JP2021107773A - Viscosity measuring apparatus and viscosity measuring method - Google Patents

Abstract

To provide a viscosity measuring apparatus that can measure the viscosity of a small amount of sample fluid as a measurement object in a non-contact manner.SOLUTION: A viscosity measuring apparatus 100 of the present invention, which is a viscosity measuring apparatus for measuring the viscosity of a liquid L, comprises: a chamber 101 having an opening 101a for accommodating a fluid; decompression means 102 for decompressing the fluid in the chamber 101; pressure measurement means 103 for measuring the pressure of the fluid in the chamber 101; a tubular unit 104 extending to the outside of the chamber 101, in which one end 104a is connected to the opening 101a, the liquid L can be accommodated from the other end 104b, and a hollow part 104A communicates with the space of the chamber 101; and means for measuring the viscosity of the liquid L, in such a way that the pressure of the fluid in the chamber 101 is reduced to a prescribed value by the decompression means 102, and that the change of measurement value of the pressure of the fluid in the chamber 101 with time is measured by the pressure measurement means when the liquid L is sucked up into the tubular unit 104.SELECTED DRAWING: Figure 1

Description

The present invention relates to a viscosity measuring device and a viscosity measuring method.

A viscometer for measuring the viscosity of a liquid generally requires a large amount of sample, and the lower the viscosity, the more difficult it is to measure. In addition, viscometers are large and expensive, so they are used only in limited facilities. On the other hand, in fields such as foods, chemicals, and pharmaceuticals, it is required to measure the viscosity easily or by using a smaller amount of sample. For example, in schools and long-term care facilities, efforts are being made to prevent aspiration by increasing the viscosity of food by thickening it. In addition, although strict viscosity control is required for the development and formulation of antibody drugs, it is difficult to secure a large number of samples for viscosity measurement because the drugs themselves are expensive.

When measuring the viscosity of blood, expensive antibody drugs or DNA solutions, it is desirable to use a method that can measure with a small amount (several μL) of sample. However, in the current commercially available viscometer, at least 50 μL of a sample is required to measure the viscosity. As an example in which the viscosity can be measured with a droplet of several μL, the viscosity may be measured from the vibration attenuation rate by measuring the vibration of the droplet as in the patent of Japanese Patent Application No. 2015-5778. However, both with this method and with other conventional methods, it is necessary to prepare a liquid sample and put it in a cup or a viscometer. Since the liquid sample after measurement comes into contact with the measurement part of the viscometer, it cannot be used for other inspections.

Japanese Unexamined Patent Publication No. 2016-130716

The present invention has been made in view of the above circumstances, and provides a viscosity measuring device and a viscosity measuring method capable of measuring the viscosity of a small amount of a sample of a liquid to be measured in a non-contact manner. The purpose.

In order to solve the above problems, the present invention employs the following means.

(1) The viscosity measuring device according to one aspect of the present invention is a viscosity measuring device for measuring the viscosity of a liquid, which accommodates a fluid, has an opening, and reduces the pressure of the fluid in the chamber. A means, a pressure measuring means for measuring the pressure of the fluid in the chamber, one end connected to the opening, extending outside the chamber, accommodating the liquid from the other end, and a hollow portion. Reduces the pressure of the fluid in the chamber to a predetermined value by the tubular portion communicating with the space in the chamber and the depressurizing means, and the pressure when the liquid is sucked up by the tubular portion. A means for measuring the viscosity of the liquid based on a time change of a measured value of the pressure of the fluid in the chamber by the measuring means is provided.

(2) In the viscosity measuring device according to (1) above, a deforming portion that deforms in response to an external force is provided on the side wall of the chamber, and as the decompression means, a tensioning device that pulls the deformed portion from the outside of the chamber. May be provided.

(3) The viscosity measuring device according to any one of (1) or (2) may include a pump for discharging the fluid in the chamber as the depressurizing means.

