JP5849539B2 - Moisture content measuring method and moisture content measuring device - Google Patents

Description

  The present invention relates to a moisture content measuring method and a moisture content measuring device for quantifying moisture content noninvasively and with high accuracy.

  Conventionally, as a moisture content measuring method for non-invasively quantifying the moisture content, for example, the infrared of measurement light whose infrared absorption changes depending on the moisture content of the measurement object, and the infrared absorption hardly changes depending on the moisture content of the measurement object. The measurement object is irradiated with infrared rays of reference light, respectively. Then, based on the amount of reflected infrared light from the measurement object, for example, an absorbance is obtained, and a method of measuring the moisture content of the measurement object by converting this absorbance into a moisture content is known (for example, patents). Reference 1).

Japanese Patent Laid-Open No. 10-176989

  However, among the constituents of the measurement target, the substance that absorbs infrared rays is not limited to water, and when the measurement target contains other components other than water, the infrared rays irradiated by other components are also included. There is a problem that measurement error increases due to absorption.

  The present invention has been made in order to solve the above-described problem, and is a moisture content measuring apparatus capable of accurately measuring only the moisture content even when a component other than water is contained in the measurement object. The purpose is to provide.

In order to solve the above problems, an embodiment of the present invention employs the following moisture content measuring method and moisture content measuring device.
That is, the moisture content measuring method of the present invention is a moisture content measuring method for measuring the moisture content contained in the object to be measured,
Irradiating light of a predetermined wavelength toward the object to be measured at a first temperature, measuring a first absorption coefficient of the object to be measured, and predetermined toward the object to be measured at a second temperature And measuring the second absorption coefficient of the object to be measured, and the first absorption based on the amount of change in the absorption coefficient according to the temperature change of water measured in advance. from the coefficient and the second absorption coefficient, wherein said calculating a moisture amount of the measurement object, Bei example, said object to be measured is a human body.

The method further includes the step of adjusting the object to be measured to the first temperature and the step of adjusting the object to be measured to the second temperature.
Further, the wavelength of the light irradiated toward the object to be measured is 1410 ± 20 nm or 1460-1530 nm.

The moisture content measuring apparatus of the present invention is characterized in that the moisture content of the object to be measured is measured using the moisture content measuring method described in each of the above items, and the object to be measured is a human body .
Further, the apparatus further comprises temperature adjusting means for adjusting the object to be measured to the first temperature and the second temperature.

   Further, a temperature sensor for detecting the temperature of the object to be measured is further provided.

It is a schematic block diagram which shows the structure of the moisture content measuring apparatus of this invention. It is a perspective view which shows an example of the measuring terminal which comprises a moisture content measuring apparatus. It is a schematic diagram which shows the cross section of a human skin tissue. It is a flowchart which shows the operation | movement which the moisture content measuring apparatus of this invention measures a moisture content. It is a graph which shows the relationship between the absorption coefficient of water and temperature. It is a flowchart of another embodiment which shows the operation | movement which the moisture content measuring apparatus of this invention measures a moisture content.

The form for implementing the moisture content measuring apparatus and moisture content measuring method of this invention is demonstrated.
In the present invention, the case where the moisture content contained in the skin of a human palm is measured as an observation target of the moisture content measuring apparatus will be described as an example.

[First Embodiment]
FIG. 1 is a schematic block diagram showing the configuration of the moisture content measuring apparatus according to the first embodiment of the present invention.
The water content measuring apparatus 100 can accurately measure the water content in a solution in which a first solute is dissolved by an absorptiometry, and includes a calculation unit 101, a storage unit 102, a display unit 103, and measurement light. An intensity acquisition unit (measurement unit) 104, an optical unit 107 including an irradiation unit 105 and a light receiving unit 106, and a temperature unit 111 including a temperature adjusting unit 108 and a temperature sensor 109 are provided. Among these, the measurement terminal 110 is constituted by the optical unit 107 and the temperature unit 111.

  For example, the moisture content measuring apparatus 100 can measure (quantify) the moisture content excluding the solute among the components constituting the body fluid (sample: solution) present in the skin (observation target).

The measurement light intensity acquisition unit (measurement unit) 104 measures the absorption coefficient (μ _a (λ)) of the first sample, that is, the skin (observation target).

   An irradiation unit (light source) 105 that is a light source irradiates light of a predetermined wavelength toward the skin (observation target). Such an irradiation unit (light source) 105 may be configured by a laser light source, for example. The irradiation part 105 should just be a light source with a wavelength with a large temperature fluctuation of the water absorption coefficient, 1410 ± 20 nm, or 1460-1530 nm, for example.

  The temperature adjusting means 108 may be configured by, for example, a heater plate that heats the measurement target, or a Peltier element that can heat and cool the measurement target. The temperature sensor 109 only needs to be composed of a radiation temperature sensor, a semiconductor temperature sensor, or the like that detects the surface temperature of the measurement target.

