JP6258708B2 - Viscosity measurement method, viscosity measurement apparatus, inspection method, body fluid electrolyte concentration and viscosity inspection system, and food production apparatus - Google Patents

Description

  The present invention relates to a technique for measuring the viscosity of an aqueous solution sample containing an electrolyte and an inspection technique using the technique.

  It is known that blood viscosity increases due to dehydration, bleeding, and other various diseases such as myocardial infarction, cerebral infarction, cirrhosis, membranous nephritis, nephrotic syndrome, and other so-called lifestyle-related diseases. A high viscosity means that blood hardly flows in blood vessels, and blood vessels are easily clogged in an extreme state. On the other hand, there is also a disease in which the value of the blood viscosity is small. Therefore, knowing the viscosity of blood and its change over time is extremely effective for the prevention, diagnosis and treatment of various diseases.

  It is known that the viscosity of the whole blood changes depending on the number of blood cells and the deformability of the blood cells. The so-called “blood smoothness test” has been developed, and a test apparatus for measuring the flow velocity of blood moving through the capillary tube has been developed. However, the viscosity of the whole blood is difficult to evaluate because it changes under the influence of various factors, both blood cells and serum or plasma.

  Conventionally, (1) capillary viscometer, (2) rotational viscometer, (3) falling ball viscometer, (4) vibration viscometer, etc. have been used for measuring the viscosity of liquid. However, since all of them require a large amount of sample and are complicated in operation, it is difficult to apply to clinical tests. Therefore, it is desired to develop an inspection method and apparatus that can easily and quickly inspect a viscosity with a small amount of sample.

  In order to overcome the drawbacks of the above-described conventional methods, a method has been proposed in which a change in the diffusion coefficient of albumin molecules in blood is measured by a light scattering technique to determine the viscosity of serum or plasma (see Patent Document 1). In this technique, a laser beam such as a He—Ne laser is incident on a serum or plasma sample, and scattered light scattered by blood albumin molecules in the sample is detected. Since the particles in the liquid are in Brownian motion, the scattered light has a wavelength distribution due to Doppler shift. From this wavelength distribution, the diffusion coefficient D is obtained, and from this, the gas constant R, the temperature T, and the particle diameter a of the albumin molecule in blood, the viscosity η is obtained based on the Einstein-Stokes equation.

  In addition, for the purpose of quickly inspecting the viscosity of a small amount of sample, two pulse lasers are focused on the sample surface with two light fluxes converged and heated instantaneously, and the laser-induced surface wave generated on the sample surface is observed and analyzed. Has proposed a method for obtaining the viscosity of a sample (see Non-Patent Document 1).

Japanese Patent No. 4958272

Shotaro Sukegawa, Yoshihiro Taguchi, Yuji Nagasaka, “Development of Optical MEMS Viscous Sensor for Realizing Simple and Rapid In Situ Viscosity Measurement”, The 33rd Japan Thermophysics Symposium (Thermophys Prop), Japan, Thermophysical Society of Japan, 2012 October 03, 33, 56-58. Walden, P.Z., "Uber organische Losungs-und Ionisierungsmittel. III. Teil: Innere Reibung und deren Zusammenhang mit dem Leitvermogen", Zeitschrift fur Physikalische Chemie, vol. 55, 1906, p.207-246. The Chemical Society of Japan, “Chemical Handbook Basics II”, 4th revised edition, Japan, Maruzen Co., Ltd., 1993, pages 445-454. Atkins, Hideaki Chihara and Nobuo Nakamura, “Physical Chemistry (below)”, 4th edition, Tokyo, Japan, July 10, 2008, p. 1155.

  The plasma viscosity measurement method described in Patent Document 1 is a great advance in the sense that it can be applied to a very small amount of sample, but the operation and the viscosity calculation method are complicated, and the inspection apparatus is also expensive, so the inspection is easy. There is a drawback that it cannot be spread to laboratories and laboratories. Moreover, since it depends on the measurement of the diffusion coefficient of albumin molecules in blood, there is a problem that it is difficult to apply to biological samples other than blood.

  In addition, the viscosity measurement method described in Non-Patent Document 1 has the advantage of being able to measure the viscosity of a very small amount of sample at high speed and in a non-contact manner, but simultaneously irradiates the sample surface with two independent pulse lasers. In addition, since it is necessary to analyze the induced surface wave, it is difficult to say that the measurement system is simple, and there is a problem that it is difficult to apply to measurement at the laboratory level.

  Therefore, an object of the present invention is to measure the viscosity of a small amount of sample at high speed and easily, and can be applied to measurement at a laboratory level, and can be applied to the measurement of viscosity of various types of liquid samples. To provide measurement technology.

[1] Background and Summary of the Invention In 1906, Walden discovered and proposed that there is a simple relationship between the viscosity and the electrical conductivity of an electrolyte solution (Non-Patent Document 2). This is now called the Walden's rule.

  Therefore, the present inventors measured the electrical conductivity of various electrolyte solutions containing seasonings such as soy sauce, and (1) the electrical conductivity varies greatly depending on the temperature, and (2) the electrolyte solution having a large viscosity. It was observed that the salt concentration calculated backward from the measured value of electrical conductivity was significantly smaller than the displayed value. The inventors have come to realize that the temperature sensitivity of the electrical conductivity and the electrical conductivity “abnormality” of the viscous liquid can be understood in a unified manner by the expanded Walden law (hereinafter “extended Walden law”).

  Then, the inventors measured the electrical conductivity of many electrolyte solutions that are candidates for biologically derived electrolyte solutions such as plasma from the observation results described in the previous section, and applied the extended Walden rule, The inventors came up with the possibility of determining the viscosity of the solution and arrived at the present invention.

  Specifically, the present inventors, as a so-called feasibility study, based on the extended Walden rule, (1) measurement of the viscosity of saline containing various concentrations of glycerin or sucrose, (2) water (3) Measurement of electrolyte concentration and viscosity of milk, (4) Measurement of electrolyte concentration and viscosity of seasoning containing salt, (5) Electrolyte concentration and viscosity of saliva (6) Measurement of plasma electrolyte concentration and viscosity of bleeding model animals and control animals, etc. were performed to verify the accuracy of viscosity measurement according to the present invention. Furthermore, in order to investigate the possibility of continuous recording of viscosity change, (7) tracking of the electrical conductivity change in the yogurt fermentation process and (8) tracking of the electrical conductivity change in the gelling process of boiling were performed. Details of the experiments (1) to (8) will be described later.

  As a result of the above preliminary experiment, the present inventors, even if the measurement object is limited to blood, (1) Comparison of serum concentration and / or plasma electrolyte concentration and viscosity of model animal and control animal, (2) Model animal (3) Comparison with normal values of electrolyte concentration and viscosity of human serum and plasma derived from disease, (4) Disease It was convinced that it can be applied to the recording of changes in electrolyte concentration and viscosity of human serum and plasma over time.

  Therefore, in the present invention, not only a technique that can easily and quickly determine the electrolyte concentration and viscosity of a sample from a measurement of electrical conductivity with a small amount of sample, but also a measurement method that contributes to the prevention, diagnosis, and treatment of various diseases and It can be applied as a device.

  Human body fluids are electrically conductive because they contain an electrolyte without exception. In other words, the measurement object of this method is not limited to blood.

[2] Assumptions and Positions in the Present Invention Hereinafter, the background of the idea that “the viscosity of an electrolyte solution can be estimated by measuring electrical conductivity” will be described with reference to known examples and examples of the present invention.

(About diffusion coefficient)
The physical quantity called the diffusion coefficient D dominates the ease of movement of molecules in the solution. The size of the diffusion coefficient D varies depending on the “molecule”. When a spherical molecule of radius a is in a solution of viscosity η, the diffusion coefficient D of this spherical molecule is

と表わされる。「ストークス・アインシュタインの式」と名付けられた式である。ここで、Ｔは絶対温度(K)であり、ｋはボルツマン定数と名付けられた物理定数である。式（１）から、他の条件が同じなら（温度Ｔや分子の半径ａが同じなら）、粘性率ηの値が大きいほど（ネバネバなほど）Ｄの値が小さい（分子は動きにくい）ということがわかる。

It is expressed as It is an expression named “Stokes Einstein's Expression”. Here, T is the absolute temperature (K) and k is a physical constant named Boltzmann constant. From the formula (1), if other conditions are the same (if the temperature T and the radius a of the molecule are the same), the value of D is smaller (the molecule is less likely to move) as the value of the viscosity η is larger (more sticky). I understand that.

(Viscosity measurement by laser scattering method)
Patent Document 1 proposes a technique for obtaining a diffusion coefficient from a measurement of light scattering of serum albumin molecules present in a large amount in serum or plasma and obtaining a viscosity of serum or plasma. This is because the viscosity (defined as the frictional force acting on macroscopic objects that can be observed with an optical microscope at least) is molecular (the serum albumin has a molecular weight of about 66,000 and a size of 8 nm). This is a practical application of viscosity measurement by applying it to the size level.

(Diffusion coefficient and mobility)
If there is an electric field in the solution and the particles (molecules or ions) in the solution have a charge q, a force acts on the particles and the particles move. An amount (velocity per unit electric field) obtained by dividing the moving speed v [m / s] by the electric field strength E [V / m] is referred to as mobility u.

つまり、粒子（イオン）の移動度は溶液の粘性率に反比例する。また式（１）と式（２）とから拡散係数と移動度の間に成り立つ関係式、

That is, the mobility of particles (ions) is inversely proportional to the viscosity of the solution. In addition, a relational expression that holds between the diffusion coefficient and the mobility from the expressions (1) and (2),

が得られる。「アインシュタインの関係式」と呼ばれている。

Is obtained. It is called “Einstein's relational expression”.

  From the equation (3), the following is conceived. Patent Document 1 is a proposal for determining the viscosity of serum or plasma by measuring the diffusion coefficient D. If the temperature T is kept constant, kT / q on the right side of the equation (3) is constant, so obtaining the diffusion coefficient D is virtually the same as obtaining the mobility u. As described below, mobility determines electrical conductivity (easy flow of electricity). That is, the viscosity of the electrolyte solution can be determined by measuring the electrical conductivity.

(Electric conduction of electrolyte solution)
Electric conduction means that “electricity” is “transmitted”. In the electrolyte solution, electric conduction (electric current) is generated by movement of ions, that is, movement of electric charges. It is the electric field in the solution that causes the movement of ions. There is a proportional relationship between the electric field E and the current density J,

が成り立つ。ここでσは該溶液の電気伝導率である。電気伝導率σは、該溶液の「電気の流れやすさ」を表す量であり、溶液の電解質濃度、粘性率などによって定まる。式（４）は、いわゆる「オームの法則」を電場と電流密度で表現したものである。電荷ｑを持った粒子（イオン）の数密度をｎとすると、

Holds. Where σ is the electrical conductivity of the solution. The electric conductivity σ is a quantity that represents the “easy flow of electricity” of the solution, and is determined by the electrolyte concentration, viscosity, etc. of the solution. Equation (4) expresses the so-called “Ohm's law” in terms of electric field and current density. When the number density of particles (ions) having a charge q is n,

が得られる。

Is obtained.

(Relationship between electrical conductivity and viscosity)
According to the chemist's habits, the number density n is expressed by the molar concentration c, and u in the formula (2) is substituted into the formula (5).

という関係が得られる。

The relationship is obtained.

