JP7377680B2 - Viscosity change determination device and viscosity change determination method - Google Patents

Description

The present invention relates to an apparatus and method for measuring changes in the viscosity of a liquid specimen due to the growth of fungi.

Deterioration in the quality of foods and beverages, such as soft drinks and dairy products, not only damages the reputation of the product, but also can lead to serious problems that damage a company's credibility. In particular, quality deterioration caused by microorganisms and bacteria can lead to food poisoning in the worst case, and to prevent this, food is usually placed under strict hygiene control.

Patent Document 1 discloses the invention of a method for specific rapid detection of beverage spoilage microorganisms by in situ hybridization. Patent Document 1 also discloses specific oligonucleotide probes used in the process of the detection method and kits containing these oligonucleotide probes. The invention detects beverage spoilage microorganisms in a sample using an oligonucleotide probe having a specific nucleic acid sequence, and according to the invention, beverage spoilage microorganisms can be detected rapidly. ing.

Patent Document 2 discloses an invention of a food quality sensor and a method thereof, the purpose of which is to quickly, simply and efficiently diagnose or judge the state of spoilage of food. The invention includes a main body, an air inlet disposed proximate to the food product, an air outlet, and at least one sensor, the sensor comprising at least one of a plurality of predetermined molecules, particles, bacteria, viruses, and biological cells. at least one sensor, wherein exposure of the sensor to one changes the electrical characteristics of the sensor; and an air pump that draws air from the inlet, through the at least one sensor, and expels the air from the outlet. It is characterized by comprising: According to the invention, it is said that the state of putrefaction of food can be diagnosed or determined quickly, easily and efficiently.

US Pat. No. 5,001,200 discloses an invention for a food and beverage quality sensor that aims to provide a spoilage detector that can adjust to variations in foodstuffs and contaminants and that responds quickly. The invention relates to a detectable substance having properties that change in response to exposure to a contaminant, the detectable substance having an inherent sensitivity to the contaminant and whose properties change in response to the contaminant accordingly; and a modulating agent in an amount sufficient to cause the detection substance to exhibit an altered sensitivity different from the inherent sensitivity. It is said that detection is possible.

Furthermore, Patent Document 4 states that even if an aqueous solution has a dielectric constant close to the dielectric constant of a reference liquid, or if the liquid is separated to form multiple layers, the liquid type can be determined without contact. An invention of a method for determining liquid type is disclosed for the purpose of reliably determining the type of liquid. The present invention applies a temporary shock to a container to cause an initial behavior in the liquid in the container, and detects changes in that behavior over time in a dielectric constant signal appearing on a dielectric constant measuring means for measuring the dielectric constant of the liquid. The type of liquid is determined by observing changes.

Further, Patent Document 5 discloses that a device is installed near a liquid object to be measured, measures the capacitance value of the liquid object to be measured, and uses the capacitance value to determine the dielectric characteristic of the object to be measured. A capacitance sensor that calculates the rate of the liquid substance to be measured, and a fluid viscosity sensor that generates a surface wave in the liquid substance to be measured and estimates the fluid viscosity of the liquid substance to be measured from the temporal attenuation characteristic of the fluctuation of the surface wave. Estimating means; Disclosed is a liquid object inspection device that identifies the liquid object to be measured based on the dielectric constant determined by the capacitance sensor and the fluid viscosity estimated by the fluid viscosity estimating means. .

Additionally, Patent Document 6 provides a technology that can easily and continuously measure the viscosity of a liquid, or a technology that can measure the viscosity of a liquid with a small device and over a wide measurement range. Discloses an invention of a liquid measuring device for the purpose of providing. The present invention is a liquid substance measuring device that measures a value related to the viscosity of a liquid substance, and includes an inlet through which the liquid substance flows and an outlet through which the liquid substance flows out, or an inflow port through which the liquid substance flows in and out. a vibration mechanism that applies vibration to the surface of a liquid in the container; a capacitance sensor that is placed adjacent to the container and outputs a signal according to a change in electric capacitance; and a signal from the capacitance sensor. and a measured value generation unit that generates a measured value based on.