FIG. 2 shows an example of a measurement terminal constituting the moisture content measuring apparatus.
The measurement terminal 110 shown in FIG. 2 is a small measurement terminal having a showerhead shape as a whole, for example. Measure against the face.
The irradiation unit 105 and the light receiving unit 106, the temperature adjusting unit 108, and the temperature sensor 109 are exposed on the measurement surface 110a.
The measurement terminal 110 is pressed against the arm or face of a human body, and the solute concentration and water content (solvent concentration) in the body fluid are measured.

Based on the absorption coefficient (μ _aw (λ, T)) of water (solvent) and the absorption coefficient (μ _a (λ)) of the observation target, the calculation unit 101 calculates the volume fraction (V _w ) of the solvent, that is, the water content. Calculate the amount. Such a calculation unit 101 may be configured by, for example, a CPU, a memory, and the like. In addition, the light receiving unit 106 may receive, for example, light that is backscattered by the skin.

Here, the structure of a human skin tissue, which is an example of a water content observation target, will be described.
FIG. 3 is a schematic diagram showing a cross-section of human skin tissue. The skin 31 is composed of three layers, an epidermis layer 32, a dermis layer (arbitrary layer) 33, and a subcutaneous tissue 34.
The epidermis layer 32 is a thin layer having a thickness of 0.2 mm to 0.3 mm on the outermost side, and is a layer containing about 60% of water, protein, lipid, etc., stratum corneum, granule layer, spiny layer, Including bottom layer.

The dermis layer 33 is a layer formed under the epidermis layer 32 and having a thickness of 0.5 mm to 2 mm. The dermis layer 33 is a layer containing approximately 60% of water, protein, and lipid. There are sebaceous glands, sweat glands, hair follicles, blood vessels, lymphatic vessels and the like.
The subcutaneous tissue 34 is a layer having a thickness of 1 to 3 mm formed under the dermis layer 33. The subcutaneous tissue 34 is mostly made of subcutaneous fat containing approximately 90% or more of lipids and the balance being water (water) to be measured. .

  As a method for measuring the amount of water using the water content measuring apparatus 100, for example, the irradiation unit (light source) 105 and the light receiving unit 106 are brought into close contact with the surface of the skin 31 with a predetermined inter-irradiation distance W. Irradiates light onto the surface of the skin 31 from the irradiation unit 105, and this light is reflected by the tissue in the skin 31, and the reflected light is scattered toward the irradiation unit 105 and the light receiving unit 106 (back scattered light). Is detected by the light receiving unit 106.

Next, the operation of the water content measuring apparatus 100, that is, the water content measuring method of the present invention will be described.
The moisture content measuring apparatus 100 calculates the temperature characteristics of the water absorption coefficient and the optical path length of light propagating through the skin in advance and measures the moisture content, and stores them in the storage unit 102 in advance. The temperature characteristic of the water absorption coefficient may be measured in advance or existing data may be used (S6). The optical path length can be calculated by Monte Carlo simulation or the like.

FIG. 4 is a flowchart showing an operation when measuring the water content and the solute concentration using the water content measuring apparatus.
First, a user (a person to be measured) places the measurement terminal 110 of the moisture content measuring device 100 on the skin such as a wrist and operates the moisture content measuring device 100 by pressing a measurement start switch (not shown) or the like. First, the moisture content measuring apparatus 100 heats or cools the skin in contact with the measurement surface 110a by the temperature adjusting means 108 so that the first measurement temperature T1 is reached (S1).

  The surface temperature of the skin is continuously measured by the temperature sensor 109, and when the temperature reaches the measurement temperature T1, the irradiation unit 105 irradiates the skin 31 with light having a wavelength λ. The wavelength λ is, for example, 1410 ± 20 nm, or 1460-1530 nm. In order to reduce the error in calculating the moisture content of the object to be measured, it is desirable to use a wavelength in which the difference in absorption coefficient exceeds ± 0.01.

The light irradiated at the time of measurement should just be the structure which irradiates one kind of light of wavelength (lambda) ₁ , and light of 2 wavelengths or more sequentially.
When the irradiation unit 105 emits light, the light receiving unit 106 receives (measures) the light emitted from the irradiation unit 105 and backscattered by the skin 31 (S2).

  Next, when the light receiving unit 106 completes the light reception, the optical path length of the skin is acquired from the optical path length information of the wavelength stored in the storage unit 102. Moreover, the calculating part 101 should just calculate the absorption coefficient of skin.

  When the absorption coefficient at the temperature T1 is measured, this time, the skin in contact with the measurement surface 110a is heated or cooled by the temperature adjusting means 108 to the second measurement temperature T2 (S3).

