Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/02—Detecting, measuring or recording for evaluating the cardiovascular system, e.g. pulse, heart rate, blood pressure or blood flow
  • A61B5/024—Measuring pulse rate or heart rate
  • A61B5/02405—Determining heart rate variability
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/42—Detecting, measuring or recording for evaluating the gastrointestinal, the endocrine or the exocrine systems
  • A61B5/4261—Evaluating exocrine secretion production
  • A61B5/4266—Evaluating exocrine secretion production sweat secretion
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/02—Detecting, measuring or recording for evaluating the cardiovascular system, e.g. pulse, heart rate, blood pressure or blood flow
  • A61B5/024—Measuring pulse rate or heart rate
  • A61B5/02438—Measuring pulse rate or heart rate with portable devices, e.g. worn by the patient
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves
  • A61B5/053—Measuring electrical impedance or conductance of a portion of the body
  • A61B5/0531—Measuring skin impedance
  • A61B5/0533—Measuring galvanic skin response
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
  • A61B5/316—Modalities, i.e. specific diagnostic methods
  • A61B5/318—Heart-related electrical modalities, e.g. electrocardiography [ECG]
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/40—Detecting, measuring or recording for evaluating the nervous system
  • A61B5/4029—Detecting, measuring or recording for evaluating the nervous system for evaluating the peripheral nervous systems
  • A61B5/4035—Evaluating the autonomic nervous system
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
  • A61B5/6801—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
  • A61B5/6813—Specially adapted to be attached to a specific body part
  • A61B5/6825—Hand
  • A61B5/6826—Finger

Definitions

• the present invention relates to a heart rate variability measurement system and a heart rate variability measurement method.
• Circulatory system diseases including heart disease, are serious diseases that lead to the highest number of deaths in Japan, and are dangerous diseases that can attack suddenly without being noticed. Therefore, monitoring of the circulatory system, including the heart, is extremely important for building a healthy society. Furthermore, since the frequency characteristics of time-based changes in heartbeat intervals are said to be correlated with autonomic nervous balance, heart rate variability measurement can also be effectively used to manage mental states and biological rhythms.
• Heart rate variability can be monitored using an electrocardiogram or the like, but an electrocardiogram is a relatively large-scale device used in medical institutions, etc., and it is difficult to easily use it for monitoring anytime and anywhere.
• Patent Document 1 describes a method of detecting the acceleration of a substrate attached to clothing using a sensor and deriving the heart rate from the acceleration. Although this method uses two sensors to prevent abnormal measurement data from being captured due to irregular posture, etc., it does not necessarily measure reliable heart rate variability because it only measures vibrations. The problem is that it is difficult to For this reason, there is a strong demand for a heart rate variability measurement system that can easily measure heart rate variability at an extremity of the body such as a finger using a small device.
• An object of the present invention is to provide a system and a method for easily measuring heart rate variability in a hand such as a finger using a small measuring device.
• a heart rate variability measurement system It has a sweat detection section and a signal calculation processing section
• the perspiration detection unit includes a micro droplet detection unit in which a first thin wire and a second thin wire are arranged side by side on an insulating substrate, and a micro droplet detection portion in which a first thin wire and a second thin wire are arranged side by side on an insulating substrate, and It has a perspiration signal output section that measures the change and outputs it as a perspiration signal
• the signal calculation processing section includes a calculation section, an information storage section, and a heart rate variability value output section, The calculation unit calculates time t, time lag ⁇ t, value CH(t) of the perspiration signal at time t, heart rate factor Y(t+ ⁇ t) indicating heart rate fluctuation at time t+ ⁇ t, coefficients a, b, and a predetermined constant as ⁇ .
• the information storage unit stores at least the coefficient a, the coefficient b, and the constant ⁇ , The system, wherein the heart rate variability value output unit outputs the heart rate factor Y.
• the coefficient a and the coefficient b are calculated from equation (3) based on the measurement of the heart rate value HB(t) at time t, which was carried out in advance at the same time as the sweat signal measurement by the heart rate variability measurement system.
• the sweat detection section includes a minute droplet detection section in which a thin wire of a first metal and a thin wire of a second metal different from the first metal are juxtaposed on an insulating substrate;
• Configuration 3 3.
• Configuration 4 The system of claim 2 or 3, wherein the second metal is selected from the group consisting of silver, copper, iron, zinc, nickel, cobalt, aluminum, tin, chromium, molybdenum, manganese, magnesium, and alloys thereof.
