JP6084361B2 - Breath sensor - Google Patents

Description

  The present invention relates to a respiration sensor. More specifically, the present invention relates to a respiration sensor that can measure respiration of a measurement subject with minimal invasiveness.

In the medical and health fields, there is a need to measure various body conditions. For this reason, many attempts have been made to measure body signals. For example, an electrocardiogram is a measurement of a faint active current that occurs when the heart muscle repeatedly expands and contracts to produce cardiac circulation. In addition, breathing is a vital physiological function for vital activities, as is cardiac circulation. Respiration measurement in a natural state during exercise is important for diagnosing the function of the respiratory tract in actual life. .
Conventionally, a spirometer has been widely used to measure the respiration of a measurement subject with minimal invasiveness. In this spirometer, a mouthpiece is attached to the mouth of a measurement subject, the expiration or inspiration of the measurement subject is passed through pipes extending from the mouthpiece, and the expiration or inspiration is measured by a sensor.

In the spirometer, since pipes extending from the mouthpiece hinder the movement of the measurement target person, it is difficult to measure the respiration during the movement of the measurement target person. For this reason, a respiration sensor that can measure respiration without interfering with the movement of the measurement subject is desired.
As a respiration sensor that can measure respiration without hindering the movement of the measurement subject, for example, the invention described in Patent Document 1 is known. In this invention, a piezoelectric film having a strain gauge is provided on a vest that is in close contact with the body of the measurement subject and extends in the horizontal and vertical directions. In the chest and abdominal regions of the vest, when the vest expands and contracts due to the torsional deformation caused by the measurement subject's breathing pattern and heart pressure, a strain gauge reacts to each expansion and contraction, and the breathing pattern and the heart The pressure is to be calculated.

Japanese Patent No. 3609404

By the way, since there is an aspect in which respiration is arbitrarily controlled as compared with the cardiac circulation function, stress applied to the measurement subject affects the measurement result of respiration. Here, in the spirometer described above, the measurement subject feels stress by wearing the mouthpiece. In addition, in the invention of Patent Document 1, since the measurement target person's breathing pattern and heart pressure are obtained from the expansion and contraction of the vest in close contact with the measurement subject's torso, Feel. In other words, each of the respiratory measurement techniques described above has a problem that it is impossible to perform a respiration measurement in a natural state of the measurement target person due to stress applied to the measurement target person.
The present invention has been devised to solve the above problems. That is, the problem to be solved by the present invention is to detect and measure the respiration of the measurement target person based on a change in capacitance, thereby eliminating the stress applied to the measurement target person at the time of respiration measurement. It is to realize the respiration measurement in the natural state.

In order to solve the above problems, the respiration sensor of the present invention takes the following means.
First, the first invention is a respiration sensor that can measure respiration of a measurement subject with minimal invasiveness. This respiration sensor obtains the change in capacitance between the pair of electrical conductors that sandwich the measurement subject's body and the pair of electrical conductors, and detects the respiration of the measurement subject from this change in capacitance. Detecting means.
Pulmonary breathing animals, including humans, repeatedly expand and contract the lungs during breathing, and also move surrounding body tissues greatly. This movement of the lungs and body tissues appears as a change in capacitance at each part of the body of the measurement subject.
Here, according to the said 1st invention, a pair of electrical conductors are arrange | positioned on both sides of a measurement subject's torso. For this reason, an electric field is applied between the pair of electrical conductors so as to pass through the inside of the measurement subject's torso, and a change in capacitance at the site is obtained. Respiration can be detected. That is, the respiration of the measurement subject can be measured without attaching the mouthpiece or tightening the vest with the vest. Accordingly, it is possible to eliminate the stress applied to the measurement target person during the respiration measurement and perform the respiration measurement in the natural state of the measurement target person.

Next, the second invention is the electric conductor according to the first invention, wherein at least one of the pair of electrical conductors sandwiches the chest of the measurement subject, and the detection means is the electrical conductor that sandwiches the chest of the measurement subject. The measurement subject inhales when detecting a decrease in capacitance between the electrical conductors for the pair, and the measurement subject when detecting an increase in capacitance between the electrical conductors. Is determined to exhale.
The capacitance between electrical conductors is proportional to the dielectric constant of the region through which the electric field passes between the electrical conductors. Note that the dielectric constant in a certain region can be obtained by multiplying the relative dielectric constant (a value that varies depending on the substance) of a substance in the region by a vacuum dielectric constant (constant). Here, the relative permittivity of the body (and water) of lung-breathing animals including humans is about 80, whereas the relative permittivity of air entering and leaving the lungs of the lung-breathing animals is approximately 1. There is a large difference in the relative dielectric constant. Therefore, the capacitance of the measurement subject's chest decreases when the measurement subject inhales and the air volume inside the lung increases, and increases when the measurement subject exhales and the air volume inside the lung decreases. To do.
That is, according to the second aspect of the invention, the change in the amount of air in the lungs of the measurement subject is caused by the change in the capacitance by utilizing the difference in relative permittivity between the animal body (and water) and the air. It is possible to detect and measure the respiration of the measurement subject.

Furthermore, in the first or second invention described above, a third aspect of the present invention relates to the first or second aspect of the invention, wherein at least one of the pair of electrical conductors sandwiches the abdomen of the measurement subject, and the detection means When a measurement subject inhales and detects a decrease in capacitance between the electrical conductors when detecting an increase in capacitance between the electrical conductors for a pair of conductors It is determined that the measurement subject exhales.
Animal bodies, including humans, are usually in contact with a grounded material or a substance having a predetermined potential, and have a potential equal to that substance. For this reason, when the electrostatic capacity is measured by sandwiching the abdomen of the measurement subject with a pair of electrical conductors, the measured capacitance is reduced due to the influence of electrostatic shielding by the abdomen of the measurement subject. Here, since the abdomen is a part adjacent to the lungs across the diaphragm, when the measurement subject inhales and the lungs expand, the electrostatic shielding by the abdomen is weakened by the air inside the lungs. For this reason, the capacitance of the measurement subject's abdomen increases when the measurement subject inhales and the effect of electrostatic shielding by the abdomen is weakened. Decreases when effect returns.
That is, according to the third aspect of the invention, utilizing the property that the electrostatic shielding by the animal's body is weakened by the air inside the lungs, the measurement subject's breathing is detected and measured by the change in capacitance. be able to.

