What Are Hematology Analyzers?

The blood cell analyzer is also called a blood cell analyzer, a blood cell meter, a blood cell counter, etc., and it is a hospital clinical examination medical device.

The blood cell analyzer is also called a blood cell analyzer, a blood cell meter, a blood cell counter, etc., and it is a hospital clinical examination medical device.
Blood cell analyzers, also known as blood cells, are mainly divided into fully automatic or semi-automatic blood cell analyzers, and animal blood cell analyzers. The blood cell analyzer is divided into three categories and five categories under the blood cell analyzer. Items, 22 items, etc.
Chinese name
Blood cell analyzer
Foreign name
Blood cell analyzer
Category Name
Blood cell analyzer
Management category
Class II medical devices

Development history of blood cell analyzer

Traditional "blood routine" tests include: white blood cell counts and differential counts, red blood cell counts, and hemoglobin quantification. The most primitive means of conventional blood routine tests was through microscopy and manual inspection, using manual methods entirely. With the development of basic medicine and the application of high science and technology, blood cell analyzers have become an important means to replace routine microscopy for blood routine analysis, especially blood cell analyzers with classification. At the beginning of this century, China's blood analyzers have made significant breakthroughs in technology, and the "three-group" instruments have basically reached the level of foreign products. "Five classification" instruments have also been successfully developed and gradually popularized.
In the late 1970s, the instrument was developed to not only count whole cell components (white blood cell count, red blood cell count, platelet count), but also analyze cell morphological parameters such as hematocrit (HCT) and average red blood cell volume ( meancorpuscularvolume (MCV), red blood cell distribution width (eddllvolumedistributionwidth (RDW), etc. Because the instrument not only counts particles, but also morphological analysis parameters, this type of device is renamed as a blood analyzer.
In the 1980s, automatic white blood cell counting and counting technology was successfully developed. The principle is divided into different groups according to the size of the cell, there are two groups, the large cell population is equivalent to neutrophils, and the small cell population is equivalent to lymphocytes. There are three groups, the large cell population is equivalent to neutrophils, the intermediate cell population is equivalent to monocytes, eosinophils, and basophils, and the small cell population is equivalent to lymphocytes. It should be noted that instruments of this kind of principle are not classified according to cell morphological characteristics, but are grouped according to cell volume. The grouping results can only be used as a reference for the classification of white blood cells when the blood test indicators are generally normal, but when the number of white blood cells is higher (lower) than the reference range, the histogram reported by the instrument is abnormal, or there is an alarm prompt, further microscopic blood pictures should be taken.
In the late 1980s, fluorescein dye was used to bind to the reticulocyte RNA to stain the reticulate structure. Reticulocytes at different stages of maturation have different amounts of RNA. When the test cells are irradiated with a laser beam, they are refracted by laser. The angle is different from the scattering angle, whereby the reticulocytes can be divided into three groups: naive, mature, and senescent, and become reticulocyte subgroups. This test has important clinical significance for tumor chemotherapy, bone marrow transplantation, and anemia evaluation.
In the mid-1990s, a new concept was introduced for blood cell analysis. This type of blood cell analyzer can simultaneously detect blood cells and plasma components within a unified standard. Such instruments only use 20ul of peripheral blood, report 15 blood cell indicators within one minute, and report whole blood C-reaction protein (CRP) within three minutes, which is of great significance for the differential diagnosis of emergencies [1] .

