JP2020047776A - Gas-permeable capacitor element, sensor element, and measurement method using them - Google Patents

Abstract

To provide a capacitor element and a sensor element that can be used to measure one or more of the presence or absence of permeation, permeation amount, temporal change of permeation amount of substances in gas, and a change in perspiration amount and can be made into a wearable device without the need for a blowing mechanism.SOLUTION: At least a capacitor element with a dielectric layer sandwiched between a pair of electrodes, which has the air permeability of 0.5 cm/(cmmin) or more when the pressure difference between one side and the other side is 125 Pa is used to measure the presence or absence of permeation and the permeation amount of substances (water vapor, other gases, mist, etc.) in gas, and a change in perspiration amount without using a blowing mechanism such as a blowing air pump.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a capacitor element and a sensor element that can be used for measuring the amount of perspiration and substances in gas, and a method for measuring the amount of perspiration and substances in gas using the same.

  In recent years, due to the prolonged life of the people and the advent of an aging society, people's awareness of health has increased, and not only medical examinations have been widely conducted at various medical facilities, but also individual There is also an interest in constantly monitoring health conditions while sending data, and with this, wearable devices that can easily monitor indices related to health conditions such as heart rate, blood pressure, body temperature, and respiratory rate ( Wearable devices) are also becoming popular. The use of such wearable devices for health care is expected to be applied not only to record management of indices related to health status and the like, but also to application development to remote diagnosis and treatment by using information communication technology and artificial intelligence technology. I have.

  Against the background of such a rise in health consciousness, sweating is a physiological phenomenon that occurs due to an increase in body temperature due to exercise and changes in temperature, tension, stimulation of sensory organs such as taste and smell, etc. It is considered to be an effective index for prevention of heat stroke, diagnosis of disease, evaluation of stress applied to the human body and various stimuli, and is attracting attention as a measurement target by a wearable device for health care.

In general, the measurement of perspiration is based on a method of detecting the presence or absence of perspiration as a change in the color of a substance due to moisture or a change in the electric resistance value of the skin surface with respect to sweat leaching from the sweat glands to the skin surface (Patent Documents 1 and 2). As a technique for quantitatively measuring the amount of water, the ventilation capsule method (Patent Document 3) is mainly used.
In the ventilation capsule method, a capsule with an air inlet / outlet is closely attached to the skin to measure perspiration, and a sufficient amount of air is flowed into this capsule by an air pump to forcibly vaporize the moisture of the sweat on the skin surface In this method, the amount of perspired moisture per unit surface area and per unit time is determined from the difference between the humidity of the air before and after passing through the capsule and the amount of the flowed air, and an apparatus using this method is commercially available.

  Although not directly related to the measurement of the amount of perspiration, a crack is provided on the surface side, which has a dielectric layer and two conductive layers on both surfaces thereof, and allows a water vapor to diffuse from the surrounding environment to the dielectric layer. A capacitive humidity sensor element provided on a conductive layer is also known (Patent Document 4).

JP 2010-46196 A JP-A-5-3875 JP-A-63-46131 JP-A-3-87642

The present inventor has studied the above-described related art, but has recognized that the following problems (1) to (4) exist.
(1) A method of detecting the presence or absence of perspiration as a change in the color of a substance due to moisture or a change in the electric resistance value of the skin surface can only detect the presence or absence of perspiration, and it is difficult to quantify the amount of perspiration for health care. .
(2) Since the ventilation capsule method does not cause measurement errors, a capsule having a sufficient space volume to eliminate sweat, which is referred to as ineffective sweat, remaining as water droplets on the skin surface, and moisture in sweat even when the amount of sweat is large. Requires an air pump capable of blowing a corresponding flow of air to actively vaporize the air. Also, at least two humidity sensor elements are required to measure the respective humidity of the air flowing into and out of the capsule. The inevitable limitations of this method, such as the measurement principle and the miniaturization and thinning of the detection unit and the entire device caused by the measurement method, are major issues in making a wearable device. It is desirable to develop a new method for measuring the amount of perspiration and a sensor element that can be made thinner, thinner and more flexible.
(3) Since the capacitive humidity sensor element in which a crack is provided in the conductive layer on the front side has a structure in which water vapor in the surrounding environment enters and exits the dielectric layer by diffusion through the crack in the conductive layer on the front side, Although the steady-state amount of water vapor in the surrounding environment can be quantified, it is difficult to quantify the amount of water vapor during perspiration and its change every moment.
(4) In addition to measuring the amount of perspiration, it is also desired to develop a sensor element and a measuring method that can easily measure the presence or absence of a substance present in various gases and the amount of permeation in a wide variety of gases.