• Configuration 5 The system according to any one of configurations 1 to 4, wherein the ⁇ is 0.2.
• Configuration 6 A plurality of at least one of the first metal thin wire and the second metal thin wire is provided, and the first metal thin wire and the second metal thin wire are directed toward the other side from opposite directions. 6.
• (Configuration 11) a minute droplet detection unit in which a thin wire of a first metal and a thin wire of a second metal different from the first metal are juxtaposed on an insulating substrate; Obtaining the value CH(t) of the perspiration signal at time t using a perspiration detection device having a perspiration signal output section that measures the galvanic current flowing between the thin metal wires and outputs it as a perspiration signal; Equations (1) and (2) shown below, where time lag ⁇ t, heart rate factor Y (t+ ⁇ t) indicating heart rate fluctuation at time t+ ⁇ t, coefficients a, b, and a predetermined constant ⁇ are used.
• the coefficient a and the coefficient b are calculated from equation (3) based on the measurement of the heartbeat value HB(t) at time t, which was performed simultaneously with the sweat signal measurement by the sweat detection device, which was carried out in advance.
• Y'(t+ ⁇ t) HB(t+ ⁇ t)-HB(t+ ⁇ t- ⁇ )...(3)
• Y'(t+ ⁇ t) a ⁇ X(t)+b...(4) Determined by regression analysis.
• Configuration 12 The method for measuring heart rate variability according to configuration 11, wherein the ⁇ is 0.2.
• a system and a method for easily measuring heart rate variability in a hand such as a finger using a small measuring device are provided.
• FIG. 1 is an explanatory diagram showing the configuration of a heart rate variability measurement system of the present invention.
• FIG. 1 is an explanatory diagram showing the configuration of a heart rate variability measurement system of the present invention.
• FIG. 2 is an explanatory diagram illustrating the configuration of a microdroplet detection section of the system of the present invention and its operating principle.
• FIG. 2 is a cross-sectional view of essential parts showing the structure of a microdroplet detection section of the system of the present invention.
• FIG. 2 is a cross-sectional view of essential parts showing the structure of a microdroplet detection section of the system of the present invention.
• FIG. 2 is a sectional view of a main part showing the structure of a sample section of the system of the present invention.
• FIG. 2 is an explanatory diagram showing the configuration of a signal calculation processing section of the system of the present invention.
• FIG. 3 is a characteristic diagram showing an example of an electrocardiogram measurement signal.
• FIG. 3 is a characteristic diagram showing an example of a sweating signal in the present invention. It is a photograph showing the appearance of the sweat sensor used in the example. It is an optical photograph taken from the top of the micro droplet detection part of the sweat sensor used in the example. It is an explanatory diagram showing a measurement procedure in an example.
• FIG. 3 is a characteristic diagram showing the correlation between sweating signal data and heart rate value data.
• FIG. 3 is a characteristic diagram showing the correlation between sweating signal data and heart rate value data.
• the heart rate variability measurement system 101 of the present invention includes a sweat detection section 11 and a signal calculation processing section 12, as shown in FIG.
• the sweat detection section 11 is a means for measuring the transpiration rate (sweating rate) of water transpired by sweating from the subject's hands, and as shown in FIG. Be prepared.
• the specimen section 21 includes a container that accommodates at least a portion of the subject's hand, and a microdroplet detection section 21a that detects microdroplets with a converted diameter size of 100 nm or more and 20 ⁇ m or less.
• the hand refers to each part of the finger, palm, and wrist, and the sweat detection unit 11 measures the transpiration rate of water that evaporates from one or more parts of the hand due to sweating. Therefore, the transpiration rate of water may be measured from any one of the fingers, the palm, the wrist, the fingers and the palm, the palm and the wrist, or the fingers, the palm, and the wrist.
• measurement using fingers makes it easier to reduce the size and weight of the device used (sweat detection device), is simple and easy to handle, and is easy to reduce costs. It has characteristics.
• Measurement using the palm of the hand has the advantage that the rate of sweating can be easily measured with high accuracy since the amount of perspiration from that area is large. Measurement at the wrist is close to the trunk of the body, making it possible to measure with less influence from factors other than sweating. Naturally, measurements using multiple parts such as fingers and palms make it possible to measure the characteristics of each part.
