Sweat analysis device and method

Abstract

This perspiration analysis device comprises: a wearable sensor (1) that outputs an electric signal derived from a wearer's perspiration amount and electrolyte concentration; a temperature sensor (2) that measures the temperature of an internal space of the wearable sensor (1) into which the wearer's sweat flows; a humidity sensor (3) that measures the relative humidity in the internal space; and an MCU section (7). The MCU section (7) calculates a perspiration amount measurement value and an in-sweat electrolyte concentration measurement value of the wearer on the basis of the electric signal, and calculates an actual value of the perspiration amount and an actual value of the electrolyte concentration which are corrected for the effects of reduction of the amount of sweat due to evaporation, on the basis of a known physical value relating to sweat evaporation, the perspiration amount measurement value, the electrolyte concentration measurement value, the temperature, and the relative humidity.

Description

[Technical Field]

[0001] The present invention relates to a sweat analysis device and method that is worn on the human body to measure the amount of sweat of the wearer and the electrolyte concentration in the sweat. [Background technology]

[0002] Due to global warming, the number of heat waves occurring is increasing in most regions of the world. In Japan in recent years, the incidence of heatstroke has increased due to the increased frequency of extreme heat. The number of patients receiving medical transport for heatstroke has remained at a high level since peaking in 2018, becoming a social problem (see Non-Patent Document 1).

[0003] Heatstroke refers to a state of multiple organ failure caused by high temperatures or strenuous exercise. Generally, human body temperature is maintained at approximately 37°C through the thermoregulatory process of the anterior hypothalamus. Physical phenomena related to sweating, such as evaporation, heat radiation, convection, and heat conduction, function to cool the body surface.

[0004] When body temperature rises, cutaneous vasodilation increases skin blood flow, initiating thermal sweating. Skin vasodilation causes a relative decrease in intravascular volume, resulting in heat syncope. Salt and water loss through sweating leads to dehydration and salt depletion, accompanied by heat exhaustion and convulsions. Further loss of salt and water reduces thermoregulatory function, and subsequently, shunting from the central circulation to the skin and muscles reduces blood flow to the internal organs, leading to organ failure and a condition known as heatstroke (see Non-Patent Document 2).

[0005] As mentioned above, water and salt in the human body play an important role in regulating body temperature. To prevent dehydration, which can lead to heat exhaustion, it is important to replenish adequate amounts of water and salt. Numerous studies have reported that the salt concentration in sweat increases linearly with increasing sweat rate. However, the rate of increase in salt concentration varies from person to person, depending on a person's sweating ability and the ability of sweat glands to reabsorb salt. It is also known that an individual's sweating ability and salt reabsorption ability change depending on their heat acclimation. Therefore, continuous monitoring of both a person's sweat rate and the salt concentration in sweat is considered effective for monitoring water and salt loss. As a prior art technique for realizing this monitoring, a wearable sensor that simultaneously measures the amount of sweat and electrolyte concentration has been proposed (see Patent Documents 1 and 2).

[0006] Fig. 11 is a cross-sectional view of the wearable sensor disclosed in Patent Document 1, and Fig. 12 is an enlarged view of Fig. 11. The wearable sensor 1 includes a substrate 10 having a through-hole 11 serving as a liquid flow path and a recess 12 communicating with the outlet end of the through-hole 11, an electrode 14 arranged on the surface of the substrate 10 where the inlet end of the through-hole 11 opens, a water-absorbent structure 15 arranged on the outlet-side surface (upper surface) of the substrate 10 so as to come into contact with the liquid that flows out from the outlet opening of the through-hole 11 into the recess 12, and a water-absorbent electrode 16 arranged on the surface of the water-absorbent structure 15 facing the substrate 10 so as to face the outlet opening of the through-hole 11. In Fig. 11, 13 denotes a recess formed on the lower surface of the substrate 10, 100 denotes the skin of a wearer of the wearable sensor 1, and 101 denotes a sweat gland of the wearer.

[0007] By using the wearable sensor 1, the amount of sweat produced by the wearer of the wearable sensor 1 and the electrolyte concentration in the sweat can be calculated based on the electrical conductivity between the electrodes 14 and 16 due to the sweat 102 that flows out from the through hole 11 into the recess 12.

[0008] Fig. 13 is a cross-sectional view of the wearable sensor disclosed in Patent Document 2, and Fig. 14 is an enlarged view of Fig. 13. Wearable sensor 1a includes a substrate 10 having a through-hole 11 and a recess 12, a water-absorbing structure 15, a laser diode (LD) 18 disposed within recess 12 and emitting light along a path within recess 12 that passes over a position above the outlet opening of through-hole 11 along the outlet surface of substrate 10, and a photodiode (PD) 19 disposed within recess 12 opposite LD 18 across the position above the outlet opening of through-hole 11 and receiving light from LD 18. Reference numeral 103 in Fig. 13 denotes light emitted from LD 18.

[0009] By using wearable sensor 1a, it is possible to calculate the amount of sweat produced by the wearer of wearable sensor 1a and the electrolyte concentration in the sweat based on the light receiving characteristics of PD 19 that receives light from LD 18.

[0010] As described above, the wearable sensors 1 and 1a disclosed in Patent Documents 1 and 2 can calculate the amount of sweat produced by the wearer and the electrolyte concentration in the sweat. However, when the amount of sweat produced is small, the effect of evaporation of the sweat that flows out from the through-hole 11 into the recess 12 becomes large, which may result in the amount of sweat being underestimated or the electrolyte concentration being overestimated. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] International Publication WO2021 / 038742 [Patent Document 2] International Publication WO2021 / 038758 [Non-patent literature]

[0012] [Non-Patent Document 1] A. Hirata, T. Miyazawa, R. Uematsu, S. Kodera, Y. Hashimoto, K. Takagahara, Y. Higuchi, H. Togo, T. Kawahara, H. Tanaka, “Body Core Temperature Estimation Using New Compartment Model With Vital Data From Wearable Devices”, IEEE Access 2021,9,124452-124462.(DOI:10.1109 / ACCESS.2021.3110252) [Non-patent document 2] T. Hifumi, Y. Kondo, K. Shimizu, Y. Miyake, “Heat stroke”, Journal of Intensive Care, 2018, 6, 1-8,<https: / / doi.org / 10.1186 / s40560-018-0298-4> Summary of the Invention [Problem to be solved by the invention]

[0013] The present invention has been made to solve the above-mentioned problems, and aims to provide a sweat analysis device and method that can reduce measurement errors in sweat volume and electrolyte concentration by taking into account the effects of sweat evaporation and performing corrections. [Means for solving the problem]