The present invention is based on the background art and the recognition of the inventor of the present invention with respect to the conventional technology, and does not require a blowing mechanism such as an air pump for blowing, and includes a method for measuring the amount of perspiration in a gas including a change in the amount of perspiration. Provided are a capacitor element and a sensor element that can be used for measurement of one or more of presence / absence, permeation amount, and temporal change of permeation amount of a substance, and can be made into a wearable device. Make it an issue.
In addition, the present invention uses the capacitor element or the measurement sensor element to determine at least one of presence / absence of permeation of a substance in a gas including a change in perspiration, a permeation amount, and a temporal change in a permeation amount. It is another object of the present invention to provide a measuring method capable of performing measurement without requiring a blowing mechanism such as a blowing air pump.

The inventor of the present invention has conducted intensive studies on the above problem, and has studied a capacitor element in which a dielectric layer is sandwiched between at least a pair of electrodes, and has a gas permeability when a pressure difference between one surface side and the other surface side is 125 Pa ( Hereinafter, it may be simply referred to as “air permeability”.) By using a capacitor element having a large air permeability of not less than 0.5 cm ³ / (cm ² · minute), a blowing mechanism such as an air pump for blowing air is used. It is found that the presence or absence of permeation of substances (water vapor, other gases, mist, etc.) in the gas including the change in the amount of perspiration, the amount of permeation, and the temporal change in the amount of permeation can be measured as the change in the capacitance of the capacitor element. did.

The present invention is based on the above findings, and the present invention provides the following inventions.
<1> A capacitor element having a dielectric layer sandwiched between at least a pair of electrodes, and having a gas permeability of 0.5 cm ³ / (cm ² · min) or more when the pressure difference between one surface and the other surface is 125 Pa. Is a capacitor element.
<2> The capacitor element according to <1>, which has flexibility.
<3> The capacitor element according to <1> or <2>, wherein the thickness is 3.0 mm or less.
<4> The capacitor element according to any one of <1> to <3>, further including a liquid absorbing layer on one electrode surface, and moving or diffusing from the liquid absorbing layer to the other electrode surface side. Capacitor element with a liquid absorbing layer that measures substances to be absorbed.
<5> The capacitor element according to claim 4, wherein the liquid-absorbing layer is a liquid-absorbing divergent layer having a specific surface area on the evaporation surface side larger than the absorption surface side.
<6> The capacitor according to any one of <1> to <5>, wherein the presence / absence, permeation amount, and permeation amount of a predetermined substance in gas are determined by a change in the capacitance of the capacitor element. A sensor element that measures one or more of temporal changes.
<7> The sensor element according to <6>, further including a mounting tool for mounting the capacitor element on a surface to be measured.
<8> The sensor element according to <6> or <7>, wherein the measurement target is a human body, and the amount of perspiration and / or its temporal change is determined.
<9> The capacitor element according to any one of <1> to <5>, wherein gas is transmitted from one electrode side to the opposite electrode side, and the gas in the gas is changed due to a change in the capacitance of the capacitor element. A method for measuring a substance in a gas, comprising measuring one or more of presence or absence of a substance, a transmission amount, and a temporal change in the transmission amount.
<10> The sensor element according to any one of <6> to <8>, wherein gas is transmitted from one electrode side to the opposite electrode side, and the gas in the gas is changed by a change in electric capacity of the capacitor element. A method for measuring a substance in a gas, comprising measuring one or more of presence or absence of a substance, a transmission amount, and a temporal change in the transmission amount.

By using the capacitor element and the measurement sensor of the present invention, one or more of the presence or absence of the substance in the gas including the change in the amount of perspiration, the amount of permeation, and the temporal change of the amount of permeation are used for ventilation. The measurement can be performed without requiring the use of a blowing mechanism such as an air pump.
According to the measuring method of the present invention, one or more of the presence or absence of permeation of the substance in the gas including the change in the amount of perspiration, the amount of permeation, and the temporal change of the amount of permeation are determined by an air pump for air blowing or the like. Can be measured without requiring the use of an air blowing mechanism.