In addition, Patent Document 7 makes it possible to measure liquid substances such as viscosity easily and continuously with higher accuracy, and also allows measurement that eliminates the influence of the temperature of liquid substances or temperature changes. The present invention discloses an invention of a liquid substance measuring device which is capable of easily, continuously and accurately determining the degree of deterioration of liquid substances such as oil. The present invention includes a container that stores a liquid, a vibration mechanism that applies vibration to the liquid in the container, and a capacitance sensor that is placed adjacent to the container and outputs a signal according to a change in electric capacitance. and a measurement value generation unit that generates a viscosity measurement value related to the viscosity of the liquid based on the alternating current component of the signal output by the capacitance sensor, and the vibration mechanism is configured to generate an inner wall dimension of the container. The surface of the liquid object is vibrated at a natural frequency calculated from the capacity of the liquid object.

Special Publication No. 2007-505638 Special Publication No. 2008-516198 Special Publication No. 2007-518102 Japanese Patent Application Publication No. 2008-203157 Japanese Patent Application Publication No. 2011-133342 Japanese Patent Application Publication No. 2016-142581 Japanese Patent Application Publication No. 2018-44900

Using the techniques described in Patent Documents 1 to 3, it is possible to detect and judge quality deterioration and spoilage of foods and drinks, etc. However, in the technique of Patent Document 1, probe agents such as oligonucleotides are used as specimens. It is necessary to add or mix it with food and drink, etc., and in the techniques of Patent Documents 2 and 3, it is necessary to use a sensor that is sensitive to specific bacteria, etc., and to bring the sensor close to the subject. That is, in any of the conventional techniques disclosed in Patent Documents 1 to 3, it is necessary to directly touch the subject or expose the subject; There was a problem that the quality could not be evaluated without touching it.

On the other hand, the applicant of the present application has filed patent applications for the inventions described in Patent Documents 5 to 7 by using the liquid type discrimination method described in Patent Document 4, and has issued Patent No. 6527342 corresponding to Patent Document 6, Patent No. 6226505 corresponding to Patent Document 7 has been issued. In this invention and the patented invention, it is possible to measure the viscosity of a liquid to be tested while the liquid is placed in a container.For example, when a drink is used as a test object, the measured viscosity and the quality of the drink can be measured. If it is possible to associate the above, it becomes possible to evaluate the quality of a drink or the like while the sample is placed in a container. However, in the case of milk drinks and beverages with a high sugar content, the liquid is sticky compared to water or alcohol, and the liquid may adhere to the inner wall of the container, causing errors such as deviations and variations in measurement results. .

An object of the present invention is to provide a technique that makes it possible to evaluate the quality that affects the viscosity of a liquid sample such as a drink in a container without directly touching the liquid sample. Another object of the present invention is to provide a technique that can realize the quality evaluation with good reproducibility and small errors.

In order to solve the above problems, a first aspect of the present invention includes: an excitation mechanism that applies vibration to a container containing a liquid sample; a capacitive sensor that outputs a capacitance signal; a viscosity measurement value generator that generates a viscosity measurement related to the viscosity of the liquid object based on the capacitance signal; and a reference value that is based on a previous viscosity measurement of the liquid object. a viscosity reference value recording unit that records a viscosity reference value indicating a viscosity reference value; and a viscosity change determination unit that compares the viscosity measurement value and the viscosity reference value to determine whether a change in viscosity of the liquid sample exceeds a predetermined value. Provided is a viscosity change determination device having the following.

The viscosity measurement value generation unit may generate the viscosity measurement value based on the capacitance signal acquired after a predetermined standby time has elapsed from the start of the vibration in the vibration mechanism. a sampling section in which the viscosity measurement value generation section samples the capacitance signal at a predetermined sampling period for a predetermined measurement period; and a norm value calculation section that calculates a norm value from each sample value sampled by the sampling section; and the norm value may be the viscosity measurement value. The vibration mechanism may apply vibration to the container at a natural frequency calculated from the inner wall dimensions of the container and the capacity of the liquid sample. The liquid specimen is a liquid whose viscosity changes with the growth of fungi, and the viscosity change determination section determines whether the number of fungi contained in the liquid specimen exceeds a predetermined number. Good too.