[0014] The sweat analysis device of the present invention is characterized by comprising: a wearable sensor configured to output an electrical signal derived from the amount of sweat and electrolyte concentration of sweat secreted from the wearer's skin; a temperature sensor configured to measure the temperature of the internal space of the wearable sensor into which the wearer's sweat flows; a humidity sensor configured to measure the relative humidity of the internal space of the wearable sensor into which the wearer's sweat flows; a sweat rate calculation unit configured to calculate a measured value of the wearer's sweat rate based on the electrical signal obtained by the wearable sensor; an electrolyte concentration calculation unit configured to calculate a measured value of the electrolyte concentration in the wearer's sweat based on the electrical signal obtained by the wearable sensor; and a correction unit configured to calculate a true value of the sweat rate and a true value of the electrolyte concentration, corrected for the effect of sweat loss due to evaporation, based on a known physical quantity related to sweat evaporation, the measured sweat rate, the measured electrolyte concentration, the temperature, and the relative humidity. [Effects of the Invention]

[0015] According to the present invention, a wearable sensor, a temperature sensor, a humidity sensor, a sweat rate calculation unit, an electrolyte concentration calculation unit, and a correction unit are provided, and the true values ​​of the sweat rate and electrolyte concentration, which are corrected for the effect of sweat loss due to evaporation, are calculated by the correction unit, thereby reducing the possibility of underestimating the sweat rate or overestimating the electrolyte concentration. As a result, the present invention can achieve highly accurate measurement of the sweat rate and electrolyte concentration. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram showing an example of changes in the value of a current flowing between electrodes, as measured by a wearable sensor. [Figure 2] FIG. 2 is a block diagram showing the configuration of a perspiration analyzer according to a first embodiment of the present invention. [Figure 3] FIG. 3 is a functional block diagram of the MCU unit of the perspiration analyzer according to the first embodiment of the present invention. [Figure 4]FIG. 4 is a flowchart illustrating the operation of the perspiration analyzer according to the first embodiment of the present invention. [Figure 5] FIG. 5 is a flowchart illustrating the operation of the correction unit of the perspiration analyzer according to the first embodiment of the present invention. [Figure 6] FIG. 6 is a flowchart illustrating the operation of the correction unit of the perspiration analyzer according to the second embodiment of the present invention. [Figure 7] FIG. 7 is a flowchart illustrating the operation of the correction unit of the perspiration analyzer according to the third embodiment of the present invention. [Figure 8] FIG. 8 is a block diagram showing the configuration of a perspiration analyzer according to a fourth embodiment of the present invention. [Figure 9] FIG. 9 is a functional block diagram of the MCU unit of a perspiration analyzer according to a fourth embodiment of the present invention. [Figure 10] FIG. 10 is a block diagram showing an example of the configuration of a computer that realizes the perspiration analyzers according to the first to fourth embodiments of the present invention. [Figure 11] FIG. 11 is a cross-sectional view of a conventional wearable sensor. [Figure 12] FIG. 12 is an enlarged cross-sectional view of a conventional wearable sensor. [Figure 13] FIG. 13 is a cross-sectional view of another conventional wearable sensor. [Figure 14] FIG. 14 is an enlarged cross-sectional view of another conventional wearable sensor. DETAILED DESCRIPTION OF THE INVENTION

[0017] [First correction method] In the present invention, the sweat rate and electrolyte concentration in sweat of a wearable sensor wearer are measured using the sweat analysis device disclosed in Patent Documents 1 and 2. The measured sweat rate of the wearer is Q [L / s], the true value of the sweat rate is Q' [L / s], the measured electrolyte concentration in the wearer's sweat is C [mol / L], the true value of the electrolyte concentration is C' [mol / L], the temperature of the internal space of the wearable sensor into which the wearer's sweat flows is T [°C], and the relative humidity of the internal space is RH [%]. In a first correction method of the present invention, the true value of the sweat rate Q' and the true value of the electrolyte concentration C' can be calculated using equations (1) to (5).

[0018]

number

[0019]

number

[0020] P s =e^{-6096.9385×(T+273.15) -1 +21.2409642-2.711193×10 -2 ×(T+273.15)+1.673952×10 -5 ×(T+273.15) 2 +2.433502×ln(T+273.15)} ···(3)

[0021]

number

[0022]

number

[0023] The second term on the right side of equation (1) represents the amount of sweat lost due to evaporation. In other words, equation (1) means that the true value of sweat rate Q' is the sum of the measured amount of sweat Q and the amount of sweat lost due to evaporation. The "^" in equation (3) represents exponentiation.

[0024] D[m 2 / s] is the diffusion coefficient of water vapor in sweat when the measured electrolyte concentration is C, ΔC [kg / m 3 ] is the difference between the density of water vapor near the gas-liquid interface of the sweat droplet 102a generated at the opening of the through-hole 11 in FIGS. 11 to 14 and the density of water vapor sufficiently far from the gas-liquid interface of the droplet 102a, ρ [kg / m 3 ] is the density of water.

[0025] r [m] is 1 / 2 of the dimension of the opening of the through-hole 11 (the diameter if the cross section of the opening is circular), θ c [rad] is the angle (static contact angle) between the surface of the electrode 16 or the surface of the water-absorbing structure 15 and the surface of the sweat droplet 102a, P s [Pa] is the saturated water vapor pressure. The density ρ of water, the value r of half the size of the opening of the through-hole 11, and the static contact angle θ c is a known physical quantity related to the evaporation of sweat.

[0026] [Second correction method] In the second correction method of the present invention, equations (6) and (7) are solved for the true value Q' of the sweat rate, and the true value C' of the electrolyte concentration is calculated using equation (5).

[0027]

number

[0028]

number

[0029] Equation (6) is the time derivative of the dynamic contact angle θ [rad] in a state where the contact angle changes continuously after the sweat droplet 102a lands on the electrode 16 or the water-absorbing structure 15. c [s] is the measured period of the upward peaks of the current flowing between electrodes 14 and 16 in Figure 11, or the measured period of the downward peaks of the photocurrent flowing through PD 19 in Figure 13. Equation (7) defines the period T cis the integral of the amount of sweat lost due to evaporation during a period.

[0030] An example of the change in the value of the current flowing between the electrodes measured by the wearable sensor disclosed in Patent Document 1 is shown in Figure 1. As explained above, in the structure shown in Figures 11 and 12, current continues to flow while sweat droplets 102a are present between electrodes 14 and 16, and the cycle of current flow changes depending on the flow rate of sweat into the wearable sensor, i.e., the amount of sweat produced, and the peak current during current flow changes depending on the electrolyte concentration.

