SU1298536A1 - Hydraulic method of determining diameter of micropipette outlet - Google Patents

Abstract

The invention relates to measurement technology. The purpose of the invention is to simplify the method for determining the hydrodynamic diameter of the outlet by detecting the rate at which the solution is drawn into a micropipette using an optical microscope. A conic part of the micropipette that is clearly visible is observed in an optical microscope. The outer diameters are measured at a given distance and the taper is calculated from them. The duration of the meniscus movement is measured by a capillary force, and the diameter of the outlet of the microscope is determined from the measured taper and the speed of movement. The method allows to detect apertures of more than 0.05 microns with an optical microscope, the resolution of which is, whose intensity is at a level of 1 micron. 2 Il. c (Oh "and L. Yu

Description

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The invention relates to a measurement technique and can be explored when determining the diameter of the outlet of micropipettes used in microinjection and microsurgery of cells, electrophysiological studies, etc.

The purpose of the invention is to simplify the method for determining the hydrodynamic diameter of the outlet by detecting the rate at which the solution is drawn into a micropipette using an optical microscope.

Figure 1 shows a measurement circuit; Fig 2 is a calculation scheme.

The controlled micropipette 1 is fixed by means of the holder 2 in the three-coordinate micromanipulator 3. The outlet 4 of the micropipette is located in the invisible zone 5 of the micropipette, i.e. in the zone5 that cannot be scanned with an optical microscope 6. The zone of visibility passes into the thickened part of the micropipette.

The conicity K of a micropipette is calculated on the basis of measurements using a microscope of outer diameters d and d, of a micropipette in zone 5, in par

ion diameters, clearly fixed by the microscope 6, according to the formula;

b

to -Zi-.

(one)

where & L is the distance between the measured diameters.

Then, using a micromanipulator 3, immerse the micropipette with the outlet 4 into a drop of the test solution and observe the movement of the meniscus in visibility zone 7 in the visibility zone 7, respectively, in sections 1 of a given length using a microscope 6 of duration t.

Using the dependence of the capillary effect on the radius g of the capillary

R

2Y

(2)

Where

P is the pressure that draws in the liquid; dL - surface coefficient

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Poisel's law for determining the hydraulic resistance, as well as the geometrical dependence for calculating the volume of the tapered part of the micropipette, on which movement of the meniscus is observed, calculate the diameter of the outlet orifice.

7

Example. Electros physiological aqueous solution is investigated.

The outer diameters d and d in the visibility zone 7 in the range of 5–10 µm along the edges of a given segment of D 100–150 µm are measured with an optical microscope. Calculate jcoH CHocTb by the formula 1.

Then a drop of 9 of the test solution was applied to a glass substrate 8, the tip of micropipette 1 was inserted into it and, observed in a microscope 6, the stopwatch of the meniscus in visibility zone 1– was recorded with a stopwatch.

Using constants: the surface tension coefficient of the water-vapor dyne / cm interface, in one

water bone 01

CM

and,

Viv the tip of a micropipette in the form of a stepped expanding capillary 10 in Fig. 2, a calculated dependence is obtained for the hydrodynamic diameter

d 0.05

(3)

According to the indicated dependence, both aai-K are unequal tapers of K and a length of x t. movements of the meniscus calculate the values of the diameter of the outlet of the micropipette, the results of the calculation can be averaged, which further improves the accuracy of determining the diameter.

The proposed method can be used to determine the diameters of the outlet orifices of more than 0.05 µm, since at smaller diameters electrokinetic phenomena in solutions occur.

Determining the diameter of the outlet of the micropipette based on the measurements of the taper and the duration of movement of the meniscus of the test solution in visibility into an optical microscope with a resolution below the controlled diameter simplifies the method of determining the hydrodynamic diameter.

Claims (1)

Invention Formula Hydraulic method for determining the diameter of the outlet of a micropipette, based on filling a micropipette with a liquid and measuring its taper using a microscope, characterized in that, in order to simplify the method for determining the hydrodynamic diameter of the outlet, an optical microscope is used, the micropipette is immersed into the solution under investigation and, in the visible area, an optical microscope is observed moving the meniscus at a predetermined distance, measuring the duration of the movement of the meniscus and the outer diameters of the micropipette, and determining the diameter of the outlet of the micropipette taking into account the dependences of the capillary effect, flow resistance and volume of the conical part of the micropipette on the diameter of its 10 aperture. HAf) solution 1 Editor S.Patrusheva Compiled by V.Gordeev Tehred M. Khodanych Proof-reader I. Erdeyi Order 875/40 Circulation 678 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, Projecto st., 4 FIG. 2