JP5708911B2 - Body sweat monitor device - Google Patents

Description

  The present invention relates to an apparatus for measuring and recording the sweating phenomenon from the skin over time.

  A sweat meter is a useful device for studying the living environment and clothing environment, studying mental phenomena such as stress, monitoring physical and mental conditions during sports and various diseases, and vital signs monitors for neonates and intensive care unit patients.

  In conventional sweat measurement, a steady air flow is applied to the skin, humidity sensors are arranged on the upstream side and downstream side of the flow, and the measurement is performed based on the humidity difference between the two sensors (the following “Patent Document”). 1, 2 ”). In principle, measurement is possible with this method, but there are three problems in practice.

  One is that it is difficult to create a steady air flow, the measurement accuracy depends on the continuity, and because mechanical parts such as a pump are necessary, it is difficult to make the device compact and portable. The second problem is that when a large amount of water evaporates like sweat during exercise, the humidity sensor is saturated, resulting in a decrease in measurement accuracy or inability to measure. The third is a mechanism that artificially creates an air flow and forcibly removes water vapor, so it is far from natural water transpiration.

  On the other hand, for a large amount of moisture transpiration, there is a possible countermeasure to heat the humid air with a heater and evaporate it to some extent as in Patent Document 3 below. The problem of rising will also arise.

  In order to solve the above-mentioned problem, a moisture transpiration measuring device already equipped with a desiccant has been devised (Japanese Patent Application No. 2010-73544). However, this apparatus requires a large amount of desiccant, and in the case of a portable type that continuously measures without restricting daily activities, the measurement time depends on the amount of desiccant. Also, it takes time to change the desiccant every time.

  JP 2001-190502 A

  Japanese Patent No. 3711521

  Japanese Patent No. 2600113

Five problems that conventional sweat meter and moisture transpiration meter could not solve,
(1) Long-term unconstrained measurement by eliminating the mechanical parts such as pumps and making them compact, lightweight, and power-saving.
(2) The ability to measure without loss of accuracy even for large amounts of moisture transpiration,
(3) Measure as natural transpiration as possible without using artificial airflow.
(4) Do not use consumables such as desiccants. (5) Detect the exact timing and magnitude (quantitative level) of sweating (physiologically known to produce sweat in a pulsed manner). Solve what you can do.

  The problems (1) to (3) listed in “Problems to be solved by the invention” have already been solved in Japanese Patent Application No. 2010-73544. In other words, a temperature / humidity sensor and a desiccant (silica gel, etc.) are built in a container with a hole in the skin contact surface.

  However, in this method, the usable time is limited by the amount of the desiccant to be filled. Therefore, instead of loading the desiccant, we devised a method of making a suitable hole in the container to release water vapor. In this case, it is calculated | required from the relationship of a container volume, skin side hole area, and case upper surface hole area instead of arbitrary holes.

  In addition, we devised a method for detecting the timing of pulse sweating by analyzing the baseline of humidity data and subtracting it.

  Since there is no mechanical mechanism and it can be constructed around the electronic circuit of the humidity sensor, it is possible to reduce the size and expand the range of use, such as collecting sweat data in everyday life while attached to the body. In addition, it can be manufactured at a lower cost than conventional devices and has a low failure rate because there are no moving parts.

  It does not require replacement of consumables (desiccant) as in the invention of Japanese Patent Application No. 2010-73544, and there is no restriction on continuous measurement time, so it can be used in situations where continuous monitoring is required for a long time such as an intensive care unit. .

FIG. 1 is for explaining the principle of the measuring apparatus. FIG. 2 shows the configuration of a device that can actually be manufactured. FIG. 3 shows a sweating phenomenon obtained by mounting the apparatus of FIG. 2 in a newborn underwear and an analysis method.

  In the measurement of skin perspiration, the conventional measurement method using a constant air flow is avoided and the temperature / humidity sensor (2) is mainly implemented as shown in FIG.

  Holes (4 and 5) having an area in consideration of the inflow / outflow balance of water vapor (sweat) are formed in the skin contact surface and the upper surface of the case (1). In addition, a shielding plate (3) is disposed in the case in order to retain water vapor for a certain period of time.

  After obtaining the humidity data using this device, the baseline fluctuation of the humidity change is obtained, and the sweating timing can be detected by subtracting this from the original data.

  In the schematic diagram 1, water vapor (sweat) flows from the hole (4) on the case skin side and is first detected by the sensor (2). After that, the flow of water is blocked by the shielding plate (3) and stays in the container for a certain period of time, but finally passes through the peripheral gap and is discharged from the outflow hole (5) of the upper lid.