In a second aspect of the present invention, there is provided a container for viscosity change determination, which is used in the viscosity change determination device according to the first aspect, and the inner surface of the container is water repellent. Here, a water-repellent material may be coated or sprayed on the inner surface of the container.

In a third aspect of the present invention, the steps include the steps of: accommodating a liquid specimen in a container; installing the container in a vibrating mechanism; and starting the vibrating mechanism to apply vibration to the container; generating a viscosity measurement value related to the viscosity of the liquid sample based on a capacitance signal output from a capacitance sensor disposed adjacent to the viscosity reference value recording unit in which the viscosity reference value is recorded; Provided is a viscosity change determination method comprising: reading a viscosity reference value; and comparing the viscosity measurement value and the viscosity reference value to determine whether the change in viscosity of the liquid specimen exceeds a predetermined value. do.

In the step of generating the viscosity measurement value, the viscosity measurement value may be generated based on the capacitance signal acquired after a predetermined waiting time has elapsed from the start of the vibration mechanism. In the step of generating the viscosity measurement value, the capacitance signal is sampled at a predetermined sampling period during a predetermined measurement period after the elapse of the waiting time, a norm value is calculated from each sampled sample value, and the norm value is calculated from each sample value. may be used as the viscosity measurement value. In the step of applying vibration, vibration may be applied to the container at a natural frequency calculated from the inner wall dimensions of the container and the capacity of the liquid sample. The liquid specimen may be a liquid whose viscosity changes as fungi multiply, and the determining step may determine whether the number of fungi contained in the liquid specimen exceeds a predetermined number.

Note that the above summary of the invention does not list all the necessary features of the invention. Furthermore, subcombinations of these features may also constitute inventions.

1 is a conceptual diagram showing an overview of a viscosity change determination device 100. FIG. They are a front view, a top view, and a side view of the container 112, in which (a) the container cross section is square, and (b) the container cross section is rectangular. 3 is a graph showing the output of a typical capacitance signal. It is a graph showing the change in capacitance signal output over time when a milk drink is used as a liquid sample, (a) is on the 1st day, (b) is on the 3rd day, (c) is on the 5th day, and (d) is on the 5th day. This is a graph on the 6th day. It is a graph showing a change in norm value over time. It is a graph showing a change over time showing a correspondence between a norm value and the number of bacteria. (a) is a graph showing the output of a capacitance signal when water repellent treatment is applied to the inside of the container, and (b) is a comparison graph showing the output of a capacitance signal when no water repellent treatment is applied to the inside of the container. .

Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. Furthermore, not all combinations of features described in the embodiments are essential to the solution of the invention.

FIG. 1 is a conceptual diagram showing an overview of a viscosity change determination device 100. The viscosity change determination device 100 includes a container holder 110, a vibration mechanism 120, a capacitance sensor 130, a viscosity measurement value generation section 140, a viscosity reference value recording section 150, a viscosity change determination section 160, a display section 170, and a housing 180. The housing 180 is the base of the viscosity change determination device 100, and inside the housing 180 there are a container holder 110, a vibration mechanism 120, a capacitance sensor 130, a viscosity measurement value generation section 140, a viscosity reference value recording section 150, and A viscosity change determination section 160 is housed therein.

Container holder 110 holds container 112 and transmits vibrations from vibration mechanism 120 to container 112. In order to transmit vibration to the container 112, the container holder 110 needs to have a degree of freedom of movement in at least one of the up-down, left-right, and front-back directions with respect to the housing 180. Further, when the capacitance sensor 130 is disposed outside the container holder 110, the container holder 110 needs to be made of a dielectric material so that the capacitance can be measured through the container holder 110. The material of the container holder 110 is not particularly limited as long as the container holder 110 does not affect the capacity measurement. Note that the container holder 110 is not essential when directly applying vibration to the container 112, or when applying vibration to the surface of the liquid sample 114 by a method other than applying vibration to the container 112.