Furthermore, a fourth aspect of the invention is any one of the first to third aspects of the invention described above, wherein the detection means is constant so high that an electrolytic solution such as blood can be regarded as a good conductor between a pair of electrical conductors. A capacitive reactance between a pair of electrical conductors with respect to the alternating voltage is measured by applying an alternating voltage having a frequency of ## EQU2 ## and a capacitance is calculated from the capacitive reactance.
Here, “capacitive reactance” refers to a pseudo resistance that acts on an AC voltage when an AC voltage is applied between electric conductors having electrostatic capacity. For this reason, for example, in a circuit in which a pair of electric conductors having electrostatic capacity and other members are connected in series, the relationship between the voltage applied to the circuit and the voltage applied to the other members is Capacitive reactance can be easily determined. Here, the capacitive reactance has a property that it is proportional to a value obtained by dividing the period of the applied AC voltage (the reciprocal of the frequency) by the capacitance between the electric conductors. In addition, electrolytes such as blood have the property of behaving like a good conductor against an alternating voltage having a high frequency. For this reason, the measurement subject's capacitance is affected by the change in the direction of the lines of electric force due to the change in blood flow distribution accompanying the measurement subject's breathing. It is reflected in addition to the influence.
That is, according to the fourth aspect of the invention, by applying an AC voltage between the pair of electrical conductors, the capacitive reactance of the pair of electrical conductors can be easily measured, and the static electricity in the pair of electrical conductors can be measured. The change in capacitance can be easily determined. In addition, since the frequency of the AC voltage is constant, it is possible to eliminate the influence of the mixing of the frequency characteristics on the AC electric field of the measurement subject's body (and water). Further, by increasing the frequency of the AC voltage, it is possible to add and reflect the influence of the change in the blood flow distribution accompanying the breathing of the measurement subject to the change in the capacitance of the pair of electrical conductors. For this reason, the calculation precision of the electrostatic capacitance in the pair of electrical conductors can be improved.

Furthermore, in a fifth aspect based on any one of the first to fourth aspects described above, the frequency of the AC voltage is such that the AC electromagnetic field generated by the AC voltage reduces the biological influence on the measurement subject. Is set to.
When an AC voltage is applied between the electrical conductors, an AC electromagnetic field having a frequency equal to the frequency of the applied AC voltage is generated between the electrical conductors. Here, animals including humans are affected by various biological effects by exposure to alternating electromagnetic fields. It is known that the type and degree of this biological effect varies depending on the frequency of the alternating electromagnetic field.
That is, according to the fifth aspect of the present invention, by setting the frequency of the alternating voltage applied between the electrical conductors, the biological influence on the measurement subject is reduced, and the measurement subject is in a more natural state. Respiratory measurement can be performed.

Furthermore, a sixth aspect of the present invention is the device according to any one of the first to fifth aspects described above, wherein the body of the measurement subject is at least from two directions facing each other by being put on the measurement subject. The measurement clothes are covered, and the pair of electric conductors is attached to the measurement clothes so as to sandwich the body of the measurement subject in the wearing state of the measurement clothes.
According to the sixth aspect of the present invention, it is possible to make it difficult for the pair of electric conductors to be detached from the measurement subject by attaching the pair of electric conductors to the measurement clothes in the respiration sensor of the present invention. Further, the breathing sensor can be easily attached / detached by attaching / detaching the measurement clothes.

Furthermore, a seventh invention is the method according to any one of the first to sixth inventions, wherein at least two pairs of electrical conductors are provided, and at least one of the pairs of electrical conductors sandwiches the chest of the measurement subject. In addition, at least one of the pairs of electrical conductors sandwiches the abdomen of the measurement subject.
Mammals, including humans, breathe by combining thoracic breathing performed by moving the intercostal muscles located between the ribs of the chest and abdominal breathing performed by moving the diaphragm located adjacent to the chest cavity of the abdominal cavity. Do. Since the combination of the chest breathing and the abdominal breathing changes depending on the exercise state and posture, it is important to separately measure the chest breathing and the abdominal breathing in the respiratory measurement during the exercise. Here, it is known in part that it is possible to distinguish and measure chest respiration and abdominal respiration by measuring the movement of each body tissue in each of the chest and abdomen.
That is, according to the seventh aspect of the present invention, the change in the air volume inside the lung is detected in each of the measurement subject's chest and abdomen by sandwiching each of the chest and abdomen of the measurement subject with a pair of electrical conductors. can do. Thereby, the measurement subject's chest respiration and abdominal respiration can be distinguished and measured.

Furthermore, an eighth invention includes any one of the first to seventh inventions described above, further comprising a gyro sensor that measures an angular velocity associated with the movement of the measurement subject and transmits the angular velocity to the detection means, and is transmitted from the gyro sensor. The detection result of the detection means is corrected based on the angular velocity data.
When performing respiration measurement during the movement of the measurement target person, the relative position of the respiration sensor with respect to the measurement target person changes depending on the angular velocity associated with the movement or posture change of the measurement target person. Here, when the respiration measurement is performed by detecting a change in capacitance, the capacitance between the electrical conductors is inversely proportional to the distance between the electrical conductors. Appears as noise against.
That is, according to the eighth aspect of the invention, by correcting the detection result of the detection means based on the angular velocity of the measurement subject measured by the gyro sensor, noise generated by the angular velocity is removed or reduced by information processing. Can do. Thereby, the precision of the respiration measurement during a measurement subject's exercise | movement can be improved.

