A system and method for measuring the viscosity of ultra-low volumes of liquid

Abstract

The application provides a system and method for measuring the viscosity of ultra-micro liquid, which comprises the following steps: depositing a small amount of liquid sample on a glass slide by using a sample transfer tool; calculating the dewetting speed of the liquid according to the spreading process of the liquid sample; calculating the surface tension of the liquid when the contact angle is 0; calculating the contact angle of the liquid according to the interference fringes formed by the micro-droplet; and calculating the viscosity of the liquid according to the dewetting speed of the liquid, the contact angle of the liquid and the surface tension of the liquid. The application realizes high-precision viscosity measurement under the condition of 1 mu l sample amount, effectively reduces sample consumption, improves the accuracy and efficiency of measurement, and is simple to operate, suitable for high-throughput and rapid screening. The application effectively overcomes the limitations of traditional viscosity measurement technology through fine physical calculation and high-precision image processing technology, and provides strong technical support for the research and application in the fields of biotechnology, chemical engineering and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of liquid viscosity measurement, in particular to a measurement system and method for ultra-micro liquid viscosity. BACKGROUND

[0002] With the rapid development of the field of biological preparation development, higher requirements are put forward for the measurement of micro-liquid sample viscosity. The existing viscosity measurement methods mainly include pressure measurement method, electroosmosis measurement method and fluorescence measurement method.

[0003] Among them, the pressure measurement method adopts VROC viscosity rheological integrated technology, which is accurate and stable in measurement, but its complex structure and strict operation requirements limit its application in early development of biological preparations with extremely small sample size, complex components and precious components.

[0004] Electroosmosis measurement method, electroosmosis is one of electrokinetic phenomena, which refers to the phenomenon that liquid moves relative to the fixed solid phase in contact with it under the action of electric field. Generally, under the action of electric field, the solution will move in a certain direction, such as the liquid dynamic viscosity measurement platform based on the principle of electroosmosis in patent CN108872016A, which uses the principle of electroosmosis and combines with infrared heating technology to measure the change characteristics of liquid viscosity with temperature.

[0005] And fluorescence measurement method, such as CN116973273A polymer coating friction contact area micro-viscosity detection method, uses molecular rotor type fluorescent probe to dye polymer coating before and after mixing different lubricants, and quantitatively tests the micro-viscosity of the contact area, and uses it as the basis to reveal the interface response mechanism of lubricant mixing instant from the perspective of micro-viscosity, and establishes the relationship between micro-viscosity and friction coefficient mutation.

[0006] However, the above viscosity measurement methods require at least 15ul of sample size in the measurement process, which is not economical in many cases and limits the application in early development of biological preparations with extremely small sample size, complex components and precious components. SUMMARY

[0007] In view of the shortcomings of the prior art, the present application provides a measurement system and method for ultra-micro liquid viscosity, which can significantly reduce the sample size required in the early development of biological preparations and improve the efficiency and accuracy of viscosity measurement.

[0008] The technical scheme of the present application is as follows: a measurement method for ultra-micro liquid viscosity, comprising the following steps:

[0009] S1), using a sample transfer tool to accurately deposit a small amount of liquid sample on a glass slide;

[0010] S2), calculating the dewetting speed of the liquid according to the spreading process of the liquid sample;

[0011] S3) calculating the liquid surface tension γ at the contact angle θ = 0;

[0012] S4) calculating the fluid contact angle θ from the interference fringes of the microdroplet formation;

[0013] S5) calculating the liquid viscosity η from the dewetting speed v, the liquid contact angle θ, and the liquid surface tension γ:

[0014]

[0015] where v represents the dewetting speed, θ is the liquid contact angle, and γ denotes the liquid surface tension; and a represents the proportional relationship. d where v represents the dewetting speed, θ is the liquid contact angle, and γ denotes the liquid surface tension; and a represents the proportional relationship.

[0016] Preferably, in step S1), a surface temperature controller is connected to the cover glass carrier, and the surface temperature of the cover glass carrier is controlled by the surface temperature controller to be stabilized at 25-30°C, and a small amount of liquid sample is accurately deposited on the glass slide using a sample transfer tool.

[0017] Preferably, in step S2), the spreading process of 1 μl of liquid sample on the glass slide is recorded by a high-speed camera; and the change of the liquid radius R within a certain time t is extracted from the video; and the dewetting speed v of the liquid is calculated. d The specific calculation formula is:

[0018]

[0019] where R is the liquid radius.

[0020] Preferably, in step S3), the liquid surface tension γ is measured by the Wilhelmy plate technique.

[0021] Preferably, in step S3), the glass cover slide is suspended on a force sensor, and when the liquid contacts the Wilhelmy plate, the tension F on the Wilhelmy plate is measured by the force sensor.