(4) In the viscosity measuring device according to any one of (1) to (3), the pressure measuring means includes a film that deforms according to the pressure in the chamber, and the degree of deformation of the film. A pressure sensor that outputs according to the above may be provided.

(5) In the viscosity measuring apparatus according to any one of (1) to (4), the pressure measuring means may include a microelectromechanical system (MEMS) pressure sensor.

(6) The viscosity measuring method according to one aspect of the present invention is a viscosity measuring method for measuring the viscosity of a liquid using the viscosity measuring device according to any one of (1) to (5) above. In the depressurizing step of depressurizing the fluid in the chamber by using the depressurizing means while the other end of the tubular member is in contact with the liquid to be measured, and in the depressurizing step, the pressure measuring means is used. It has a pressure measuring step of measuring a time change of the pressure of the fluid in the chamber.

(7) In the viscosity measuring method according to (6), the pressure of the fluid in the chamber is reduced to a predetermined value by the depressurizing means in the depressurizing step, and the liquid to be measured in the pressure measuring step. The viscosity of the liquid may be measured from the measurement of the time change of the pressure of the fluid in the chamber when the fluid is sucked up into the tubular portion.

In the viscosity measuring device of the present invention, the pressure measuring means is arranged apart from the liquid to be measured via the chamber and the tubular portion, and does not come into contact with the liquid to be measured. Therefore, problems such as contamination of the liquid to be measured can be avoided, and the measured liquid can be repeatedly used for the same measurement, returned to the original liquid source, and used for the original purpose. It can also be used for other purposes. Further, in the viscosity measuring device of the present invention, in order to detect the fluidity of the liquid in the tubular portion when it is sucked up by the tubular portion by a pressure change, the viscosity is measured with a small amount of liquid, for example, about several μL. This is effective when the liquid to be measured is difficult to manufacture or rare and difficult to obtain.

It is sectional drawing of the viscosity measuring apparatus which concerns on 1st Embodiment of this invention. It is sectional drawing of the structural example of the viscosity measuring apparatus of FIG. It is sectional drawing of another configuration example of the viscosity measuring apparatus of FIG. (A)-(d) It is sectional drawing of the object to be processed in the manufacturing process of a pressure sensor. It is sectional drawing of the viscosity measuring apparatus used as the Example of this invention. (A), (b) is a graph which shows the measurement result of the viscosity of the liquid obtained in the Example of this invention. It is a graph which shows the relationship between the viscosity of a liquid and the damping coefficient of the pressure change of a chamber obtained in the Example of this invention.

Hereinafter, the viscosity measuring apparatus and the viscosity measuring method according to the embodiment to which the present invention is applied will be described in detail with reference to the drawings. In the drawings used in the following description, in order to make the features easier to understand, the featured parts may be enlarged for convenience, and the dimensional ratios of each component may not be the same as the actual ones. do not have. Further, the materials, dimensions, etc. exemplified in the following description are examples, and the present invention is not limited thereto, and the present invention can be appropriately modified without changing the gist thereof.

<First Embodiment>
FIG. 1 is a cross-sectional view schematically showing the configuration of a main part of the viscosity measuring device 100 according to the embodiment of the present invention. The viscosity measuring device 100 mainly includes a chamber 101, a depressurizing means 102, a pressure measuring means 103, a tubular portion (needle) 104, and a viscosity measuring means (not shown).

The chamber 101 accommodates an arbitrary fluid (not shown) such as air, an inert gas, or a liquid, and has a first opening 101a that penetrates a part of the side wall. The material of the side wall of the chamber 101 is not particularly limited as long as it can maintain the airtightness inside the chamber 101.

The decompression means 102 decompresses the fluid in the chamber 102, and its configuration includes, for example, a type that reduces the amount of fluid in the chamber 101, a type that expands the space in the chamber 101, and the like. Can be mentioned. Examples of the type that reduces the amount of fluid in the chamber 101 include a pump that discharges the fluid in the chamber 101. The type that expands the space in the chamber 101 will be described later.