The container 112 has a main body 112a and a lid portion 112b, and contains a liquid sample 114 that is a measurement target. Hereinafter, unless otherwise specified, when the container 112 is referred to, the main body 112a of the container 112 is referred to. At least the main body 112a of the container 112 needs to have enough chemical stability and mechanical strength to hold the liquid sample 114. Further, since it is necessary to measure the capacitance through the container 112, at least the main body 112a of the container 112 needs to be a dielectric material. In FIG. 1, the surface of the liquid sample 114 in the container 112 is shown by a solid line or a broken line, with the solid line showing a wavy state due to vibration and the broken line showing a state at rest. Note that h in the figure is the distance from the bottom of the container 112 to the surface of the liquid sample 114 when it is at rest, and a is the distance between the inner walls when the cross section of the container is square, or This is the distance between the short sides of the inner walls when the cross section is rectangular.

The liquid specimen 114 can be, for example, a liquid whose viscosity changes as fungi grow. In this case, the viscosity change determination unit 160 can determine whether the number of fungi contained in the liquid sample 114 exceeds a predetermined number. For example, food and beverage products such as dairy products contain liquids whose viscosity increases or decreases due to the growth of fungi. If the liquid is the liquid specimen 114, it becomes possible to estimate the growth status of fungi based on the degree of change in viscosity. When the measured value is reached, it can be determined that the number of bacteria exceeds a predetermined value.

The vibration mechanism 120 applies vibration to the container 112 containing the liquid sample 114. By applying vibrations to the container 112, vibrations are applied to the liquid sample 114 inside the container 112. As a result of vibration being applied to the liquid object 114, waves are generated on the surface of the liquid object 114, and the magnitude of the waves is measured by the capacitive sensor 130, thereby obtaining a viscosity measurement value related to the viscosity of the liquid object 114. can be measured.

As shown in FIG. 1, the vibration mechanism 120 of the first embodiment is a vibration mechanism having an eccentric cam 122 and a motor control section 124, and is of a type that generates waves on the surface of the liquid sample 114 through vibration of the container 112. This is a container vibration mechanism. The eccentric cam 122 is driven by a motor, and the rotation speed, that is, the vibration period, is controlled by the motor control section 124. In addition to the mechanism using the eccentric cam 122, a known vibration generating mechanism can be used as the vibration mechanism 120.

The vibration mechanism 120 applies vibration to the container 112 at a natural frequency calculated from the inner wall dimensions of the container 112 and the capacity of the liquid sample 114, for example. When the vibration mechanism 120 vibrates the surface of the liquid object 114 at the natural frequency, the amplitude (wave height) of the wave generated on the surface of the liquid object increases, and the output of the capacitive sensor 130 can be increased. . The natural frequency includes harmonic frequencies in addition to the fundamental frequency. Furthermore, the concept of natural frequency in the present invention is not limited to a value that exactly matches the fundamental frequency or harmonic frequency derived by calculation, but rather deviates slightly from the value obtained by calculation. As long as a sufficiently high wave height can be obtained on the surface of the liquid object even if the value is deviated, the range is assumed to have a certain range that includes such outlier values.

但し、ωは固有角周波数、ｇは重力加速度、ｎは自然数（ｎ＝１，２，…）であり、ａは容器１１２の横断面における内壁間距離、ｈは容器１１２底面から液状被検体１１４表面までの距離である。 FIG. 2 is a front view, a top view, and a side view of the container 112, in which (a) shows a case where the cross section of the container is square, and (b) shows a case where the cross section of the container is rectangular. When the cross-sectional shape of the container 112 is square or rectangular as shown in FIG. 2, the natural frequency (f=ω/2π) can be a value calculated using Equation 1.

However, ω is the natural angular frequency, g is the gravitational acceleration, n is a natural number (n=1, 2,...), a is the distance between the inner walls in the cross section of the container 112, and h is the distance from the bottom of the container 112 to the liquid sample 114. It is the distance to the surface.

In Equation 1, when n=1, it is the natural frequency of the fundamental wave, as shown in Equation 2. The vibrations applied to the container 112 can be sinusoidal vibrations having a natural frequency or pulse vibrations synchronized with the vibrations having a natural frequency.