At this time, the sweating amount w (t) [g / m ^ 3] is expressed by the following equation using the absolute humidity x (t) [g / m ^ 3] and the outside air humidity H [g / m ^ 3] detected by the sensor. (T is time).
w (t) = change in case + outflow to outside air (assuming natural diffusion)
= (V / A1) (Δx / Δt) + (D / L2) (A2 / A1) {x (t) −H} (1)
Here, each constant is as follows.
V: Case volume [m ^ 3]
A1: Hole area on the skin contact side [m ^ 2]
A2: Hole area on the upper surface [m ^ 2]
L1: Diffusion distance between virtual sweat source and sensor unit [m]
L2: Assumed diffusion distance between case and outside air [m]
D: Diffusion coefficient of water vapor in air [m ^ 2 / s]
However, the above formula (1) is established when the outside air humidity H is constant, and in actuality, measurement is assumed in an environment where the humidity is kept relatively constant, such as in clothes or bedding.

  As can be seen from the above equation (1), the ratio of the amount of change in the case to the amount of sweating depends on the magnitude of the coefficient V / A1, while the portion flowing out from the case to the outside air depends on the coefficient A2 / A1. . That is, both coefficients represent the sensitivity to each change.

  In order to increase the sensitivities V / A1 and A2 / A1, the area A1 may be reduced. However, in reality, the amount of inflowing steam is reduced and the accuracy is lowered. Also, if A2 is increased, the outflow is faster, so the sensitivity (response) of the sensor cannot catch up. When V is further increased, it takes time until the humidity in the case is uniformly stabilized, which also affects the accuracy.

  The design is made by adjusting these conditions and the area of the shielding plate, and calculating backward from the overall size of the device that is directly attached to the skin and does not hinder the behavior. Specifically, for a case with an inner diameter of 25 mm, stable measurement was possible at approximately V / A1 = 75, A2 / A1 = 1.5, and a shielding plate diameter of 21 mm (measurement example described later).

  The actual device (Fig. 2) is equipped with a microcomputer, memory, and battery, and calculates perspiration at the measurement execution scene. The calculation may be performed in a microcomputer and stored in a built-in memory. If an external computer is connected, the calculation may be performed and displayed in real time. As already described, the shielding plate that inhibits the flow of water vapor is also an important factor, but in FIG. 2, the electronic circuit board (7) plays the role.

  FIG. 3 [A-1] shows an example in which the actual skin data (newborn; wearing an underwear and a thin comforter) is recorded using the apparatus of FIG. This figure is a record of the absolute humidity change due to sweating detected by the sensor in the case. The pulse-like sweating phenomenon is buried in this large change. Therefore, the baseline that fluctuates due to the delay caused by the size of the case and the response characteristics of the humidity sensor is obtained by peak analysis. Although it is actually a “negative peak” or bottom line analysis, it is referred to as peak analysis according to common usage.

  The baseline fluctuation obtained by peak analysis is shown in FIG. 3 [A-2], and when this is subtracted from the original data, a pulsed sweating phenomenon can be captured (FIG. 3 [B]). As a result, the timing of sweating and the level of sweating can be compared.

  Peak analysis may be performed on the entire waveform after all data has been acquired (that is, after completion of measurement). When monitoring in real time at the measurement site, a certain amount of data (preferably 10 or more) is collected. It is also possible to carry out partly sequentially at the time.

  Physiological examination during long outdoor work, driving of cars and trains and operation of equipment, development of clothing and equipment during exercise with sweating, physiological research during bathing, etc. Use in the field of restraint measurement can be expected. Therefore, it is possible to provide basic data for all product developments such as health industry, cosmetics, exercise equipment, clothes, bedding, and living environment.

  In medical and dental treatment, it is useful as a patient monitor during surgery and intensive care. In particular, as in the example of the newborn shown in FIG. 3, it can be used as vital sign recording that does not hinder movement (that is, simple without wiring, piping, and large fasteners).

DESCRIPTION OF SYMBOLS 1 Case 2 Temperature / humidity sensor 3 Shielding board 4 Inflow hole 5 Outflow hole 6 Top cover 7 Electronic circuit board 8 Temperature / humidity sensor 9 Case (frame)
10 Bottom plate

Claims (1)

A moisture suction hole (area A1) in the center of the bottom surface (skin-bonding surface) of the thin circular capsule (case) to be in close contact with the skin surface, a water vapor outlet hole (area A2) opened along the upper periphery, and the center of the inner ceiling surface Using a sweating probe having a structure in which a temperature / humidity sensor is arranged and the relationship including the capsule volume V is approximately V / A1 = 75 and A2 / A1 = 1.5, Using the absolute humidity time change x (t) [g / m ^ 3] detected by the sensor and the change Δx / Δt [g / m ^ 3 / s] of x per unit time,
Formula w (t) = (V / A1) (Δx / Δt) + (D / L2) (A2 / A1) {x (t) −H}
(Here, the constants are as follows.
V: Case volume [m ^ 3]
A1: Hole area on the skin contact side [m ^ 2]
A2: Hole area on the upper surface [m ^ 2]
L1: Diffusion distance between virtual sweat source and sensor unit [m]
L2: Assumed diffusion distance between case and outside air [m]
D: Diffusion coefficient of water vapor in air [m ^ 2 / s]
H: outside air humidity [g / m ^ 3])
Monitoring device which measures perspiration amount change w (t) “g / m ^ 3].

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