• the device should either contain the part of the hand to be measured, or should have a structure that prevents sweat from escaping from the measurement part of the hand when it is in close contact with or close to the part of the hand to be measured, such as a box-shaped device with a hand insertion opening. Or make it into a cup shape that can be used as a lid to place the measuring part such as a finger. Further, the device has a small cavity (space capacity) during measurement so that the sweating rate can be measured in a short time without touching the microdroplet detection section 21a with the hand to be measured. For this reason, the capacity of the sample portion, which is the space created in the container during measurement, is preferably 0.05 cm 3 or more and 2.5 cm 3 or less.
• the micro droplet detection unit 21a detects water evaporated from sweat as micro droplets.
• the configuration of the minute droplet detection section 21a the configuration of a sensor section of a droplet sensor that monitors changes in electrical resistance and capacitance between thin wires, galvanic current flowing between thin wires, etc. can be adopted.
• droplet sensors are of the type that detects the state of transpired water that accompanies perspiration in the form of droplets or aggregated water molecules, and are now of the type that uses a porous layer etc. to absorb the transpired water. In comparison, it is preferable because it has high responsiveness to the detection target.
• a first metal thin wire (first metal thin wire) 23 arranged side by side on an insulating substrate with a minute interval d apart, and a second metal thin wire (first metal thin wire) different from the first metal.
• a galvanic current measurement method that includes a second thin metal wire 25 and measures the galvanic current flowing between the first thin metal wire 23 and the second thin metal wire 25 is particularly preferable from its responsiveness.
• the first thin metal wire 23 is electrically connected to a first electrode 24 which is a collector electrode
• the second thin metal wire 25 is electrically connected to a second electrode 26 which is a collector electrode and bundled.
• FIG. 3 shows the principle by which a minute droplet can be detected by the minute droplet detection section 21a using the galvanic current measurement method. Note that this principle is also described in Patent Document 2. Moisture from the evaporated water becomes minute droplets and floats in the air, and due to adsorption/condensation phenomena, they straddle the first thin metal wire 23 made of metal A and the second thin metal wire 25 made of metal B. Droplets (water droplets containing impurity ions from sweat) are formed on the metal, and a galvanic current flows due to the electrochemical potential difference between the metals.
• the rate of change of the galvanic current corresponds to the rate of formation of minute droplets, that is, the rate of perspiration.
• This consonant relationship can be quantitatively known by obtaining a calibration curve in advance. Therefore, the rate of sweating can be determined by monitoring the rate of change of the galvanic current.
• the rate of change of the galvanic current the first derivative of the galvanic output current, the reciprocal of the rise time until reaching the galvanic output current value set based on a certain standard, etc. can be used.
• This method of measuring sweating rate is a physical adsorption detection method, which is different from the chemisorption detection method used in general humidity sensors.
• the above-mentioned physical adsorption detection method detects moisture due to perspiration in the micro droplet detection section 21a, which includes the first thin metal wire 23 and the second thin metal wire 25 arranged side by side on an insulating substrate with a minute distance d between them.
• the detection method has the characteristic that droplets can be adsorbed in a layered manner on the sensor surface (microdroplet detection surface), so that an accurate response can be obtained depending on the amount of moisture even under high humidity.
• the adsorption capacity is limited by monomolecular layer adsorption, so when the amount of perspiration, that is, the amount of droplets due to perspiration increases, adsorption saturation occurs and measurement accuracy decreases.
• At least one of the first thin metal wire 23 and the second thin metal wire 25 is provided in plural numbers, and the first thin metal wire 23 and the second thin metal wire 25 are arranged in opposite directions.
• the electrodes run parallel to each other so as to extend toward the other side, and by using narrow electrodes, that is, thin wires, the exclusive area of the microdroplet detection section 21a is suppressed, and both electrodes are brought close to each other.
• the opposing parts can be made longer.
• the battery capacity can be increased, that is, the galvanic current that can be taken out can be increased.
• Increasing the galvanic current is preferable because it improves the S/N in perspiration rate measurement.
• Examples of configurations that increase the length of the adjacent portion between the thin wire electrodes (hereinafter referred to as parallel running distance) by arranging the thin wire electrodes in parallel include, for example, a comb-shaped structure and a double spiral structure. be able to.
• the structure itself for making the parallel running distance of two thin wires as long as possible within a certain plane area is well known in the field of semiconductor devices, and such a structure may also be adopted as necessary.