[0031] On the other hand, in the wearable sensor disclosed in Patent Document 2, when droplets 102a of sweat 102 are formed, the photocurrent of PD 19 decreases, and when the droplets 102a disappear, the photocurrent of PD 19 increases. In other words, the period of the downward peaks of the photocurrent of PD 19 changes depending on the amount of sweat, and the peak current changes depending on the concentration of electrolytes.

[0032] [Third correction method] Next, a third correction method of the present invention will be described. The dynamic contact angle θ of the sweat droplet 102a at time t is defined as θ(t). A small non-zero value (e.g., 0.1 deg or 1 deg) is set as the initial value θ(0) of the dynamic contact angle at time t=0. Furthermore, a value within the range of the measured sweat rate Q and a predetermined sweat rate value is set as the estimated value of the true sweat rate Q', and the following equations (8) and (9) are calculated.

[0033] The above-mentioned predetermined value of the amount of sweating is the amount of sweating where the influence of evaporation is negligible, or the upper limit of the amount of sweating Q max There is an upper limit Q max For this purpose, it is sufficient to set a value that corresponds to the actual situation based on the results of past measurements.

[0034]

number

[0035]

number

[0036] Here, Δt [s] is the calculation interval, and f(Q') is the evaluation function for evaluating the accuracy of the estimated value of the true value Q' of the sweat rate. c The total amount of sweating during the period Q' is estimated (=Q'T c ) and the total amount of sweat measured Q (= QT c ) and the period T c This means that the evaluation function f(Q') is the value obtained by subtracting the amount of sweat lost due to evaporation during this period.

[0037] While changing the estimated value of the true value Q' by a predetermined step width of the sweat rate (for example, 0.01 μL / min), the calculations of Equation (8) and Equation (9) are performed for each estimated value of the true value Q'. Then, the square of the evaluation function f(Q') calculated for each estimated value of the true value Q', f(Q'), 2 The estimated value that minimizes this is taken as the true value Q' of the sweat rate. Furthermore, the true value C' of the electrolyte concentration is calculated using equation (5).

[0038] [First Example] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Fig. 2 is a block diagram showing the configuration of a perspiration analysis device according to a first embodiment of the present invention. The perspiration analysis device includes a wearable sensor 1, a temperature sensor 2, a humidity sensor 3, an AFE (Analog Front End) unit 4, a data recording unit 5, a memory unit 6, an MCU (Micro Control Unit) unit 7, a communication unit 8, and a power supply unit 9.

[0039] Wearable sensor 1 outputs an electrical signal (for example, a current with the waveform shown in FIG. 1) derived from the amount of sweat secreted from the skin of the wearer and the electrolyte concentration. The temperature sensor 2 measures the temperature T of the internal space of the wearable sensor 1 into which the sweat secreted from the wearer's skin flows. The humidity sensor 3 measures the relative humidity RH of the internal space of the wearable sensor 1 into which the sweat secreted from the wearer's skin flows. The temperature sensor 2 and humidity sensor 3 may be integrated.

[0040] The AFE unit 4 includes an analog front end and amplifies the weak electrical signal output from the wearable sensor 1. The data recording unit 5 includes an ADC (Analog Digital Converter), and converts the analog signal amplified by the AFE unit 4 into digital data at a predetermined sampling frequency, and stores the digital data in the storage unit 6 .

[0041] The storage unit 6 stores the digital data output from the data recording unit 5. The storage unit 6 is realized by a non-volatile memory such as a flash memory, or a volatile memory such as a DRAM (Dynamic Random Access Memory). The MCU unit 7 is a circuit that performs signal processing to calculate the amount of sweat and the electrolyte concentration from the digital data stored in the storage unit 6.

[0042] The communication unit 8 includes a circuit for wirelessly or wiredly transmitting the measurement results and analysis results obtained by the MCU unit 7 to an external device (not shown) such as a smartphone. Examples of wireless communication standards include Bluetooth (registered trademark) Low Energy (BLE). Examples of wired communication standards include Ethernet (registered trademark). The power supply unit 9 is a circuit that serves to supply power to the perspiration analyzer.

[0043] The wearable sensor 1 in this embodiment is the same as that disclosed in Patent Document 1, so the structure of the wearable sensor 1 will be described with reference to FIGS. The wearable sensor 1 comprises a substrate 10 having a through hole 11 and a recess 12 communicating with the outlet end of the through hole 11, an electrode 14 arranged on the surface of the substrate 10 where the inlet end of the through hole 11 opens, a water-absorbing structure 15 arranged on the outlet surface (upper surface) of the substrate 10 so as to come into contact with the liquid that flows out from the outlet opening of the through hole 11 into the recess 12, and a water-absorbing electrode 16 arranged on the surface of the water-absorbing structure 15 facing the substrate 10 so as to face the outlet opening of the through hole 11.

[0044] The substrate 10 may be made of, for example, a hydrophilic glass material or a resin material. Alternatively, the substrate 10 may be made of a water-repellent material, the surface of which and the inner surfaces of the through-holes 11 have been subjected to a surface treatment to impart hydrophilic properties. The upper surface of the substrate 10 is formed with recesses 12 that are recessed into the upper surface so as to communicate with the through-holes 11. Conversely, the lower surface of the substrate 10 is formed with recesses 13 that are recessed into the lower surface so as to communicate with the through-holes 11.

[0045] The electrode 14 is made of, for example, a thin metal film formed on the surface (lower surface) of the substrate 10 where the entrance ends of the through-holes 11 are open. Examples of the water-absorbing structure 15 include fibers such as cotton and silk, and porous ceramic substrates. Examples of the electrode 16 include a porous thin metal film formed on the surface of the water-absorbing structure 15 by plating, for example, a water-absorbing structure 15 in which the fibers are impregnated with a conductive polymer, or a structure in which conductive fibers are woven.

[0046] Wearable sensor 1 is attached to the body of a wearer so that the underside of substrate 10 faces skin 100 of the wearer, as shown in Fig. 11. Reference numeral 101 in Fig. 11 denotes sweat glands of the wearer. When the wearer sweats, the sweat 102 is introduced into the through-holes 11 from the recesses 13 of the base material 10 by capillary action. Furthermore, as the amount of sweat increases, the sweat 102 rises inside the through-holes 11 and reaches the recesses 12.

[0047] As shown in the enlarged view of Fig. 12, a water-repellent portion 17 is provided on the inner surface of the recess 12. When a hydrophilic material is used for the substrate 10, the water-repellent portion 17 can be formed by subjecting the inner surface of the recess 12 to a water-repellent surface treatment. When a water-repellent material is used for the substrate 10, the water-repellent portion 17 can be provided by leaving only the inner surface of the recess 12 made of a water-repellent material.