The pressure measuring means 103 measures the pressure in the chamber 101, and examples thereof include those including a microelectromechanical system (MEMS) pressure sensor and the like. The pressure sensor in this case has a film (membrane) that communicates with the chamber 101 and deforms according to the pressure in the chamber 101, and outputs according to the degree of deformation of the film. The configuration of the pressure sensor will be described later.

One end 104a of the tubular portion 104 is connected to the first opening 101a and extends to the outside of the chamber 101 to accommodate the liquid L from the other end 104b. The other end 104b of the tubular portion serves as a suction port for the liquid L for which the viscosity is to be measured. Here, a state in which the other end 104b of the tubular portion is inserted into the liquid L housed in the predetermined container V and the liquid L is sucked up is illustrated. When the liquid L to be sucked up may be mixed with the fluid in the chamber 101, it is preferable to provide a partition portion that can move according to the pressure at the boundary between the liquid L and the fluid.

The shape of the tubular portion 104 is not particularly limited, but from the viewpoint of facilitating the suction of the liquid L, it is preferable that the tubular portion 104 has a cylindrical shape having a substantially uniform inner diameter. From the same viewpoint, the inner diameter of the tubular portion 104 is preferably 0.1 mm or more, while the inner diameter of the tubular portion 104 is 3 mm or less from the viewpoint of performing viscosity measurement with a small amount of liquid L. preferable.

The space (hollow portion) 104A in the tubular portion 104 communicates with the space 101A in the chamber 101. From the viewpoint of checking the position of the liquid surface L ₁ visually, cylindrical portion 104 is preferably transparent to visible light. Examples of the material of the tubular portion 104 include glass.

The viscosity measuring means reduces the pressure of the fluid in the chamber 101 to a predetermined value by the depressurizing means 102, and the pressure of the fluid in the chamber 101 by the pressure measuring means 103 when the liquid L is sucked up by the tubular portion 104. It is an apparatus for measuring the viscosity of the liquid L based on the time change of the measured value. Actually, the damping coefficient is obtained from the time change of the measured value of the pressure using a personal computer (processor) or the like, and the liquid L corresponding to the damping coefficient is referred to by referring to the database including the correlation between the damping coefficient and the viscosity. The viscosity of can be determined.

The viscosity measurement using the viscosity measuring device 100 can be mainly performed by the following procedure. First, the liquid L whose viscosity is to be measured is contained in a predetermined container V, and the fluid in the chamber 101 is depressurized (depressurized) by using the depressurizing means 102 in a state where the other end 104b of the tubular member is in contact with the liquid L. Process). It is assumed that the liquid level of the liquid L in the container V is in contact with the atmosphere outside the chamber 101.

The depressurization here is to make the pressure smaller than the initial state, and it is sufficient that there is a predetermined pressure change regardless of the initial pressure value. The range of the pressure change is not particularly limited, but at least it is sufficient as long as the liquid L can be sucked up (about 1 kPa).

When the pressure inside the chamber 101 becomes small, the force of the air outside the chamber 101 pushing the liquid L inside the container V becomes relatively strong, so that the liquid L enters the tubular portion 104 and is sucked up in the direction of the chamber 101. become.

In a vacuum process, reducing the pressure of the fluid in the chamber 101 to a predetermined value by the pressure reducing means, the pressure in the chamber 101 is lower than the pressure outside the chamber, raise the liquid level L _1, the chamber 101 accordingly The pressure inside increases over time. The decay rate (decrease rate) of the absolute value of the pressure change amount is calculated, and the viscosity of the liquid is obtained (pressure measurement step).

The pressure in the chamber 101 is P _atm -Ce- ^αt (P _{atm: the} pressure in the chamber before decompression, P _atm -C: the pressure in the chamber 101 at the time of decompression, α: damping coefficient (P atm: pressure in the chamber before decompression, α: damping coefficient It changes as represented by the decrease coefficient) and t: elapsed time). The damping coefficient α at this time has a proportional relationship with the viscosity of the liquid. The higher the viscosity, the smaller the damping coefficient α, and the lower the viscosity, the larger the damping coefficient α. Therefore, by comparing the damping coefficient α of the pressure of the fluid in the chamber 101, it is possible to confirm the magnitude relationship of the viscosities of different liquids.

