UA31236U - Device for automated measurement of viscosity of biological liquids - Google Patents

Abstract

Device for automated measurement of viscosity of biological liquids consists of reservoir for liquid and capillary. Reservoir is represented with two cuvettes placed on supports. The ends of the capillary are immersed to cuvettes, there electrodes are placed as well. To electric chain voltmeter and ampermeter are connected, those through adapters are connected to personal computer.

Description

Description of the invention

The useful model refers to medicine and can be used in scientific research, clinical laboratory diagnostics, clinical medicine to determine the viscosity of biological fluids, blood.

An analogue of the useful model is the electrical conductivity measuring cell SI 5 50 | Conductivity measuring cell. Si 50. REr:/Lymly.Kirvegmiv.gshey a) siv 50.ypit. - 2007). In inductive conductivity measurement, the alternating current of the solenoid generates an alternating magnetic field, inducing an electrical voltage in the liquid. The movement of liquid ions (current) increases depending on the concentration. The current in the liquid generates an alternating magnetic field 70 in the receiving (second) solenoid. Such a current is converted into ion concentration through electrical conductivity. That is, the analogue operates with the parameters of the electrical conductivity of the solution in order to determine its concentration and is an electrophysical method of analysis that is not aimed at measuring the viscosity of the liquid during its flow.

The disadvantage of the analogue is that, based on the measurement of electrical conductivity, there is a large volume of the liquid under study 12, the fundamental impossibility of measuring the viscosity of the liquid under study.

The closest analogue of a useful model is a device for measuring the viscosity of a liquid, consisting of a reservoir for a liquid and a capillary in which the liquid moves (E.M. Gershenzon, N.N. Malov, A.N. Mansurov

Molecular physics: textbook. - M.: Academy, 2000. - 272 pp. Y1. The prototype is a capillary Poiseuille viscometer, which is an O-shaped glass tube with a wide elbow that expands to the bottom. The second knee accommodates a capillary soldered inside, ending at the top in a ball that expands to the top. Below the ball and above it are marked two labels that limit a certain volume. The measurement is carried out as follows.

The viscometer is lowered into the container with the test liquid so that its level is above the upper mark of the viscometer. When filling the viscometer (ball), a time proportional to the viscosity of the liquid is recorded.

The disadvantage of the closest analogue is the large volume of the liquid being tested, the small range of measurements, etc.

We offer a solution that eliminates these shortcomings. 2

The useful model is based on the task of improving the device for measuring the viscosity of biological fluids by introducing a new functional unit for measuring electrical conductivity and a computer into the Mo capillary, which evaluates the rate of reaction to ensure objective measurement of a small volume of liquid. co

The task is solved by the fact that in the device for automated measurement of the viscosity of biological fluids, which consists of a reservoir for liquid and a capillary, according to a useful model, the reservoir is represented by two cuvettes that are on stands, the ends of the capillary are immersed in the cuvettes, to the same electrodes are placed, a voltmeter and an ammeter are connected to the electric circuit, which are connected to the PC of a personal computer through adapters. 325 Fig. 1 shows the general scheme of the claimed device, where it is indicated: 1, 2 - cuvettes with liquid samples under investigation; Z - voltmeter (87-21); 4 - ammeter (87-21); 5 - a capillary in which the tested liquid moves: b - stands for adjusting the position of the cuvettes; 7, 8 - adapters to a personal computer (9). "

Common features of the closest analogue and the claimed device are the presence of a reservoir with water and a capillary. t s The useful model differs from the closest analog by the presence of a unit for measuring electrical conductivity with computer analysis.

A comparison of the claimed method and the prototype method is presented in the table. 4th analog of electrolyte) (applied method) of 50 flow through the capillary about » liquid flow

Description of the device in a dynamic state In the proposed contact device for measuring 59 electrophysical parameters of small volumes of aqueous solutions of electrolytes, the studied liquid is passed through a polymer tube (capillary) with a diameter of 0.1-1.0 mm and a length of 700 mm. The ends of the tube are immersed in volumes of liquids with a cross-section of О » 4, where electrodes are placed for measuring the transmission of an electric current of the order of 1о0μКА - О,ТНА (Fig. 1). Under such conditions, almost the entire electric field is concentrated along the capillary, so the potential gradient in the near-electrode zone is negligible and measurements are carried out under the action of direct current. for Theoretical and experimental substantiation of the action of the claimed device.