(Estimated)
From Equation (6), the following “estimation” is derived.
“Consider solutions with the same electrolyte concentration c. Change the viscosity by raising or lowering the temperature of the solution or adding glycerin. At this time, the product ση of electrical conductivity and viscosity is constant.”

  Equation (6) is a conclusion derived by calculation under the condition that the interaction between ions is negligible. This is an idealized situation that is realized only when the electrolyte concentration is infinitely dilute. The situation is much more complicated with a finite electrolyte concentration (NaCl 150 mM or so) such as serum or plasma to be measured by the present invention. In the case of an electrolyte solution with physiological concentration, it is common knowledge in chemistry to think that the formula (6) is rather not “simple in a simple form”. Examples 3, 4, 6, and 7 to be described later are measurements for examining how appropriate the “estimation” is.

(Molar conductivity and ultimate molar conductivity)
The amount obtained by dividing the electrical conductivity σ by the molar concentration c is called “molar conductivity” and is represented by Λ _m .

  Therefore, equation (6) becomes

と書くことができる。

Can be written.

The limiting molar conductivity Λ _m ⁰ is the value of molar conductivity when the electrolyte is infinitely diluted (no ions interact).

(Walden rule)
Walden's rule or Walden's rule is a rule derived from empirical observations. The text of physical chemistry (Non-Patent Document 4) describes as follows.
“Walden's rule is an empirical observation that if the product ηΛ _m is the same ion, it is almost constant in various solvents.”
In other literatures, there are many examples where “the product of viscosity and ultimate molar conductivity is constant”.

  Walden's “observation result” is the same as the equation (8) derived from the elementary discussion of the electric conduction of the electrolyte solution.

  However, the text quoted above is followed by: “... How useful this rule is is confusing when considering solvation, because different solvents have the same degree of solvation, even with the same ion, and both the fluid radius and viscosity vary with the solvent.”

(Inventors' position: 1)
Walden's law proposes that "if the product ηΛ _m is the same kind of ion, it is almost constant in various solvents". In addition, considering that there is a reference to the ultimate molar conductivity in many literatures, it is considered that the rule is “only valid for dilute electrolyte solutions”. However, “limited to dilute solutions” is not practical because electrolyte solutions with physiological concentrations such as blood and spinal fluid cannot be handled. Therefore, the present inventors have expanded the Walden rule, so to speak,
(1) It is assumed that “the product of the electrical conductivity and the viscosity of the solution is substantially constant if the electrolyte concentration is constant even at physiological concentrations”. Hereinafter, the extended Walden rule as in this assumption is referred to as an “extended Walden rule” to distinguish it from the original Walden rule.

On the other hand, the present inventors
(2) It is not required that “the product of electrical conductivity and viscosity is almost constant in various solvents”.

(The inventors' position: 2)
The validity of (1) in the previous paragraph must be verified by experiment. The inventors of the present invention assume that “there should be a correlation” between the viscosity value obtained by relying on the “extended Walden rule” and the viscosity value determined by the conventional method. We do not require that the values match exactly.

(The inventors' position: 3)
The meaning of what has been described in (2) above will be described. The present inventors consider that it is an important issue to discuss the magnitude of the value by comparing the viscosity of “human plasma” and “human saliva”, for example, by the method according to the present invention. Absent. Moreover, comparing the values of “viscosity of human plasma” and “viscosity of milk” is not considered an issue. By the method according to the present invention, the present inventors have made various samples (average samples showing normal values or samples derived from diseases, for example, within a limited category of “human plasma” or “human cerebrospinal fluid”. ) To measure the viscosity and detect the change in the value or the value with time. Example 7 “Measurement of viscosity of rat plasma” described later is a demonstration experiment from this viewpoint.

[3] Configuration and operation of the present invention The viscosity measuring method according to the present invention is a viscosity measuring method for measuring the viscosity of a liquid sample containing an electrolyte and impurities other than the electrolyte,
A first step of measuring the electrical conductivity σ ₀ of the sample stock solution;
The electrical conductivity σ ₂ in an aqueous solution in which the sample electrolyte is dissolved in pure water so that the electrolyte concentration c ₂ is the same as the electrolyte concentration c ₂ of the stock solution of the sample is expressed as follows: A second step of estimating by referring to a conversion table or conversion formula representing the relationship of
And a third step of calculating a viscosity η of the stock solution of the sample from a ratio between the estimated electrical conductivity σ ₂ and the electrical conductivity σ ₀ of the stock solution of the sample.

  As explained in [2] above, this viscosity measurement method makes it possible to calculate the viscosity only from the measurement of the electrical conductivity of the sample. Applicable to measurement at room level. Moreover, it was proved that the present invention can be applied to viscosity measurement of various types of liquid samples from the verification test described later.

  Here, the “conversion equation” refers to an equation representing the relationship between the electrolyte concentration and the electrical conductivity obtained by fitting theoretical data or conversion table data (approximation by the least square method or the like).

  In the viscosity measurement method of the present invention, the known predetermined solution may be an aqueous electrolyte solution in which solute ions form a hydrated state.

  The electrolyte ions that contribute to the electrical conduction of the aqueous electrolyte solution used in the conversion table or conversion formula need to have a correlation between the mobility and the viscosity, but the aqueous electrolyte solution in which the solute ions form a hydrated state. This correlation ensures this correlation.

As the “aqueous electrolyte solution that forms a hydrated state”, for example, an aqueous solution of NaCl, KCl, CaCl ₂ , MgSO ₄ , NH ₄ Cl, or the like can be used. However, electrolytes whose cation medium is hydrogen ions, such as HCl and H ₂ SO ₄ , and aqueous solutions of weak acids such as acetic acid, lactic acid, and citric acid are excluded. It is known that the mobility of hydrogen ions hardly depends on the viscosity of the solution, and the weak acid changes the ratio of the medium that ionizes depending on the concentration, so conversion of the electrical conductivity σ ₁ to the electrical conductivity σ ₂ This is because it cannot be performed normally. In addition, although it is preferable that the electrolyte used for a conversion table or a conversion type | formula is the same as the main electrolyte component of a sample, it does not necessarily need to be the same.

Also, the viscosity measuring method according to the present invention for measuring the electrolyte concentration c ₂ and the viscosity η of the sample whose electrolyte concentration c ₂ is unknown, in the second step,
Measuring the electrical conductivity σ ₁ of a diluted solution obtained by diluting the stock solution of the sample with pure water to a predetermined magnification n;
From the electrical conductivity σ ₁ of the diluted solution, by referring to a conversion table or a conversion formula representing the relationship between the concentration of the known predetermined solution and the electrical conductivity, the electrolyte concentration c ₂ of the stock solution of the sample and the electrolyte And obtaining a conductivity σ ₂ converted to a concentration.

When the stock solution of the sample is diluted with distilled water, the concentration of the solute decreases, so that the concentration of impurities (hereinafter simply referred to as “impurities”) other than the electrolyte such as a polymer substance contained in the sample decreases. Therefore, the electrolyte ions in the diluted solution can freely migrate in the solution without being disturbed by impurities, and the electric conductivity of the diluted solution is the pure concentration of the same electrolyte containing no impurities. It can be considered that it is almost equal to the electrical conductivity of the solution. Therefore, if the electric conductivity σ ₁ of the diluted solution is regarded as the electric conductivity of a pure solution of the same electrolyte, the electrolyte concentration of the diluted solution can be estimated by a conversion table or a conversion formula. Next, the electrical conductivity σ ₂ of the pure solution of the electrolyte before dilution is estimated by virtually concentrating the estimated electrolyte concentration to the concentration before dilution and referring to the conversion table or conversion formula again. The Therefore, the viscosity of the stock solution can be estimated by applying the extended Walden rule to the ratio between the converted electrical conductivity σ ₂ and the electrical conductivity σ ₀ of the sample stock solution. As described above, the original Walden law is not a theoretically determined law, but was supposed to be established only in the case of infinite dilution, but in the present invention, by applying the extended Walden law together with the above conversion method, It was experimentally confirmed that the viscosity of the stock solution can be calculated almost accurately for many types of samples.

  In the present invention, the “predetermined magnification n” satisfies the condition that “the viscosity of the diluted solution diluted to the predetermined magnification n is very close to the viscosity of pure water (1.0 mPa · s at 20 ° C.)”. It should be set as follows.

In the viscosity measurement method of the present invention, in measuring the electrical conductivity of the sample in the first or second step, a CR timing system oscillation circuit is used,
Impedance configured by arranging a pair of electrodes apart in the sample liquid is incorporated as an impedance for determining the time constant of the CR timing oscillation circuit, and the CR timing oscillation circuit is oscillated to By measuring the oscillation frequency or the oscillation period, the electrical conductivity of the sample can be determined from the oscillation frequency or the oscillation period.

  For measuring the electrical conductivity of a sample solution (stock solution or diluted solution), an impedance bridge or a Wien bridge oscillation method or a measurement method including an AC oscillation circuit and an AC current measuring device can be used. By using the oscillation frequency or the oscillation period of the timing system oscillation circuit, it is possible to measure the accurate electrical conductivity of the sample solution with a simple measuring instrument configuration.

  In the present invention, as the “CR timing oscillation circuit”, a CMOS Schmitt trigger or an astable multivibrator employing an operational amplifier as an active element can be used. The oscillation circuit may be any circuit that oscillates a periodic waveform having a specific fundamental oscillation frequency such as a rectangular wave or a sine wave having a duty of about 50%.

The first configuration of the viscosity measuring device according to the present invention is a viscosity measuring device that measures the viscosity of a liquid sample containing an electrolyte and impurities other than the electrolyte.
Measure the electrical conductivity σ ₀ of the stock solution of the sample,
The electrical conductivity σ ₂ in an aqueous solution in which the sample electrolyte is dissolved in pure water so that the electrolyte concentration c ₂ is the same as the electrolyte concentration c ₂ of the stock solution of the sample is expressed as follows: Estimated by referring to a conversion table or conversion formula representing the relationship of
The viscosity η of the stock solution of the sample is calculated from the ratio between the estimated electrical conductivity σ ₂ and the electrical conductivity σ ₀ of the stock solution of the sample.

  This configuration makes it possible to calculate the viscosity only from the measurement of the electrical conductivity of the sample, so the viscosity of a very small amount of sample can be measured at high speed and easily, and the device configuration is simpler than before. Applicable to measurement at room level. Further, it has been proved that the present invention can be applied to viscosity measurement of various types of liquid samples from a verification test described later.

  The second configuration of the viscosity measuring apparatus according to the present invention is characterized in that, in the first configuration, the known predetermined solution is an aqueous electrolyte solution in which solute ions form a hydrated state.

  As described above, the electrolyte ions that contribute to the electrical conduction of the aqueous electrolyte solution used in the conversion table or conversion formula must have a correlation between the mobility and the viscosity of the solution, but the solute ions are in a hydrated state. This correlation is ensured by using an aqueous electrolyte solution that forms.

A third configuration of the viscosity measuring apparatus in which the electrolyte concentration c ₂ according to the present invention measures the electrolyte concentration c ₂ and the viscosity of the unknown of the sample η, in the structure of the first or 2, wherein the sample The electrical conductivity σ ₁ of a diluted solution obtained by diluting the stock solution of
From the electrical conductivity σ ₁ of the diluted solution, by referring to a conversion table or a conversion formula representing the relationship between the concentration of the known predetermined solution and the electrical conductivity, the electrolyte concentration c ₂ of the stock solution of the sample and its electrolyte An electrical conductivity σ ₂ converted to a concentration is calculated.