It is a figure showing typically a capacitor element or a sensor element with a liquid absorption layer (liquid absorption divergence layer) of one embodiment of the present invention. An AC voltage of 5 V was applied between both electrodes of the capacitor element (the average pore diameter of the dielectric layer was 0.22 μm, and the air permeability of the capacitor element was 1.8 cm ³ / (cm ² · minute)) prepared in Example 1. FIG. 4 is a diagram showing the frequency dependence of the impedance and capacitance of the capacitor element when the frequency is swept from 200 Hz to 2 MHz. An AC voltage of 5 V was applied between both electrodes of the capacitor element (the average pore diameter of the dielectric layer was 0.22 μm, and the air permeability of the capacitor element was 1.8 cm ³ / (cm ² · minute)) prepared in Example 1. FIG. 4 is a diagram showing, in comparison with the case of measurement under water vapor exposure and the case of measurement under normal atmosphere, the frequency dependence of the capacitance of the capacitor element when the frequency is swept from 200 Hz to 2 MHz. 5 V between both electrodes of the capacitor element with a paper piece (the average pore diameter of the dielectric layer was 0.22 μm, and the permeability of the capacitor element alone without the paper piece was 1.8 cm ³ / (cm ² · min)) produced in Example 3. FIG. 5 is a diagram showing a change over time of the capacitance of the capacitor element when a center of a paper piece is intermittently impregnated with 1 to 5 μL of water droplets in a state where an AC voltage of 300 Hz is applied. A voltage of 5 V was applied between both electrodes of the capacitor element with paper strip (average pore diameter of dielectric layer: 0.1 μm, air permeability of the capacitor element alone without paper strip: 1.6 cm ³ / (cm ² · min)) produced in Example 4. FIG. 6 is a diagram showing a change over time of the capacitance of the capacitor element when a center of a paper piece is intermittently impregnated with 1 to 5 μL of water droplets while an AC voltage of 300 Hz is applied. A voltage of 5 V was applied between both electrodes of the capacitor element with a paper strip (average pore diameter of the dielectric layer of 0.45 μm, air permeability of the capacitor element alone without a paper strip of 6.1 cm ³ / (cm ² · min)) produced in Example 5. FIG. 6 is a diagram showing a change over time of the capacitance of the capacitor element when a center of a paper piece is intermittently impregnated with 1 to 5 μL of water droplets while an AC voltage of 300 Hz is applied. Capacitor element with paper piece manufactured in Example 6 (average pore diameter of dielectric layer 0.65 μm, air permeability of capacitor element alone without paper piece is not measured, but exceeds 6.1 cm ³ / (cm ² · min) In the state where an AC voltage of 5 V and 300 Hz is applied between both electrodes, the time change of the electric capacity of the capacitor element when the center of a paper piece is intermittently impregnated with 1 to 5 μL of water droplets is shown. FIG. Between the two electrodes of the capacitor element with a woven fabric produced in Example 7 (the average pore diameter of the dielectric layer is 0.22 μm, and the permeability of the capacitor element alone without the woven fabric is 1.8 cm ³ / (cm ² · min)) FIG. 5 is a diagram showing a change over time in the capacitance of the capacitor element when a total amount of 1 μL of water is discharged onto a woven fabric at a rate of 50 nanoL / min while applying an AC voltage of 5 V and 300 Hz. 5 V between both electrodes of the capacitor element with a paper piece (the average pore diameter of the dielectric layer was 0.22 μm, and the permeability of the capacitor element alone without the paper piece was 1.8 cm ³ / (cm ² · min)) produced in Example 3. FIG. 4 is a diagram showing a change over time in the electric capacity of the capacitor element when 1-5 μL of ethyl alcohol is intermittently impregnated into the center of a paper piece with an AC voltage of 300 Hz applied.

Embodiments for carrying out the present invention will be described below with reference to specific examples. However, the present invention is not limited to the following contents without departing from the gist of the present invention, and can be carried out with appropriate modifications.
In this specification, “to” indicating a numerical value range is used as a meaning including numerical values described before and after the numerical value range as a lower limit value and an upper limit value.

