biological information measuring device according to claim 1, wherein the biological information measuring device is switched .   The drive measurement circuit modulates the intensity of the emitted light at a frequency other than the Doppler shift frequency used for blood flow measurement, and measures the pulse information of the living body from the time change of the intensity peak of the line spectrum in the frequency spectrum region. The biological information measuring device according to claim 3. A light source that emits outgoing light toward the living body, a light receiving element that receives scattered light generated in the living body by the outgoing light from the light source and outputs a photocurrent, and a light source that drives the light source, A method for controlling a biological information measuring apparatus having a driving measurement circuit for measuring the blood flow of the living body and the pulse of the living body by the photocurrent of
An emission step of causing the light source to switch between laser oscillation light and spontaneous emission light by changing the modulation intensity, and to emit as the emitted light; and
A measurement step for causing the drive measurement circuit to measure a blood flow of the living body when the light source emits the laser oscillation light, and to measure a pulse of the living body when the light source emits the spontaneous emission light; In order. The control method of the biological information measuring device characterized by the above-mentioned. In the emission step, the drive measurement circuit causes the light source to modulate the intensity of the emitted light in a pulse shape at a low frequency so that the intensity modulation region includes the oscillation threshold value of the laser oscillation light of the light source. the method of the biological information measuring apparatus according to claim 5, characterized in that to switch the laser oscillation light and spontaneous emission light. In the emission step, the drive measurement circuit modulates the intensity of the emitted light in a sinusoidal shape at a high frequency so that the intensity modulation region includes the oscillation threshold of the laser oscillation light of the light source, thereby causing the light source to emit laser light. the method of the biological information measuring apparatus according to claim 5, characterized in that to switch the oscillation light and spontaneous emission light. The emission step causes the drive measurement circuit to modulate the intensity of the emitted light at a frequency other than the Doppler shift frequency used for blood flow measurement,
8. The method of controlling a biological information measuring apparatus according to claim 7, wherein the measuring step causes the driving measurement circuit to measure pulse information of the living body from a time change of an intensity peak of a line spectrum in a frequency spectrum region. .

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