Furthermore, a ninth invention includes any one of the first to eighth inventions described above, further comprising an acceleration sensor that measures an acceleration accompanying the movement of the measurement subject and transmits the acceleration to the detection means, and is transmitted from the acceleration sensor. The detection result of the detection means is corrected based on the acceleration data.
When performing respiration measurement during exercise of the measurement target person, the relative position of the respiration sensor with respect to the measurement target person changes due to a speed change (acceleration) accompanying the movement of the measurement target person. Here, when the respiration measurement is performed by detecting a change in capacitance, the capacitance between the electrical conductors is inversely proportional to the distance between the electrical conductors. Appears as noise against.
That is, according to the ninth aspect of the invention, by correcting the detection result of the detection means based on the acceleration of the measurement subject measured by the acceleration sensor, noise generated by the acceleration is removed or reduced by information processing. Can do. Thereby, the precision of the respiration measurement during a measurement subject's exercise | movement can be improved.

Furthermore, a tenth aspect of the invention includes any one of the first to ninth aspects of the invention described above, further comprising a thermometer that measures the body temperature of the measurement subject and transmits the temperature to the detection means, and the temperature data transmitted from the thermometer Based on the above, the detection result of the detection means is corrected.
It is generally known that the relative permittivity of animal bodies including humans (and water) varies with temperature. For this reason, when the measurement subject's respiration measurement is detected as a change in capacitance, if the measurement subject's body temperature changes due to exercise or the like, the respiration measurement result also changes in accordance with the change in the body temperature.
That is, according to the tenth aspect of the present invention, by correcting the detection result of the detection means based on the body temperature of the measurement subject measured by the thermometer, the effect of the change in body temperature can be processed by information processing from the measurement result of respiration. Can be removed or reduced. Thereby, while being able to compare easily the measurement result of a measurement subject's respiration, the precision of respiration measurement can be improved.

Furthermore, an eleventh invention is a respiratory measurement system using the respiratory sensor according to any one of the first to tenth inventions described above. The respiration measurement system includes a wireless transmission device that wirelessly transmits the output of the respiration sensor, and a wireless reception device that receives wireless transmission from the wireless transmission device.
According to the eleventh aspect, since the output of the respiration sensor is wirelessly transmitted to the outside, an external measurer can restrict the respiration of the measurement subject without limiting the action range and the exercise state of the measurement subject. It can be measured in a stationary state.

It is a front view showing the respiration sensor concerning a 1st embodiment of the present invention. It is the schematic diagram showing the use condition of the said respiration sensor. It is a schematic diagram showing the inside of a measurement subject's body in the above-mentioned use state, and represents the state where the measurement subject inhaled. It is a schematic diagram showing the inside of a measurement subject's body in the above-mentioned use state, and represents the state where the measurement subject exhaled. It is a block diagram showing schematic structure of the detection means of the said respiration sensor. It is a circuit diagram of an AC oscillation circuit and an AC-DC conversion circuit of the detection means. It is a line graph showing the time change of the output voltage in the AC-DC conversion circuit of the detection means. It is a line graph showing the time change of the electrostatic capacitance between the electrode pairs of the respiration sensor. It is a line graph showing the time change of the respiration volume in the conventional spirometer. It is the schematic diagram showing the use condition of the respiration sensor which concerns on the 2nd Embodiment of this invention.

EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated using drawing. In the following, the illustration and detailed description of the incidental configurations such as the battery and the connector are omitted.
<First Embodiment>
First, the configuration of the respiratory sensor 10 according to the first embodiment will be described with reference to FIGS. 1 to 6. As shown in FIG. 2, the respiration sensor 10 uses a human as a measurement target P, and does not place a burden on the measurement target P for breathing in the daily life of the measurement target P (that is, a minimally invasive). It is a wearable respiratory sensor for measurement.

As shown in FIGS. 1 and 2, the respiration sensor 10 has a pair of electrodes 11 attached to a measurement jacket 13 (T-shirt in the present embodiment), and a detection means 12 is attached to a cable 11 </ b> C extending from each electrode 11. It has a connected configuration. The measurement clothing 13 is configured to cover the trunk upper part of the measurement subject P from the front and the rear in the wearing state (see FIG. 2) worn by the measurement subject P. Moreover, the detection means 12 is carried by the measurement subject P in the wearing state.
Here, each electrode 11 is detachably attached to the measurement ring 13 by a button (not shown). The cable 11C is detachably connected to each electrode 11 and the detection means 12 via a connector (not shown). For this reason, the breathing sensor 10 separates the measurement clothing 13 from other members, thereby improving the storage property when the breathing sensor 10 is not used and making the measurement clothing 13 washable.

Each of the electrodes 11 is formed by cutting a cloth formed of a two-layer structure yarn having a conductive fiber as a core portion and an insulating fiber as a sheath portion into a rectangular shape, and cutting the cut portion with a conductive adhesive (not shown). It is formed by hardening and short-circuiting the conductive fibers. Here, by forming each electrode 11 with a cloth using a conductive fiber, the comfort of the measurement clothes 13 to which each electrode 11 is attached is ensured. Further, by using a two-layer structure yarn in which conductive fibers are covered with insulating fibers in each electrode 11, it is possible to prevent electric leakage from each electrode 11 to the outside while applying an electric field between the electrodes 11.
In the present embodiment, a stainless steel wire having a diameter of 0.04 [mm] covered with a cotton fiber as the two-layer structured yarn is used as the conductive adhesive, and DOITEXA-910 (DOTITE) manufactured by Fujikura Kasei Co., Ltd. is used. Are registered trademarks).