FIG. 1 schematically shows a capacitor element or a sensor element according to an embodiment of the present invention. The capacitor element of the present invention comprises a dielectric layer 1 made of a dielectric material and at least one pair of electrodes opposed to each other with the dielectric layer interposed therebetween, and made of a conductive material for applying an electric field to the dielectric layer. Includes 2 and 3.
Both the dielectric layer and both electrodes have gas permeability, and the air permeability of the capacitor element when the differential pressure between one side and the other side of the capacitor element is 125 Pa (hereinafter, simply referred to as “air permeability”) Is 0.5 cm ³ / (cm ² · min) or more [preferably 1.0 cm ³ / (cm ² · min) or more, more preferably 1.5 cm ³ / (cm ² · min) or more]. By doing so, it is possible to realize the smooth permeation of gas without using an air blowing mechanism such as an air pump for air blowing, and to check for the permeation of substances in the gas (water vapor, other gases, mist, etc.) including changes in the amount of perspiration , The amount of transmission, and the temporal change in the amount of transmission can be measured. The upper limit of the air permeability of the capacitor element, but are not limited to, the so large a measurement sensitivity is lowered tendency, preferably 10cm ³ / (cm ² · min) or less, 8cm ³ / (cm ² · Min) The following is more preferred.
The air permeability (= Q / A) in the present invention is measured by measuring the air permeation amount Q when the differential pressure between one side and the other side of the capacitor element is 125 Pa according to the Frazier-type air permeability test (JIS L1096). Then, the value is calculated by dividing by the measurement area A. At this time, the value and the position of the measurement area A are determined according to whether the surface area of the capacitor element is larger than a circle having a diameter of 9 mm or not. Set by (a).
(A) When the surface area of the capacitor element is larger than the circle having a diameter of 9 mm, a circle having a diameter of 9 mm whose position is selected so as to maximize the amount of air permeation (for example, when the air permeability of the dielectric layer is uniform) In ( ² ), the inside of a circle having a diameter of 9 mm where the total area of the holes formed in the electrodes in the circle is the largest is defined as a measurement area (0.638 cm ² ).
(A) If the surface area used by the capacitor element is small and cannot be within a circle having a diameter of 9 mm, the surface area (entire area) used by the capacitor element is used as the measurement area.
However, when the surface area of the capacitor element is larger than a circle having a diameter of 9 mm, the lower limit of the air permeability defined in the present invention [that is, 0.5 cm ³ / (cm ² · min) or more, 1.0 cm ³ / (Cm ² · min) or 1.5 cm ³ / (cm ² · min) or more is satisfied when any of the circles having a diameter of 9 mm in the surface area of the capacitor element is used as a measurement area. If the requirement of the lower limit is satisfied, it is confirmed. Therefore, when confirming only the satisfaction of the requirement of the lower limit value of the air permeability, it is not always necessary to select the circle at the position where the amount of air passage becomes the largest as described in (a) above. is not.

  Generally, the electric capacity of a capacitor element is determined by the electrode area and the dielectric constant and thickness of a dielectric layer. If a capacitor element is formed in the dielectric layer that has an appropriate gap through which gas or insulating liquid can move and permeate, the dielectric layer can be adjusted according to the concentration and density of the gas or insulating liquid in the dielectric layer. When a constant voltage is applied to the capacitor element and a gas or insulating liquid is allowed to pass through the dielectric layer while measuring the capacitance, the amount of the substance passing through the dielectric layer can be changed. And its temporal variation can be obtained by converting it into a change in the capacitance of the capacitor element.

The dielectric layer 1 has a porous structure in which gas and liquid can move by diffusion and the like, and secures electrical insulation between the opposed electrodes 2 and 3 to move inside. The material is selected from materials that do not significantly change chemically and physically due to the changing gas or liquid. Examples of such a dielectric layer include, but are not limited to, those made of porous ceramics and glass fibers, and chemically stable polymer porous films. Examples of the polymer of the porous membrane include, but are not limited to, poly (vinylidene fluoride), polytetrafluoroethylene, an analogous copolymer thereof, polypropylene, polyethylene, and polycarbonate.
The thickness of the dielectric layer is preferably as thin as possible within a range where electrical insulation, mechanical strength, and fluid permeability are ensured, in that the operating voltage can be set low. Usually, it is 2 mm or less, preferably 1 mm or less, more preferably 500 μm or less, and when applied to a wearable device, it is 5 to 200 μm, preferably 5 to 100 μm.
The porosity of the dielectric layer [= (true density−apparent density) × 100 / true density] can be selected from a range in which air permeability and use strength can be ensured. Although it depends on the material of the dielectric, it is preferably 30 to 90%, more preferably 50 to 80%.
The air permeability of the dielectric layer may be in any range as long as the capacitor element satisfies the air permeability requirements, but is usually at least 1.0 cm ³ / (cm ² · min), preferably Is at least 2.0 cm ³ / (cm ² · min), more preferably at least 2.5 cm ³ / (cm ² · min). The upper limit of the air permeability of the dielectric layer is not limited as in the case of the lower limit, but if it is too large, the measurement sensitivity tends to decrease. Therefore, the upper limit is preferably 20 cm ³ / (cm ² · min) or less, and more preferably 10 cm ^3. / (Cm ² · min) or less is more preferable.
The air permeability of the dielectric layer is measured by measuring the air permeation Q when the pressure difference between one side and the other side of the dielectric layer is 125 Pa, in accordance with the Frazier-type air permeability test (JIS L1096), similarly to the capacitor element. Then, it is divided by the measurement area A and calculated. At this time, similarly to the capacitor element, the value and position of the measurement area A may be set according to the above (A) or (A), but the permeability of the dielectric layer is uniform regardless of the position of the measurement area. In this case, an arbitrary measurement area at an arbitrary position (for example, a circle having a diameter of 5 to 20 mm) can be adopted.