With this configuration, as described above, the viscosity of the stock solution of the sample can be obtained from the ratio of the electrical conductivity σ ₂ and the electrical conductivity σ ₀ of the stock solution using the extended Walden rule. In the present invention, the actual measurement part is only the measurement of the electrical conductivity of the stock solution and the diluted solution of the sample, and this measurement can be performed using a simple measuring device. Since the conversion of the rate can also be performed by a simple calculation (division and table reference (or conversion formula reference)), the entire apparatus can be simplified and downsized. Therefore, it is sufficiently applicable to measurement at the laboratory level. Furthermore, it is possible to easily realize a measuring apparatus having a palm size or less by driving a battery as a whole including automation of dilution operation.

  In addition, when the electrolyte concentration of the stock solution is known, the dilution operation is not necessary, and the viscosity measuring device in that case is only an electric circuit, so that further miniaturization is possible. If IC manufacturing technology is applied, it is possible to make an ultra-compact measuring chip that supplies power from outside RF, such as RFID (Radio Frequency IDentification), and returns the measurement result by RF.

  If only the trend of changes in electrolyte concentration and viscosity of body fluid and the trend over time are to be captured, an electrode provided in the body fluid container (cell) is provided in a CR timing system oscillation circuit as shown in FIG. It is possible to simply connect and continuously record and monitor the frequency or period. A small and light “body fluid monitoring device” that is smaller than the palm size and issues an alarm when it deviates from a preset threshold value becomes possible. Here, the body fluid refers to blood, lymph, cerebrospinal fluid, intestinal fluid, bile, pancreatic juice, tears (aqueous humor), saliva, sweat, and the like.

Moreover, the 4th structure of the viscosity measuring apparatus which concerns on this invention is a container which stores the said sample in the said 3rd structure,
Electrical conductivity measuring means for measuring electrical conductivity of the sample stored in the container;
Water injection means for injecting water into the sample stored in the container;
After measuring the electrical conductivity σ ₀ of the stock solution of the sample stored in the container by the electrical conductivity measuring means, the stock solution of the sample is diluted with pure water to a predetermined magnification n by the water injection means, Measurement control means for measuring the electrical conductivity σ ₁ of the diluted solution;
From the electrical conductivity σ ₁ of the diluted solution, by referring to a conversion table or a conversion formula representing the relationship between the concentration of the predetermined known solution and the electrical conductivity, the electrolyte concentration c ₂ of the sample stock solution and its electrolyte An electrical conductivity conversion means for calculating an electrical conductivity σ ₂ converted into a concentration;
Viscosity calculation means for calculating the viscosity of the sample stock solution from the ratio between the converted electrical conductivity σ ₂ and the electrical conductivity σ ₀ of the sample stock solution;
It is provided with.

Further, a fifth configuration of the viscosity measuring device according to the present invention is the fourth configuration, wherein the electrical conductivity measuring means is
A CR timing oscillation circuit in which an impedance configured by separating a pair of electrodes in the sample liquid is incorporated as an impedance for determining a time constant;
An oscillation state measuring instrument for measuring an oscillation frequency or an oscillation period of the CR timing oscillation circuit;
Electrical conductivity conversion means for determining the electrical conductivity of the sample from an oscillation frequency or an oscillation period measured by the oscillation state measuring device.

  Here, the “oscillation state measuring device” may measure the oscillation frequency and the oscillation period simultaneously. In order to facilitate subsequent data processing such as electrical conductivity conversion, it is preferable to use an oscillation state measuring instrument that converts the measured oscillation frequency or oscillation period into digital data and transmits it.

In the present invention, the measurement control means, the electric conductivity conversion means, and the viscosity calculation means are provided as a computer program, and the program is read into the computer and executed, whereby the computer is configured with the fourth configuration. You may make it operate | move as a measurement control means, electrical conductivity conversion means, and viscosity calculation means in the viscosity measuring device.

  The program may be recorded on a CD-ROM, DVD-ROM, memory stick or other program recording medium, or distributed to a computer as needed through an electric communication line such as the Internet. Also good. The “computer” is not limited to a general-purpose computer such as a personal computer or a workstation, but also includes a chip computer such as a microcomputer and a reconfigurable logic circuit.

  The test method for blood or vascular disease according to the present invention is characterized by measuring the viscosity of serum or plasma electrolyte and the concentration of electrolyte obtained at the same time by the viscosity measurement method, and comparing this with a normal value. To do.

  Conventional viscosity measurement methods (for example, a method using a vibratory viscometer) require a relatively large number of samples (blood) for measurement, so it is practically possible to measure the viscosity of a very small amount of blood. However, in the viscosity measuring method according to the present invention, it is only necessary to measure the electrical conductivity of the sample (blood), and therefore it is possible to measure the viscosity of a very small amount of blood.

  Further, the method for examining blood or vascular disease or its pathological change according to the present invention is to measure and record the viscosity of serum or plasma and the electrolyte concentration obtained simultaneously with the viscosity measurement method, and record the viscosity. It is characterized by examining blood or vascular diseases or pathological changes thereof based on changes in the rate and electrolyte concentration over time.

  In addition, the method for examining blood or vascular disease according to the present invention or the method for examining blood or vascular disease or its pathological change according to the present invention may be used to examine a disease that causes an increase in serum or plasma viscosity. it can. “Disease causing increase in serum or plasma viscosity” refers to myeloma, primary macroglobulinemia, chronic hepatitis, myocardial infarction, cerebral infarction, membranous nephritis, and other so-called lifestyle-related diseases.

  In addition, it is possible to examine a disease state in which the viscosity of serum or plasma is reduced by the method for examining blood or vascular disease according to the present invention or the method for examining blood or vascular disease or its pathological change according to the present invention. it can. “A disease state in which the viscosity of serum or plasma is reduced” refers to various anemias such as iron deficiency anemia and hemolytic anemia, and hypoproteinemia such as nephrotic syndrome and liver damage.

  The body fluid electrolyte concentration and viscosity testing system according to the present invention is a body fluid viscosity testing system for measuring a body fluid viscosity, and includes the viscosity measuring device having any one of the first to fifth configurations. Features. Here, “body fluid” refers to blood, lymph, cerebrospinal fluid, intestinal fluid, bile, pancreatic juice, tears (aqueous humor), saliva, sweat, and the like.

  The food production apparatus according to the present invention is a food production apparatus that measures, controls, and records the temperature and viscosity of a food material in a liquid or gel food production process. A viscosity measurement device is provided.

  As described above, according to the present invention, it is possible to easily and quickly determine the electrolyte concentration and viscosity using a small amount of sample. By utilizing this, it becomes possible to provide each inspection method, body fluid viscosity inspection system, and food production apparatus as described above.

It is a figure showing the relationship between the density | concentration of NaCl, KCl aqueous solution, and molar conductivity. It is a block diagram showing the whole structure of the viscosity measuring apparatus which concerns on Example 1 of this invention. It is a figure which shows an example of one measurement cell 10 of the electrical conductivity measurement cell group 3 of FIG. It is a block diagram showing the function structure of the impedance measuring device 6 and the computer 7 of FIG. FIG. 5 is a diagram illustrating a specific configuration example of a CR timing oscillation circuit 21 in FIG. 4. FIG. 5 is a diagram illustrating another specific configuration example of the CR timing oscillation circuit 21 of FIG. 4. It is a flowchart showing operation | movement of the viscosity measuring apparatus which concerns on Example 1 of this invention. It is a figure which shows the relationship between the resistance value R of a timing resistor, and the oscillation period T. It is a figure which shows the correlation with the measured value by the viscosity measuring method of the present invention, and the measured value by the viscosity measuring method of this invention of the viscosity of the glycerol-salt aqueous solution in Example 4 with a ready-made viscometer (Viscomate). It is a figure which shows the relationship between the temperature of a pure water and NaCl diluted solution, and a viscosity. It is a figure which shows the relationship between the temperature of a pure water and a KCl dilute solution, and a viscosity. It is a figure which shows the relationship between the temperature and viscosity of a pure water and HCl dilute solution. It is a figure which shows the relationship between the temperature of a pure water and diluted seawater, and a viscosity. It is the measurement result which followed the fermentation process of yogurt as a change of electrical conductivity. FIG. 6 is a diagram in which the boiled food that has been fluidized by raising the temperature is left at room temperature, and its electrical conductivity is measured as an oscillation frequency using the CR timing oscillation circuit 21 of FIG. 5 and continuously recorded. It is a figure which shows the measurement result of the change of the impedance of the polymer film type | mold humidity sensor using CR timing system oscillation circuit. It is a block diagram showing the whole structure of the viscosity measuring apparatus which concerns on Example 17. FIG. It is a figure which shows an example of the measurement cell 10 of FIG.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

[1] Basic concept of viscosity measuring method according to the present invention Basically, the present invention is a technique for measuring the electrical conductivity of a sample under a specific temperature condition and converting the electrical conductivity into a viscosity. It is. The extended Walden's law representing the relationship between the molar conductivity of ions in solution and the viscosity is applied to the measured electrical conductivity data of the sample to calculate the electrolyte concentration and the viscosity of the sample. The electrical conductivity of the electrolyte solution is considered to be determined by combining both the electrolyte concentration of the sample and the viscosity of the sample. Therefore, “contribution of electrolyte concentration” and “contribution of viscosity” to electrical conductivity must be separated. This “separation” is easy if the electrolyte concentration is known. However, when the electrolyte concentration is unknown, it is necessary to devise the measurement operation.

In the present invention, in addition to the measurement of the electrical conductivity σ ₀ of the sample stock solution, a new measurement of “the electrical conductivity σ ₁ of a diluted solution obtained by diluting the sample stock solution with water (pure water) to a predetermined magnification n” is performed. It solves this problem by adding a new measurement step. The dilution factor (predetermined factor n) may satisfy the condition that the viscosity of the diluted solution is very close to the viscosity of pure water (1.0 mPa · s at 20 ° C.). If this condition is satisfied, the “contribution of viscosity” to the electrical conductivity can be ignored. Refer to a published conversion table (for example, see Non-Patent Document 3), From the “rate”, “the electrolyte concentration of the diluted solution” is obtained. If the electrolyte concentration of the diluted solution is determined, it can be “arithmetically concentrated” by the dilution factor n to determine “the electrolyte concentration of the stock solution of the sample”. An “arithmetically concentrated sample”, that is, an electrolyte solution having the same concentration as the sample stock solution is virtually “a solution in which electrolyte is dissolved in pure water free of impurities such as protein and sugar” (hereinafter referred to as “virtual solution”). "). Then, referring to the conversion table again, the electrical conductivity σ ₂ of the virtual solution is obtained. The measured value σ ₀ of the electrical conductivity of the sample stock solution is necessarily smaller than the electrical conductivity σ ₂ of the virtual solution.

  When the viscosity of the sample stock solution is η and the extended Walden law is applied, the viscosity η can be obtained by the following equation.

  Therefore, an unknown sample is obtained by (1) diluting the sample, (2) measuring the electric conductivity twice, and (3) calculating the electrolyte concentration by referring to the conversion table (electrical conductivity-concentration conversion table). Can be obtained.