Basic structure of blood cell analyzer

The basic structure of a blood cell analyzer (BCA) is mainly composed of mechanical systems, electrical systems, and optical systems [1] .
  1. computer system
    The mechanical system includes mechanical devices (such as sampling needle components, syringe components, mixers, blood separators, volume measuring tubes, etc.) and vacuum pumps to complete the aspiration, dilution, transfer, mixing and transfer of samples to the corresponding test At the same time, the liquid circuit system is the core part of the mechanical system, which mainly includes the sensor part, the colorimetric tank part, the hemolytic agent addition and mixing part, the dilution part, the volume measurement part, the vacuum part, the pressure part and the auxiliary part. The fluid system performs the following functions:
    1. Prepare diluent for whole blood and pre-dilution mode;
    2. Blood cell count and hemoglobin measurement;
    3. Precisely dilute the solution;
    4. Automatic backflushing, flushing and cleaning cycles;
    5. Control of pressure vacuum.
  2. Electrical system
    The electrical system consists of the main power supply, the main control board, various circuit control boards (power drive board, analog amplifier board, button board, recorder drive board, volume metering board, switching power supply board, power indicator board, etc.), temperature control system , Display, monitoring and alarm system.
  3. Optical system
    The optical system is mainly composed of a blood cell detection system and a hemoglobin detection system. Blood cell detection systems mainly include electrical impedance detection technology and light scattering detection technology. The electrical impedance detection technology system consists of a detector, an amplifier, a discriminator, a threshold adjuster, a detection counting system, and an automatic compensation device; a flow light scattering detection technology system consists of a laser light source, a detection device and a detector, an amplifier, a discriminator, and a threshold value Regulator, detection and counting system and automatic compensation device. The hemoglobin detection system consists of a light source, a lens, a filter, a flow colorimetric cell, and a photoelectric sensor.

How a blood cell analyzer works

Blood cell analyzer blood cell counting principle

Blood cell counting methods include: electrical impedance pulse method (electrical impedance method for short), photoelectric counting method and laser counting method. After practical comparison, the electrical impedance method is simple and practical, and is widely used. Here we only introduce the principle of blood cell counting by electrical impedance method [1] .
  1. Principle of blood cell counting with electrical impedance pulse method
    Blood cells are poor conductors of electricity. Placing blood cells in the electrolyte does not affect the conductivity of the electrolyte because the cells are very small. However, if the cross section of a small section of the electrolyte constituting the circuit is small and its size can be compared with the diameter of the cell, then when a cell floats to this point, the equivalent resistance of the entire section of the electrolyte will be significantly increased. If the electrolyte is connected to a constant current source (providing a constant current regardless of the change in load resistance), the voltage between the two electrodes in the electrolyte is increased at this time, and the voltage pulse signal generated is proportional to the resistivity of the blood cells. Directly proportional. If the electrolytic solution in which blood cells are quantified is controlled to pass through a small section, even if the blood cells sequentially pass through the small section, a series of pulses can be obtained, and the number of blood cells can be obtained by counting these pulses. Due to the different diameters of various blood cells, the resistivity is also different, and the measured pulse amplitudes are also different. Based on this feature, various blood cells can be classified and counted. This is the principle of the variable resistance pulse method. Because the resistance type blood cell analyzer is easy to operate, fast, has many analysis parameters, and is cheap, it has been widely used in China.
  2. Principle of laser blood cell counting
    The blood is diluted by a certain ratio to form a very thin liquid stream that passes through the laser beam. Each blood cell is irradiated by the laser light, which generates light scattering and is received by the photomultiplier tube. The forward angular scattering of a cell is related to the volume of the cell, and the lateral angle (or high-angle) scattering is related to the internal structure and particle properties of the cell. The number of cells is the same as the number of pulses of light scattering when the cell passes the laser beam. Various detection signals are amplified, screened, and processed by computer to obtain the average number of various blood cells and volume size, coefficient of variation, percentage of whole blood volume, and volume size distribution histogram. The hemoglobin measurement is the same as the resistance type instrument. White blood cells can be divided into three types of cells. The laser type is more stable than the resistance type and is less susceptible to interference from external electric fields, but the life of the laser tube is limited.