  When the surface temperature of the skin is continuously measured by the temperature sensor 109 and reaches the measurement temperature T <b> 2, the irradiation unit 105 irradiates the skin 31 with light having a wavelength λ.

The light irradiated at the time of measurement should just be the structure which irradiates one kind of light of wavelength (lambda) ₁ , and light of 2 wavelengths or more sequentially.
When the irradiation unit 105 emits light, the light receiving unit 106 receives (measures) the light emitted from the irradiation unit 105 and backscattered by the skin 31 (S4).

  Next, when the light receiving unit 106 completes the light reception, the optical path length of the skin is acquired from the optical path length information of the wavelength stored in the storage unit 102. Moreover, the calculating part 101 should just calculate the absorption coefficient of skin.

  Next, referring to the absorption coefficient at the temperature T1, the absorption coefficient at the temperature T2, and the graph showing the change in the absorption coefficient per 1 ° C. of ultrapure water shown in FIG. 5, the water content (volume fraction), the solute concentration Is obtained (S5).

  Note that the change in absorption coefficient per 1 ° C. of ultrapure water shown in FIG. 5 may be measured in advance or existing data may be used (S6).

  For example, in the case of water and one kind of solute as the solution (solution corresponding to body fluid), the relationship between the absorption coefficient and the volume fraction of water and solute is expressed by equation (1).

In Equation 1, μ _a (λ, T): absorption coefficient of measurement object μ _ag (λ): absorption coefficient of solute at wavelength λ μ _aw (λ, T): absorption coefficient V of water at wavelength λ, temperature T _g : Volume fraction of solute V _w : Volume fraction of water Based on these equations (1), the volume fraction of water (water content) and the volume fraction of solute from two temperatures (T1, T2) The relationship is expressed by equation (2). In this equation (1), since μ _ag (λ) (absorption coefficient of solute at wavelength λ) is an extremely small value, equation (2) is derived assuming that the temperature does not substantially change.

However, in Equation 2, T1: first measurement temperature T2: second measurement temperature μ _a (λ, T ₁ ): absorption coefficient μ _a (λ, T ₂ ) at measurement target temperature T1: measurement target temperature T2 Absorption coefficient μ _aw (λ, T ₁ ): Wavelength λ, Water absorption coefficient at temperature T ₁ μ _aw (λ, T ₂ ): Water absorption coefficient at wavelength λ, temperature T ₂ V _g : Solute volume fraction V _w : volume fraction of water (∂ / ∂T) μ _aw (λ): change in absorption coefficient per 1 ° C. of water

By applying the absorption coefficient at the temperature T1 obtained in steps S1 and S2 and the absorption coefficient at the temperature T2 to the formula (2) that takes into account the change in the absorption coefficient per 1 ° C. of ultrapure water, the volume of water Calculate the fraction (water content) and the volume fraction of the solute.
Then, the obtained water volume fraction (water content) may be output to the display unit 103 of the water content measuring apparatus 100, for example, a monitor screen or a printer (S7).

  In the above-described embodiment, the absorption coefficient of one kind of solute is applied, but the characteristics of the entire solute other than water, that is, the absorption coefficient of the entire solute included may be applied.

[Second Embodiment]
FIG. 6 is a flowchart of another embodiment in which a moisture content and a solute concentration are measured using a moisture content measurement device.
First, a user (a person to be measured) places the measurement terminal 110 of the moisture content measuring device 100 on the skin such as a wrist and operates the moisture content measuring device 100 by pressing a measurement start switch (not shown) or the like. The moisture content measuring apparatus 100 measures the surface temperature (T1) of the skin with the temperature sensor 109 and then irradiates the skin 31 with light having a wavelength λ. The wavelength λ is, for example, 1410 ± 20 nm, or 1460-1530 nm. In order to reduce the error in calculating the moisture content of the object to be measured, it is desirable to use a wavelength with a difference in absorption coefficient exceeding ± 0.01.

The light irradiated at the time of measurement should just be the structure which irradiates the light of one kind of wavelength (lambda), and the light more than 2 wavelengths sequentially.
When the irradiation unit 105 emits light, the light receiving unit 106 receives (measures) the light emitted from the irradiation unit 105 and backscattered by the skin 31 (S10).

  Next, when the light receiving unit 106 completes the light reception, the optical path length of the skin is acquired from the optical path length information of the wavelength stored in the storage unit 102. Moreover, the calculating part 101 should just calculate the absorption coefficient of the skin in temperature T1.

  When the absorption coefficient at the temperature T1 is measured, a fixed time elapses until the temperature of the measurement object naturally changes from T1 to T2 (S11).

  The water content measuring apparatus 100 again measures the surface temperature (T2) of the skin with the temperature sensor 109 and then irradiates the skin 31 with light having a wavelength λ.