[2] Selection of Dilution Rate Here, how to determine the dilution rate n in the viscosity measuring method according to the present invention will be considered. As described above, since the dilution operation of the sample stock solution is performed for the purpose of removing the “contribution of viscosity” to the electrical conductivity of the sample, the viscosity of the diluted solution is basically the viscosity of pure water. What is necessary is just to dilute so that it may become comparable to a rate. Therefore, as a preliminary experiment, it is a familiar electrolyte solution,
(A) Soy sauce (viscosity 3-4 mPa · s)
(B) Milk (Viscosity ~ 1.8mPa · s)
Was diluted 21 times with pure water, and the viscosity was measured with a ready-made viscometer. As a result, the viscosity of any diluted solution was very close to the viscosity of pure water (1 mPa · s). Therefore, it was estimated that a 21-fold dilution would be sufficient for biological samples such as plasma.

  In the measurement of the viscosity of rat plasma, which will be described later, since the amount of the sample stock solution that can be used is as small as about 1 mL, the viscosity of the diluted solution was not confirmed, and a 21-fold dilution was adopted. After the measurement, each sample was diluted to about 20 mL, and the viscosity was measured with a ready-made viscometer. As a result, the viscosity of any diluted solution was very close to the viscosity of pure water.

[3] Electrolyte concentration: the concept of “standard electrolyte conversion” In the above-described viscosity measurement method according to the present invention, regarding “(1) Sample dilution operation” and “(2) Measurement of electrical conductivity twice” There is no particular problem. However, in “(3) Calculation of electrolyte concentration by referring to conversion table (electrical conductivity-concentration conversion table)”, “electrical conductivity σ ₁ ” to “electrolyte concentration c ₁ ”, “ It is necessary to convert and determine “electrical conductivity σ ₂ ” from the electrolyte concentration nc ₁ ”. However, since the conversion table cannot be referred to unless the type of electrolyte in the diluted solution is determined, the conversion cannot be performed.

  In the examples described later, the concept of “standard electrolyte conversion” (specifically “NaCl conversion”) was adopted to estimate the viscosity of milk, soy sauce, saliva, rat plasma, and the like. "Standard electrolyte conversion" means that the electrolyte dissolved in the sample is only a specific representative electrolyte, and conversion between conductivity and concentration is performed using the standard electrolyte conversion table. It is a way of thinking. That is, for example, in the case of “NaCl conversion”, each sample is simply regarded as “saline mixed with impurities (which do not contribute to electrical conduction)” and the concentration of the salt is determined.

  Since soy sauce is a concentrated salt solution in the first place, it is natural to approximate it by NaCl conversion. However, the ionic composition of milk, plasma and other biological samples is generally much more complex. It is necessary to examine whether it is appropriate to approximate the electrolyte solution having such a complicated composition with a simple saline solution and apply “NaCl conversion”.

  This is not a problem that can be determined theoretically. This is because even a pure NaCl solution has a physiological concentration (˜150 mM), it is difficult to explain its electric conduction from the first principle, and it becomes more difficult when it becomes a mixture. It is also pointed out that the original Walden rule is an empirical rule that can be established with an infinitely diluted electrolyte solution, and there are exceptions. Therefore, as a standpoint in the present invention, the viscosity is calculated using the approximation “standard electrolyte conversion” and the extended Walden rule for the time being, and the validity of this approximation is verified by experiment.

In general, sodium ions (Na ⁺ ) are the main role (cations) of electrical conduction in animal body fluids including humans. In the present invention, the contribution to electrical conduction of other ions (for example, calcium ions) mixed in other than that is represented by a typical ion species (standard electrolyte) as “corresponding to this concentration if sodium ions”. It is approximated by conversion. On the other hand, the contribution of anions is similarly approximated in terms of chloride ions (Cl ⁻ ).

  In the present invention, the “standard electrolyte” is not limited to “NaCl”, and an appropriate “standard electrolyte” may be appropriately selected according to the sample to be measured.

Potassium ions (K ⁺ ) are present in large amounts in animal cells, but are small outside the cells (ie, in body fluids). Therefore, for example, it is biologically unnatural to evaluate the salt concentration of human plasma in terms of KCl. However, the aqueous KCl solution is similar in concentration to the conductivity of NaCl (see FIG. 1). Therefore, even if approximated by “KCl conversion”, a viscosity value approximated by “NaCl conversion” should be obtained. As shown in Examples described later, it has been experimentally confirmed that the viscosity value of rat plasma determined by “KCl conversion” matches the viscosity value calculated by “NaCl conversion” with good accuracy. .

  The viscosity measuring method according to the present invention includes a container (blind-end glass tube, test tube, beaker, etc.) for storing a sample solution, a conductivity meter (electric conductivity meter) for measuring the electrical conductivity of a liquid, and other electrical devices. As long as there is a conductivity measuring device and a device (pipette, dispenser, washing bottle, etc.) for injecting / injecting a sample or water into the container, the measurer performs the conductivity measurement manually, and the above calculation method is used. It is possible to calculate the viscosity. Since this operation is a mechanical operation, it can be automated to some extent and measurement can be performed easily. Therefore, in the present embodiment, an embodiment of a viscosity measuring device that can easily perform the above-described conductivity measurement will be described.

  FIG. 2 is a block diagram illustrating the overall configuration of the viscosity measurement device according to the first embodiment of the present invention. The viscosity measuring device 1 of this embodiment includes a distilled water tank 2, an electric conductivity measuring cell group 3, a sample diluting device 4, a cell cleaning / drying device 5, an impedance measuring device 6, a computer 7, a display device 8, and an input / output. A device 9 is provided.

  The distilled water tank 2 stores distilled water (pure water) used for dilution or washing. The electrical conductivity measurement cell group 3 includes one or more measurement cells (containers) for measuring the electrical conductivity of the sample solution. The sample diluting device 4 is a device (water injection means) for diluting the sample solution by supplying a set amount of distilled water from the distilled water tank 2 to each measuring cell of the electrical conductivity measuring cell group 3. The cell washing / drying device 5 supplies distilled water from the distilled water tank 2 to each measurement cell of the electrical conductivity measurement cell group 3 to wash each measurement cell, and blows dry air to each measurement cell. An apparatus for drying each measurement cell. The cell cleaning / drying device 5 may be configured to generate and mix microbubbles in distilled water to be sent to each measurement cell to enhance the cleaning capability. The impedance measuring device 6 is a device (electric conductivity measuring means) that measures the electric conductivity of the sample solution in each measurement cell of the electric conductivity measuring cell group 3.

The computer 7 is a control device for performing overall viscosity measurement control and data calculation. The computer 7 includes a storage device therein, and the storage device stores a conversion table that represents the relationship between the concentration of the standard electrolyte and the electrical conductivity. The computer 7 measures the electrical conductivity σ ₀ of the sample stock stored in each measurement cell with the impedance measuring device 6, and then dilutes the sample stock with distilled water to a predetermined magnification n with the sample diluting device 4. , And functions as a measurement control means for measuring the electrical conductivity σ ₁ of the diluted solution by the impedance measuring device 6. Further, the computer 7 refers to an electrical conductivity conversion means for calculating the electrical conductivity σ ₂ converted to the concentration of the stock solution of the sample by referring to the conversion table from the electrical conductivity σ ₁ of the diluted solution, and the conversion A program that also functions as a viscosity calculating means for calculating the viscosity of the sample stock solution from the ratio of the measured electrical conductivity σ ₂ and the sample stock solution conductivity σ ₀ is installed.

  The display device 8 is a display connected to the computer 7. The input / output device 9 is an input / output device connected to the computer 7 such as a mouse, a keyboard, a CD-ROM drive, a DVD-ROM drive, an external storage device, and a printer.

  FIG. 3 is a diagram illustrating an example of one measurement cell 10 in the electrical conductivity measurement cell group 3 of FIG. The measurement cell 10 has a housing chamber 12 formed in a hollow shape inside a housing 11 made of glass, resin, or the like, and an upper opening 12a that opens upward is formed in the upper portion of the housing chamber 12. Yes. In addition, narrow tubular inflow passages 13 and outflow passages 14 are horizontally drilled in the left and right side walls of the storage chamber 12, and the outer ends of the inflow passage 13 and the outflow passage 14 project in a tubular shape from the side walls of the housing 11. It opens at its tip. An inflow side cock 15 that opens and closes the inflow path 13 is provided in the middle of the inflow path 13, and an outflow side cock 16 that opens and closes the outflow path 14 is provided in the middle of the outflow path 14. The inflow side cock 15 and the outflow side cock 16 are electrically driven by a motor, and the opening / closing operation thereof is controlled by the computer 7. In addition, electrodes 17 a and 17 b are inserted into the storage chamber 12 from above, and the lower ends of the electrodes 17 a and 17 b extend to the vicinity of the inner bottom surface of the storage chamber 12. The electrodes 17a and 17b are covered with an insulator except for the tips. The tips of the electrodes 17a and 17b are plated with gold in order to provide corrosion resistance. The electrical conductivity of the liquid in the storage chamber 12 is measured by the electrodes 17a and 17b. The proximal ends of the electrodes 17 a and 17 b are connected to the impedance measuring device 6. Furthermore, a temperature sensor 18 for measuring the temperature of the liquid in the storage chamber 12 is installed on the side wall near the bottom surface of the storage chamber 12. A Peltier element 19 for controlling the temperature of the liquid in the storage chamber 12 is installed on the bottom surface of the storage chamber 12. The temperature sensor 18 and the Peltier element 19 are connected to the computer 7 so that the temperature of the liquid in the storage chamber 12 can be measured and controlled from the computer 7.

  FIG. 3 shows a configuration in which the electrodes 17a and 17b are used for measuring the electrical conductivity, but a sensor such as a conductivity meter (electrical conductivity meter) is used instead of the electrodes 17a and 17b. You can also.

  FIG. 4 is a block diagram showing functional configurations of the impedance measuring device 6 and the computer 7 of FIG. 4, components corresponding to those in FIGS. 2 and 3 are denoted by the same reference numerals.

  The impedance measuring device 6 includes a CR timing system oscillation circuit 21 and an oscillation state measurement circuit 23. The CR timing oscillation circuit 21 is an oscillation circuit using a normal CR circuit, and the impedance (timing resistance) part that determines the time constant is the electrodes 17a and 17b. The oscillation state measurement circuit 23 detects the fundamental frequency or period of the voltage of the oscillation signal and outputs it as a digital signal (frequency detection value signal) proportional to the frequency value or period value. The oscillation state measurement circuit 23 can be configured using a microcomputer or the like.

  The computer 7 includes an open / close control circuit 31, a current control circuit 32, an A / D conversion circuit 33, an I / F circuit 34, an electrical conductivity conversion unit 35, a conversion table storage unit 36, a viscosity calculation unit 37, and a measurement control unit 38. It has.

The open / close control circuit 31 is a circuit that outputs a control signal for controlling the opening / closing of the inflow side cock 15 and the outflow side cock 16 of each measurement cell 10. The current control circuit 32 is a circuit that controls the current supplied to the Peltier element 19 of each measurement cell 10. The A / D conversion circuit 33 is a circuit that converts an analog voltage signal output from the temperature sensor 18 of each measurement cell 10 into a digital signal. The I / F circuit 34 is a circuit for receiving the frequency detection value signal output from the oscillation state measurement circuit 23 of the impedance measuring device 6.
The electrical conductivity conversion unit 35 converts the value of the frequency detection value signal into electrical conductivity.
The conversion table storage unit 36 stores a conversion table representing the relationship between the standard electrolyte solution concentration and the electrical conductivity.