Hemoglobin determination principle of blood cell analyzer

Any type of blood analyzer makes the diluted blood added to the hemolysing agent to lyse red blood cells, and the released hemoglobin combines with the relevant components in the hemolysing agent to form a hemoglobin derivative. It enters the hemoglobin test system, and the colorimetry at a specific wavelength. The hemoglobin content is directly proportional and the instrument can report its concentration. Different systems of blood analyzers have different formulations of hemolytic agents, and the hemoglobin derivatives formed are different, and the absorption spectrum is different. However, the method selected so far by the blood cell analyzer has a maximum absorption of approximately 540 nm. This is because the cyanide methemoglobin HiCN recommended by the International Committee of Hematology Standards has a maximum absorption of 540nm, and the calibration instrument must be based on the HiCN value. Most series of blood analyzer hemolysing agents contain potassium cyanide, which forms cyanated hemoglobin after interacting with hemoglobin. Its characteristics are stable color development, and the maximum absorption is close to 540nm, but the absorption spectrum is different from HiCN. This point should be paid great attention when the instrument is calibrated. In order to reduce the toxicity of hemolytic agents and avoid the treatment of dirt after the detection of cyanohemoglobin derivatives, in recent years, some blood analyzers use non-oxidizing blood solvents. Experiments have proved that the derivative formed is similar to the HiCNI absorption spectrum, and the accuracy of the test results is the same as that of the hemolytic agent containing cyanide, which not only guarantees the quality of the experiment, but also avoids the toxicity of the reagent to the analyst and environmental pollution [1 ] .

Blood cell analyzer

This type of instrument is a highly comprehensive application of a variety of advanced cell analysis technologies, with more parameters for blood cells and more accurate results. For example, the Coulter VCS blood cell analyzer uses a number of technologies such as volume analysis, high frequency conduction and laser scattering, and the Technicon H * 3 blood cell analyzer uses laser flow cytometry, cytochemical staining, and cell spectrometry technology. Technicon H * 3 analysis parameters can reach more than forty items. In addition to the general analysis of red blood cells, it can also quantitatively describe the changes in hemoglobin content, concentration, cell size, and pigmentation in a single cell. Reticulocyte quantity, morphology, volume, hemoglobin content and concentration, etc. Leukocytes can be divided into three types and 5 types and indicate the number of naive cells. It can also shift nuclear image to the left, nuclear image to the right, and peroxidase staining intensity. Quantitative description, and analysis of lymphocyte subsets.
The performance of this type of comprehensive instrument represents the latest development trend of today's blood cell analyzer, but the price is prohibitive, and it is still difficult to popularize in clinical routine hematology examination.