The light irradiated at the time of measurement should just be the structure which irradiates the light of one kind of wavelength (lambda), and the light more than 2 wavelengths sequentially.
When the irradiation unit 105 emits light, the light receiving unit 106 receives (measures) the light emitted from the irradiation unit 105 and backscattered by the skin 31 (S12).

  Next, when the light receiving unit 106 completes the light reception, the optical path length of the skin is acquired from the optical path length information of the wavelength stored in the storage unit 102. Moreover, the calculating part 101 should just calculate the absorption coefficient of the skin in temperature T2.

  Next, referring to the absorption coefficient at the temperature T1, the absorption coefficient at the temperature T2, and the graph showing the change in the absorption coefficient per 1 ° C. of ultrapure water shown in FIG. 5, the water content (volume fraction), the solute concentration Is obtained (S13).

  The change in absorption coefficient per 1 ° C. of ultrapure water shown in FIG. 5 may be measured in advance or existing data may be used (S14).

  For example, in the case of water and one kind of solute as the solution (solution corresponding to body fluid), the relationship between the absorption coefficient and the volume fraction of water and solute is expressed by equation (3).

In Equation 3, μ _a (λ, T): absorption coefficient of measurement object μ _ag (λ): absorption coefficient of solute at wavelength λ μ _aw (λ, T): absorption coefficient of water V at wavelength λ, temperature T _g: volume fraction of solute V _w: the volume fraction of water based on this equation (3), two temperatures (T1, T2) from the volume fraction of water (water content), the volume fraction of the solute The relationship is expressed by equation (4). In this equation (3), since μ _ag (λ) (absorption coefficient of solute at wavelength λ) is an extremely small value, equation (4) is derived assuming that the temperature does not substantially change.

However, in Equation 4, T1: first measurement temperature T2: second measurement temperature μ _a (λ, T ₁ ): absorption coefficient μ _a (λ, T ₂ ) at measurement target temperature T1: measurement target temperature T2 Absorption coefficient μ _aw (λ, T ₁ ): Wavelength λ, Water absorption coefficient at temperature T ₁ μ _aw (λ, T ₂ ): Water absorption coefficient at wavelength λ, temperature T ₂ V _g : Solute volume fraction V _w : volume fraction of water (∂ / ∂T) μ _aw (λ): change in absorption coefficient per 1 ° C. of water

By applying the absorption coefficient at temperature T1 obtained in steps S1 and S2 and the absorption coefficient at temperature T2 to Equation (4) that takes into account the change in absorption coefficient per 1 ° C. of ultrapure water, the volume of water Calculate the fraction (water content) and the volume fraction of the solute.
Then, the obtained water volume fraction (water content) may be output to the display unit 103 of the water content measuring apparatus 100, for example, a monitor screen or a printer (S15).

  In this embodiment, the absorption coefficient of one kind of solute is applied, but the characteristics of the entire solute other than water, that is, the absorption coefficient of the entire solute included may be applied.

  As described above, according to the present invention, light is absorbed by a substance (solute) other than water (solution) contained in a solution (measurement target) by measuring absorption coefficients of a plurality of temperature measurement targets. The water content can be measured with high accuracy.

DESCRIPTION OF SYMBOLS 31 ... Skin (observation object), 100 ... Water content measuring device (concentration quantification device), 102 ... Memory | storage part, 103 ... Display part, 104 ... Measurement light intensity acquisition part, 105 ... Irradiation part (light source), 106 ... Light receiving part 108 ... Temperature adjusting means, 109 ... Temperature sensor.

Claims (6)

A moisture content measuring method for measuring the moisture content contained in a measured object,
Irradiating light of a predetermined wavelength toward the object to be measured at a first temperature, and measuring a first absorption coefficient of the object to be measured;
Irradiating light of a predetermined wavelength toward the object to be measured at a second temperature, and measuring a second absorption coefficient of the object to be measured;
Calculating the moisture content of the object to be measured from the first absorption coefficient and the second absorption coefficient based on the amount of change of the absorption coefficient according to the temperature change of water measured in advance;
Equipped with a,
The method for measuring moisture content, wherein the object to be measured is a human body .   The method of measuring moisture content according to claim 1, further comprising: adjusting the object to be measured to the first temperature; and adjusting the object to be measured to the second temperature. .   The water content measuring method according to claim 1 or 2, wherein the wavelength of light irradiated toward the object to be measured is 1410 ± 20 nm or 1460 to 1530 nm. Using the moisture content measuring method according to any one of claims 1 to 3, the moisture content of the object to be measured is measured ,
The moisture content measuring apparatus, wherein the object to be measured is a human body .   The moisture content measuring apparatus according to claim 4, further comprising temperature adjusting means for adjusting the object to be measured to the first temperature and the second temperature.   The water content measuring apparatus according to claim 4 or 5, further comprising a temperature sensor for detecting a temperature of the object to be measured.

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