The viscosity calculation unit 37 calculates the concentration of the standard electrolyte from the electrical conductivity by referring to the conversion table. Further, the electric conductivity of the standard electrolyte solution corresponding to the electrolyte concentration of the stock solution calculated from the electrolyte concentration of the diluted solution is calculated by referring to the conversion table. Further, the viscosity η of the sample stock solution is calculated from the electrical conductivity σ ₀ of the sample stock solution calculated by the electrical conductivity conversion unit 35 and the converted electrical conductivity σ ₂ of the standard electrolyte solution.

  The measurement control unit 38 controls the cell cleaning / drying device 5, the open / close control circuit 31, the current control circuit 32, the A / D conversion circuit 33, the electrical conductivity conversion unit 35, and the viscosity calculation unit 37, thereby measuring the viscosity. Take overall control.

  FIG. 5 is a diagram illustrating a specific configuration example of the CR timing oscillation circuit 21 of FIG. The CR timing oscillation circuit 21 is an astable multivibrator including a Schmitt inverter 41, a capacitor 42, and a feedback impedance 43. The oscillation frequency of this circuit is determined by a time constant determined by the capacitor 42 and the feedback impedance 43. Therefore, the feedback impedance 43 is set to the electrodes 17a and 17b (or conductivity sensor) of the measurement cell 10. Thereby, the fundamental frequency of oscillation is determined in inverse proportion to the resistance of the electrodes 17a and 17b. Therefore, by detecting the fundamental frequency of the voltage at the output terminal OUT with the oscillation state measuring circuit 23, the resistance between the electrodes 17a and 17b (that is, the conductivity of the sample solution) can be measured.

  FIG. 6 is a diagram showing another specific configuration example of the CR timing oscillation circuit 21 of FIG. In FIG. 6, instead of the Schmitt inverter 41 of FIG. 5, a non-stable multivibrator is configured using a differential amplifier 41 '. Also in this case, the feedback impedance 43 is set to the electrodes 17a and 17b (or conductivity sensor) of the measurement cell 10. As a result, the fundamental frequency of oscillation is determined in proportion to the resistance of the electrodes 17a and 17b. Therefore, by detecting the fundamental frequency of the voltage at the output terminal OUT with the oscillation state measuring circuit 23, the resistance between the electrodes 17a and 17b (that is, the conductivity of the sample solution) can be measured.

  5 and 6 are examples, and other known CR timing oscillation circuits can be used. For example, there is a possibility that the current waveform flowing through the sample may be a sine wave. In this case, a sine wave oscillator can be used for the CR timing oscillation circuit 21.

  In the present embodiment, the configuration using the CR timing oscillation circuit 21 for measuring the electrical conductivity of the sample solution has been described. However, in the present invention, other known methods are employed for measuring the electrical conductivity. You can also For example, (b) a method using an impedance bridge circuit, (b) an oscillator, an IV converter, and an A / D converter can be considered.

  The operation of the viscosity measuring apparatus according to the first embodiment of the present invention configured as described above will be described below. FIG. 7 is a flowchart showing the operation of the viscosity measuring device according to the first embodiment of the present invention.

First, the measurer injects a stock solution of a sample whose viscosity is to be measured into the storage chamber 12 of the measurement cell 10 from the upper opening 12a (S101). Here, the “sample” is a liquid sample containing an electrolyte and impurities other than the electrolyte. For example, body fluids such as blood and lymph, and gel foods. The stock solution is injected using a pipette or the like. At this time, the inflow side cock 15 and the outflow side cock 16 are in a closed state. Then, the user operates the computer 7 to start the viscosity measurement program. The measurer then measures the amount of the stock solution injected into the measurement cell 10 (volume V ₀ or mass m ₀ ), the set temperature T _{0 at} which the viscosity measurement is performed, the type of standard electrolyte (NaCl, KCl, etc.) used for conversion, After inputting the measurement conditions such as the dilution factor n and the cell constant (the frequency of the measurement cell 10-the calibration constant when converting the electrical conductivity) to the computer 7, an instruction to start measurement is input from the input / output device 9.

When an instruction to start measurement is input, the measurement control unit 38 measures the temperature T of the sample stock solution with the temperature sensor 18, and controls the energization of the Peltier element 19 with the current control circuit 32. The temperature T is adjusted to the set temperature T ₀ (S102).

Next, the measurement control unit 38 energizes the stock solution of the sample by the impedance measuring device 6 and detects its oscillation frequency or oscillation cycle. Then, the oscillation frequency or oscillation cycle detected by the electrical conductivity conversion unit 35 is converted into electrical conductivity σ ₀ and output to the measurement control unit 38 (S103).

Next, the measurement control unit 38 calculates the amount of water used for dilution from the amount of the stock solution (volume V ₀ or mass m ₀ ), and calculates the amount of injected water that becomes the magnification n at which the dilution factor is set. Then, the inflow side cock 15 is opened by the open / close control circuit 31, and the sample dilution device 4 injects pure water of the injection water amount calculated from the distilled water tank 2 into the storage chamber 12, and the sample solution in the storage chamber 12 is multiplied by n times. (S104).

Next, the measurement control unit 38 measures the temperature T of the diluted solution of the sample by the temperature sensor 18, and controls the energization of the Peltier element 19 by the current control circuit 32, so that the temperature T of the diluted solution of the sample becomes the set temperature. Adjustment is made so as to be T ₀ (S105).

Next, the measurement control unit 38 energizes the stock solution of the sample by the impedance measuring device 6 and detects its oscillation frequency or oscillation cycle. Then, the oscillation frequency or oscillation cycle detected by the electrical conductivity conversion unit 35 is converted into the electrical conductivity σ ₁ and output to the viscosity calculation unit 37 (S106). The viscosity calculation unit 37 calculates the standard electrolyte concentration c ₁ corresponding to the electrical conductivity σ ₁ with reference to the set standard electrolyte conversion table (or conversion formula) (S107).

Next, the viscosity calculation unit 37 calculates the electrolyte concentration c ₂ = n · c ₁ of the stock solution, and refers to the standard electrolyte conversion table (or conversion formula), and the standard corresponding to the electrolyte concentration c ₂ The electrical conductivity σ ₂ of the electrolyte is calculated, and the electrolyte concentrations c ₁ and c ₂ and the electrical conductivities σ ₁ and σ ₂ are output to the measurement control unit 38 (S108). Then, the viscosity calculating unit 37 calculates the viscosity η = (σ ₂ / σ ₀ ) × η _w (η _w is the viscosity of the aqueous solution at the same temperature and the same electrolyte concentration) of the sample stock solution, and the measurement control unit 38. (S109).

Next, the measurement control unit 38 outputs / displays the measured or calculated viscosity η, electrolyte concentrations c ₁ , c ₂ , and electrical conductivity σ ₀ , σ ₁ , σ ₂ on the display device 8, and inputs and outputs It outputs to the apparatus 9 (S110).

  When the measurement is finished, the measurer inputs a cleaning execution instruction from the input / output device 9 to the computer 7 (S110). When the cleaning execution instruction is input, the measurement control unit 38 first opens the outflow side cock 16 by the open / close control circuit 31 to discharge the solution in the storage chamber 12 (S201).

  Next, the measurement control unit 38 opens the inflow side cock 15 by the open / close control circuit 31 and outputs a cleaning instruction to the cell cleaning / drying device 5. The cell cleaning / drying apparatus 5 repeatedly injects distilled water into the storage chamber 12 (S202) and discharges (S203) a predetermined number of times N (S204), thereby cleaning the measurement cell 10.

  After completion of the cleaning, the cell cleaning / drying device 5 blows dry air into the storage chamber 12 of the measurement cell 10 to dry the storage chamber 12 and ends the cleaning process (S205).

By the above method, the viscosity of the sample η and electrolyte concentration c ₂ is measured. Since the viscosity measuring apparatus 1 of the present embodiment can easily measure a very small amount of sample, it can be applied in various fields where the conventional sample is too small to measure the viscosity. Become. For example, the viscosity measuring device 1 measures the viscosity of the electrolyte of serum or plasma or other body fluids and the concentration of the electrolyte obtained at the same time, and compares this with the normal value, so that a blood or vascular disease testing device or body fluid can be obtained. It can be applied as a viscosity inspection system (see Examples 7 to 9). In addition, the temperature and viscosity of the food material in the liquid or gel food manufacturing process are measured, controlled and recorded by the viscosity measuring device 1 of this embodiment, so that it can be applied to the food manufacturing device. (See Examples 10, 11, 12, 16).

  Below, some examples performed for verification of the accuracy and effectiveness of the viscosity measuring method according to the present invention will be described.

(Measurement of electrical conductivity using Schmitt inverter oscillation circuit)
First, an experimental procedure for measuring the electrical conductivity of the electrolyte solution using the CR timing oscillation circuit 21 and the pair of electrodes 17a and 17b shown in FIG. 5 will be described. The electrodes 17a and 17b were formed by connecting lead wires to gold-plated “header pin terminals” and waterproofing the connecting portions.

  FIG. 8 is a diagram in which an oscillation period is calculated and plotted from an oscillation frequency measured by connecting a dial resistor (YOKOGAWA 2768) as the timing resistor R in FIG. 5 and changing the resistance value. The horizontal axis represents the resistance value of the timing resistor R, and the vertical axis represents the oscillation period T. 8 that the oscillation period T is completely proportional to the timing resistance R.

  Next, instead of the dial resistor, the lead wires of the electrodes 17a and 17b are connected, and the electrodes 17a and 17b are connected to respective standard electrolyte solutions (10 mM NaCl solution, 10 mM KCl solution, 100 mM KCl solution, and 100 mM NaCl solution). Oscillation was performed by sequentially immersing, and the oscillation frequency was measured. The interelectrode resistance R corresponding to each salt solution was determined from the oscillation frequency. The interelectrode resistance R can be obtained from the graph of FIG. 8, but this time, in order to increase the measurement accuracy, a dial resistor is connected again instead of the electrodes 17a and 17b, and the oscillation corresponding to each reference solution is performed. The frequency was reproduced and determined. Table 1 also shows the interelectrode resistance R and the electrical conductivity of each solution (Non-Patent Document 3).

  According to the rudimentary theory of the electrical conductivity of the electrolyte solution (Non-patent Document 3), the electrical conductivity σ of the electrolyte solution and the interelectrode resistance R immersed therein have the following relationship: .

ここで、定数Ｋは電極１７ａ，１７ｂや収容室１２の幾何学的形状によって定まる固有の量で電極定数（セル定数）と呼ばれる。

Here, the constant K is a specific amount determined by the geometric shapes of the electrodes 17a and 17b and the storage chamber 12, and is called an electrode constant (cell constant).

From the results in Table 1, it can be said that the resistance value of the interelectrode resistance R expressed as the oscillation frequency of the Schmitt inverter oscillation circuit correctly reflects the electrical conductivity of the electrolyte solution. Also, from this measurement, the average value of the electrode constant K of the electrodes 17a and 17b used in this experiment was 334m- ¹ .

As already described, the measurement of the electrical conductivity σ _x of an unknown sample using the CR timing system oscillation circuit 21 can be performed by the following procedure.
(1) A pair of electrodes 17a and 17b whose electrode constant K is known are prepared.
(2) The electrodes 17a and 17b are connected to the CR timing oscillation circuit 21.
(3) The oscillation frequency is measured by immersing the electrodes 17a and 17b in the sample solution.
(4) A resistance value _Rx corresponding to the measured oscillation frequency is determined using a graph, a regression equation, or a dial resistor as shown in FIG.
(5) The electrical conductivity σ _x of the unknown sample is calculated using Equation (11).