[0048] When the sweat 102 reaches the recess 12, which is the internal space of the wearable sensor 1, it turns into spherical droplets 102a as shown in FIG. 12. As the amount of sweat increases, the diameter of the droplets 102a increases and they eventually reach the electrode 16 and the water-absorbent structure 15. The droplets 102a that have reached the electrode 16 and the water-absorbent structure 15 evaporate while moving through the numerous pores in the electrode 16 and the water-absorbent structure 15 due to capillary action. This causes the droplets 102a to disappear. In this way, the formation and disappearance of the droplets 102a repeatedly generates electricity between the electrodes 14 and 16 of the wearable sensor 1.

[0049] The temperature sensor 2 measures the temperature T of the atmosphere filling the recess 12 of the wearable sensor 1. The humidity sensor 3 measures the relative humidity RH inside the recess 12. Specifically, the temperature sensor 2 and the humidity sensor 3 are installed near the electrode 16 or near the water-absorbing structure 15 in FIGS. 11 and 12.

[0050] 11 and 12 are used as examples of the structure of wearable sensor 1, but the structure is not limited to these. Wearable sensors with other structures may be used as long as they allow current to flow intermittently between the electrodes due to droplets that are intermittently formed inside the wearable sensor as the wearer sweats.

[0051] 3 is a functional block diagram of the MCU unit 7 of this embodiment. The MCU unit 7 functions as a sweat rate calculation unit 70, an electrolyte concentration calculation unit 71, and a correction unit 72.

[0052] The sweat rate calculation unit 70 calculates a measured value Q of the amount of sweat of the wearer based on the current flow characteristics between the electrodes of the wearable sensor 1. The electrolyte concentration calculation unit 71 calculates a measured value C of the electrolyte concentration in the sweat of the wearer based on the current flow characteristics between the electrodes of the wearable sensor 1.

[0053] The correction unit 72 calculates the true value Q' of the sweat rate and the true value C' of the electrolyte concentration, corrected for the effect of sweat loss due to evaporation, based on known physical quantities related to sweat evaporation, the measured value Q of the sweat rate, the measured value C of the electrolyte concentration, the measured value T of the temperature, and the measured value RH of the relative humidity.

[0054] 4 is a flowchart illustrating the operation of the perspiration analyzer of this embodiment. The AFE unit 4 detects the current flowing between electrodes 14 and 16 of the wearable sensor 1 (step S1 in FIG. 4). The AFE unit 4 also receives a signal indicating temperature T from the temperature sensor 2 (step S2 in FIG. 4) and a signal indicating relative humidity RH from the humidity sensor 3 (step S3 in FIG. 4).

[0055] The data recording unit 5 converts the signal amplified by the AFE unit 4 into digital data at a predetermined sampling rate (step S4 in FIG. 4) and stores the digital data in the memory unit 6 (step S5 in FIG. 4). At this time, the data recording unit 5 adds information about the sampling time to the digital data and stores the digital data in the memory unit 6. In this way, the memory unit 6 stores time-series data for the current, temperature T, and relative humidity RH.

[0056] The perspiration rate calculation unit 70 calculates the measured perspiration rate Q [L / s] of the wearer of the wearable sensor 1 based on the digital data stored in the storage unit 6 (step S6 in FIG. 4). Specifically, the perspiration rate calculation unit 70 calculates the volume V [L] of the perspiration droplet 102a by multiplying the period T c By dividing by [s], the measured sweat rate Q [L / s] can be calculated.

[0057] As described in Patent Document 1, the volume V of sweat droplet 102a generated between electrodes 14 and 16 of wearable sensor 1 can be calculated in advance as an actual value.

[0058] The electrolyte concentration calculation unit 71 calculates the electrical resistivity Rρ of sweat, which changes depending on the electrolyte concentration C [mol / L] in the sweat of the wearer, and calculates the measured value C [mol / L] of the electrolyte concentration in the sweat from this electrical resistivity Rρ (Step S7 in Figure 4).

[0059] Specifically, electrolyte concentration calculation unit 71 calculates the resistance by dividing the value of the known voltage applied between electrodes 14 and 16 by AFE unit 4 by the current peak value at the most recent time of current application, which is indicated by the digital data stored in memory unit 6. Then, electrolyte concentration calculation unit 71 calculates the electrical resistivity Rρ based on the resistance value, the known distance between electrodes 14 and 16, and the cross-sectional area of ​​sweat between electrodes 14 and 16. For the cross-sectional area of ​​sweat, a specified value that is used when the cross-sectional area of ​​sweat between electrodes 14 and 16 is considered to be constant may be used.

[0060] It is known that there is a linear relationship between the electrical resistivity Rρ of sweat and the electrolyte concentration C (mainly the concentration of NaCl) in sweat. Electrolyte concentration calculation unit 71 calculates the measured value C [mol / L] of the electrolyte concentration from the electrical resistivity Rρ based on the known relationship between the electrical resistivity Rρ and the electrolyte concentration C.

[0061] Next, the correction unit 72 corrects the measured value Q of the amount of sweat calculated by the amount of sweat calculation unit 70 and the measured value C of the electrolyte concentration calculated by the electrolyte concentration calculation unit 71 (step S8 in FIG. 4). FIG. 5 is a flowchart illustrating the operation of the correction unit 72.

[0062] The correction unit 72 calculates the value of the measured sweat rate Q, the measured temperature T, the measured relative humidity RH, the density of water ρ, half the size r of the opening of the through-hole 11 (or the diameter if the cross section of the opening is circular), and the known static contact angle θ of the droplet 102a. c Based on the above, the true value Q' of the amount of sweating corrected for the effect of sweat loss due to evaporation is calculated using equations (1) to (4) (step S100 in FIG. 5). c For example, a value determined by a prior experiment may be set as the value.

[0063] Furthermore, the correction unit 72 calculates the true value C' of the electrolyte concentration corrected for the effect of sweat loss due to evaporation, using equation (5) based on the true value Q' of the sweat rate, the measured value Q of the sweat rate, and the measured value C of the electrolyte concentration (step S101 in Figure 5).

[0064] The communication unit 8 transmits the calculation result of the sweat rate calculation unit 70, the calculation result of the electrolyte concentration calculation unit 71, and the correction result of the correction unit 72 to an external device (not shown) such as a smartphone (step S9 in FIG. 4).

[0065] The perspiration analyzer repeatedly executes the processes of steps S1 to S9 until, for example, an instruction to end the measurement is received from the wearer (YES in step S10 in FIG. 4).

[0066] As described above, according to this embodiment, by providing the temperature sensor 2, humidity sensor 3, and correction unit 72, it is possible to calculate the true value of the sweat rate and the true value of the electrolyte concentration, thereby reducing the possibility of underestimating the sweat rate or overestimating the electrolyte concentration.