[0022] And the liquid surface tension γ is calculated according to the tension F on the Wilhelmy plate, the wetting perimeter l, and the contact angle θ = 0 of the fluid droplet with the Wilhelmy plate; and the calculation expression is:

[0023]

[0024] where cos θ = 1 when the contact angle θ = 0.

[0025] Preferably, in step S3), the wetting perimeter l = 2w + 2d; w and d are the width and thickness of the Wilhelmy plate, respectively.

[0026] As preferred, in step S4), the calculation of the contact angle θ is specifically:

[0027] By using a micro-liquid transfer device to accurately deposit the sample on a microscope slide, a micro-droplet with an average radius of 5 μm is formed, and a high-definition image of the micro-droplet is captured using a pE-300 ultra LED light source with a narrow-band filter and a high-power microscope. By analyzing the interference fringes formed by the micro-droplet, the contact angle θ of the droplet is calculated according to the incremental height difference of the interference fringes and the distance in the radial direction of the interference fringes, i.e.:

[0028]

[0029] In the formula, Δh is the incremental height difference of the first two interference fringes; Δx is the distance in the radial direction between the first two interference fringes.

[0030] As preferred, the present application further provides a system for measuring ultra-micro liquid viscosity, comprising:

[0031] a cover glass holder for fixing a cover glass;

[0032] a surface temperature controller connected to the cover glass holder and used to control the surface temperature of the cover glass holder to be stabilized at 25-30℃;

[0033] a high-speed camera for capturing the spreading video of the liquid sample on the slide;

[0034] a force sensor for collecting the tension when the liquid contacts the Wilhelmy plate;

[0035] a high-power microscope for capturing high-definition images of the micro-droplet;

[0036] a pE-300 ultra LED light source with a narrow-band filter for cooperating with the high-power microscope to capture high-definition images of the micro-droplet;

[0037] a computer system connected with the high-speed camera, the force sensor and the high-power microscope respectively; the computer system acquires the spreading video of the liquid sample on the slide captured by the high-speed camera to calculate the dewetting speed v d of the liquid;

[0038] the computer system further acquires the tension data F collected by the pressure sensor to calculate the surface tension γ of the liquid;

[0039] the computer system further acquires the micro-droplet image captured by the high-power microscope, analyzes the interference fringes formed by the micro-droplet, and calculates the contact angle θ of the droplet;

[0040] Finally, the liquid viscosity η is calculated according to the liquid dewetting speed v d , the liquid contact angle θ, and the liquid surface tension γ.

[0041] The beneficial effects of the present application are:

[0042] 1. The present application realizes high-precision viscosity measurement under the condition of 1 μl sample amount, effectively reduces sample consumption, improves measurement accuracy and efficiency, and is simple to operate, suitable for high-throughput and rapid screening.

[0043] 2. The present application effectively overcomes the limitations of traditional viscosity measurement techniques through fine physical calculation and high-precision image processing technology, providing strong technical support for research and application in the fields of biotechnology, chemical engineering, etc. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 is a flowchart of the method of the present application;

[0045] Figure 2 is a schematic diagram of the framework of the method of the present application. DETAILED DESCRIPTION

[0046] The specific embodiments of the present application will be further described below in conjunction with the accompanying drawings:

[0047] Example 1

[0048] As shown in Figure 1 and 2 , the present embodiment provides a method for measuring ultra-micro liquid viscosity, comprising the following steps:

[0049] S1), using a sample transfer tool to accurately deposit the sample on a glass slide;

[0050] In this embodiment, by connecting the surface temperature controller to the cover glass carrier, after the temperature is stabilized at 25-30℃, 1 μl of liquid sample is accurately deposited on the glass slide using a sample transfer tool.

[0051] And during the sample deposition process, avoid excessive exposure of the sample to air to prevent evaporation from causing viscosity measurement errors,

[0052] S2), calculating the dewetting speed of the liquid;

[0053] After the liquid sample is deposited, the spreading process of the 1 μl liquid sample on the glass slide is recorded by a high-speed camera; and the change of the liquid radius R within a certain time t is extracted from the video; to calculate the dewetting speed v d of the liquid, the specific calculation formula is:

[0054]

[0055] In the embodiment, the high-speed camera records the angle perpendicular to the liquid spreading plane when recording the spreading process of the liquid sample on the slide, while ensuring the clarity of the droplet edge;

[0056] S3), calculate the liquid surface tension γ when the contact angle θ is 0;

[0057] In the embodiment, the liquid surface tension γ is measured by using the Wilhelmy plate technique, specifically:

[0058] By suspending the glass cover glass on the force sensor, when the liquid contacts the Wilhelmy plate, the tension F on the Wilhelmy plate is measured by the force sensor; and according to the tension F on the Wilhelmy plate, the wetting perimeter l, and the contact angle θ = 0 of the fluid droplet and the Wilhelmy plate, the surface tension γ of the liquid is calculated; the calculation expression is:

[0059]

[0060] In the formula, when the contact angle θ = 0, cos θ = 1.