The electrode 2 and the electrode 3 are made of a material having high conductivity (electrical conductivity of 10 ⁵ S / m or more) and having a structure that does not hinder the permeation of gas or liquid. Are selected that do not cause significant changes in Examples of such an electrode include, but are not limited to, a metal plate, a foil, and a thin metal wire in which through holes such as holes and slits of an appropriate size are formed in a predetermined distribution state by punching or the like. Metal mesh and the like.
Opposing electrodes do not necessarily have to be the same material and the same shape as long as the above conditions are satisfied, and the electrode on at least one surface of the dielectric layer may be a plurality of partial electrodes. That the dielectric layer 1 and the electrodes 2 and 3 are shifted in the same shape and the same area in that the change in the dielectric constant due to the diffusion of the liquid or the liquid into the dielectric layer is obtained as a change in the capacitance of the capacitor element. It is more preferable that they do not overlap.
The area of the electrode and the dielectric layer is larger, the larger the change in electric capacity is, but it is disadvantageous for a wearable device, so it is usually 1 to 1000 mm ² , preferably 5 to 500 mm ² , more preferably 10 to 200 mm. ²
The thickness of the electrode is usually 1 mm or less, preferably 500 μm or less, and when applied to a wearable device, is 5 to 200 μm, more preferably 5 to 100 μm.
When applied to a wearable device, stainless steel, titanium, or the like is preferable as a material for the metal foil or the metal mesh because metal allergy or the like is unlikely to occur.

When the capacitor element or sensor element is used for measuring leachate such as perspiration or its vapor, the liquid on the electrode on the leachate side of the capacitor element absorbs leachate on one surface and evaporates as vapor from the other surface. 4 can be a capacitor element with a liquid absorbing layer or a sensor element with a liquid absorbing layer attached so that the evaporation surface is in contact with the electrode. One of the liquid absorbing layers, a liquid absorbing and diffusing layer 4 having an improved function of efficiently absorbing leachate on one surface and quickly evaporating the vapor as vapor from the other surface. A capacitor element with a divergence layer or a sensor element with a liquid absorption divergence layer can also be used. When a liquid absorbing layer (including a liquid absorbing layer) is attached, the gas permeability between the electrode 2 and the electrode 3 is made anisotropic, and the liquid absorbing layer (including the liquid absorbing layer) 4 is attached with a gas. The measurement can be performed more efficiently by adjusting the direction to be superior in transmission efficiency.
Examples of the liquid absorbing layer include, but are not limited to, liquid absorbing paper (paper, Japanese paper), woven fabric, nonwoven fabric, and porous or foamed materials made of hydrophilic resin.
The liquid absorbing layer is not limited, but is commercially available or known as a sweat-absorbing quick-drying material or a water-absorbing quick-drying material (for example, Toray Co., Ltd. Field Sensor Second Dry (registered trademark), Toyobo Co., Ltd.) Megatech Dry (registered trademark)) and similar structures thereof. As an example of the structure of the liquid absorbing layer, the liquid absorbed from one surface using the capillary effect is efficiently moved to the opposite side to the absorbing surface, and the specific surface area is larger than the liquid absorbing surface side. A woven fabric made of a chemical fiber such as polyester or polypropylene which quickly evaporates and diffuses as vapor from the side, and a woven fabric laminate including a water-absorbent woven fabric layer and a water-repellent woven fabric layer.

  The capacitor element and the sensor element of the present invention can include a mounting tool for facilitating mounting on a measurement target surface such as a human body. Examples of such a mounting tool include a bonding tool for bonding or adhering one electrode or a liquid absorbing layer (liquid absorbing layer) of a capacitor element or a sensor element to a surface to be measured, a band or a belt for closely holding the surface to be measured. And the like.