[0067] [Second Example] In the first embodiment, the sweat rate and electrolyte concentration are corrected based on a first correction method. In the second embodiment of the present invention, the sweat rate and electrolyte concentration are corrected based on a second correction method. The difference between this embodiment and the first embodiment is the operation of the correction unit 72. The operation of the correction unit 72 in this embodiment will be described with reference to FIG. 6.

[0068] The correction unit 72 calculates the measured value Q of the amount of sweating, the measured value T of the temperature, the measured value RH of the relative humidity, the density ρ of water, the value r of half the size of the opening of the through-hole 11, and the current peak period T used by the sweating amount calculation unit 70 to calculate the measured value Q of the amount of sweating. c Based on this, the time derivative of the dynamic contact angle θ of the sweat droplet 102a and the period T c The true value Q' of the amount of sweating is calculated by solving equation (7) for Q', which is the integral of the amount of sweat loss due to evaporation during this period (step S200 in FIG. 6). As in the first embodiment, the difference ΔC in the density of water vapor can be calculated using equations (2) and (3), and the diffusion coefficient D of water vapor can be calculated using equation (4).

[0069] Furthermore, the correction unit 72 calculates the true value C' of the electrolyte concentration using equation (5) based on the true value Q' of the sweat rate, the measured value Q of the sweat rate, and the measured value C of the electrolyte concentration (step S201 in FIG. 6). Other configurations of the perspiration analyzer are the same as those in the first embodiment.

[0070] [Third Example] In a third embodiment of the present invention, the sweat rate and electrolyte concentration are corrected based on a third correction method. The difference between this embodiment and the first embodiment is the operation of the correction unit 72. The operation of the correction unit 72 in this embodiment will be described with reference to FIG. 7.

[0071] The correction unit 72 sets a small non-zero value as the initial value θ(0) of the dynamic contact angle of the sweat droplet 102a at time t = 0 (step S300 in FIG. 7). The correction unit 72 also sets a value within a range equal to or greater than the measured value Q of the sweat rate and equal to or less than a predetermined value Q of the sweat rate as an estimate of the true value Q' of the sweat rate (step S301 in FIG. 7).

[0072] The correction unit 72 calculates the current peak period T used by the sweat rate calculation unit 70 to calculate the measured value Q of the sweat rate based on the initial value θ(0) of the dynamic contact angle, the estimated value Q' of the true value of the sweat rate, the measured value T of the temperature, the measured value RH of the relative humidity, the water density ρ, and the value r of half the size of the opening of the through-hole 11. c The dynamic contact angle θ of the droplet 102a during this period is calculated at every calculation interval Δt using equation (8) (step S302 in FIG. 7). As in the first embodiment, the difference ΔC in the density of water vapor can be calculated using equations (2) and (3), and the diffusion coefficient D of water vapor can be calculated using equation (4).

[0073] Next, the correction unit 72 calculates the measured sweat rate Q, the estimated true value Q′ of the sweat rate, and the current peak period T c Based on the calculation result of step S302, the current peak period T c The total amount of estimated true value Q' during the period (=Q'T c ) and the total amount of sweat measured Q (= QT c ) and the period Tc The value obtained by subtracting the amount of sweat loss due to evaporation during this period is calculated as an evaluation function f(Q') for evaluating the accuracy of the estimated true value Q' of the amount of sweat (step S303 in FIG. 7).

[0074] If the calculation process of steps S302 and S303 has not been completed for all estimated values ​​of the true value Q' of the sweat rate (NO in step S304 in FIG. 7), the correction unit 72 returns to step S301 and changes the estimated value of the true value Q' of the sweat rate. As described above, the correction unit 72 changes the estimated value by a predetermined step width of the sweat rate. In this way, the correction unit 72 calculates the evaluation function f(Q') for each of the multiple estimated values ​​of the true value Q' of the sweat rate.

[0075] The correction unit 72 determines whether the estimated value calculated from the measured perspiration rate Q reaches a predetermined perspiration rate value (for example, an upper limit value Q) when the calculation process of steps S302 and S303 for the predetermined number of estimated values ​​is completed or when the estimated value calculated from the measured perspiration rate Q reaches a predetermined perspiration rate value (for example, an upper limit value Q) when the calculated perspiration rate ... max ), it is determined that the calculation process of steps S302 and S303 has ended.

[0076] The correction unit 72 determines the best evaluation function f(Q') among the evaluation functions f(Q') calculated for each estimate of the true value Q' of the sweat rate as the true value Q' of the sweat rate (step S305 in FIG. 7). 2 The estimated value that minimizes this is taken as the true value Q' of the sweat rate.

[0077] Furthermore, the correction unit 72 calculates the true value C' of the electrolyte concentration using equation (5) based on the true value Q' of the sweat rate, the measured value Q of the sweat rate, and the measured value C of the electrolyte concentration (step S306 in FIG. 7). Other configurations of the perspiration analyzer are the same as those in the first embodiment.

[0078] [Fourth Example] 8 is a block diagram showing the configuration of a perspiration analyzer according to a fourth embodiment of the present invention. The perspiration analyzer includes a wearable sensor 1a, a temperature sensor 2, a humidity sensor 3, an AFE unit 4, a data recording unit 5, a memory unit 6, an MCU unit 7a, a communication unit 8, and a power supply unit 9.

[0079] The wearable sensor 1a in this embodiment is the same as that disclosed in Patent Document 2, so the structure of the wearable sensor 1a will be described with reference to FIGS. The wearable sensor 1a comprises a substrate 10 having a through hole 11 and a recess 12, a water-absorbing structure 15, an LD 18 arranged within the recess 12 and emitting light along a path within the recess 12 that passes along the outlet side surface of the substrate 10 and above the opening of the outlet side of the through hole 11, and a PD 19 arranged within the recess 12 facing the LD 18 across the opening of the outlet side of the through hole 11 and receiving light from the LD 18.

[0080] Examples of the water-absorbing structure 15 include fibers such as cotton and silk, and porous ceramic substrates. Note that the water-absorbing structure 15 does not need to cover the entire surface of the outlet opening of the through-hole 11 and the recess 12, as long as it is positioned so as to be able to come into contact with droplets that flow out from the outlet opening of the through-hole 11 into the recess 12.

[0081] Wearable sensor 1a is attached to the body of a wearer so that the lower surface of base material 10 faces skin 100 of the wearer, as shown in FIG. When the wearer sweats, the sweat 102 is introduced by capillary action from the recesses 13 of the base material 10 into the through-holes 11. Furthermore, as the amount of sweat increases, the sweat 102 rises inside the through-holes 11 and reaches the recesses 12 provided on the top surface of the base material 10 so as to communicate with the through-holes 11.