• platcing thin wires (thin wire electrodes) side by side on a substrate” does not mean specifying the mutual orientation of a plurality of thin wires placed on a substrate, but refers to spacing the thin wires on the same plane of the substrate. It means to arrange the
• the material for the first thin metal wire 23 include gold (Au), platinum (Pt), silver (Ag), titanium (Ti), and alloys thereof; Mention may be made of materials selected from the group of carbon (C).
• the material of the second thin metal wire 25 is, for example, silver (Ag), copper (Cu), iron (Fe), zinc (Zn), nickel (Ni), Mention may be made of materials selected from the group of cobalt (Co), aluminum (Al), tin (Sn), chromium (Cr), molybdenum (Mo), manganese (Mn), magnesium (Mg) and alloys thereof.
• a material other than silver and its alloy is used as the material for the second thin metal wire 25.
• the output depends on the combination of materials for the thin metal wires.
• the silver/iron combination has a higher corrosion rate per same area, so the obtained current value is larger.
• gold/silver has a longer lifespan because the electrode wears out less.
• silver it is preferable to use silver as the first thin metal wire 23 or the second thin metal wire 25 because it has the effect of preventing mold from growing in the area where water droplets are detected.
• the first electrode 24 and the second electrode 26 be made of the same material as the first thin metal wire 23 and the second thin metal wire 25, since this simplifies the manufacturing process of the sweat detection device.
• the distance d between the first thin metal wire 23 and the second thin metal wire 25 is preferably 0.1 ⁇ m or more and 10 ⁇ m or less, more preferably 1.0 ⁇ m or more and 5 ⁇ m or less, and even more preferably 1.5 ⁇ m or more and 3 ⁇ m or less.
• the inventor has found from accumulating a large amount of experimental data that when the interval d is within this range, the resolution and measurement reproducibility of sweating rate is high.
• the thickness of the first thin metal wire 23 and the second thin metal wire 25 is preferably 10 nm or more and 300 nm or less.
• the thickness of the first thin metal wire 23 and the second thin metal wire 25 is less than 10 nm, problems arise in that the electrical resistance becomes too large, making it difficult to extract the output, and that the output changes easily over time.
• the thickness of the first thin metal wire 23 and the second thin metal wire 25 exceeds 300 nm, no particular effect is observed and materials are wasted.
• the thin metal wires on the anode side can be made thicker, or the width of the thin metal wires on the anode side can be increased, and instead of the thin metal wires on the cathode side, the thin metal wires on the cathode side can be made thicker. All you have to do is narrow the width.
• the protective cap 32 On the upper surface of the first thin metal wire 23 and the second thin metal wire 25 arranged in the container 31.
• the protective cap 32 preferably has a so-called overhang shape having an eave for the first thin metal wire 23 and the second thin metal wire 25 in order to improve protection from unnecessary sweat.
• the hand for example, the fingertips
• the protective cap 32 may touch or come close to the protective cap 32.
• Static electricity inside the body may be discharged, and an unintended current value may be measured. Therefore, it is also preferable to make part or all of the material of the protective cap 32 conductive so that static electricity inside the body can be dissipated when a hand touches or comes close to the protective cap 32.
• the protective cap 32, the first thin metal wire 23, and the second thin metal wire 25 are configured to be electrically insulated.
• Examples of the film used for the protective cap 32 include SiO 2 , SiON, SiO x , SiN x , Si 3 N 4 , HfO x , Al 2 O 3 , polyimide, acrylic, polystyrene (PS), polypropylene (PP), and polyethylene.
• PET Terephthalate
• PC polycarbonate
• PTFE polytetrafluoroethylene
• PFA tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer
• FEP tetrafluoroethylene/hexafluoropropylene copolymer
• ETFE ethylene copolymer
• a protective cap having an opening through which gas passes is formed above the first thin metal wire 23, the second thin metal wire 25, and the protective cap 32.
• a mesh 41 is provided.
• the openings in the protective mesh 41 allow moisture due to perspiration (moisture from transpiration) to pass through the protective mesh 41.
• the protective mesh 41 it is possible to prevent hands from touching the first thin metal wire 23 and the second thin metal wire 25.
• the protective mesh 41 include, but are not limited to, mesh members such as mesh plates and mesh films, woven fabrics, and nonwoven fabrics.
• the material of the protective mesh 41 is not particularly limited, and metals, oxides, nitrides, oxynitrides, silicon, organic materials, and the like can be used.
