SU1573429A1 - Apparatus for determining optical density of biological suspensions - Google Patents

Abstract

The invention relates to biology and medicine and can be used in research and clinical laboratories in the study of red blood cells. The purpose of the invention is to improve the measurement accuracy by registering the relative magnitude of fluctuations. The goal is achieved by introducing into the composition of the known device an electronic tachometer 6, a converter 7, a band-pass filter 8, a divider 9. Using a light source 1 with low beam divergence (less than ± 1.5 °) and eliminating the upper cut of the high-frequency component of the signal formed by the vibration of the device, allows to increase the accuracy of determining the fluctuations of extinction and, consequently, the accuracy of the measurements. 1 il.

Description

(21) 428 159 / 28-1

(22) 07.15.87

(46) 06.23.90. Bul No. 23

(71) Institute for Problems of Cryobiology and Cryomedicine of the Academy of Sciences of the Ukrainian SSR

(72) A.V. Degt roar, S.V. Rudenko and T.P.Bondarenko

(53) 615.475 (088.8)

(56) USSR Copyright Certificate No., cl. G 01 N 33/48, 1980. (DEVICE FOR DETERMINING THE OPTICAL DENSITY OF BIOLOGICAL SUSPENSIONS

(57) The invention relates to biology and medicine and can be used in research and clinical laboratories in the study of

red blood cells. The purpose of the invention is to increase the measurement accuracy by registering the relative magnitude of fluctuations. The goal is achieved by introducing into the composition of the known device an electronic tachometer 6, a converter 7, a band-pass filter 8, a divider 9. Using a light source 1 with low beam divergence (less than ± 1.5 °) and eliminating the upper cut of the high-frequency component of the signal formed by the vibration of the device, it allows to increase the accuracy of determination of fluctuations of extinction and, therefore, the accuracy of the measurements. 1 il.

e ss

V)

The invention relates to biology and medicine and can be used in research and clinical laboratories in the study of red blood cells.

The purpose of the invention is to improve the measurement accuracy by registering the relative magnitude of fluctuations.

The drawing shows the functional diagram of the device for determining the optical density of biological suspensions.

The device contains a light source 1 with a light beam divergence of no more than + 1.5 ° C, a cuvette 2 for a biological suspension, a stirrer 3, a Photodetector 4, to the output of which a logarithmic amplifier 5 is connected, a tachometer 6, a frequency-to-voltage converter 7, a band-pass filter 8, a divider 9 for determining the relative magnitude of the noise, and a recording device 10.

The device works as follows.

Collimated beam of light from

The source 1 passes through a cuvette 2 with a biological suspension, which is continuously stirred by a stirrer 3 at a constant speed. After passing through the cuvette 2, a beam of light hits the photodetector 4, which forms an electrical signal proportional to the light flux falling on it. This signal is even fed to a logarithmic amplifier 5, the output of which is an electrical signal proportional to the extinction coefficient Ј of the suspension. Constant mixing of the cell suspension leads to the fact that, due to the orientation of the cells in the hydrodynamic flow, the optical density of the suspension varies in time with the type of fluctuations, the amplitude of which depends on the shape of the cells. The amplitude of the fluctuations of the light flux decreases as the degree of cell diskoids decreases and increases if the degree of discovery in the red blood cell population increases. After the logarithmic amplifier 5, an electrical signal is fed to the input of the bandpass filter 8, the lower cut-off frequency of which is controlled by the converter 7 so that

wed

 1/2 f

Where

,

Yu

15 20

25

30 35 40 45 50 55

f H cf

- lower cutoff frequency of the filter;

fw is the frequency of rotation of the stirrer. This choice of the cutoff frequency f is due to the fact that it is necessary to cut off the constant component of the signal, which is proportional to the extinction of the biological suspension. On the other hand, the passband of the filter must include the rotational speed of the agitator, since the fundamental harmonic of the fluctuations of the luminous flux is equal to the rotational frequency of the agitator. The upper cut-off frequency of the filter cuts off the high-frequency components of the signal, due to the vibration of the instrument, the work of the mixing device and the design features of the electrical circuits of the amplifiers. The value of the upper cut-off frequency is set in the range of 400-1000 Hz. From the output of the band-pass filter 8, the signal, which is the extinction fluctuation (noise) signal, is fed to the first of the inputs of the divider 9 for determining the relative noise level, the second input of which is fed from the logarithmic amplifier 5. The divider 9 for determining the relative noise value determines the root-mean-square fluctua value

extinction coz signal Ј

The second is fed to its first input and divides the value obtained by the average value of the extinction. (L, the signal which arrives at its second input. The obtained value in the form of an analog signal from the divider 9 determines the relative magnitude of the noise enters the recording device 10, where it is displayed.

Claims (1)

Invention Formula A device for determining the optical density of biological suspensions, including a source of light radiation, a cuvette for a liquid, a stirrer, a photodetector with a logarithmic amplifier connected to it and a recording device, characterized in that, in order to improve the measurement accuracy by detecting the relative magnitude of fluctuations, an electronic tachometer mounted on a stirrer, band-pass filter, transducer, 51573429 the divider, the output of the tachometer of which is connected to the first input, is connected to the input of the converter, the litter, and the output of the logarithmic output of which is connected to the control loop connected to its second input by the input of a bandpass filter, the output of which and the first input of the bandpass filter.