[0082] As shown in the enlarged view of FIG. 14, a water-repellent portion 17 is provided on the inner surface of the recess 12. When sweat 102 reaches the recess 12, which is the internal space of the wearable sensor 1a, it turns into spherical droplets 102a as shown in FIG. 14. As the amount of sweat increases, the diameter of the droplets 102a increases and finally reaches the water-absorbent structure 15. The droplets 102a that have reached the water-absorbent structure 15 pass through the many pores of the water-absorbent structure 15 due to capillary action and evaporate while moving within the water-absorbent structure 15. As a result, the droplets 102a disappear.

[0083] When measuring the amount of sweat, the light-emitting element LD18 emits light along a path within the recess 12 that passes through a position above the outlet opening of the through-hole 11 along the outlet surface (top surface) of the substrate 10, as shown in Figures 13 and 14. The PD 19, which is a light receiving element, receives the light from the LD 18.

[0084] When a droplet 102a of sweat 102 is formed, light 103 emitted from LD 18 propagates through the air in recess 12, droplet 102a, and air in recess 12 in this order, and then enters PD 19. When droplet 102a disappears, light 103 propagates through the air in recess 12 and then enters PD 19. When droplet 102a is formed again, light 103 propagates through the air in recess 12, droplet 102a, and air in recess 12 in this order, and then enters PD 19. In this way, the difference in the medium through which light 103 propagates is reflected in the amount of light received by PD 19. In other words, the formation and disappearance of droplet 102a changes the photocurrent flowing through PD 19.

[0085] The temperature sensor 2 measures the temperature T of the atmosphere filling the recess 12 of the wearable sensor 1a. The humidity sensor 3 measures the relative humidity RH within the recess 12. The configurations of the AFE unit 4, data recording unit 5, memory unit 6, communication unit 8, and power supply unit 9 of the perspiration analyzer are the same as those in the first embodiment. The AFE unit 4 only needs to amplify the output signal (photocurrent) of the PD 19, a signal indicating the temperature T, and a signal indicating the relative humidity RH.

[0086] 9 is a functional block diagram of the MCU unit 7a of this embodiment. The MCU unit 7a functions as a sweat rate calculation unit 70a, an electrolyte concentration calculation unit 71a, and a correction unit 72a.

[0087] The perspiration rate calculation unit 70a calculates a measured value Q of the amount of perspiration of the wearer based on the light receiving characteristics of the PD 19. The electrolyte concentration calculation unit 71a calculates a measured value C of the electrolyte concentration in the sweat of the wearer based on the light receiving characteristics of the PD 19.

[0088] The correction unit 72a calculates the true value Q' of the amount of sweat and the true value C' of the electrolyte concentration, corrected for the effect of sweat loss due to evaporation, based on known physical quantities related to sweat evaporation, the measured value Q of the amount of sweat, the measured value C of the electrolyte concentration, the measured value T of the temperature, and the measured value RH of the relative humidity.

[0089] The processing flow of the perspiration analyzer of this embodiment is the same as that of the first embodiment, so the operation of the perspiration analyzer will be explained using FIG. The AFE unit 4 detects the photocurrent of the PD 19 of the wearable sensor 1a (Step S1 in FIG. 4). The AFE unit 4 also receives a signal indicating the temperature T from the temperature sensor 2 (Step S2 in FIG. 4) and a signal indicating the relative humidity RH from the humidity sensor 3 (Step S3 in FIG. 4).

[0090] The data recording unit 5 converts the signal amplified by the AFE unit 4 into digital data at a predetermined sampling rate (step S4 in FIG. 4), and stores the digital data in the storage unit 6 (step S5 in FIG. 4).

[0091] The perspiration rate calculation unit 70a calculates the measured perspiration rate Q of the wearer of the wearable sensor 1a based on the digital data stored in the storage unit 6 (step S6 in FIG. 4). Specifically, the perspiration rate calculation unit 70a calculates the volume V of the sweat droplet 102a by multiplying the period T from the immediately preceding current peak to the most recent current peak by c The measured sweat rate, Q, is calculated by dividing by

[0092] In this embodiment, when a droplet 102a of sweat is formed in the recess 12, the photocurrent of the PD 19 decreases, and when the droplet 102a disappears, the photocurrent of the PD 19 increases. Therefore, the sweat amount calculation unit 70a calculates the period T c The measured sweat rate Q is calculated using the above formula.

[0093] The electrolyte concentration calculation unit 71a calculates a measured value C of the electrolyte concentration in the sweat of the wearer based on the amount of light received by the PD 19 (step S7 in FIG. 4). In this embodiment, the laser wavelength of the LD 18 is set to the absorption wavelength of a specific component in the sweat. This allows the electrolyte concentration calculation unit 71a to calculate the measured value C of the electrolyte concentration based on the amount of light received by the PD 19 when the amount of light reaches a minimum value.

[0094] The correction unit 72a corrects the measured value Q of the sweat rate calculated by the sweat rate calculation unit 70a and the measured value C of the electrolyte concentration calculated by the electrolyte concentration calculation unit 71a (step S8 in FIG. 4). In this embodiment, the correction is performed using a first correction method. The operation of the correction unit 72a is the same as that of the correction unit 72 in the first embodiment.

[0095] The communication unit 8 transmits the calculation results of the sweat rate calculation unit 70a, the calculation results of the electrolyte concentration calculation unit 71a, and the correction results of the correction unit 72a to an external device such as a smartphone (Step S9 in FIG. 4).

[0096] The perspiration analyzer repeatedly executes the processes of steps S1 to S9 until, for example, an instruction to end the measurement is received from the wearer (YES in step S10 in FIG. 4). Thus, in this embodiment, as in the first embodiment, it is possible to reduce the possibility of underestimating the amount of sweat or overestimating the electrolyte concentration.

[0097] In this embodiment, the sweat rate and electrolyte concentration are corrected based on the first correction method, but correction may also be performed based on the second correction method. In this case, the operation of the correction unit 72a is the same as that of the correction unit 72 of the second embodiment. The difference from the correction unit 72 is that the correction unit 72a uses the period T of the downward peaks of the photocurrent of the PD 19 instead of the period of the peaks of the current flowing between the electrodes 14 and 16. c The true value of sweat rate Q' is calculated using

[0098] The sweat rate and electrolyte concentration may also be corrected based on a third correction method. In this case, the operation of the correction unit 72a is the same as that of the correction unit 72 of the third embodiment. The difference from the correction unit 72 is that the correction unit 72a uses the period T of the downward peaks of the photocurrent of the PD 19 instead of the period of the peaks of the current flowing between the electrodes 14 and 16. c The objective is to calculate the evaluation function f(Q') using

[0099] The data recording unit 5, storage unit 6, MCU units 7, 7a, and communication unit 8 described in the first to fourth embodiments can be realized by a computer equipped with a CPU (Central Processing Unit), a storage unit, and an interface, and a program that controls these hardware resources. An example of the configuration of this computer is shown in Figure 10.