Since the capacitor element and the sensor element of the present invention as described above have a relatively high air permeability based on the gas permeability of both the electrode and the dielectric layer, the air permeability is utilized from various sources by utilizing this air permeability. A substance in gas that diffuses naturally (water vapor, other gas, mist, etc.) is transmitted from one surface of the capacitor element placed near the source to the other surface, and the dielectric constant of the dielectric layer depends on the amount of the substance. By utilizing the change, the amount of transmission of the substance can be quantified as a change in the capacitance of the capacitor element.
Also, by attaching the liquid absorbing layer to one of the electrode surfaces, liquid such as sweat generated in the human body by the sweating action can be absorbed by the liquid absorbing layer and sent to the capacitor element as vaporized vapor without leakage. It is considered that the amount of various exudates such as the amount of water excreted outside the body due to sweat can be more accurately and quickly detected as a change in electric capacity.
The substance in the gas to be measured is, but not limited to, an insulating liquid, vapor, mist, or the like, and includes, for example, water such as sweat and various alcohols.

  EXAMPLES The capacitor element and the sensor element of the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

(Example 1)
A 40 μm thick flexible stainless steel foil (Maxell's 8834 stainless steel tape), one surface of which is adhesively treated with a silicone adhesive, is processed into a 12.5 mm diameter circle, and a 1 mm diameter circular through hole is formed. 1, 6, and 12 electrodes were opened at equal intervals on the center of the circle and at equal intervals on concentric circles having diameters of 3.8 mm and 7.6 mm, respectively, to produce electrodes having gas permeability. Using two of these electrodes, the air permeability when the average pore diameter is 0.22 μm, the porosity is 70%, the thickness is 125 μm, and the differential pressure is 125 Pa (hereinafter, may be simply referred to as “air permeability”) is 3. 2 cm ³ / (cm ² · min)], a porous membrane made of poly (vinylidene fluoride) (Durapore (registered trademark) made by Merck Millipore) is sandwiched by using an adhesive surface, so that a gas-permeable diameter can be obtained. A 12.5 mm circular flexible capacitor element (air permeability: 1.8 cm ³ / (cm ² · minute)) was produced. An AC voltage having a frequency of 200 Hz to 2 MHz and 5 V was applied between both electrodes of the device while sweeping the frequency, and the capacitance and impedance were measured at room temperature in the atmosphere. FIG. 3 shows the relationship between the frequency of the applied AC voltage and the capacitance and impedance. Although the capacitance did not show a large change with respect to the frequency, the impedance showed a typical tendency for the capacitor element to decrease exponentially with the increase in the frequency, and the present flexible element was established as a capacitor element. I confirmed that.

(Example 2)
The flexible capacitor element [air permeability: 1.8 cm ³ / (cm ² · min)] prepared in Example 1 was placed directly above a water-impregnated sponge (12 mm wide, 30 mm long) on one electrode surface. Are placed in parallel with each other at a distance of about 2 mm from the surface of the sponge, and are exposed to water vapor that naturally evaporates from the sponge, and in the same manner as in Example 1, an AC voltage of 200 Hz to 2 MHz and 5 V AC voltage is applied. The voltage was applied while sweeping, and the capacitance was measured. FIG. 3 shows the relationship between the frequency of the applied AC voltage and the electric capacity together with the measurement results under the normal atmosphere in Example 1 shown in FIG. Under water vapor exposure, an increase in electric capacity corresponding to a change in capacitance due to water vapor diffused and transmitted through the porous dielectric layer constituting the capacitor element was detected in a frequency band of about 200 Hz to 6 kHz. From this, the gas-permeable flexible capacitor element manufactured in Example 1 operates as a gas (water vapor) sensor element that can detect a quantitative change in gas molecules passing through the element as a change in electric capacity. It was confirmed that.

(Example 3)
A circular piece of paper having a diameter of 10 mm and having excellent water absorbability was concentrically attached to one electrode surface of the flexible capacitor element [air permeability: 1.8 cm ³ / (cm ² · minute)] produced in Example 1. . With an AC voltage of 5 V and 300 Hz applied between both electrodes of the element, a small amount of water is dropped with a micro syringe at the center of the sheet to impregnate the sheet with water, and a capacitor element for water vapor evaporating through the sheet. The time change of the electric capacity of the sample was measured. FIG. 4 shows the change over time of the capacitance of the capacitor element when 1 to 5 μL of water droplets are dropped on a piece of paper. It was confirmed that, depending on the amount of each drop, the temporal increase or decrease in the amount of evaporation caused by the evaporation and drying of the moisture impregnated into the paper pieces as water vapor can be detected as a time change in the electric capacity of the capacitor element. From this, it can be seen that the combination of the gas-permeable capacitor element manufactured in Example 1 and the water-absorptive layer functions as a gas (water vapor) sensor element capable of measuring the amount of absorbed water droplets and its temporal change. confirmed.