If the damping coefficient is calculated for each of a plurality of liquid samples having known viscosities by the above method and the relational expression between the viscosity and the damping coefficient is obtained as a database, any liquid can be used through this relational expression. It is possible to know the value of the viscosity corresponding to the measurement result of the damping coefficient.

FIG. 2 is a cross-sectional view schematically showing a configuration example of the viscosity measuring device 100A when a means for increasing the volume (volume) of the fluid in the chamber 101 is used as the depressurizing means. A deformed portion 101B made of a flexible material and deformed in response to an external force is provided on a part of the side wall of the chamber 101. Further, as the depressurizing means, a pulling device 102A for pulling the deformed portion from the outside of the chamber 101 is provided. The configuration other than the deformed portion 101B and the tensioning device 102A is the same as the configuration of the viscosity measuring device 100 shown in FIG.

The tensioning device 102A mainly supports a metal member (metal ball) 110 fixed (adhered) to the deformed portion 101B, an electromagnet 111 arranged so as to face the chamber 101 with the metal member 110 interposed therebetween, and an electromagnet 111. It is composed of a support member 112 and a support member 112.

By driving the electromagnet 111 to generate a magnetic field and attracting the metal member 110, the deformed portion 101B fixed to the metal member 110 is pulled together and deformed. As a result, the chamber 101 expands and the inside of the chamber 101 is depressurized.

FIG. 3A is a cross-sectional view schematically showing a configuration example of a viscosity measuring device 100B when a pressure sensor 103A to which a microelectromechanical system (MEMS) technology is applied is used as a pressure measuring means. FIG. 3B is a plan view of the pressure sensor 103A from the thickness direction of the membrane. FIG. 3 (c) is a cross-sectional view of the pressure sensor 103A of FIG. 3 (b) cut along the line AA'in the thickness direction. The configuration other than the pressure sensor 103 is the same as the configuration of the viscosity measuring device 100 shown in FIG. As the depressurizing means 102, the tensioning device 102A shown in FIG. 2 may be applied.

Of the side walls of the chamber 101, the connection portion of the pressure sensor 103A has an opening (second opening) so that the pressure sensor 103A can detect the pressure of the fluid in the chamber 101, that is, the fluid contacts the membrane. Part) 101b is provided. Here, the case where the chamber 101 is directly connected to the chamber 101 is illustrated, but the chamber 101 may be indirectly connected to the chamber 101 via a pipe or the like.

The pressure sensor 103A is mainly composed of a substrate 105, an _{insulating film 106 made of silicon oxide (SiO 2} ) or the like, a semiconductor film 107 made of silicon doped with impurities and functioning as a piezoresistive element, and gold and chrome. It is composed of a conductor film 108 made of a resin such as parylene and a membrane 109 made of a resin such as parylene. The substrate 105 is made of a rigid body such as silicon and has a through hole 105A penetrating in the thickness direction. On one main surface 105a of the substrate, an insulator film 106, a semiconductor film 107, and a conductor film 108 are laminated in this order around the through hole 105A. A part of the semiconductor film 107 has a protruding portion 107a that projects above the through hole 105A and functions as a cantilever.

The membrane 109 covers at least a region overlapping the through hole 105A in a plan view from the thickness direction of the substrate 105, and the outer peripheral portion 109a is supported by the conductor film 108 or the protruding portion 107a of the semiconductor film. Membrane 109, when the fluid in the chamber 101 is in contact, in response to the pressure of the fluid, the warp in the thickness direction T _2, Accordingly, even protrusion 107a of the semiconductor film which supports the membrane 109, the thickness warp in the direction _{T 1.} Since the electric resistance of the protrusion 107a changes according to the amount of warpage, it is possible to know the pressure change of the fluid in the chamber 101 through the change of the electric resistance.