[0100] The computer includes a CPU 200, a storage device 201, and an interface device (I / F) 202. The I / F 202 is connected to hardware such as the ADC of the data recording unit 5 and hardware such as the communication unit 8. In such a computer, a program for implementing the perspiration analysis method of the present invention is stored in the storage device 201. The CPU 200 executes the processes described in the first to fourth embodiments in accordance with the program stored in the storage device 201.

[0101] Some or all of the above embodiments can be described as, but are not limited to, the following supplementary notes.

[0102] (Appendix 1) The sweat analysis device of the present invention is characterized by comprising: a wearable sensor configured to output an electrical signal derived from the sweat rate and electrolyte concentration of sweat secreted from the skin of a wearer; a temperature sensor configured to measure the temperature of the internal space of the wearable sensor into which the sweat of the wearer flows; a humidity sensor configured to measure the relative humidity of the internal space of the wearable sensor into which the sweat of the wearer flows; a sweat rate calculation unit configured to calculate a measured value of the sweat rate of the wearer based on the electrical signal obtained by the wearable sensor; an electrolyte concentration calculation unit configured to calculate a measured value of the electrolyte concentration in the sweat of the wearer based on the electrical signal obtained by the wearable sensor; and a correction unit configured to calculate a true value of the sweat rate and a true value of the electrolyte concentration, corrected for the effect of sweat loss due to evaporation, based on a known physical quantity related to sweat evaporation, the measured sweat rate, the measured electrolyte concentration, the temperature, and the relative humidity.

[0103] (Supplementary Note 2) In the perspiration analysis device described in Supplementary Note 1, the correction unit calculates the amount of sweat loss due to evaporation based on known physical quantities related to sweat evaporation, the temperature, and the relative humidity, calculates the true value of the sweat rate by adding the amount of sweat loss to the measured sweat rate, and calculates the true value of the electrolyte concentration based on the true value of the sweat rate, the measured sweat rate, and the measured electrolyte concentration.

[0104] (Appendix 3) In the sweat analysis device described in Appendix 1, the electrical signal is a current that changes due to droplets that are intermittently generated in the internal space of the wearable sensor due to sweating by the wearer, and the sweat rate calculation unit calculates a measured value of the sweat rate of the wearer based on the period of the peaks of the current, and the correction unit calculates a true value of the sweat rate by solving an equation for the time derivative of the dynamic contact angle of the droplet and an equation for the integral of the amount of sweat loss due to evaporation during the period between the peaks of the current based on a known physical quantity related to sweat evaporation, the measured value of the sweat rate, the temperature, the relative humidity, and the period of the peaks of the current, and calculates a true value of the electrolyte concentration based on the true value of the sweat rate, the measured value of the sweat rate, and the measured value of the electrolyte concentration.

[0105] (Appendix 4) In the sweat analysis device described in Appendix 1, the electrical signal is a current that changes due to droplets that are intermittently generated in the internal space of the wearable sensor due to sweating by the wearer, the sweat rate calculation unit calculates the measured value of the sweat rate of the wearer based on the period of the peaks of the current, the correction unit sets multiple estimates of the true value of the sweat rate within a predetermined range, and calculates, for each estimate, a dynamic contact angle of the droplets during the period between the peaks of the current based on a known physical quantity related to sweat evaporation, the estimated value, the temperature, and the relative humidity, calculates an evaluation function for each estimate based on the known physical quantity related to sweat evaporation, the measured sweat rate, the estimated value, the period of the peaks of the current, and the calculation result of the dynamic contact angle, and determines the estimated value that yields the best evaluation function as the true value of the sweat rate, and calculates the true value of the electrolyte concentration based on the true value of the sweat rate, the measured sweat rate, and the measured electrolyte concentration.

[0106] (Appendix 5) In the sweat analysis device described in Appendix 1, the electrical signal is a current that changes due to droplets that intermittently form in the internal space of the wearable sensor due to sweating by the wearer, the sweat amount calculation unit calculates a measured value of the sweat amount of the wearer based on the period of the peaks of the current, and the electrolyte concentration calculation unit calculates a measured value of the electrolyte concentration in the sweat of the wearer based on the peak value of the current.

[0107] (Appendix 6) In the perspiration analysis device described in Appendix 5, the wearable sensor comprises a substrate having a through hole that serves as a path for sweat of the wearer and an internal space that communicates with the outlet end of the through hole, a first electrode arranged on the surface of the substrate where the inlet end of the through hole opens, a water-absorbing structure arranged on the outlet side surface of the substrate so as to come into contact with sweat that flows out from the outlet opening of the through hole into the internal space, and a water-absorbing second electrode arranged on the surface of the water-absorbing structure facing the substrate so as to face the outlet opening of the through hole, and the electrical signal is a current that flows between the first electrode and the second electrode due to droplets that are intermittently formed in the internal space due to sweating of the wearer.

[0108] (Appendix 7) In the perspiration analysis device described in Appendix 5, the wearable sensor comprises a substrate having a through-hole that serves as a path for sweat of the wearer and the internal space that communicates with the outlet end of the through-hole, a water-absorbing structure arranged on the outlet surface of the substrate so as to come into contact with sweat that has flowed out from the outlet opening of the through-hole into the internal space, a light-emitting element configured to emit light toward the sweat that has flowed out from the outlet opening of the through-hole into the internal space, and a light-receiving element configured to receive light that has passed through the sweat or light reflected by the sweat, and the electrical signal is a current that flows through the light-receiving element due to droplets that are intermittently formed in the internal space due to sweating of the wearer.