• the openings of the protective mesh 41 may be holes or grooves formed in the protective mesh material, fiber spaces when cloth is used as the protective mesh material, or the like, which ensure a path for moisture permeation.
• the micro droplet detection unit 21a in which the first thin metal wire 23 and the second thin metal wire 25 are arranged is connected to the hand (finger 51 in the figure). It may be placed below, or may be placed above (FIG. 6(b)) or to the side at a distance that does not make contact with the hand.
• the space 61 (capacity of the sample section) can be made compact and the sweat dripping from the hand can directly contact the first thin metal wire 23 and the second thin metal wire 25. This improves the measurement accuracy and reliability of sweating rate.
• the space 61 be made as small as possible in order to perform short-term measurement of the perspiration rate.
• the measurement unit 22 is equipped with an ammeter 28 that is electrically connected to the first metal electrode 24 and the second metal electrode 26 via wiring 27.
• the galvanic current generated by the thin metal wire 25 can be measured.
• the current value and the time change in the current value are sent to the signal calculation processing section 12 via the signal path 29 as a perspiration signal.
• the measuring section 22 functions as a perspiration signal output section that measures the change in galvanic current between the first thin metal wire 23 and the second thin metal wire 25 and outputs the result as a perspiration signal.
• the signal path 29 may be electrical wiring, wireless distribution, or electronic media, but electrical wiring or wireless distribution is preferable from the viewpoint of quick response.
• the measuring section (sweating signal output section) 22 may be placed inside the container 31 constituting the specimen section 21, placed outside, or placed across the inside and outside. good.
• the sweat detection device When placed inside the container, the sweat detection device can be made compact.
• the failure rate is reduced because the measuring section (sweating signal output section) 22 can be placed in an environment with relatively lower humidity than inside the device; (3) Since the heat generated from the device is less likely to affect the inside of the device, the accuracy and reliability of measuring sweating rate can be improved.
• a moderate effect can be obtained between placing it inside and outside.
• the signal calculation processing section 12 includes a calculation section 71, an information storage section 72, and a heart rate variability value output section 73.
• the information storage unit 72 stores at least coefficients a, b, and constant ⁇ .
• Heart rate variability value output section 73 outputs heart rate factor Y.
• the coefficients a and b are calculated from equation (3) based on the measurement of the heart rate value HB(t) at time t performed at the same time as the sweat signal measurement by the heart rate variability measurement system 101, which was performed in advance.
• Y'(t+ ⁇ t) HB(t+ ⁇ t)-HB(t+ ⁇ t- ⁇ )...(3)
• Y'(t+ ⁇ t) a ⁇ X(t)+b...(4) determined by regression analysis.
• the constant ⁇ is typically 0.2. It has been revealed through numerous experiments that when the constant ⁇ is set to 0.2, a high T value is obtained, the degree of relationship between X and Y increases, and the accuracy of heart rate variability measurement increases.
• the heart rate measurement heart rate factor Y' calculated by the above formula (3) is a heart rate factor calculated using the constant ⁇ based on the previously measured heart rate value HB(t) at time t.
• the heartbeat factor Y obtained by the above equation (1) is X(t) (i.e., the sweat signal They differ in that they are factors that have a linear relationship with change), and in order to distinguish between the two, the former is expressed using the symbol "Y'” and the latter is expressed using the symbol "Y". .
• heartbeat factor Y and heartbeat measurement heartbeat factor Y' are essentially the same factor.
• equations (3) and (4) used to determine coefficients a and b can also be rearranged as follows by replacing the symbol "Y'" with "Y".
• Y(t+ ⁇ t) HB(t+ ⁇ t) ⁇ HB(t+ ⁇ t ⁇ )
• X(t) CH(t)-CH(t- ⁇ )
• Y(t+ ⁇ t) a ⁇ X(t)+b
• the determination of the coefficients a and b will be exemplified.
• the latter for example, when one measurement period is set to 60 seconds, consider dividing into a plurality of sections with 4 seconds as one section.
• the time range of one section may be shorter or longer than 4 seconds, and it should be set so that the beats that can be converted to bpm (beats per minute), which is usually used as the unit of heart rate value, can be confirmed.
• bpm beats per minute
• the measurement period is 60 seconds and one section is 4 seconds, so we will set the starting point of the section in the interval from 0 seconds at the start of measurement to 56 seconds. Become.