4 (a) to 4 (d) are diagrams showing a flow of a main manufacturing process of the pressure sensor 103A. First, as shown in FIG. 4A, the insulator film 106, the semiconductor film 107, and the conductor film 108 are formed on one main surface 105a of the substrate by using a known film forming method such as a CVD method or a sputtering method. Form in order. Next, as shown in FIG. 4B, a predetermined pattern is formed on the semiconductor film 107 and the conductor film 108 by using a photolithography method. Next, as shown in FIG. 4C, a membrane 109 covering the central region where the through holes are formed is formed by using a thin-film deposition method or the like. Finally, as shown in FIG. 4D, the substrate 105 and the insulating film 106 are removed from the other main surface 101b side of the substrate so that the through hole 105A is formed by using an etching method. A pressure sensor 103A can be obtained.

As described above, in the viscosity measuring device 100 according to the present embodiment, the pressure measuring means 103 is arranged apart from the liquid L to be measured via the chamber 101 and the tubular portion 104, and the liquid to be measured is measured. Does not come into contact with L. Therefore, problems such as contamination of the liquid L to be measured can be avoided, and the measured liquid L can be repeatedly used for the same measurement, or returned to the original liquid source and used for the original purpose. Alternatively, it can be diverted to other uses. Further, since the viscosity measuring device 100 according to the present embodiment detects the fluidity of the liquid L in the tubular portion 104 when it is sucked up by the tubular portion 104 by a pressure change, a small amount, for example, about several μL. The viscosity can be measured with the liquid of the above, and it is effective when the liquid to be measured is difficult to manufacture or rare and difficult to obtain.

Hereinafter, the effects of the present invention will be made clearer by examples. The present invention is not limited to the following examples, and can be appropriately modified and implemented without changing the gist thereof.

The viscosities of the two liquid samples 1 and 2 were measured using the viscometer measuring device to which the above embodiment was applied. FIG. 5 is a cross-sectional view schematically showing the configuration of the viscosity measuring device 200. The tensioning device 102A was applied as the depressurizing means, and the pressure sensor 103A was applied as the pressure measuring means. Although not shown in FIGS. 2 and 3, the driving means 113 for driving the electromagnet 111, the amplifier circuit 114 for acquiring the output of the pressure sensor, and the oscilloscope 115 are shown here. Other configurations are the same as the configuration of the viscosity measuring device 100 shown in FIG. As the tubular member 104, a glass tube having an inner diameter of 1 mm was used. The liquid sample 1 was water, and the liquid sump 2 was a mixed liquid containing water and glycerol in a ratio of 50:50.

6 (a) and 6 (b) are graphs showing the measurement results of the output of the sensor for the liquid samples 1 and 2, respectively. The horizontal axis of the graph shows the measurement time (s), and the vertical axis of the graph shows the rate of change ΔR / R of the output resistance obtained from the pressure sensor. The rate of change ΔR / R of the output resistance is inversely proportional to the pressure in the chamber 101. Therefore, from these graphs, it can be seen that the decompression is performed using the depressurizing means 102 at time 0 (s), and the absolute value of the resistance change rate rises sharply in a short time. Further, after time 0 (s), it ^{tends to gradually decrease according to Ce − αt} (C: resistance change rate at the time of decompression, α: attenuation coefficient, t: elapsed time), and particularly after time 20 (s). , It can be seen that it approaches a nearly constant value.

In the graph of the liquid sample 1 having a low viscosity (FIG. 6A), the pressure change per unit time is 1 mPa · s. On the other hand, in the graph of the liquid sample 1 having a high viscosity (FIG. 6B), the pressure change per unit time is 6 mPa · s. From these results, when a liquid L having a high viscosity was used, the pressure in the chamber 101 tended to change slowly, and conversely, when a liquid L having a low viscosity was used, the pressure in the chamber 101 was used. The pressure tends to change rapidly.