As shown in FIG. 2, each electrode 11 sandwiches the abdomen of the measurement subject P between the abdominal electrode 11 </ b> A and the waist electrode 11 </ b> B in the wearing state where the measurement clothing 13 is worn on the measurement subject P. . And the detection means 12 calculates | requires the change (refer FIG. 8) of the electrostatic capacitance C between 11 A of abdominal electrodes, and the waist electrode 11B, and detects the measurement subject's P respiration from this change of the electrostatic capacitance C. FIG. That is, each electrode 11 corresponds to an “electric conductor” in the present invention. The respiration detected by the detection means 12 is output to the monitor 12F (see FIG. 1) of the detection means 12 as a waveform indicating the temporal change in the ventilation amount.
According to each configuration described above, the respiration of the measurement subject P can be measured from the change in the capacitance C between the electrodes 11 without attaching the mouthpiece or tightening the vest with the measurement subject P. it can. Thereby, it is possible to eliminate the stress applied to the measurement target person P during the respiration measurement and perform the respiration measurement in the natural state of the measurement target person P. Moreover, attaching each electrode 11 to the measurement clothing 13 makes it difficult to remove each electrode 11 from the measurement subject P, and allows the breathing sensor 10 to be easily attached and detached by attaching and detaching the measurement clothing 13.
Note that the respiration sensor 10 is configured so that the measurement target person P has a short measurement dress 13 and the electrodes 11 do not reach the abdomen of the measurement target person P. Respiration can be measured even in a pinched state (in this embodiment, a state where the periphery of the sternum is pinched from the front-rear direction). That is, the detection means 12 is switched from the change in capacitance between the abdominal electrode 11A and the waist electrode 11B sandwiching the chest of the measurement subject P by manually switching the measurement mode by a changeover switch (not shown). It is possible to detect the respiration of the measurement subject P.

Subsequently, the principle of measurement of the respiration sensor 10 described above will be described. As shown in FIGS. 3 and 4, the lung P <b> 3 of the measurement target person P repeats expansion and contraction as the measurement target person P breathes in and out of the air. Further, the body tissue of the measurement subject P (for example, the diaphragm P2 shown in FIGS. 3 and 4) moves greatly in accordance with the expansion and contraction of the lung P3.
Incidentally, the expansion and volume change (i.e., vital capacity) of the lungs P3 in contraction of lung P3 is in the case of healthy adult males ^{2000 [cm 3] ~3000 [cm} 3]. Since the movement of the lung P3 and the above-described tissue in the body appear as a change in capacitance in each part of the body of the measurement subject P, the measurement subject P is detected from the change in capacitance and measured. be able to.

Now, in the abdomen of the measurement subject P, when the abdominal electrode 11A of the electrode 11 is located on the front side (navel side) and the waist electrode 11B is located on the rear side (waist side), an AC voltage is applied between the electrodes 11. The AC electric field E is generated so as to pass around the diaphragm P2 of the measurement subject P in the front-rear direction. Here, when the measurement subject P inhales, as shown in FIG. 3, the diaphragm P2 located below the lung P3 moves downward as the lung P3 expands to the lower side (foot side). .
For this reason, the AC electric field E passes through the lung P3 and more air that has entered the lung P3. On the other hand, when the measurement subject P exhales, as shown in FIG. 4, the diaphragm P2 moves upward as the lung P3 contracts upward (head side). For this reason, the AC electric field E passes through more tissues in the body P1 of the measurement subject P located below the diaphragm P2.

By the way, the person to be measured P is usually in a grounded state or in contact with a substance having a predetermined potential and has a potential equal to that substance. For this reason, when the capacitance C between the electrodes 11 is measured by applying the alternating electric field E between the electrodes 11 with the electrodes 11 sandwiching the abdomen of the measurement subject P, the measured capacitance C is It becomes small due to the influence of electrostatic shielding by the abdomen of the measurement subject P. Here, since the abdomen is a part adjacent to the lung P3 across the diaphragm P2, when the measurement subject P inhales and the lung P3 expands, electrostatic shielding by the abdomen is performed by the air inside the lung P3. Be weakened. For this reason, the capacitance C in the abdomen of the measurement target person P increases when the measurement target person P inhales and the effect of electrostatic shielding by the abdomen is weakened, and the measurement target person P exhales and breathes out. It decreases when the effect of electrostatic shielding is restored.
The respiration of the measurement subject P can be measured by obtaining the change in the capacitance C (see FIG. 8) by the detection means 12. That is, the detecting means 12 inhales the measurement subject P when detecting an increase in the capacitance C between the electrodes 11 and detects the decrease in the capacitance C between the electrodes 11. Therefore, it is possible to measure the respiration of the measurement subject P.

On the other hand, when measuring the electrostatic capacitance C between the electrodes 11 by applying the alternating electric field E between the electrodes 11 with the electrodes 11 sandwiching the chest of the measurement subject P, the alternating electric field E is in the lungs in which air has entered. Pass a lot through P3. For this reason, the influence of the difference in relative dielectric constant between the body (and water) of the measurement subject P and air is more largely reflected in the measured capacitance C than the influence of the electrostatic shielding described above. That is, the relative permittivity of the human body (and water) is about 80, whereas the relative permittivity of air entering and exiting the lung is approximately 1, and there is a large difference in the relative permittivity. For this reason, the more the AC electric field E passes through the air that has entered the lung P3 of the measurement subject P (that is, the more the measurement subject P inhales), the smaller the capacitance C between the electrodes 11. In addition, the capacitance C between the electrodes 11 increases as the range in which the AC electric field E passes through the air that has entered the lungs P3 of the measurement subject P becomes narrower (that is, the measurement subject P exhales).
And the change of the electrostatic capacity C is calculated | required by the detection means 12, and the change of the air quantity in the lung P3 of the measurement subject P can be detected. That is, the detection means 12 inhales the measurement target person P when detecting a decrease in the capacitance C between the electrodes 11, and detects the increase in the capacitance C between the electrodes 11. Therefore, it is possible to measure the respiration of the measurement subject P.