(Example 4)
In Example 1, instead of the Durapore membrane having an average pore diameter of 0.22 μm and air permeability of 3.2 cm ³ / (cm ² · min), the porosity is 70% and the thickness is 125 μm, and the average pore diameter is 0.1 μm. , breathable 1.8cm ³ / (cm ² · minute), except that was used different Durapore membrane in the same manner as in example 1 flexible capacitor element [air permeability 1.6cm ³ / (cm ² · min )], And the time change of the capacitance of the capacitor element when 1 to 5 μL of water droplets were dropped on a piece of paper was examined in the same manner as in Example 3. The result is shown in FIG. The responsivity (the amount of change in electric capacity) of the flexible capacitor element of Example 4 whose air permeability was lower than that of Example 1 was slightly lower than that of Example 1, but it was confirmed that the flexible capacitor element functioned as a sensor element.

(Example 5)
In Example 1, instead of the Durapore membrane having an average pore diameter of 0.22 μm and a gas permeability of 3.2 cm ³ / (cm ² · min), the porosity is 70%, the thickness is 125 μm, and the average pore diameter is 0.45 μm. , breathable 13.1cm ³ / (cm ² · minute), except that was used different Durapore membrane in the same manner as in example 1 flexible capacitor element [air permeability 6.1cm ³ / (cm ² · min )], And the time change of the capacitance of the capacitor element when 1 to 5 μL of water droplets were dropped on a piece of paper was examined in the same manner as in Example 3. FIG. 6 shows the result. The responsivity (the amount of change in electric capacity) of the flexible capacitor element of Example 5, which has higher air permeability than that of Example 1, was significantly lower than that of Examples 1 and 4, but functioned as a sensor element. Was confirmed.

(Example 6)
In Example 1, instead of the Durapore membrane having an average pore diameter of 0.22 μm and air permeability of 3.2 cm ³ / (cm ² · min), the porosity is 70% and the thickness is 125 μm, and the average pore diameter is 0.65 μm. , Air permeability [not measured, but air permeability exceeding 13.1 cm ³ / (cm ² · minute)]. ] Except that a Durapore membrane was used in the same manner as in Example 1 [not measured, but having a gas permeability exceeding 6.1 cm ³ / (cm ² · min). ], And the change over time of the electric capacity indicated by the capacitor element when 1 to 5 μL of water droplets were dropped on a piece of paper was examined in the same manner as in Example 3. FIG. 7 shows the result. The responsivity (the amount of change in electric capacity) of the flexible capacitor element of Example 6 having higher air permeability than that of Example 5 was lower than that of Example 5, but it was confirmed that the flexible capacitor element functioned as a sensor element.
In view of the above Examples 3 to 6, the capacitor element having a gas permeability of 0.5 cm ³ / (cm ² · min) or more can be adopted, and a preferable gas permeability is 1.0 cm ³ / (cm ² ·· cm). Min) or more, more preferably 1.5 cm ³ / (cm ² · min) or more. Further, without limitation on the upper limit of the air permeability, as measurement sensitivity is not lowered significantly, 20cm ³ / (cm ² · min) can adopt the following ones, preferably 10cm ³ / (cm ² · min ) It is considered as follows.

(Example 7)
Water droplets were quickly absorbed on one electrode surface of the capacitor element [air permeability: 1.8 cm ³ / (cm ² · minute)] manufactured in Example 1, and the absorbed water was removed by capillary action. It is moved to the other surface, and a high water absorption fast drying polyester woven fabric (Toray Co., Ltd. Field Sensor Second Dry (registered trademark)) having a function of quickly evaporating moisture as water vapor from the other surface is cut out into a circular shape having a diameter of 10 mm. A sweat sensor element was formed by concentrically adhering and attaching the water vapor diverging surfaces so as to be in contact with each other. In order to simulate the sweating phenomenon on the skin surface, using a syringe pump, a small amount of water discharged from the micro syringe at an arbitrary flow rate was attached to the capacitor element from the tip of the tube through a tube with an inner diameter of 125 μm. Introduced to the water-absorbing surface of the cloth, and in the same manner as in Example 3, the relationship between the discharge rate of water and the change over time of the electric capacity was examined with an AC voltage of 5 V and 300 Hz applied between both electrodes of the capacitor element. Was. FIG. 8 shows the electric capacity of the perspiration rate sensor element when water is discharged at a rate of 50 nanoL per minute and 100 nanoL per minute and absorbed by a polyester woven fabric until the total discharge amount becomes 1 μL. Shows the time change. It was confirmed that the release of water corresponding to the low-level region of the thermal sweating action, which is mainly caused by lowering the elevated body temperature, can be detected as a temporal change in the electric capacity indicated by the present sensor element.