The specified conditions make it possible to determine the specific electrical conductivity of the electrolyte solution from the expression of the law

Ohma in differential form: 152 se, (1) de. !/. 4. (23 b5 I- C da" -D-

From in-M

Yikes

Then c - Kk (4) 95 la and specific resistance 1 di (5) ty

The ends of the capillary were immersed in the volumes of the distillate and the studied electrolyte, with a given pressure dr, which caused the movement of their distribution along the capillary at a speed o, which depends on the viscosity of the liquids. If at the same time we neglect the mixing of liquids in the capillary (small diameter, etc.), then the ohmic resistance of the liquids in it at a certain moment of time Y is equal to:

Of (6)

Second century

R d) R: in 15 where ru and ro are the specific electrical conductivities of the distillate and solution I. and I" their paths traveled in the capillary will be: kt (7)

By substituting i" from (7) into (6), we obtain: i-th 1-3 voi (8)

B-you are kn Vita ra ri v ra v v g 20 . and

During the movement of liquids in the capillary: (FO 2 holes (9)

For convenience, we consider that at the initial moment of time I. is 0, then (8) taking into account (9) will take the form: v-V-rosoli Rayu (10) 25 5 Z

Having previously measured ρ and ρ according to formula (5) and determined the values |

AMC In I V, (11) where d VI - RI) 5 dO Bak

So you can find the speed of liquids in the capillary. co

During the experiment, the dependence was measured (MYU at SHO-sopv with the help of digital voltmeters 87-21, which were connected to the RT port of the computer through interface adapters, and the compiled program allowed to observe on the computer display graphic time dependences of the experimental

I-5(9) and computing 1 functions at O-sop (Figs. 1 and 2). -- t- 50

She co

Since your Sho, then on the computer display you can observe a direct dependence of K(O-A.DV, from where

The program determined the effective velocity of the liquid in the capillary according to the formula: "1 11 "Mk kiv What 2 s where o, - the angle of inclination of the tangent for the dependence of K(O) to the time axis y. :z" For a round cylindrical tube, the Navier-Stokes equation has view |Z): 14.05, Ar - - | - -B--

Kok ak tik be de,- 2 tu? 7 The distance to the axis of the tube, and the distribution of fluid velocities along the cross-section of the tube has the form: чв- Ав ва) as ko Ак with 20 Then the second flow rate of the liquid volume is determined by the Poiseuille formula: тв

Mov t A 4) sec Vyk r de 0 Mrek-| HF - ef Z- sope (15) t s By measuring the change in the mass of the liquid in one of the volumes of the liquid during time y:

Tesek- Yshcha 5- SOP

AND

6o0 it is possible to calculate the viscosity of the liquid: n-vylyu (6) po

VikSri

The effective velocity of the liquid in the capillary according to (13) is written in the form: b5 vr-s Av, (7) those

Having found y, from (11), p from (16) and measuring dr, we will find from (17) the constant C for this capillary.

Next, we will determine the effective viscosity of liquids in this capillary for fixed dr from (17):

Ap (18 p- SseV 118) this

Thus, it is shown on different liquids that this method can be used to study the change in specific electrical conductivity s, the effective speed of movement of liquids in the capillary, and the effective viscosity of liquids at OO - nozzle.

As mentioned, a program was created to measure viscosity, which builds dependencies (0 and 10/(O - Fig. 2.

An example of practical use of the method.

The research was carried out at (1-202C. Initially, reference liquids were used: 1 - distilled water H - 1.005 mPa.s, p - 0.9982; 2 - physiological solution H - 1.022 mPa.s - 0.996 mass solution. For them, the program calculated 75 effective the velocity of the flow of liquids in the capillary is m - 3.89 mm/s. Knowing the difference in the heights of the levels of distilled water and the physiological solution n - 2.00 cm and taking into account that p - roy (19) at 9 - 9.8 m/s?, we calculated the installation constant C - 2,014.106МН.s2. After that, you can study the viscosity of any biological fluid, having previously measured its density by means of selective weighing of the studied volume of fluid.

During the research, the program calculated the speed of plasma movement in the capillary m - 3.554 mm/s. Having previously measured the value of the specific density of plasma p - 1.027g/cm3 according to formulas (18, 19), we obtain the value of the dynamic viscosity of the studied blood plasma (4 - 1.141mpPa.s).

Technical result: the use of the claimed device allows you to measure the viscosity of small volumes of liquid and obtain an objective result. what with

Claims (1)

Formula of the invention Device for automated measurement of the viscosity of biological fluids, consisting of a reservoir for liquid and a capillary, which is characterized by the fact that the reservoir is represented by two cuvettes, which are located on two stands, the ends of the capillary are immersed in the cuvettes, the electrodes are placed there, to the electrical connected to the circuit (a voltmeter and an ammeter, which are connected to a personal computer through adapters. with . and? o - ko o (42) c 60 b5