As shown in FIG. 5, the detection means 12 measures the capacitive reactance when an AC voltage having a constant frequency is applied between the electrodes 11, and the capacitance C between the electrodes 11 is measured based on the measurement result. It is configured to calculate and determine the change. Hereinafter, the principle by which the detection unit 12 calculates the change in the capacitance C will be described. In the following description, the voltage value of each component of the detection means 12 is a value based on the potential of the casing (not shown) of the detection means 12 (that is, 0 [V]) unless otherwise specified. .
As shown in FIGS. 5 and 6, the detection means 12 has a configuration in which a fixed capacitor 12 </ b> D and an AC oscillation circuit 12 </ b> B are connected in series to the pair of electrodes 11. An AC-DC conversion circuit 12C having an output terminal 12E is connected in parallel to the capacitor 12D. As shown in FIG. 5, a data processing device 12A is connected to the output terminal 12E of the AC-DC conversion circuit 12C. The data processing device 12A, the AC oscillation circuit 12B, the AC-DC conversion circuit 12C, and the capacitor 12D are each installed in a casing (not shown) of the detecting means 12.

The AC oscillation circuit 12B applies an AC voltage having a constant frequency and voltage in series between a pair of electrodes 11 and a capacitor 12D, and has an AC electric field having the same frequency as the AC voltage applied between the electrodes 11. E (see FIGS. 3 and 4) is generated. Here, the frequency of the sine wave voltage is set to a constant value high enough to ensure sufficient time resolution in respiration measurement and to be able to consider an electrolyte such as blood as a good conductor. As a result, the influence of the change in the direction of the electric lines of force due to the change in the blood flow distribution accompanying the measurement subject P's breathing on the capacitance C of the measurement subject P is due to the air inside the lung P3 described above. Added to the effect of changes in quantity.
Further, the frequency of the sine wave voltage is set to a value that can reduce the biological influence of the AC electric field E generated by the sine wave voltage on the measurement subject P. Examples of the biological effect include an induced current generated in the body of the measurement subject P or a feeling of being heated that is felt by the measurement subject P. The influence of the former increases when the frequency of the sine wave voltage is 100 [kHz] or less, and the latter increases when the frequency of the sine wave voltage is 10 [MHz] or more.
In the present embodiment, the quadrature oscillation circuit shown in FIG. 6 is used as the AC oscillation circuit 12B. This quadrature oscillation circuit has a frequency of 400 [kHz] (period is 2.5 [μs]) and a peak-to-peak voltage (that is, a difference between the maximum voltage and the minimum voltage in a sine wave voltage) of 6 [V]. Generate a sine wave voltage.

At this time, when the electrostatic capacitance C between the electrodes 11 decreases due to the respiration of the measurement subject P, the capacitive reactance between the electrodes 11 increases, and the AC voltage applied to the capacitor 12D decreases. On the other hand, when the electrostatic capacitance C between the electrodes 11 increases due to the respiration of the measurement subject P, the capacitive reactance between the electrodes 11 decreases, and the AC voltage applied to the capacitor 12D increases.
Here, the AC oscillation circuit 12B applies the same AC voltage as the AC voltage applied to the capacitor 12D to the AC-DC conversion circuit 12C connected in parallel to the capacitor 12D. Then, the AC-DC conversion circuit 12C converts the AC voltage applied from the AC oscillation circuit 12B into a DC output voltage V1 (see FIG. 7), and outputs it from the output terminal 12E to the data processing device 12A.

The data processing device 12A calculates the capacitive reactance between the electrodes 11 from the output voltage V1 of the output terminal 12E, and divides the period of AC voltage (2.5 [μs]) by this capacitive reactance to give a predetermined coefficient. The capacitance C between the electrodes 11 is obtained by applying (constant). Then, the data processing device 12A sets the change in the capacitance C between the electrodes 11 as a change in the air amount inside the lung P3 (see FIGS. 3 and 4) of the measurement subject P on the monitor 12F (see FIG. 1). Display.
According to each of the above configurations, the AC oscillation circuit 12B applies an AC voltage having a constant frequency between the electrodes 11, so that the influence of the frequency characteristics on the AC electric field of the measurement subject's body (and water) is ignored. The capacitive reactance between each electrode 11 and the capacitance C can be easily obtained. In addition, by setting the frequency of the AC voltage, the calculation accuracy of the capacitance C can be improved by adding and reflecting the influence of the change in the blood flow distribution accompanying the breathing of the measurement subject P. The biological influence on the person P can be reduced, and the respiration measurement of the measurement person P in a more natural state can be performed.

The present inventors conducted an experiment to examine the correspondence between the measurement result of the above-described respiration sensor 10 and actual respiration. Hereinafter, experimental results of this experiment will be described with reference to FIGS.
In the following experiment, the measurement subject P performed breathing stop B1, resting breathing B2, deep breathing B3, and hyperventilation (rapid breathing at a rapid pace) B4 while sitting. In addition, since the measurement target person P puts the measurement clothes 13 of the respiration sensor 10 in a state having a sufficient space, the measurement target person P did not feel uncomfortable with the measurement clothes 13. In addition, each electrode 11 of the measurement clothes 13 sandwiches the lower periphery of the measurement target person P from the front-rear direction.

  First, the time change of the output voltage V1 output from the AC-DC conversion circuit 12C to the data processing device 12A was recorded while measuring the respiration of the measurement subject P. According to this experiment, as shown in FIG. 7, the output voltage V1 increases when the measurement subject P inhales, and the output voltage V1 decreases when the measurement subject P exhales. A repetitive signal of the output voltage V1 corresponding to the number of breaths of the subject P was obtained. It was confirmed that this repetitive signal is clearly larger than the magnitude of the noise component of the output voltage V1 (about 0.01 [V]) and changes depending on the respiratory state of the measurement subject P. That is, as compared with the repetitive signal in the resting breath B2, the repetitive signal in the deep breath B3 has a larger signal amplitude, and the repetitive signal in the hyperbreathing B4 is recorded with a shorter signal cycle. In addition, it was confirmed that the repetitive signal stopped during the breathing stop B1.