(Measurement of viscosity of saline solution with various concentrations of glycerin)
Next, taking as an example the case of using glycerin as a sample, the procedure for estimating the viscosity of the electrolyte solution from the electrical conductivity measurement will be described in detail.

(sample)
Saline solutions with various concentrations of glycerin were prepared. All of the glycerin solutions are adjusted so that the NaCl concentration is strictly 150 mM, and the glycerin concentration is changed so that the viscosity is within the range of 1.0 to 1.2 mPa · s. It was created. A 150 mM NaCl solution containing no glycerin was used as a reference sample. The viscosity of this reference sample was 1 mPa · s, the same as that of pure water.

(Off-the-shelf viscometer)
A comparison was made between the viscosity value measured with a commercially available vibratory viscometer (yamco MODEL VM-1A: hereinafter referred to as “Viscomate”) and the viscosity value obtained by the viscosity measurement method according to the present invention. . The Viscomate was calibrated with pure water (viscosity 1 mPa · s) at room temperature (˜20 ° C.).

(Oscillation circuit)
As in Example 2, a Schmitt inverter oscillation circuit was used as the oscillation circuit used for measuring the electrical conductivity. As described in the second embodiment, the oscillation period T of this oscillation circuit is strictly proportional to the resistance value of the timing resistor R. That is, the following equation holds.

  When the timing resistance R is replaced with the electrodes 17a and 17b immersed in the electrolyte solution, the oscillation period is proportional to the interelectrode resistance. As shown in Example 2, “the resistance value of the interelectrode resistance is inversely proportional to the electrical conductivity of the solution”.

  Since the oscillation frequency f is 1 / T, from the equations (12) and (13), if the same electrode is used (if K is the same), “the oscillation frequency is proportional to the electrical conductivity of the solution. Result. That is, the following equation holds.

  The electrolyte concentrations of the samples used in Example 3 are all the same. Therefore, if there is a difference in electrical conductivity between samples, it is not due to a difference in electrolyte concentration. Based on the extended Walden rule, the main factor of the difference in electrical conductivity between the samples is the viscosity of the sample (estimation) in the present invention. The extended Walden rule is expressed by the following equation.

ここで、σは溶液の電気伝導率、ηはこの溶液の粘性率である（尚、多くの文献に記載されている本来のWalden則は、極限モル伝導率と粘性率との積が一定である（ηΛ_ｍ ^０＝const.）という形式で書かれている）。式（１４），式（１５）から、次式が導かれる。

Where σ is the electrical conductivity of the solution and η is the viscosity of the solution (note that the original Walden law described in many literatures has a constant product of ultimate molar conductivity and viscosity. (It is written in the form of ηΛ _m ⁰ = const.) From the equations (14) and (15), the following equation is derived.

  From formula (16), it can be seen that if a reference solution with a known viscosity is prepared, the viscosity can be calculated simply by measuring the oscillation frequency.

Here, the measurement conditions and assumptions that lead to the expression (16) are summarized as follows.
(1) A CR timing type oscillation circuit in which the oscillation period is proportional to the timing resistance value is adopted.
(2) All the electrolyte concentrations of the samples were the same, and the difference in electrical conductivity was due only to the difference in viscosity.
(3) The same electrode (cell) was used, and the resistance value between the electrodes was assumed to be inversely proportional to the electrical conductivity of the solution.
(4) It was assumed that Walden's law was established at a finite electrolyte concentration (extended Walden's law).

  In FIG. 9, the correlation of the measured value by the existing viscosity meter and the measured value by the viscosity measuring method of this invention of the viscosity of the glycerol-salt aqueous solution in Example 3 is shown. As can be seen from FIG. 9, the viscosity of the glycerin-salt aqueous solution obtained from the equation (16) and the viscosity obtained with an off-the-shelf viscometer have different absolute values but are linearly correlated with each other. This was confirmed by experiments.

(Viscosity determination method when electrolyte concentration is known)
In Example 2, the viscosity of saline (150 mM NaCl) to which various concentrations of glycerin are added is estimated based on a 150 mM NaCl aqueous solution (solution in which NaCl is dissolved in pure water) whose viscosity is known. Said. If the electrolyte concentration of the sample is known (eg, known to contain 150 mM NaCl), it is not necessary to prepare a “reference solution”. This is because the electric conductivity of the “reference solution” is known.

The procedure for viscosity estimation is as follows.
(1) The electrical conductivity σ _x of the sample is determined by the method described in Example 1.
(2) The electrical conductivity σ of the electrolyte solution having the concentration is calculated with reference to a conversion table (for example, “Chemical Handbook”) or a conversion formula.
(3) Based on the extended Walden rule, the value obtained by multiplying the value obtained by dividing σ by σ _x by the viscosity of the reference solution (it is known as 1 mPa · s at 20 ° C. for pure water) It is.

  Table 2 shows the values (hereinafter referred to as “Walden viscosity”) estimated by the above-described method of the viscosity of various concentrations of sucrose liquid in which the NaCl concentration is strictly adjusted to 150 mM, and the vibration-type viscosity. This is a comparison of the values measured by a Viscomate (hereinafter referred to as “Viscomate viscosity”). As the viscosity increases, the relative error tends to increase, but even in the sucrose solution, the Viscomate sample has a large Walden viscosity value, that is, the order of the measured viscosity values is as follows. You can see that it is reproduced correctly.

(Measurement of temperature dependence of water viscosity)
It is known that the viscosity of water is approximately proportional to an exponential function of the absolute temperature T. That is, the temperature dependence of the viscosity η of water is approximately

The viscosity of water at various temperatures is provided by a detailed table (see, for example, National Astronomical Observatory, “Science Chronology of 2012 (Vol. 85)”, page 389). In this experimental example, samples (final concentration of about 10 mM) obtained by adding trace amounts of various electrolytes (NaCl, KCl, HCl, and seawater) to distilled water are prepared, and the electrical conductivity is set as the oscillation frequency by changing the temperature. Recorded. The measurement results are shown in FIGS. The horizontal axis is the reciprocal of absolute temperature (unit: mK ⁻¹ ), and the vertical axis is the logarithm of viscosity (unit: mPa · s). In each figure, the viscosity data of pure water is cited from Non-Patent Document 3. The data of the electrolyte dilute aqueous solution represents the logarithm of the measured oscillation period.

  From FIG. 10 to FIG. 13, when distilled water added with NaCl, KCl, and seawater is used as a sample, the oscillation period of the CR timing oscillation circuit 21 changes in temperature substantially in parallel with the viscosity of pure water. Can be seen. On the other hand, when distilled water added with HCl is used as a sample, the oscillation period of the CR timing oscillation circuit 21 does not depend much on the temperature. That is, the electrical conductivity of the distilled water sample to which HCl has been added is not significantly affected by the viscosity of the water.

  This is an observation result that reinforces the effectiveness of the viscosity measurement method according to the present invention. The mechanism of electrical conduction by hydrogen ions is completely different from the mechanism of electrical conduction by other ions. When an electric field is applied to hydrogen ions, the charge moves by a mechanism called a "chain mechanism", so it is virtually unaffected by the viscosity of water. Further, it can be seen from this result that the viscosity measurement method according to the present invention cannot be applied to the measurement of the viscosity of a liquid (for example, gastric juice) in which hydrogen ions are the main component of the electrolyte.

(Measurement of milk viscosity)
Milk has no known electrolyte concentration or viscosity. Therefore, the method as used in Example 4 cannot be applied to estimate the viscosity. Hereinafter, the process of estimating the viscosity of milk using the viscosity measurement method according to the present invention and the results thereof will be described.

(sample)
As a sample, commercially available milk was used. The electrolyte component is described as 42 g sodium and 114 mg calcium per 100 mL in the package, but nothing more is known. As a preliminary experiment, the viscosity of a diluted sample obtained by diluting this milk 21 times with distilled water was measured with Viscomate, and it was confirmed that it was very close to 1 mPa · s (viscosity of distilled water) at room temperature.

(Measurement procedure)
(1) A sample (hereinafter referred to as “diluted sample”) prepared by accurately diluting a milk stock solution (hereinafter referred to as “stock solution”) 21 times with distilled water is prepared.
(2) For each of the stock solution and the diluted sample, the electrical conductivity is measured by the procedure described in Example 2 and Example 4. The electrical conductivity of the stock solution was calculated to be 0.515 S / m, and the electrical conductivity of the diluted sample was calculated to be 0.0467 S / m.
(3) Since the viscosity of the diluted sample is the same as that of pure water, the contribution of the viscosity to the electrical conductivity is considered negligible. Therefore, assuming that the diluted sample is an aqueous solution of a standard electrolyte (in this case, NaCl is used), a conversion table or a conversion formula (an approximate curve formula derived from the conversion table) as shown in FIG. 1 is used. To calculate the concentration of the diluted sample. The electrical conductivity of this diluted solution is calculated to be equivalent to a 3.9 mM NaCl solution.
(4) Multiply the calculated concentration of the diluted sample by the dilution factor to calculate the electrolyte concentration of the stock solution. Here, the electrolyte concentration (salt concentration) of the stock solution is 3.9 × 21 = 81.9 mM in terms of NaCl.
(5) The electrical conductivity at the electrolyte concentration of the stock solution is calculated again from the standard electrolyte conversion table or conversion formula. Here, the electrical conductivity of the 81.9 mM NaCl solution is calculated to be 0.850 S / m.
(6) Calculate the viscosity of the stock solution according to the extended Walden rule (formula (15)). In this case, the viscosity η of the stock solution is

と算出される。尚、原液をViscomateで測定した粘性率の値は１．８５ｍＰａ・ｓであった。本発明に係る粘性率測定方法によって、相対誤差およそ１０％で粘性率が求められた。

Is calculated. The viscosity value of the stock solution measured by Viscomate was 1.85 mPa · s. With the viscosity measurement method according to the present invention, the viscosity was determined with a relative error of about 10%.

  Through the above verification test, a method for measuring the electrolyte concentration and viscosity by measuring the electrical conductivity of an electrolyte solution in which (1) the amount of the specimen is very small and (2) the salt concentration and the viscosity are unknown is established.

(Comparison of plasma viscosity between bleeding model animals and control animals)
(sample)
A catheter was inserted into the rat femoral artery and allowed to bleed until its mean blood pressure was approximately 35 mmHg. Three hours after the treatment, blood was collected in a Spitz supplemented with an anticoagulant (EDTA), centrifuged to remove blood cells, and the obtained plasma was used as a sample derived from a “bleeding model rat”. For the samples derived from the bleeding model rats and the control rats, the electrolyte concentration and viscosity were estimated by the same method as in Example 6.

(Measurement procedure)
Each sample was measured for electrical conductivity using a sample diluted exactly 21 times with distilled water as a diluted sample. The measurement results are shown in Table 3. Table 4 shows the NaCl-concentrated electrolyte concentration and viscosity calculated by the same method as in Example 6.

  In the hemorrhage model rat, it can be seen that the plasma viscosity and electrolyte concentration are significantly higher than those of the control rat. Since the amount of each sample is about 1 mL, it is difficult to realize with the conventional viscosity measurement method. The viscosity measurement method according to the present invention also has an advantage that results are obtained easily and quickly. It should also be noted that the plasma viscosity of control rats obtained by this method is very close to the reported normal value of human plasma viscosity.