[0109] (Appendix 8) The sweat analysis method of the present invention is characterized by including a first step of detecting electrical signals derived from the sweat rate and electrolyte concentration of sweat secreted from the wearer's skin using a wearable sensor; a second step of measuring the temperature of the internal space of the wearable sensor into which the wearer's sweat flows; a third step of measuring the relative humidity of the internal space of the wearable sensor into which the wearer's sweat flows; a fourth step of calculating a measured value of the wearer's sweat rate based on the electrical signal obtained by the wearable sensor; a fifth step of calculating a measured value of the electrolyte concentration in the wearer's sweat based on the electrical signal obtained by the wearable sensor; and a sixth step of calculating a true value of the sweat rate and a true value of the electrolyte concentration, corrected for the effect of sweat loss due to evaporation, based on a known physical quantity related to sweat evaporation, the measured value of the sweat rate, the measured value of the electrolyte concentration, the temperature, and the relative humidity. [Industrial Applicability]

[0110] The present invention can be applied to a technique for analyzing the amount of sweat and the electrolyte concentration in sweat of a person. [Explanation of symbols]

[0111] 1,1a...wearable sensor, 2...temperature sensor, 3...humidity sensor, 4...AFE unit, 5...data recording unit, 6...memory unit, 7,7a...MCU unit, 8...communication unit, 9...power supply unit, 10...substrate, 11...through hole, 12,13...recess, 14,16...electrode, 15...water-absorbing structure, 17...water-repellent unit, 18...laser diode, 19...photodiode, 70,70a...sweating rate calculation unit, 71,71a...electrolyte concentration calculation unit, 72,72a...correction unit.

Claims

1. a wearable sensor configured to output an electrical signal derived from the amount of sweat secreted from the skin of a wearer and the electrolyte concentration; a temperature sensor configured to measure the temperature of an internal space of the wearable sensor into which sweat of the wearer flows; a humidity sensor configured to measure the relative humidity of an internal space of the wearable sensor into which sweat of the wearer flows; a sweat rate calculation unit configured to calculate a sweat rate measurement value of the wearer based on the electrical signal obtained by the wearable sensor; an electrolyte concentration calculation unit configured to calculate a measured electrolyte concentration in the sweat of the wearer based on the electrical signal obtained by the wearable sensor; a correction unit configured to calculate true values ​​of sweat rate and electrolyte concentration corrected for the effect of sweat loss due to evaporation, based on known physical quantities related to sweat evaporation, the sweat rate measurement value, the electrolyte concentration measurement value, the temperature, and the relative humidity.

2. The sweat analyzer according to claim 1, the correction unit calculates the amount of sweat loss due to evaporation based on a known physical quantity related to sweat evaporation, the temperature, and the relative humidity, calculates the true value of the sweat rate by adding the amount of sweat loss to the measured sweat rate, and calculates the true value of the electrolyte concentration based on the true value of the sweat rate, the measured sweat rate, and the measured electrolyte concentration.

3. The sweat analyzer according to claim 1, the electrical signal is a current that changes due to droplets that are intermittently generated in an internal space of the wearable sensor due to sweating by the wearer; the sweat rate calculation unit calculates a sweat rate measurement value of the wearer based on the period of the peaks of the current; The correction unit calculates the true value of the sweat rate by solving an equation for the time derivative of the dynamic contact angle of the droplet and an equation for the integral of the amount of sweat loss due to evaporation during the period between the current peaks, based on known physical quantities related to sweat evaporation, the sweat rate measurement value, the temperature, the relative humidity, and the period of the current peaks, and calculates the true value of the electrolyte concentration based on the true value of the sweat rate, the sweat rate measurement value, and the electrolyte concentration measurement value.

4. The sweat analyzer according to claim 1, the electrical signal is a current that changes due to droplets that are intermittently generated in an internal space of the wearable sensor due to sweating by the wearer; the sweat rate calculation unit calculates a sweat rate measurement value of the wearer based on the period of the peaks of the current; the correction unit sets a plurality of estimates of the true value of the sweat rate within a predetermined range, calculates the dynamic contact angle of the droplet during the period between the peaks of the current for each estimate based on a known physical quantity related to sweat evaporation, the estimate, the temperature, and the relative humidity, calculates an evaluation function for each estimate to evaluate the accuracy of the estimate based on the known physical quantity related to sweat evaporation, the measured sweat rate, the estimate, the period of the current peaks, and the calculation result of the dynamic contact angle, determines the estimated value that yields the best evaluation function as the true value of the sweat rate, and calculates the true value of the electrolyte concentration based on the true value of the sweat rate, the measured sweat rate, and the measured electrolyte concentration.

5. The sweat analyzer according to claim 1, the electrical signal is a current that changes due to droplets that are intermittently generated in an internal space of the wearable sensor due to sweating by the wearer; the sweat rate calculation unit calculates a sweat rate measurement value of the wearer based on the period of the peaks of the current; The sweat analysis device is characterized in that the electrolyte concentration calculation unit calculates a measured value of the electrolyte concentration in the sweat of the wearer based on the peak value of the current.

6. 6. The perspiration analyzer according to claim 5, The wearable sensor includes: a base material having a through hole serving as a flow path for sweat of the wearer and the internal space communicating with an end portion on the outlet side of the through hole; a first electrode disposed on the surface of the substrate where the inlet end of the through hole is open; a water-absorbing structure disposed on the outlet side surface of the base material so as to come into contact with sweat that has flowed into the internal space through the outlet side opening of the through-hole; a water-absorbent second electrode disposed on a surface of the water-absorbing structure facing the substrate so as to face an outlet-side opening of the through-hole; The perspiration analysis device, characterized in that the electrical signal is a current flowing between the first electrode and the second electrode due to droplets that are intermittently formed in the internal space as the wearer sweats.

7. 6. The perspiration analyzer according to claim 5, The wearable sensor includes: a base material having a through hole serving as a flow path for sweat of the wearer and the internal space communicating with an end portion on the outlet side of the through hole; a water-absorbing structure disposed on the outlet side surface of the base material so as to come into contact with sweat that has flowed into the internal space through the outlet side opening of the through-hole; a light-emitting element configured to emit light toward the sweat that has flowed out into the internal space from an opening on the outlet side of the through hole; a light receiving element configured to receive light transmitted through sweat or light reflected by sweat, The perspiration analysis device is characterized in that the electrical signal is a current flowing through the light-receiving element due to droplets that are intermittently formed in the internal space as the wearer sweats.

8. A first step of detecting an electrical signal derived from the amount of sweat secreted from the skin of a wearer and the electrolyte concentration using a wearable sensor; a second step of measuring the temperature of an internal space of the wearable sensor into which sweat of the wearer flows; a third step of measuring the relative humidity of an internal space of the wearable sensor into which sweat of the wearer flows; a fourth step of calculating a sweat rate measurement of the wearer based on the electrical signal obtained by the wearable sensor; a fifth step of calculating a measured electrolyte concentration in the sweat of the wearer based on the electrical signal obtained by the wearable sensor; and a sixth step of calculating true values ​​of the sweat rate and the electrolyte concentration, corrected for the effect of sweat loss due to evaporation, based on known physical quantities related to sweat evaporation, the measured sweat rate, the measured electrolyte concentration, the temperature, and the relative humidity.

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