Next, an experiment was performed in which both the respiratory sensor 10 of the present invention and a known spirometer were attached to the measurement subject P, and respiratory measurement was performed simultaneously, and the measurement results were compared. In this experiment, RF-H manufactured by Minato Medical Science Co., Ltd. was used as a known spirometer. This spirometer attaches a mouthpiece to the measurement subject's mouth, takes in the breath of the measurement subject, measures the ventilation volume with a hot-wire velocimeter, and outputs it as an output voltage V2 (see FIG. 9).
According to the above experiment, as shown in FIGS. 8 and 9, the waveform of the output voltage V2 obtained from the spirometer and the waveform of the capacitance C obtained from the respiration sensor 10 are the waveform, period, It was also confirmed that the amplitude variation range was similar. For this reason, it is estimated that the change of the capacitance C measured by the respiration sensor 10 of the present invention can be used to observe the change of the ventilation amount in the respiration of the measurement subject P.

<Second Embodiment>
Then, the structure of the respiration sensor 20 which concerns on 2nd Embodiment is demonstrated using FIG. The respiration sensor 20 according to the second embodiment is an embodiment obtained by modifying the respiration sensor 10 according to the first embodiment. Therefore, for the configuration that is common to each configuration of the respiration sensor 10 according to the first embodiment, the tenth digit is represented by “10” from the reference numerals attached to each configuration of the respiration sensor 10 according to the first embodiment. The reference numerals replaced with “2” are assigned to correspond, and detailed description thereof is omitted.
As shown in FIG. 10, the respiration sensor 20 of the second embodiment measures the respiration of a plurality of measurement subjects P without burdening each measurement subject P (that is, in a minimally invasive state). Is part of the respiratory measurement system. Instead of the pair of electrodes 11 in the breathing sensor 10 of the first embodiment, two pairs of electrodes 21 are detachably attached to the measurement clothes 23 of the breathing sensor 20 by hook-and-loop fasteners (not shown). .

Each of the electrodes 21 is a measurement target of the measurement subject P with the abdominal electrode 21A and the waist electrode 21B and the chest electrode 21D and the back electrode 21E in the wearing state in which the measurement clothing 23 is worn on the measurement subject P. The chest of the person P is sandwiched from the front-rear direction. For this reason, the respiration sensor 20 can detect a change in capacitance as a change in the amount of air in the lungs in each of the chest and abdomen of the measurement subject P.
Of the detection results of the respiration sensor 20, a lot of information on the abdominal breathing of the measurement subject P is obtained from the change in the capacitance of the abdomen, and the chest of the measurement subject P is obtained from the change in the capacitance of the chest. A lot of information on expression respiration is obtained. Thereby, the measurement subject person P's chest respiration and abdominal respiration can be distinguished and measured.

In the measurement clothes 23, in addition to the electrodes 21, the detection means 22 is provided on the right shoulder, the motion state measuring device 24 is provided on the left shoulder, and the thermometer 25 is provided between the abdominal electrode 21A and the chest electrode 21D. Removably attached. The detection means 22 is connected in a state where a wireless transmission device 26 (in the present embodiment, a commercially available ZIGBEE (registered trademark) product) is assembled, and each electrode 21 described above is connected via a cable 21C. The exercise state measuring device 24 and the thermometer 25 are connected to the wireless transmission device 26 via cables 24A and 25A, respectively.
The detection means 22 calculates | requires the electrostatic capacitance between 21 A of abdominal electrodes, and the waist electrode 21B, and outputs it to the wireless transmission apparatus 26 as a capacitance of the measurement subject's P abdomen. Moreover, the detection means 22 calculates | requires the electrostatic capacitance between the chest electrode 21D and the back electrode 21E, and outputs it to the wireless transmission device 26 as the electrostatic capacitance of the chest of the measurement subject P. In addition, the motion state measuring device 24 includes a triaxial acceleration sensor (not shown), detects the acceleration (speed change) caused by the motion of the measurement subject P, and outputs the acceleration data to the wireless transmission device 26 as acceleration data. To do. In addition, the motion state measuring device 24 includes a triaxial gyro sensor (not shown), detects an angular velocity associated with a change in the motion or posture of the measurement subject P, and outputs the angular velocity data to the wireless transmission device 26 as angular velocity data. To do. The thermometer 25 measures the body temperature of the measurement subject P, and outputs the measurement result to the wireless transmission device 26 as temperature data. Then, the wireless transmission device 26 adds the acceleration data, temperature data, and angular velocity data described above to the capacitance data of the abdomen and chest of the measurement subject P in synchronization with each other, and further identifies the respiration sensor 20. A radio wave R is added and wirelessly transmitted.

The radio wave R wirelessly transmitted from the wireless transmission device 26 is received by the wireless reception device 27 including the monitor 27A as shown in FIG. The wireless receiving device 27 extracts the capacitance data, acceleration data, angular velocity data, temperature data, and the identification code of the respiration sensor 20 from the radio wave R, respectively, of the abdomen and chest of the measurement subject P. Next, the wireless reception device 27 performs correction to remove the influence of acceleration, angular velocity, and temperature change from the extracted capacitance data based on the extracted acceleration data, angular velocity data, and temperature data.
According to the above configuration, by correcting the detection result of the detection unit 22 based on the acceleration and angular velocity of the measurement target person P measured by the motion state measuring device 24, noise generated by the acceleration or angular velocity is removed by information processing. Or it can be reduced. Thereby, the precision of the respiration measurement during the exercise | movement of the measurement object person P can be improved. Further, by correcting the detection result of the detection means 22 based on the body temperature of the measurement subject P measured by the thermometer 25, the influence of this change in body temperature can be removed or reduced by information processing from the measurement result of respiration. it can. Thereby, while being able to compare easily the measurement result of the respiration of the measurement object person P, the precision of respiration measurement can be improved.