Note that the inner surface of the container 112, at least the inner surface of the main body 112a, can be made water repellent. For example, a water-repellent material can be coated or sprayed on the inner surface of the container 112 to make the inner surface water-repellent. Examples of water-repellent materials include fluororesins, petroleum hydrocarbons, and Class 4 petroleum products. By making the inner surface of the container 112 water-repellent, even when the viscosity of the liquid sample 114 is high, the surface of the liquid sample 114 can be appropriately undulated, and viscosity measurement values can be stably measured. can do.

Capacitance sensor 130 is placed adjacent to container 112 and outputs a capacitance signal in response to a change in electrical capacitance. The capacitive sensor 130 includes a capacitor electrode pair consisting of a detection electrode 132 and a ground electrode 134, and a C/V converter 136 that converts the capacitance value of the detection electrode 132 into a voltage. When the surface of the liquid sample 114 in the container 112 is undulated by vibration, the capacitance value of the detection electrode 132 changes depending on the state of the surface waves, for example, the wave height. The C/V converter 136 outputs this change in capacitance value as a voltage change. In other words, the signal (capacitance signal) output from the capacitance sensor 130 reflects the wave motion (wave height) on the surface of the liquid object 114. The vibrations of the liquid surface can be modeled using a second-order linear differential equation using viscosity, surface tension, and density as parameters. Under conditions where the surface tension and density do not change, the vibrations of the liquid surface depend on the viscosity. become. Therefore, by measuring the vibration of the surface of the liquid object 114 based on the change in capacitance, it is possible to measure a viscosity measurement value related to viscosity. Note that the stray capacitance of the detection electrode 132 can be stabilized by the ground electrode 134, and the influence of the stray capacitance included in the output signal (capacitance signal) from the capacitance sensor 130 can be reduced.

The C/V converter 136 can be configured by, for example, a capacitance-frequency conversion circuit that outputs a change in capacitance as a change in frequency, and a frequency-voltage conversion circuit that converts frequency into voltage. The capacitance-frequency conversion circuit can be constructed by appropriately combining a general LC resonant circuit and a NOT logic circuit, for example.

The viscosity measurement value generation unit 140 generates a viscosity measurement value related to the viscosity of the liquid object 114 based on the output signal (capacitance signal) of the capacitance sensor 130. The viscosity measurement value generation section 140 can include, for example, a sampling section 142 and a norm value calculation section 144. That is, the sampling unit 142 and the norm value calculation unit 144 may digitally process the output signal (capacitance signal) from the capacitance sensor 130 and perform signal processing to extract only the alternating current component. In this case, the norm value can be a viscosity measurement value.

The sampling section 142 samples the capacitance signal at a predetermined sampling period for a predetermined measurement period, and the norm value calculation section 144 calculates a norm value from each sample value sampled by the sampling section 142. For example, the sampling unit 142 repeatedly samples the capacitance signal from the capacitance sensor 130 at an appropriate sampling interval ΔT during the sampling period T, and the norm value calculation unit 144 calculates each sample value x _i sampled by the sampling unit 142. From this, the norm value RAW shown in Equation 3 is calculated.

Here, x _av is the average value of each sample value x _i , T _start is the sampling start time, T _end is the sampling end time, and the appropriate sampling interval ΔT is a time shorter than 1/2 of the signal period, e.g. An example is a time period of about 1/10 of the cycle. It is preferable that the sampling period T=T _end −T _start be longer than the signal period, for example, several times the signal period.

FIG. 3 is a graph showing a representative output of a capacitive signal at the output of capacitive sensor 130. In FIG. 3, the vertical axis shows the value of the capacitance signal, and the horizontal axis shows time T. Vibration by the vibration mechanism 120 is started at time T=0 msec.

As shown in Figure 3, after starting the excitation at time T = 0 msec, the baseline of the capacitance signal undershoots from a high value of about 2000 to a low value of about 300 between T = 0 and about 3000 msec. It stabilizes at a value of about 800 after T = about 3000 msec. Further, the capacitive signal is a signal in which a short-period sinusoidal waveform is superimposed on the baseline.