[0061] In the embodiment, the wetting perimeter l = 2w + 2d; w and d are the width and thickness of the Wilhelmy plate, respectively.

[0062] S4), calculate the fluid contact angle θ according to the interference fringes formed by the microdroplets; specifically:

[0063] By using a micro-liquid transfer device to accurately deposit the sample on a microscope slide, a microdroplet with an average radius of 5 μm is formed, and a high-definition image of the microdroplet is obtained by using a pE-300 ultra LED light source with a narrow-band filter and a high-magnification microscope. By analyzing the interference fringes formed by the microdroplets, the contact angle θ of the droplet is calculated according to the incremental height difference of the interference fringes and the distance in the radial direction of the interference fringes, that is:

[0064]

[0065] In the formula, Δh is the incremental height difference of the first two interference fringes; Δx is the distance in the radial direction between the first two interference fringes.

[0066] S5), calculate the liquid viscosity η according to the liquid dewetting speed, the liquid contact angle, and the liquid surface tension:

[0067]

[0068] In the formula, v drepresents the liquid dewetting speed, θ is the liquid contact angle, γ represents the liquid surface tension; represents the proportional relationship.

[0069] Embodiment 2

[0070] The embodiment provides a measurement system for ultra-micro liquid viscosity, comprising:

[0071] A cover glass carrier is arranged for fixing the cover glass.

[0072] A surface temperature controller is connected to the cover glass carrier and used for controlling the temperature of the cover glass carrier to be stable at 25-30℃.

[0073] A high-speed camera is arranged for collecting the spreading video of the liquid sample on the glass slide.

[0074] A force sensor is arranged for collecting the tension when the liquid contacts the Wilhelmy plate.

[0075] A high-power microscope is arranged for collecting the high-definition image of the microdroplet.

[0076] A pE-300 ultra LED light source with a narrow-band filter is arranged for cooperating with the high-power microscope to collect the high-definition image of the microdroplet.

[0077] A computer system is connected with the high-speed camera, the force sensor and the high-power microscope respectively; the computer system is used for obtaining the spreading video of the liquid sample on the glass slide collected by the high-speed camera, so as to calculate the dewetting speed v d of the liquid.

[0078] The computer system is also used for obtaining the tension data F collected by the force sensor, so as to calculate the surface tension γ of the liquid.

[0079] The computer system is also used for obtaining the image of the microdroplet collected by the high-power microscope, and calculating the contact angle θ of the droplet by analyzing the interference fringes formed by the microdroplet.

[0080] Finally, the viscosity η of the liquid is calculated according to the dewetting speed of the liquid, the contact angle of the liquid and the surface tension of the liquid.

[0081] As preferred in the embodiment, the computer system extracts the change of the liquid radius R within a certain time t from the spreading video of the liquid sample on the glass slide, so as to calculate the dewetting speed v d of the liquid. The specific calculation formula is as follows:

[0082]

[0083] As preferred in the embodiment, the computer system calculates the surface tension γ of the liquid according to the tension F received by the Wilhelmy plate, the wetting perimeter l, and the contact angle θ=0 of the fluid droplet with the Wilhelmy plate; the calculation expression is:

[0084]

[0085] In the formula, when the contact angle θ=0, cosθ=1.

[0086] As preferred in the embodiment, the computer system calculates the contact angle θ of the droplet according to the incremental height difference of the interference fringes and the distance in the radial direction of the interference fringes, i.e.

[0087]

[0088] In the formula, Δh is the incremental height difference of the first two interference fringes; Δx is the distance in the radial direction between the first two interference fringes.

[0089] As preferred in the embodiment, the calculation expression of the liquid viscosity η is:

[0090]

[0091] In the formula, v d represents the liquid dewetting speed, θ is the contact angle of the liquid, γ represents the surface tension of the liquid; α represents the proportional relationship.

[0092] The above embodiment and the description in the specification only illustrate the principles and the best mode of the present application, and the present application can have various changes and improvements without departing from the spirit and the scope of the present application, and these changes and improvements all fall within the scope of the present application.