After the correction, the wireless receiver 27 monitors the corrected capacitance of the abdomen and chest of the measurement subject P together with the identification code of the respiratory sensor 20 as a change in the air amount inside the lung of the measurement subject P. 27A is displayed. The monitor 27A can be monitored by an external measurer or an automatic monitoring device (not shown), and can measure the respiration of the measurement subject P over a long period of time. Thereby, the health condition of the measurement subject P can be diagnosed.
According to the above configuration, the output from the respiration sensor 20 is displayed on the external monitor 27A by wireless transmission. Therefore, the respiration of the measurement subject P can be measured in a state where an external measurer (not shown) is stationary without limiting the action range and the motion state of the measurement subject P. Further, by displaying the output from the respiration sensor 20 together with the identification code of the respiration sensor 20, it is possible to prevent the measurement results from being mixed up when measuring the respiration of the plurality of measurement subjects P.

The present invention is not limited to the appearance and configuration described in the first and second embodiments described above, and various modifications, additions, and deletions can be made without changing the gist of the present invention. For example, the following various forms can be implemented.
(1) In the respiration sensor of the second embodiment described above, the location of the motion state measuring device and the thermometer can be changed as appropriate. That is, for example, a configuration in which the motion state measuring device is fixed to the waist of the measurement subject by a belt, or a configuration in which the thermometer is integrated with the electrode can be used. In addition, the motion state measurement device does not need to be configured to detect the angular velocity and acceleration of the measurement subject with three axes, and the number of detection axes of angular velocity and acceleration can be appropriately reduced. Also, the detection function of either angular velocity or acceleration can be omitted from the motion state measuring device.
(2) In the respiration sensor according to the second embodiment described above, it is possible to use a configuration in which the capacitance data of the measurement subject P is corrected by the data processing device of the detection means and then output by the wireless transmission device. .
(3) The configuration for the sensing means to measure the capacitive reactance between the pair of electrodes is not limited to the configuration in which a fixed-capacitance capacitor is connected in series to the pair of electrodes. That is, for example, it is possible to use a configuration in which a resistor is connected in series to a pair of electrodes and the capacitive reactance between the electrodes is obtained from the voltage applied to the resistor. Further, the detection means obtains an effective value of the alternating voltage applied between the electrodes and an effective value of the alternating current flowing between the electric conductors, and multiplies the effective value of the alternating current by the period of the alternating voltage to obtain the alternating current. It is also possible to use a configuration for calculating the capacitance between the electric conductors by dividing the effective value of the voltage and applying a predetermined coefficient (constant).
(4) The configuration in which the detection means obtains the capacitance between the electrode pair is not limited to the configuration that measures the capacitive reactance when an AC voltage is applied to the electrode pair. That is, for example, it is possible to use a configuration in which a predetermined amount of electric charge is charged in a pair of electrodes and a capacitance between the pair of electrodes is obtained from a potential difference generated between the pair of electrodes.
(5) An electrode is not limited to what is arrange | positioned so that a measurement subject's abdomen or a chest may be inserted | pinched from the front-back direction. That is, the electrode arrangement can be changed as appropriate, for example, by arranging electrodes on both axilla portions of the measurement subject in order to sense the expansion and contraction of the lung in the front-rear direction due to the intercostal muscles. Further, the electrodes are not limited to those arranged so as to face each other from the front, and the arrangement angle of the electrodes can be adjusted as appropriate.
(6) The cloth which forms an electrode is not limited to what was formed with the two-layer structure yarn which covered the stainless steel wire with the cotton fiber. That is, in the double-layer structure yarn for forming the electrode, the core material is made of metal such as copper, aluminum, iron, nichrome, gold, silver, titanium nickel alloy, or carbon such as PAN or pitch. The good conductor fiber, the fiber made conductive by blending the good conductor such as metal and carbon, or the insulating fiber, copper sulfide such as CuS, Cu ₂ S, Cu ₉ S ₅ or silver, copper, By coating a good conductor such as nickel, aluminum, gold, graphite, or carbon nanotube, a fiber having conductivity can be obtained. In addition, in the two-layer structure yarn for forming the electrode, the material of the sheath part is an insulating natural fiber such as silk, wool, or polyester, polyacrylonitrile, nylon, rayon, polypropylene, polyvinyl alcohol, polyethylene, An insulating synthetic fiber such as polyurethane can be used. In place of the two-layer structure yarn, a yarn obtained by twisting the fibers mentioned as the core material and insulating fibers, and a yarn obtained by coating the fibers mentioned as the core material with an insulating resin are used. You can also
(7) The structure which short-circuits the cloth which forms an electrode is not limited to an electroconductive adhesive agent, For example, electroconductive ink, a coating material, a coating agent, etc. can be changed suitably. When the good conductor is present on the surface of the yarn, the entire electrode cloth can be short-circuited without using a conductive adhesive, but it is necessary to cover the electrode cloth with an insulating material to prevent leakage to the outside. is there. As this insulating material, synthetic resins such as polyester, polyurethane, fluororesin, acrylic resin, polycarbonate, polypropylene, polyvinyl alcohol, and polyethylene can be used. As a method of covering the electrode cloth with an insulating material, a method such as film lamination or coating can be used.
(8) The cloth having conductive fibers for each electrode of the respiration sensor can be a cloth having an arbitrary structure such as a woven fabric, a non-woven fabric, or a knitted fabric. Moreover, each said electrode is not limited to the cloth which has a conductive fiber. That is, each electrode only needs to be conductive and conductive as a whole. For example, each electrode can be a foil or a net formed of a good conductor such as metal, and the shape thereof can be set as appropriate. it can. However, it is desirable that each electrode has flexibility and does not cause discomfort or stress to the measurement subject during respiration measurement.
(9) The configuration in which the electrode is detachably attached to the measurement clothes of the respiration sensor is not limited to the button or the hook-and-loop fastener, and can be appropriately changed, for example, a point fastener, a wire fastener, a hook, or the like.
(10) The respiration sensor is not limited to the configuration in which the electrode is detachably attached to the measurement clothes. That is, for example, a structure in which electrodes are fixed to measurement clothes by sewing, heat fusion or adhesion, or a part of the measurement clothes is made to be an electric conductor, and this electric conductor is used for measurement. It is also possible to use a configuration for obtaining the capacitance of the measurement target person with the person in between. It is also possible to use a configuration in which the measurement conductor is omitted from the respiration sensor and the electric conductor is directly attached to the measurement subject.