(Example 8)
A capacitor with a paper sheet having a 10 mm-diameter circular water-absorbing paper sheet that is closely attached concentrically to one electrode surface of the capacitor element (air permeability: 1.8 cm ³ / (cm ² · minute)) produced in Example 3. A small amount of ethyl alcohol (concentration: 99.5% by volume) was dropped into the center of the piece of paper with a microsyringe in a state where an AC voltage of 5 V and 300 Hz was applied to the element as in Example 3, and the alcohol was applied to the piece of paper. The change over time of the capacitance of the capacitor element with respect to the alcohol vapor that was impregnated and evaporated through a piece of paper was measured. FIG. 9 shows a change over time of the capacitance of the capacitor element when 1 to 5 μL of ethyl alcohol is dropped on a piece of paper. It was confirmed that, depending on the amount of each drop, the time-dependent increase or decrease in the amount of evaporation caused by the evaporation and drying of the ethyl alcohol impregnated in the paper pieces as vapor can be detected as a time-dependent change in the capacitance indicated by the capacitor element. From this, the gas-permeable capacitor element manufactured in Example 1 can measure the amount of the gaseous compound evaporated and diverged in addition to the water vapor, and the gas (alcohol) capable of measuring the change with time as a change in electric capacity. It was confirmed that it functioned as a (vapor) sensor element.

  The capacitor element and the sensor element of the present invention are capable of measuring the presence / absence of the substance in the gas including the change in the amount of perspiration, the amount of permeation, and the temporal change in the amount of permeation without requiring the use of a ventilation mechanism. It can be widely used not only for measuring the amount of perspiration, but also for measuring various types of insulating leachate and its vapor, measuring gas or vapor and mist in the airflow, and is also small, light and thin. Since it can be easily made flexible, it is expected to be used as a wearable device.

1: a porous dielectric layer having gas permeability,
2, 3: a gas-permeable electrode made of a conductive material;
4: Liquid absorption layer (liquid absorption divergence layer)

Claims (10)

A capacitor element having a dielectric layer sandwiched between at least a pair of electrodes, and having a gas permeability of 0.5 cm ³ / (cm ² · min) or more when the pressure difference between one surface and the other surface is 125 Pa. element.   The capacitor element according to claim 1, wherein the capacitor element has flexibility.   3. The capacitor element according to claim 1, wherein the thickness is 3.0 mm or less.   The capacitor element according to any one of claims 1 to 3, further comprising a liquid absorbing layer on one electrode surface, and measuring a substance which moves or diffuses from the liquid absorbing layer to the other electrode surface side. Capacitor element with a liquid absorbing layer.   The capacitor element according to claim 4, wherein the liquid absorbing layer is a liquid absorbing and diffusing layer having a specific surface area on the evaporation surface side larger than that on the absorption surface side.   It includes the capacitor element according to any one of claims 1 to 5, wherein the presence / absence, permeation amount, and permeation amount of a predetermined substance in a gas are changed by a change in electric capacity of the capacitor element. Sensor element that measures one or more of   7. The sensor element according to claim 6, further comprising a mounting tool for mounting the capacitor element on a surface to be measured.   8. The sensor element according to claim 6, wherein the measurement target is a human body, and the amount of perspiration and / or its temporal change is determined.   The capacitor element according to any one of claims 1 to 5, wherein gas is transmitted from one electrode side to an opposite electrode side, and the presence or absence of permeation of a substance in the gas due to a change in the capacitance of the capacitor element. A method for measuring a substance in a gas, the method comprising measuring one or more of a transmission amount, and a temporal change in the transmission amount.   The sensor element according to any one of claims 6 to 8, wherein gas is transmitted from one electrode side to the opposite electrode side, and the presence or absence of permeation of a substance in the gas due to a change in the capacitance of the capacitor element. A method for measuring a substance in a gas, the method comprising measuring one or more of a transmission amount, and a temporal change in the transmission amount.

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