The fluctuation of the baseline from T=0 to approximately 3000 msec corresponds to the phenomenon in which the liquid analyte 114 adheres to the inner wall of the container 112 until it becomes stable. It is thought that this corresponds to a phenomenon in which the liquid object 114 is stably attached to the surface. Furthermore, the short-period sinusoidal waveform is considered to be due to the vibration waveform of the surface of the liquid object 114.

Based on the above knowledge, the period during which the baseline fluctuates is associated with the waiting time Tw in viscosity measurement, and the period during which the baseline is stable is associated with the measurement time Tm in viscosity measurement. The measured value generation unit 140 can be operated. That is, the viscosity measurement value generation unit 140 of the present embodiment generates the viscosity measurement value based on the capacitance signal acquired after a predetermined standby time Tw has elapsed from the start of vibration in the vibration mechanism 120 (time T = 0 msec). be able to. If we associate it with the parameters in Equation 3, the sampling start time Tstart is the time when the waiting time Tw has elapsed from the start of vibration (T=0) (T=Tw), and the sampling end time Tend is the time when the waiting time Tw has elapsed from the start of vibration (T=0), and the sampling end time Tend is the time when the waiting time Tw has elapsed from the start of vibration (T=0). It is assumed that the measurement time Tm has elapsed from the time Tw (T=Tw+Tm). In this way, by starting the viscosity measurement after the waiting time Tw has elapsed, it becomes possible to eliminate the influence of baseline fluctuations and stably measure the value based on the vibration waveform on the surface of the liquid object 114.

Although an example has been described in which the viscosity measurement value generation section 140 described above includes the sampling section 142 and the norm value calculation section 144, the present invention is not limited to this. For example, the viscosity measurement value generation section 140 may be configured by combining a bandpass filter, a rectifier circuit, and an integration circuit. That is, the DC component of the output signal of the capacitive sensor 130 may be removed through a bandpass filter, rectified by a rectifier circuit, and then a value obtained by integrating the AC component over a predetermined period by an integrating circuit may be output. In this case, the influence of stray capacitance and the like is removed by the bandpass filter, and signals caused by vibrations on the surface of the liquid object 114 can be extracted. Furthermore, the integrating circuit efficiently extracts minute signals or appropriately extracts signals containing a plurality of frequencies.

The viscosity reference value recording unit 150 records the viscosity reference value. The viscosity reference value is a reference value based on a previous viscosity measurement value of the liquid object 114. Examples of viscosity reference values include values predetermined through preliminary experiments and the like. Further, the viscosity reference value may be an initial value (reference value before time-dependent change) when observing changes in the liquid subject 114 over time.

The viscosity change determining unit 160 compares the measured viscosity value with a viscosity reference value and determines whether the change in viscosity of the liquid sample 114 exceeds a predetermined value. Here, the predetermined value is an arbitrary value, and can be determined in consideration of measurement error and change tolerance.

The display unit 170 displays the viscosity measurement value generated by the viscosity measurement value generation unit 140 and displays the determination result of the viscosity change determination unit 160.

The casing 180 is fixed against displacement or movement of the container 112, and functions as an entity that provides a ground potential. For this reason, the housing 180 preferably has a mass that does not move due to vibrations, and is preferably made of an electrical conductor. Furthermore, when measuring capacitance using the capacitance sensor 130, it is preferable to minimize the influence of a disturbance electric field. From this point of view, it is preferable that the entire casing 180 is made of a conductive material and that it surrounds the entire viscosity change determination device 100. The housing 180 made of a conductor constitutes an electrical shield, and the accuracy of capacitance measurement by the capacitance sensor 130 can be improved.

According to the above-described viscosity change determination device 100, the vibrating mechanism 120 applies vibration to the surface of the liquid subject 114 in the container 112, and the viscosity measurement value of the liquid subject 114 can be obtained from the viscosity measurement value generation unit 140. By using the liquid specimen 114 as a liquid whose viscosity changes as fungi multiply, it becomes possible to evaluate the quality that affects the viscosity of the liquid specimen 114 without directly touching the liquid specimen 114. . Furthermore, it is possible to provide a technique that can realize the quality evaluation with good reproducibility and small errors.