Claims

1. A method of measuring the viscosity of an ultra-low volume liquid, characterized in that, The method comprises the following steps: S1), using a sample transport tool to accurately deposit a small amount of liquid sample on a glass slide; By connecting the surface temperature controller to the cover glass carrier, the surface temperature of the cover glass carrier is controlled by the surface temperature controller to be stable at 25-30℃, and then the liquid sample is accurately deposited on the glass slide using the sample transport tool; S2), calculate the dewetting speed of the liquid according to the spreading process of the liquid sample; After the liquid sample is deposited, the spreading process of 1 μl liquid sample on the glass slide is recorded by a high-speed camera; and extract from the video the change in liquid radius over a certain time t; to calculate the dewetting speed of the liquid R , in particular the formula is: ​ ； wherein R is the liquid radius; S3), calculating the contact angle θ the liquid surface tension γ when θ = 0; S4) calculating the liquid contact angle from the interference fringes of the microdroplet formation θ S5), calculate the liquid viscosity η according to the liquid dewetting speed, liquid contact angle, and liquid surface tension: wherein represents the liquid dewetting speed, θ is the liquid contact angle, and γ represents the liquid surface tension; represents a proportional relationship.

2. The method of measuring the viscosity of an ultra-low volume liquid according to claim 1, characterized in that: In step S3), the liquid surface tension γ is measured by Wilhelmy plate technology.

3. The method of measuring the viscosity of an ultra-low volume liquid according to claim 2, wherein: In step S3), by hanging a glass cover glass on a force sensor, when the liquid contacts the Wilhelmy plate, the tension F on the Wilhelmy plate is measured by the force sensor; and the contact angle of the fluid droplet with the Wilhelmy plate l、 and the contact angle of the fluid droplet with the Wilhelmy plate θ = 0, the surface tension of the liquid γ is calculated; the calculation expression is: ； In the formulae, .

4. The method of measuring the viscosity of an ultra-low volume liquid according to claim 3, wherein: In step S3), the wetted perimeter l= 2 w + 2 d ; w and d are the width and thickness of the Wilhelmy plate, respectively.

5. The method of measuring the viscosity of an ultra-low volume liquid according to claim 1, wherein: In step S4), the contact angle θ is calculated in particular as follows: By using a micro-liquid transfer device to precisely deposit a liquid sample onto a microscope slide, a micro-droplet with an average radius of 5 μm is formed, and the micro-droplet is imaged in high definition using a pE-300 ultra LED light source with a narrow-band filter and a high-magnification microscope, and the contact angle of the micro-droplet is calculated from the interference fringes formed by the micro-droplet θ i.e.: wherein is the incremental height difference between the first two interference fringes; is the distance in the radial direction between the first two interference fringes.

6. A system for measuring the viscosity of an ultra-low volume liquid, characterized in that The system uses the method of any one of claims 1-5 to measure the concentration of the liquid, and the system comprises: a cover glass carrier for fixing the cover glass; a surface temperature controller connected to the cover glass carrier and used to control the surface temperature of the cover glass carrier to be stable at 25-30℃; a high-speed camera for collecting the spreading video of the liquid sample on the glass slide; a force sensor for collecting the tension when the liquid contacts the Wilhelmy plate; a high-power microscope for collecting high-definition images of microdroplets; a pE-300 ultra LED light source with a narrow-band filter for collecting high-definition images of microdroplets in cooperation with the high-power microscope; A computer system is connected with a high-speed camera, a force sensor, and a high-power microscope, respectively; a spreading video of a liquid sample on a slide collected by the high-speed camera is acquired by the computer system to calculate the dewetting speed of the liquid ​ The computer system also calculates the liquid surface tension γ by acquiring tension data collected by a pressure sensor F ​ The computer system also obtains a microdroplet image collected by a high-power microscope, calculates a contact angle of the microdroplet by analyzing interference fringes formed by the microdroplet θ ; Finally, the liquid viscosity η is calculated from the liquid dewetting speed , the liquid contact angle θ , and the liquid surface tension γ.

7. The system for measuring the viscosity of an ultra-low volume liquid according to claim 6, characterized in that: The computer system extracts changes in the inner liquid radius from the video of the spreading of the liquid sample on the glass slide t over time R to calculate the dewetting speed of the liquid , specifically by the formula: ； The computer system calculates the surface tension γ of the liquid according to the tension F received by the Wilhelmy plate, the wetting perimeter L and the contact angle θ of the fluid droplet with the Wilhelmy plate l、 = 0, the surface tension γ of the liquid is calculated; the calculation expression is: θ = 0, the surface tension γ of the liquid is calculated; the calculation expression is: In the formulae, ; The computer system calculates the contact angle of the liquid droplet according to the incremental height difference of the interference fringes and the distance in the radial direction of the interference fringes θ That is: wherein is the incremental height difference between the first two interference fringes; is the distance in the radial direction between the first two interference fringes.

8. The system for measuring the viscosity of an ultra-low volume liquid according to claim 7, characterized in that: The calculation expression of the liquid viscosity η is: wherein represents the liquid dewetting speed, θ is the liquid contact angle, and γ represents the liquid surface tension; represents a proportional relationship.

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