• a starting point is set every 0.05 seconds
• Time series data of CH(t) can be obtained.
• a number of analysis target data corresponding to the number of set values of the time lag ⁇ t are obtained from one time series data. be able to.
• Regression analysis is performed using the large amount of analysis target data obtained in this way.
• a simple regression analysis can be performed as a regression analysis method.
• regression coefficients a and b as well as a coefficient of determination and a correlation coefficient are obtained from each data to be analyzed. Thereafter, using the T value of the correlation coefficient as an index, those whose T value exceeds +2 are extracted. Thereby, the reliability of the determined values of coefficients a and b can be increased. Then, the average value of the regression coefficients a and b is determined from the extracted data group, and this value is used as the determined value of the coefficients a and b, and is stored in the information storage unit 72.
• the sweat detection section 11 and the signal calculation processing section 12 may be housed in one housing, or may be placed in physically separate locations. In the latter case, even if the perspiration signal 74 measured by the perspiration detection unit 11 is transmitted from the perspiration detection unit 11 to the signal calculation processing unit 12 via communication (wireless communication), the perspiration signal 74 measured by the perspiration detection unit 11 is transmitted via electronic media such as a USB, a memory card, or a disk. or may be transmitted via a wired connection. Among these, when transmitting by wireless communication, the sweat detection device attached to the hand can be made smaller and lighter like a finger cot, and the signal processing unit 12 receives data from a large number of subjects and performs calculations.
• Methods using electronic media are characterized by the ability to efficiently process time-series data over a relatively long period of time.
• the heart rate variability measurement method of the present invention uses the heart rate variability measurement system (sweating detection device) to measure the value CH(t) of the sweating signal at time t, and calculates a heart rate factor Y indicating the heart rate variability at time lag ⁇ t and time t+ ⁇ t. (t+ ⁇ t), coefficients a, b, and a predetermined constant ⁇ , the above-mentioned equations (1) and (2) are calculated, and the calculated heartbeat factor Y is output.
• the coefficients a and b are calculated using the above-mentioned formula (3) from the measurement of the heart rate value HB(t) at time t, which was performed at the same time as the sweat signal measurement by the heart rate variability measurement system (sweat detection device).
• the heartbeat measurement heartbeat factor Y' is calculated and determined by regression analysis of the above-mentioned equation (4).
• the constant ⁇ is typically 0.2.
• the constant ⁇ is set to 0.2, a high T value is obtained, the degree of relationship between X and Y increases, and the accuracy of heart rate variability measurement increases.
• the determination of the coefficients a and b is as exemplified above. With this measurement method, heart rate variability can be easily measured using a compact device and an easy-to-handle hand such as a finger.
• Example 1 Through numerous experiments, the inventor discovered that the rate of perspiration (amount of perspiration per unit time) from the extremities of the body, such as fingers, is correlated with heart rate fluctuations at a specific time lag. Based on this discovery, he formulated a method based on regression analysis and invented a method for measuring heart rate variability from sweat rate. Examples thereof are shown below.
• FIG. 8 shows an example of waveform data of an electrocardiogram, which is often used in medical settings as a method of monitoring the state of the heartbeat, that is, the movement of the heart.
• FIG. 9 shows an example of a sweat signal measured by a sweat sensor prototyped as a sweat detection device including the sweat detection section 11 of the system of the present invention.
• (a) shows the measurement results for a time (time) of 0 to 60 s
• (b) shows the results obtained by enlarging the range of time (time) of 30 to 40 s in (a).
• data was recorded for 60 seconds after the electrocardiograph (manufactured by Parama Tech, EP-501) started and the electrocardiogram waveform started to appear.
• the time point at which recording of the sweating signal (current value) output from the sweating sensor starts is 0 s, and at about 5 s, the subject places his or her finger on the specimen part of the sweating sensor (measuring the sweating signal). (start), and at a time of about 62 seconds, the finger was removed from the specimen part.
• FIG. 10 shows an external photograph of the sweat sensor used in this example
• FIG. 11 shows an optical photograph taken from above of the sensor section (corresponding to the minute droplet detection section 21a).
• FIG. 10(a) is a photograph of a single sweat sensor
• FIG. 10(b) is a photograph of a state in which a finger is placed on the container of this sensor.
• the container of the specimen part is a cup-shaped approximately rectangular in plan view, and the upper part is open, and when the subject places (covers) his/her finger, the finger acts as a lid. becomes.