Development of blood cell analyzer technology

With the continuous progress of various technologies and the increasing demand for instruments and equipment in laboratory work, the various uses and usages of blood cell analyzers have also continued to progress. This is first reflected in the convenience and accuracy of the application of blood cell analyzers. And as many parameters as possible.
  1. Advances in blood cell analyzer dilution technology
    Early blood cell analyzers generally required manual dilution before measurement, so many operations require directly taking 20 to 40 ul of peripheral blood to add to the dilution. The white blood cell dilution ratio is mostly 1: 251 and 1: 501 times, and the red blood cells need to be diluted twice. The dilution factor is between 6.25 and 250,000 times. Then the diluted specimen is placed in a counting cup for counting. Add hemolysing agent to the leukocyte dilution suspension. Due to the time-consuming, labor-intensive and poor accuracy of manual dilution, some subsequent blood cell counters were equipped with a special diluter, which was specially designed for this type of instrument to perform off-machine dilution, which reduced the error and trouble caused by manual dilution and improved efficiency. Then modern blood cell analyzers are more advanced. Automatic dilution technology and automatic sampling methods have been added to the instrument body, which improves the technical content, the accuracy of sampling and dilution, and makes the speed and operability of the injection more Convenient, while making detection faster.
  2. Increase in blood cell analyzer parameters
    As mentioned earlier, the early blood cell counter can only count red and white blood cells, and it is necessary to count red and white cells by switching, so it is appropriate to call it a blood cell counter. Due to the increased demand for hemoglobin determination in routine blood tests, the Sali Colorimetry cannot meet the clinical needs due to the inaccuracy and inconvenience of operation. A separate hemoglobin colorimeter has been equipped. The sample after adding the special hemolyzing agent will be counted by white blood cells. Pour it into a hemoglobin colorimeter to get the hemoglobin result determined by colorimetry. Due to the increased requirements for the determination of hemoglobin, a set of colorimetric devices can be added to the instrument to facilitate the determination of hemoglobin. It can also measure the cell volume while resisting the legal number of cells. Therefore, the measurement and calculation of the average red blood cell volume (MCV), hematocrit (HCT), average red blood cell hemoglobin (MCH), and average red blood cell hemoglobin concentration (MCHC) have also become Standard parameters of blood cell counter.
  3. Improvement of the quantitative section of the blood cell analyzer
    In order to accurately perform cell counting, in addition to accurately diluting blood, the amount of liquid directly entering the counting wells must also be quantitatively controlled. Therefore, the requirements of the quantification department for blood cell analyzers are very strict. At the beginning of the blood cell counter, a U-shaped mercury tube manometer was designed to control the amount of specimen inhaled by the weight of mercury and the distance between the two electrodes. Later, people used two photocells to understand the time and volume required for a liquid to pass through a fixed distance to control the amount of sample inhaled. Some companies also designed and used micro-injector technology and float quantification technology to control the number of counted samples. The latest photoelectric timing capacity control technology controls the amount of specimens entering the counting area, which can make the cell suspension entering the counting area more accurate and pollution-free, and can also determine whether the small holes are clogged or semi-clogged, and facilitate maintenance.
  4. Increased platelet count function
    Platelets are the smallest particles in blood cells, and early blood cell counters did not include platelet counts. Since the 1960s, foreign countries have begun to develop platelet counters. In the 70s, there have been relatively mature products. Such instruments generally require PRP plasma to be used, that is, to use special centrifugation speed to precipitate red blood cells and white blood cells, so that the upper plasma can be kept as abundant as possible. Platelets, and then use this PRP plasma for platelet count.
  5. Automatic sampling technology
    Since the blood cell analyzer requires automatic sampling and dilution of whole blood, the sampling volume also needs to be precisely controlled. The initial instrument required manual sampling and dilution. Later, there was an external dedicated sampling diluter. Later, a built-in negative pressure sampling diluter was set inside the instrument to draw blood samples according to the amount of negative pressure. This requires high accuracy in controlling negative pressure. In addition, there is a micro syringe sampling technology that relies on the photoelectric tube to control the blood. Sampling technology, etc. The rotary valve sampling technology is considered to be a more accurate method. Inside the rotary cutting, there are multiple small holes designed according to a certain volume. When the blood moves further, the rotary cutting turns from the small hole that is inhaled to the small hole that is discharged. At this time, the blood cannot enter again. The fixed amount of blood remaining in the well enters the dilution section of the instrument, then is washed, and then enters the next cycle. Many more advanced blood cell analyzers use ceramic rotary valves to dispense blood samples.

Blood cell analyzer detection range

White blood cells (WBC)
Lymphocyte percentage (LY%)
Lymphocyte absolute value (LY #)
Monocyte percentage (MO%)
Monocyte absolute value (MO #)
Granulocyte percentage (GR%)
Granulocyte absolute value (GR #)
Hemoglobin (HGB)
Red blood cells (RBC)
Hematocrit (HCT)
Mean red blood cell volume (MCV)
Red blood cell volume distribution width standard deviation (RDW-SD)
Mean red blood cell hemoglobin content (MCH)
Red blood cell volume distribution width variation coefficient (RDW-CV)
Mean red blood cell hemoglobin concentration (MCHC)
Platelet volume distribution width (PDW)
Platelets (PLT)
WBC Histogram
Mean platelet volume (MPV)
Red blood cell (RBC) histogram
Platelet Hematocrit (PCT)
Platelet (PLT) histogram

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