10 Respiration sensor 11 Electrode (electrical conductor)
11A Abdominal electrode 11B Lumbar electrode 11C Cable 12 Detection means 12A Data processing device 12B AC oscillation circuit 12C AC-DC conversion circuit 12D Capacitor 12E Output terminal 12F Monitor 13 Measurement clothes 20 Respiration sensor 21 Electrode (electric conductor)
21A Abdominal electrode 21B Lumbar electrode 21C Cable 21D Chest electrode 21E Back electrode 22 Detection means 22A Data processing device 23 Measurement clothes 24 Movement state measurement device 24A Cable 25 Thermometer 25A Cable 26 Wireless transmission device 27 Wireless reception device 27A Monitor B1 Breathing stop B2 Resting breath B3 Deep breathing B4 Hyperbreathing C Capacitance E AC electric field P Measurement subject P1 Body P2 Diaphragm P3 Lung R Radio wave V1 Output voltage V2 Output voltage

Claims (10)

A respiration sensor that can measure respiration of a measurement subject in a minimally invasive manner,
Directly attached in a state where measurement clothes are omitted for the measurement subject, and a pair of electrical conductors that sandwich the measurement subject's torso,
Detection means for obtaining a change in capacitance at a body part of the measurement subject between the pair of electrical conductors, and detecting respiration of the measurement subject from the change in capacitance. A respiration sensor. A respiration sensor that can measure respiration of a measurement subject in a minimally invasive manner,
By being in a wearing state worn by the measurement subject, measurement clothing covering the measurement subject's body from at least two directions facing each other;
Said As in the worn state of the measuring wearing sandwich torso of the measured person, said pair of measuring electrostatic attached to clothes care conductor,
A change in capacitance in the body part of the measurement subject between the pair of electrical conductors in the wearing state of the measurement clothing is obtained, and respiration of the measurement subject is detected from the change in capacitance. A respiration sensor. The respiration sensor according to claim 1 or 2,
At least one pair of the pair of electrical conductors sandwiches the chest of the measurement subject, and the detection means includes the electrical conductor with respect to the pair of electrical conductors that sandwich the chest of the measurement subject. Determining that the measurement subject inhales when detecting a decrease in capacitance between them, and that the measurement subject exhales when detecting an increase in capacitance between the electrical conductors Respiratory sensor characterized by. The respiratory sensor according to any one of claims 1 to 3,
At least one of the pair of electrical conductors sandwiches the abdomen of the measurement subject, which is a part adjacent to the lung across the diaphragm in the measurement subject, and the detection means is configured to include the abdomen of the measurement subject. For the pair of electric conductors that sandwich the gap, the measurement subject inhales when detecting an increase in the capacitance between the electric conductors, and the capacitance decreases between the electric conductors. A respiration sensor characterized by determining that the person to be measured has exhaled when detecting a breath. The respiration sensor according to any one of claims 1 to 4,
The detection means applies an alternating voltage having a constant frequency high enough to allow an electrolyte such as blood to be regarded as a good conductor between the pair of electrical conductors, and the electrical conductors with respect to the alternating voltage are applied. A respiratory sensor characterized by measuring a capacitive reactance between a pair and calculating the capacitance from the capacitive reactance. The respiratory sensor according to claim 5, wherein
The respiratory sensor according to claim 1, wherein the frequency of the AC voltage is set so as to reduce a biological influence exerted on the measurement subject by an AC electromagnetic field generated by the AC voltage. The respiration sensor according to any one of claims 1 to 6,
The electric conductor is provided with at least two pairs, at least one of the electric conductor pairs sandwiches the chest of the measurement subject, and at least one of the electric conductor pairs is the measurement subject's chest. A respiratory sensor characterized by sandwiching the abdomen. A respiration sensor according to any one of claims 1 to 7,
A gyro sensor that measures an angular velocity associated with the movement of the measurement subject and transmits the angular velocity to the detection unit is provided, and the detection result of the detection unit is corrected based on angular velocity data transmitted from the gyro sensor. Breathing sensor. The respiration sensor according to any one of claims 1 to 8,
An acceleration sensor that measures acceleration associated with the measurement subject's movement and transmits the acceleration to the detection unit is provided, and the detection result of the detection unit is corrected based on acceleration data transmitted from the acceleration sensor. Breathing sensor. A respiration sensor that can measure respiration of a measurement subject in a minimally invasive manner,
A pair of electrical conductors sandwiching the measurement subject's torso,
A detecting means for obtaining a change in capacitance between the pair of electrical conductors, and detecting respiration of the measurement subject from the change in capacitance.
A thermometer that measures the body temperature of the measurement subject and transmits the temperature to the detection means, and corrects the detection result of the detection means based on temperature data transmitted from the thermometer. Breathing sensor.

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