FIG. 4 is a graph showing the change in capacitance signal output over time when a milk drink is used as the liquid sample 114, in which (a) is the first day, (b) is the third day, and (c) is the fifth day. , (d) is a graph on the 6th day. As shown in the changes over time for 1 to 6 days shown in (a) to (d), the change in the volume signal of the milk beverage over time is significant, and the change in the volume signal over time corresponds to the change in viscosity over time.

FIG. 5 is a graph showing changes in norm values over time. The milk drink in FIG. 4 corresponds to "Sample 2". "Sample 1" is a commercially available milkshake (milk drink) that has only been opened, and is shown as a comparative example. "Sample 3" is an example in which one drop of pond water was added to a commercially available milkshake (milk drink) as a source of bacteria. "Sample 2" is an example in which two drops of pond water were added to a commercially available milkshake (milk drink) as a source of bacteria. "Sample 2" and "Sample 3" show a tendency for the norm value to decrease (increase in bacteria) after the 4th day, although there is some variation, and there is a tendency for the norm value to decrease (increase in bacteria), and there are more sources of bacteria (2 drops of pond water were added). ) This tendency is strong in "Sample 2". On the other hand, in "Sample 1" shown as a comparative example in which no germ source was added, no particular tendency of the norm value to decrease was observed in the 6-day follow-up observation.

FIG. 6 is a graph of changes over time showing the norm value and the number of bacteria in association with each other. The number of bacteria was measured by preparing a sample by adding appropriate bacteria to a milk drink, culturing the sample every number of days in a Petri dish, and counting the number of bacteria. As the number of days elapsed increases, the norm value decreased (viscosity increased) and the number of bacteria increased. The results show that there is a clear correlation between viscosity and the number of bacteria. From the above points, it is clear that the number of bacteria in milk drinks and the like can be accurately estimated by the viscosity change determination device 100 of this embodiment.

In the above embodiments, the present invention has been described as a viscosity change determination device, but the viscosity change determination device of the present invention can also be understood as a viscosity change determination method. That is, a step of accommodating the liquid sample 114 in the container 112, a step of installing the container 112 in the vibration mechanism 120, a step of starting the vibration mechanism 120 to apply vibration to the container 112, and a step of placing the container 112 adjacent to the container 112. a step of generating a viscosity measurement value related to the viscosity of the liquid sample 114 based on the capacitance signal output from the capacitance sensor 130, and a step of generating a viscosity reference value from the viscosity reference value recording unit 150 in which the viscosity reference value is recorded This can be understood as a viscosity change determination method that includes a step of reading out the viscosity measurement value and a step of comparing the viscosity measurement value and the viscosity reference value to determine whether the change in viscosity of the liquid sample 114 exceeds a predetermined value. . In this case, in the step of generating the viscosity measurement value, the viscosity measurement value may be generated based on the capacitance signal acquired after a predetermined standby time has elapsed since the activation of the vibration mechanism 120. In addition, in the step of generating the viscosity measurement value, the capacitance signal is sampled at a predetermined sampling period during a predetermined measurement period after the waiting time has elapsed, a norm value is calculated from each sampled sample value, and the norm value is It can be a viscosity measurement. Further, in the step of applying vibration, vibration may be applied to the container 112 at a natural frequency calculated from the inner wall dimensions of the container 112 and the capacity of the liquid sample 114. Furthermore, the liquid specimen 114 is a liquid whose viscosity changes as fungi multiply, and in the determining step, it may be determined whether the number of fungi contained in the liquid specimen 114 exceeds a predetermined number.

Further, the viscosity change determination device of the present invention can also be understood as a viscosity change determination container. In this case, as described above, the inner surface of the container may be made water repellent, and a water repellent material may be coated or sprayed on the inner surface of the container. FIG. 7(a) is a graph showing the output of the capacitance signal when the inside of the container is subjected to water-repellent treatment, and FIG. 7(b) is a graph showing the output of the capacitance signal when the inside of the container is not subjected to water-repellent treatment. It is a comparison graph showing. As shown in the figure, while the baseline fluctuation is large in the case of the comparative example without water repellent treatment, the baseline fluctuation in the capacitance signal is small when water repellent treatment is applied, allowing stable measurement. I understand something.