(Experimental example in which rat plasma viscosity was evaluated in terms of KCl)
In Examples 6 and 7, the electrolyte concentration was estimated using NaCl as a standard electrolyte, and the viscosity was obtained. Here, although it is biologically unnatural, the electrolyte concentration is calculated using KCl as the standard electrolyte. In other words, the rat plasma is virtually regarded as “a solution in which impurities (sugar, protein, etc.) are mixed in an aqueous KCl solution”. According to the conversion table described in Non-Patent Document 3, if the concentration is the same, the electrical conductivity of the KCl aqueous solution is necessarily higher than that of the NaCl aqueous solution (see FIG. 1). Therefore, it is clear that the electrolyte concentration calculated backward from the electrical conductivity is smaller in KCl than in NaCl. On the other hand, since the viscosity is a ratio of electrical conductivity at two concentrations, the difference in electrolyte concentration calculated backward from the electrical conductivity is offset. Table 5 shows the KCl equivalent electrolyte concentration and viscosity calculated using KCl as the standard electrolyte.

It can be seen that the calculated viscosity value agrees within a relative error of 5% regardless of whether NaCl or KCl is used as the standard electrolyte. Of course, the magnitude relationship of the viscosity is the same regardless of which standard electrolyte is used for the calculation. As can be seen from FIG. 1, the curve shape of the change in electrical conductivity with respect to the electrolyte concentration is almost the same between NaCl and KCl (that is, σ _Na (c) / σ _K (c) = almost constant. The relationship is established).

(Measurement of saliva viscosity)
Human saliva was used as a sample. The amount of saliva collected was just over 1 mL. The measurement was carried out as it was without filtration or centrifugation. As in the case of the above-described milk and plasma, the electrical conductivity was measured for a saliva stock solution and a sample (diluted sample) diluted 21 times with distilled water. The electric conductivity of the stock solution was 0.807 S / m, and the electric conductivity of the diluted sample was 0.0495 S / m. When the standard electrolyte is NaCl, the electrolyte concentration calculated from these electrical conductivities is 0.00408 M (NaCl equivalent) for the diluted sample and 0.0857 M (NaCl equivalent) for the stock solution. Therefore, the electrical conductivity of the NaCl solution having the same concentration as the stock solution is 0.921 S / m. The viscosity of saliva calculated by the extended Walden law is 0.921 / 0.807 = 1.141 mPa · s.

(Measurement of viscosity of low fat milk drink)
The viscosity of the commercially available low fat milk drink was measured. The raw material names listed on the product packaging were milk, dairy products, lactose, and fragrance. Using this low-fat milk beverage as a sample, the viscosity was measured by (1) a commercially available viscometer Viscomate and (2) the viscosity measurement method according to the present invention for comparison. The viscosity measurement of this sample by Viscomate was 1.55 mPa · s at 20 ° C. (that is, this low fat milk drink is smoother than normal milk).

  As a result of measurement by the viscosity measurement method according to the present invention, the electrical conductivity of the sample stock solution was 0.496 S / m, and the electrical conductivity of the 21-fold diluted solution was 0.0523 S / m. When the standard electrolyte is NaCl, from the electrical conductivity, the electrolyte concentration of the diluted solution is 0.0043M, and the electrolyte concentration of the stock solution is 0.0903M. Again, referring to the conversion table, the electrical conductivity of the NaCl 0.0903M aqueous solution is 0.968 S / m. Therefore, the viscosity of the stock solution of the sample was estimated to be 0.968 / 0.496 = 1.95 mPa · s, which was larger than the value measured by Viscomate than normal milk.

  So when I contacted the manufacturer, the reason became clear. The “dairy product” described as a raw material was “whey powder” (a powdered whey produced during the production of yogurt). “Whey” contains a large amount of lactic acid, and since lactic acid is a weak acid, the degree of dissociation increases by dilution. Therefore, diluting lactic acid produces the same effect as adding new ions, not just thinning. Therefore, if the electrolyte concentration of the stock solution is estimated using the electrical conductivity of the diluted solution, a value larger than the actual value will be estimated. Therefore, when the extended Walden rule is simply applied, a viscosity higher than the actual viscosity can be obtained.

  From the above experiments, the viscosity measurement method according to the present invention is based on a sample in which the main body of electrical conduction is hydrogen ions, or a sample in which a weak acid such as lactic acid or acetic acid exists even if it is a supporting role in electrical conduction. It was confirmed that it is not suitable for the measurement of viscosity.

(Continuous tracking of yogurt fermentation process)
FIG. 14 shows measurement results obtained by tracking the fermentation process of yogurt as a change in electrical conductivity. The first approximately 60 minutes is the change in electrical conductivity of milk only. The milk taken out from the refrigerator was transferred to Yogurt Maker (manufactured by Toshiba) which was kept at 38 ° C., and the oscillation frequency (corresponding to electrical conductivity one-to-one) was continuously recorded using the CR timing oscillation circuit 21 of FIG. It is. The increase in electrical conductivity with increasing temperature was recorded. When the temperature reached a substantially constant value, seed yogurt warmed to the same temperature was added (when the frequency jumped in FIG. 14), and recording of the oscillation frequency was continued. The oscillation frequency (electrical conductivity) continued to increase and reached an almost constant value. A yogurt with no fluidity was completed.

  We anticipated a decrease in electrical conductivity due to yogurt “solidification”, but this was not the case. It was interpreted that the electrical conduction by hydrogen ions released by lactic acid fermentation masked the effect of the increase in viscosity. Although “solidification” could not be detected, it was found that the fermentation process of yogurt could be continuously tracked by simply monitoring the oscillation frequency continuously. It can be applied to product management.

(Tracking boiled gelation)
FIG. 15 shows the result of continuous recording by measuring the electrical conductivity as an oscillation frequency using the CR timing system oscillation circuit 21 of FIG. . In this sample, the electrolyte concentration does not change with time.

  As the temperature gradually decreases, the viscosity increases with gelation. Since the change in the oscillation frequency (electric conductivity) includes both factors of temperature and viscosity, it is difficult to interpret this data itself.

  However, with the same idea as this experiment, for example, the clotting process of plasma can be continuously monitored. In the plasma coagulation process, the experiment can be performed with both the electrolyte concentration and the temperature constant, so that the change in viscosity during the plasma coagulation (gelation) process can be recorded continuously.

(Continuous monitoring of plasma clotting process)
Blood clotting is a complex and dynamic physiological process involving many factors. When a blood vessel is damaged and bleeds, a blood clot is formed to stop bleeding from the damaged site. In other words, hemostasis is its role. If blood coagulation progresses excessively in the blood vessel, a blood clot is formed and the blood vessel is clogged. On the other hand, if the blood coagulation system does not work well, the result is that bleeding is difficult to stop. Both are dangerous situations for the living body.

  A large amount of blood transfusion may be performed at the time of injury, childbirth, or surgery, but an anticoagulant (EDTA, etc.) is added to the transfused blood to suppress blood coagulation, resulting in serious coagulopathy after transfusion. Therefore, it is necessary to quickly return to the original state in order to prevent excessive bleeding. In order to maintain a delicate balance between coagulation and bleeding, it is necessary to continuously monitor the blood coagulation ability (coagulation time) of a patient at regular intervals.

  In the conventional method for monitoring the blood clotting time, for example, a system is commercially available in which a small steel ball is placed in a blood sample collected from a patient and is vibrated with an external oscillating magnetic field to magnetically detect the vibration amplitude of the ball from outside. (Fully automatic blood coagulation and fibrinolysis measuring device STA Compact: manufactured by Roche Diagnostics Co., Ltd.)

  As seen in Example 12, when the electrolyte solution gels (solidifies), the viscosity increases, which can be detected as a decrease in electrical conductivity. That is, the process of blood coagulation can be monitored by the same method as the tracking of the gelation of the above-mentioned boiled food. On the other hand, as described in Examples 2 and 4, the electrical conductivity of the electrolyte solution can be measured with a simple electric circuit. That is, (1) a container (cell) having a pair of electrodes, (2) a mechanism for measuring an electric resistance value between the electrodes, and (3) a mechanism for converting the resistance value into electric conductivity and displaying it. I just need it. It is not necessary to calculate and display an accurate value of the viscosity for measuring the blood coagulation time. Therefore, the blood coagulation time measurement system using an electrical method can be realized as a very simple inspection apparatus, and can be an apparatus for continuously and simply inspecting at the bedside of a patient.

(Continuous tracking of blood cell disintegration process)
There are many potassium ions in blood cells. When the blood cell collapses, potassium ions are released into the external fluid and the plasma electrolyte concentration increases. Furthermore, since the mobility of potassium ions is larger than the mobility of sodium ions, the blood cell disintegration process can be observed as an increase in blood electrical conductivity.

  Whole blood obtained by adding an anticoagulant to blood collected from animals was used as a sample. After standing at room temperature (23 ° C.), the electrical conductivity was continuously recorded. This records the blood cell decay process as an increase in electrical conductivity.

(Continuous humidity recording)
The CR timing oscillation circuit 21 used in the viscosity measurement device according to the present invention can be applied not only as a viscosity measurement but also as a sensor for detecting a change in impedance. In particular, the impedance variation range is large, and the conventional impedance-voltage conversion method can greatly improve the simplification of the circuit when applied to measurement that requires complicated circuit technology such as logarithmic conversion. .

  As one application example, an example in which the CR timing oscillation circuit 21 is applied to a humidity sensor is shown. The polymer film type humidity sensor HS15P (manufactured by General Electric Company (GE)) changes its resistance value over several orders of magnitude depending on the environmental humidity (typically 200Ω at 100% RH and> 10MΩ at 20% RH). ). Thus, impedance measurement of an object whose impedance varies over a wide range is difficult with conventional techniques and requires complex circuit technology.

  Therefore, the portion of the timing resistor R of the CR timing oscillation circuit 21 described above is replaced with a humidity sensor, and a change in impedance of the humidity sensor is detected as a change in oscillation frequency. FIG. 16 shows a measurement result of a change in impedance of the polymer film type humidity sensor using the CR timing type oscillation circuit 21. In FIG. 16, the humidity sensor includes (a) the room (humidity of 40% or less) and three reference humidity spaces ((b) saturated NaCl solution space (RH 77%), (c) saturated KCl solution space ( RH 85%)) and then (d) a saturated water vapor space (RH 100%) for continuous recording. It can be seen that continuous recording from 20 Hz to 25 kHz (600 kΩ to 200 Ω in terms of the resistance value of the sensor) can be performed without changing any circuit constants other than the sensor. Considering this again in the electrolyte solution, it can be seen that NaCl 0.0005 M to NaCl about 1.0 M can be recorded automatically as “oscillation frequency” with the “same circuit constant”.

(Measurement of viscosity of “soy sauce”)
3 kinds of seasonings including salt,
B) White soup b) Thin mouth soy sauce) The viscosity of dark soy sauce is estimated in the same procedure as in Examples 6 to 7 (Walden viscosity) and compared with the value measured with a vibration viscometer (Viscomate viscosity). Table 6 shows. In the table, the salt concentration (indicated) is a concentration calculated from the amount of salt described on the packaging (described as 17 g per 100 mL or 2.5 g per 15 mL). The salt concentration (measurement) is a value obtained from the electric conductivity of a diluted sample obtained by diluting each sample 21 times.