FIG. 7 is a graph showing the relationship between the viscosity of the liquid and the damping coefficient of the pressure of the liquid for the two liquid samples 1 and 2 and the two newly added liquid samples 3 and 4. The liquid sump 3 was a mixed liquid containing water and glycerol at a ratio of 70:30, and the liquid sump 4 was a mixed liquid containing water and glycerol at a ratio of 30:70. The horizontal axis of the graph shows the viscosity of the liquid (mPa · s), and the vertical axis of the graph shows the damping coefficient of the pressure change in the chamber 101. From this graph, it can be seen that the data of the four samples are on one curve. It can be seen that the higher the viscosity of the sample, the smaller the damping coefficient of the pressure change. These tendencies are considered to be the same even if the number of samples is increased. Therefore, if a calibration curve showing the correlation between the attenuation coefficient and the viscosity as shown in FIG. 7 or a conversion table or conversion formula corresponding to the calibration curve is obtained using a plurality of samples having known viscosities, this is used as a database. Can be used as. That is, the corresponding viscosity value can be obtained from the attenuation coefficient obtained by measuring the viscosity of the present invention using this database.

100, 100A, 100B ... Viscosity measuring device 101 ... Chamber 101a ... First opening 101A ... Space in the chamber 102 ... Decompressing means 102A ... Tensioning device 103 ... Pressure measurement Device 103A ... Pressure sensor 104 ... Cylindrical member 104a ... One end of the tubular member 104b ... The other end of the tubular member 104A ... Space in the tubular member 105 ... Substrate 105a ... ... One main surface 105b of the substrate ... The other main surface 105A of the substrate ... Through hole 106 ... Insulator film 107 ... Semiconductor film 108 ... Conductor film 109 ... Membrane 110 ... Metal member 111 ... Electromagnet 112 ... Support member 113 ... Drive means 114 ... Amplifier circuit 115 ... Oscilloscope L ... Liquid L ₁ ... Liquid level V ... Container

Claims (7)

A viscometer measuring device that measures the viscosity of a liquid.
A chamber that houses fluid and has an opening,
A decompression means for depressurizing the fluid in the chamber, and
A pressure measuring means for measuring the pressure in the chamber and
A tubular portion having one end connected to the opening, extending outside the chamber and accommodating the liquid from the other end, and a hollow portion communicating with the space in the chamber.
The time of the measured value of the pressure of the fluid in the chamber by the pressure measuring means when the pressure of the fluid in the chamber is reduced to a predetermined value by the depressurizing means and the liquid is sucked up into the tubular portion. A means for measuring the viscosity of the liquid based on the change,
A viscosity measuring device. A deformed portion that deforms in response to an external force is provided on the side wall of the chamber.
The viscosity measuring device according to claim 1, further comprising a pulling device for pulling the deformed portion from the outside of the chamber as the depressurizing means. The viscosity measuring device according to claim 1, wherein the decompression means includes a pump for discharging the fluid in the chamber. 3. The viscosity measuring device according to item 1. The viscosity measuring device according to any one of claims 1 to 4, wherein the pressure measuring means includes a microelectromechanical system (MEMS) pressure sensor. A viscosity measuring method for measuring the viscosity of a liquid using the viscosity measuring device according to any one of claims 1 to 5.
A decompression step of decompressing the fluid in the chamber using the decompression means while the other end of the tubular member is in contact with the liquid to be measured.
A viscosity measuring method comprising a pressure measuring step of measuring a time change of the pressure of the fluid in the chamber by using the pressure measuring means in the depressurizing step. In the depressurizing step, the pressure of the fluid in the chamber is reduced to a predetermined value by the depressurizing means.
The claim is characterized in that, in the pressure measuring step, the viscosity of the liquid is measured from the measurement of the time change of the pressure of the fluid in the chamber when the liquid to be measured is sucked up into the tubular portion. The viscosity measuring method according to 6.

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