Further, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various changes or improvements can be made to the embodiments described above. It is clear from the claims that such modifications or improvements may be included within the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 100... Viscosity change determination device, 110... Container holder, 112... Container, 112a... Main body, 112b... Lid part, 114... Liquid sample, 120... Vibration mechanism, 122... Eccentric cam, 124... Motor control unit, 130... Capacitance sensor, 132... Detection electrode, 134... Ground electrode, 136... C/V converter, 140... Viscosity measurement value generation section, 142... Sampling section, 144... Norm value calculation section, 150... Viscosity reference value recording section, 160... Viscosity change determination section, 170...display section, 180...casing.

Claims (10)

The container is a container for containing a liquid specimen and has an inner surface treated with water repellent treatment;
a vibration mechanism that applies vibration to the container to generate waves on the surface of the liquid sample in the container ;
a capacitance sensor disposed adjacent to the container and outputting a capacitance signal according to a change in capacitance;
a viscosity measurement value generation unit that generates a viscosity measurement value related to the viscosity of the liquid object based on the capacitance signal;
a viscosity reference value recording unit that records a viscosity reference value indicating a reference value based on a previous viscosity measurement value of the liquid object;
a viscosity change determination unit that compares the viscosity measurement value with the viscosity reference value and determines whether the change in viscosity of the liquid specimen exceeds a predetermined value;
A viscosity change determination device having: The viscosity change determination device according to claim 1, wherein the viscosity measurement value generation unit generates the viscosity measurement value based on the capacitance signal acquired after a predetermined waiting time has elapsed from the start of the vibration in the vibration mechanism. The viscosity measurement value generation section,
a sampling unit that samples the capacitance signal at a predetermined sampling period for a predetermined measurement period;
a norm value calculation unit that calculates a norm value from each sample value sampled by the sampling unit;
The viscosity change determination device according to claim 1 or 2, wherein the norm value is the viscosity measurement value. The viscosity change according to any one of claims 1 to 3, wherein the vibration mechanism applies vibration to the container at a natural frequency calculated from the inner wall dimensions of the container and the capacity of the liquid sample. Judgment device. The liquid specimen is a liquid whose viscosity changes with the growth of fungi,
The viscosity change determination device according to any one of claims 1 to 4, wherein the viscosity change determination unit determines whether the number of fungi contained in the liquid specimen exceeds a predetermined number. a step of preparing a container treated with water repellent treatment;
accommodating a liquid analyte in the container;
installing the container in a vibrating mechanism and starting the vibrating mechanism to apply vibrations to the container to generate waves on the surface of the liquid sample in the container ;
generating a viscosity measurement related to the viscosity of the liquid analyte based on a capacitance signal output from a capacitance sensor located adjacent to the container;
reading the viscosity reference value from a viscosity reference value recording unit in which the viscosity reference value is recorded;
Comparing the viscosity measurement value and the viscosity reference value to determine whether the change in viscosity of the liquid sample exceeds a predetermined value;
A method for determining viscosity change. The viscosity change determination method according to claim 6 , wherein in the step of generating the viscosity measurement value, the viscosity measurement value is generated based on the capacitance signal acquired after a predetermined standby time has elapsed from the start of the vibration mechanism. In the step of generating the viscosity measurement value, the capacitance signal is sampled at a predetermined sampling period during a predetermined measurement period after the elapse of the waiting time, a norm value is calculated from each sampled sample value, and the norm value is calculated from each sample value. The viscosity change determination method according to claim 7 , wherein the viscosity measurement value is the viscosity measurement value. The viscosity according to any one of claims 6 to 8 , wherein in the step of applying vibration, vibration is applied to the container at a natural frequency calculated from the inner wall dimensions of the container and the capacity of the liquid sample. Change determination method. The liquid specimen is a liquid whose viscosity changes with the growth of fungi,
The viscosity change determination method according to any one of claims 6 to 9 , wherein in the determining step, it is determined whether the number of fungi contained in the liquid specimen exceeds a predetermined number.

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