• FIG. 11(a) is an optical photograph of the minute droplet detection part of the sweat sensor.
• the image on the right is an enlarged image of the first thin metal wire 202 and the second thin metal wire 203 observed from above.
• This sweat sensor can measure the rate of sweat evaporating from the finger (fingertip) when the finger is placed on the device as shown in Figure 10(b), and can transmit the measurement data to the server via wireless communication.
• the first thin metal wire 202 was made of aluminum (Al)
• the second thin metal wire 203 was made of gold (Au)
• the interval between the first thin metal wire 202 and the second thin metal wire 203 was 1 ⁇ m.
• the electrocardiograph measurement time is set to 60 seconds, and after the start-up and preparation period, the electrocardiogram waveform starts to appear on the screen (when the electrocardiograph starts sounding). , started recording the sweat signal output from the sweat sensor. This synchronized the timing of the start of displaying the electrocardiogram waveform and the start of recording the sweating signal, so that the elapsed time of measurement by both devices was the same.
• the measurement time by the sweat sensor should be longer than the measurement time by the electrocardiograph (about a few seconds), and after the electrocardiogram measurement is completed, the subject should remove the finger from the sample part (vessel) of the sweat sensor. I decided to let go. Note that in this experiment, there may be a slight lag (several seconds delay) between the start of recording the sweat signal and the time the subject places his or her finger on the sample part (vessel) of the sweat sensor, but due to the synchronization process and adjustment of the measurement time described above, , it is possible to match the electrocardiogram waveform and the sweating signal waveform.
• each subject was asked to perform the above-mentioned measurements at least once a day, and the measurements were carried out over a period of 3 months. Although the total number of measurements varied depending on the subject, a total of more than 30 measurements were performed for each subject. Then, using the data to be analyzed obtained by dividing the 60-second measurement period into a plurality of sections with each section being 4 seconds as exemplified above, the equations (1) to ( 4) was used to perform regression analysis calculations to obtain the coefficients a, b, and constant ⁇ , and also calculated the T value to evaluate the validity of the heart rate variability measurement of the present invention.
• FIGS. 13 and 14 The results are shown in FIGS. 13 and 14.
• (a) shows the T value with respect to the time lag ⁇ t
• (b) shows its appearance frequency.
• Figure 13 shows the data when the subject is at rest
• Figure 14 shows the data when the subject is exercising (going up and down one floor's worth of stairs). This is the data when doing one round trip).
• the constant ⁇ was set to 0.2, which allows a high degree of relationship to be obtained from the large amount of data acquired in this example.
• a high T value of around 2 was periodically obtained every time lag ⁇ t of about 0.6 seconds, demonstrating that the heart rate variability measurement system of the present invention can measure heart rate variability.
• FIG. 13 shows the data when the subject is at rest
• Figure 14 shows the data when the subject is exercising (going up and down one floor's worth of stairs). This is the data when doing one round trip).
• the constant ⁇ was set to 0.2, which allows a high degree of relationship to be obtained from the large amount of data acquired in this
• the heart rate variability measurement system can easily measure heart rate variability in a hand such as a finger using a small and lightweight measuring device.
• Daily measurement of heart rate variability makes it possible to issue warnings about abnormalities or signs of abnormality in the heart and circulatory system, and can also be effectively used to manage mental conditions and biological rhythms. Therefore, the heart rate variability measurement system and the heart rate variability measurement method of the present invention will become the cornerstone of building a healthy society, and are likely to be widely used in industry.
• Sweating detection section 12 Signal calculation processing section 21: Sample section 21a: Micro droplet detection section 22: Measuring section (sweating signal output section) 23: First thin metal wire 24: First metal electrode 25: Second thin metal wire 26: Second metal electrode 27: Wiring 28: Ammeter 29: Signal path 31: Vessel 32: Protective cap 41: Protective mesh 51: Finger 61: Space 71: Arithmetic unit 72: Information storage unit 73: Heart rate variability value output unit 74: Sweat signal, input signal 101: Heart rate variability measurement system 102: Sample unit 103: Sample unit 201: Silicon chip (galvanic array) ) 202: First thin metal wire (aluminum) 203: Second thin metal wire (gold) 204: Scale

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• 2023
  • 2023-03-01 EP EP23766650.8A patent/EP4491107A4/en active Pending
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