  Similar to the example of the viscosity of the sucrose solution in Example 2, the larger the viscosity, the greater the relative error between the values of the viscosity by the two measurement methods. Moreover, when comparing the viscosity of white soup and thin-mouthed soy sauce, the viscomate viscosity is about 3.3% larger than the former, but the Walden viscosity is about 2.6% smaller than the former.

  This “reversal of the viscosity measurement value” is understood as follows. Referring to the equation (10), the viscosity of the sample is obtained by multiplying the ratio of electrical conductivity by the “viscosity of pure saline”. However, the Walden viscosity values shown in Table 6 are calculated by adopting “viscosity of pure water”, that is, 1.0 mPa · s as “viscosity of pure saline”. This is a good approximation if the salt concentration is around 150 mM, ie around physiological saline. However, the viscosity of concentrated saline having a salt concentration of 2 to 3 M cannot be approximated by the “viscosity of pure water”.

Since the value of viscosity of concentrated saline is not provided as a data table (conversion table),
1) Viscomate measures the viscosity of saline solution at three different concentrations (1.04M, 2.36M, and 4.67M)
2) From these values, the viscosity of the saline solution corresponding to the NaCl concentration of each “soy sauce” is estimated by interpolation,
3) Using that value, the Walden viscosity values in Table 6 were recalculated.

  The results were 3.10, 3.68, and 3.93 (in units of mPa · s) in the order of white soup, light soy sauce, and dark mouth soy sauce, and “the magnitude reversal of the viscosity measurement value” was resolved.

  When the electrolyte concentration of the sample is very large, the result of this example shows that there is a limit to “estimation of viscosity (Walden viscosity) by conductivity measurement” according to the present invention. In the above example, “soy sauce” can be thought of as a sample in which “impurities” are mixed in concentrated saline, so the viscosity of “pure concentrated saline” is estimated by interpolation using Viscomate. The value was substituted to calculate “Walden viscosity”. The original simplicity of calculating the viscosity of the sample was lost just by “twice electrical conductivity measurements and data table reference”. Furthermore, if the ionic composition is unknown although it is a concentrated electrolyte solution (high electrical conductivity), the above procedure cannot be adopted.

  However, when the amount of the sample that can be used is small (for example, 1 mL or less) and the conventional method of viscosity measurement is difficult to apply, it is still effective as a means for estimating the approximate value of the viscosity. Since the conventional method (for example, Viscomate) has only to measure the viscosity of concentrated saline (generally a concentrated electrolyte solution), there is no quantitative limitation on the reference sample. If necessary, a conversion formula can be created based on this measured value.

  In the present embodiment, another embodiment of the viscosity measurement device according to the present invention will be described. FIG. 17 is a block diagram illustrating the overall configuration of the viscosity measurement device according to the seventeenth embodiment. Compared with Example 1, in this example, the measurement cell 10 is provided with one cell 10a for a stock solution and one cell 10b for a diluent, and is provided with impedance measuring instruments 6a and 6b correspondingly. In addition, the sample diluting device 4, the cell cleaning / drying device 5, the inflow side cock 15, and the outflow side cock 16 are omitted. The stock solution cell 10a and the dilution solution cell 10b are measurement cells dedicated to the sample stock solution and the sample dilution solution, respectively. Each of the stock solution cell 10a and the diluent cell 10b includes electrodes 17a and 17b, a temperature sensor 18, and a Peltier element 19.

  FIG. 18 is a diagram illustrating an example of the measurement cell 10 of FIG. The measurement cell 10 penetrates from the upper surface to the lower surface of the container 11, and is formed with one hole-shaped storage chamber 12 for the stock solution cell 10a and the diluent solution cell 10b. The upper surface side of each storage chamber 12 is open, and this forms the upper opening 12a. Moreover, the lower surface side of each storage chamber 12 is obstruct | occluded by the Peltier element 19, and becomes a container shape. Electrodes 17 a and 17 b and a temperature sensor 18 are arranged on the inner surface of each storage chamber 12 so as to protrude into the storage chamber 12.

  In the viscosity measuring apparatus of the present embodiment, the user needs to manually perform the dilution operation of the sample stock solution. First, the user prepares a stock solution and a diluted solution of the sample, and injects them into the storage chambers 12 of the stock solution cell 10a and the diluted solution cell 10b, respectively, with a pipette or the like. And the computer 7 is operated, the electrical conductivity of the solution in each cell is measured, and the viscosity is calculated. The method for calculating the viscosity is the same as the method described in the first embodiment, and thus the description thereof is omitted.

DESCRIPTION OF SYMBOLS 1 Viscosity measuring device 2 Distilled water tank 3 Electrical conductivity measurement cell group 4 Sample dilution device 5 Cell washing / drying device 6, 6a, 6b Impedance measuring device 7 Computer 8 Display device 9 Input / output device 10 Measurement cell 10a Stock solution cell 10b Diluent cell 11 Container 12 Storage chamber 12a Upper opening 13 Inflow path 14 Outflow path 15 Inflow side cock 16 Outflow side cocks 17a and 17b Electrode 18 Temperature sensor 19 Peltier element 21 CR timing system oscillation circuit 23 Oscillation state measurement circuit 31 Opening and closing Control circuit 32 Current control circuit 33 A / D conversion circuit 34 I / F circuit 35 Electrical conductivity conversion unit 36 Conversion table storage unit 37 Viscosity calculation unit 38 Measurement control unit 41 Schmitt inverter 41 'operational amplifier (op amp)
42 Capacitor 43 Feedback impedance

Claims (15)

A viscosity measurement method for measuring a viscosity of a liquid sample containing an electrolyte and impurities other than the electrolyte,
A first step of measuring the electrical conductivity σ ₀ of the sample stock solution;
The electrical conductivity σ ₂ in an aqueous solution in which the sample electrolyte is dissolved in pure water so that the electrolyte concentration c ₂ is the same as the electrolyte concentration c ₂ of the stock solution of the sample is expressed as follows: A second step of estimating by referring to a conversion table or conversion formula representing the relationship of
A third step of calculating a viscosity η of the stock solution of the sample from a ratio between the estimated electrical conductivity σ ₂ and the electrical conductivity σ ₀ of the stock solution of the sample.   2. The viscosity measurement method according to claim 1, wherein the known predetermined solution is an aqueous electrolyte solution in which solute ions form a hydrated state. The electrolyte concentration c ₂ is a viscosity measurement method of claim 1, wherein measuring the electrolyte concentration c ₂ and the viscosity of the unknown of the sample eta,
In the second step,
Measuring the electrical conductivity σ ₁ of a diluted solution obtained by diluting the stock solution of the sample with pure water to a predetermined magnification n;
From the electrical conductivity σ ₁ of the diluted solution, by referring to a conversion table or a conversion formula representing the relationship between the concentration of the known predetermined solution and the electrical conductivity, the electrolyte concentration c ₂ of the stock solution of the sample and the electrolyte And a step of obtaining an electrical conductivity σ ₂ converted into a concentration. In measuring the electrical conductivity of the sample in the first or second step, a CR timing type oscillation circuit is used,
Impedance configured by arranging a pair of electrodes apart in the sample liquid is incorporated as an impedance for determining the time constant of the CR timing oscillation circuit, and the CR timing oscillation circuit is oscillated to The viscosity measurement method according to any one of claims 1 to 3, wherein the electrical conductivity of the sample is determined from the oscillation frequency or the oscillation cycle by measuring the oscillation frequency or the oscillation cycle. A viscosity measuring device for measuring a viscosity of a liquid sample containing an electrolyte and impurities other than the electrolyte,
Measure the electrical conductivity σ ₀ of the stock solution of the sample,
The electrical conductivity σ ₂ in an aqueous solution in which the sample electrolyte is dissolved in pure water so that the electrolyte concentration c ₂ is the same as the electrolyte concentration c ₂ of the stock solution of the sample is expressed as follows: Estimated by referring to a conversion table or conversion formula representing the relationship of
_2. A viscosity measuring apparatus, wherein the viscosity η of the stock solution of the sample is calculated from a ratio between the estimated electrical conductivity σ ₂ and the electrical conductivity σ ₀ of the stock solution of the sample.   6. The viscosity measuring apparatus according to claim 5, wherein the known predetermined solution is an aqueous electrolyte solution in which solute ions form a hydrated state. The electrolyte concentration c ₂ is a viscosity measurement apparatus according to claim 5 or 6, wherein measuring the electrolyte concentration c ₂ and the viscosity of the unknown of the sample eta,
The electrical conductivity σ ₁ of a diluted solution obtained by diluting the stock solution of the sample with pure water to a predetermined magnification n is measured,
From the electrical conductivity σ ₁ of the diluted solution, by referring to a conversion table or a conversion formula representing the relationship between the concentration of the known predetermined solution and the electrical conductivity, the electrolyte concentration c ₂ of the stock solution of the sample and its electrolyte Viscosity measuring apparatus characterized by calculating electrical conductivity σ ₂ converted to concentration. A container for storing the sample;
Electrical conductivity measuring means for measuring electrical conductivity of the sample stored in the container;
Water injection means for injecting water into the sample stored in the container;
After measuring the electrical conductivity σ ₀ of the stock solution of the sample stored in the container by the electrical conductivity measuring means, the stock solution of the sample is diluted with pure water to a predetermined magnification n by the water injection means, Measurement control means for measuring the electrical conductivity σ ₁ of the diluted solution;
From the electrical conductivity σ ₁ of the diluted solution, by referring to a conversion table or a conversion formula representing the relationship between the concentration of the predetermined known solution and the electrical conductivity, the electrolyte concentration c ₂ of the sample stock solution and its electrolyte An electrical conductivity conversion means for calculating an electrical conductivity σ ₂ converted into a concentration;
Viscosity calculation means for calculating the viscosity of the sample stock solution from the ratio between the converted electrical conductivity σ ₂ and the electrical conductivity σ ₀ of the sample stock solution;
The viscosity measuring apparatus according to claim 7, further comprising: The electrical conductivity measuring means includes
A CR timing oscillation circuit in which an impedance configured by separating a pair of electrodes in the sample liquid is incorporated as an impedance for determining a time constant;
An oscillation state measuring instrument for measuring an oscillation frequency or an oscillation period of the CR timing oscillation circuit;
The viscosity measuring apparatus according to claim 8, further comprising: an electrical conductivity conversion unit that determines an electrical conductivity of the sample from an oscillation frequency or an oscillation period measured by the oscillation state measuring device.   5. A test for blood or vascular disease, characterized in that the viscosity of serum or plasma electrolyte and the concentration of electrolyte obtained at the same time are measured by the viscosity measurement method according to claim 3 and compared with a normal value. Method.   5. The viscosity of the serum or plasma electrolyte and the concentration of the electrolyte obtained at the same time are measured and recorded by the viscosity measuring method according to claim 3 or 4, and blood or An inspection method for inspecting vascular disease or its pathological change.   The test method according to claim 10 or 11, wherein a disease causing an increase in viscosity of serum or plasma is tested.   The test method according to claim 10 or 11, wherein a pathological condition in which a decrease in viscosity of serum or plasma occurs is tested.   A body fluid viscosity inspection system for measuring a body fluid viscosity, comprising the viscosity measuring device according to any one of claims 5 to 9.   10. Viscosity measurement according to any one of claims 5 to 9, wherein the viscosity of the food material is measured in a food production device that measures, controls and records the temperature and viscosity of the food material in the liquid or gel food production process. A food production apparatus comprising the apparatus.

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