Automated Blood Analyser’s Testing Principles

Blood analyzers are commonly used equipment in clinical blood tests which mainly use two principles: electrical and optical. The electrical principle mainly involves impedance and radiofrequency conductance methods, while the optical principle mainly involves laser scattering and spectrophotometry.CN MEDITECH is currently going to show you the hematological analyzer.

Principle of Electrical-Impedance Cell Counting

Electrical-Impedance Method: It is the main principle of the three-part blood analyzer. The principle of blood cell counting is the Coulter principle: In an isotonic electrolyte solution, suspended red bloodcells have non-conductivity. When passing through counting apertures with stable currents on both sides, the induction zone resistance increases, causing a voltage change, and forming a pulse signal. Based on this, the blood cell count and volume are measured.
The strength of the pulse signal reflects the size of the cell volume, and the number of pulse signals reflects the number of cells. These pulse signals are detected through signal generators, amplifiers, threshold adjusters, discriminators, shapers, counting systems, and automatic control protection systems to complete the measurement of cell count and volume.

Principle of Radiofrequency Conductance Cell Counting

Radiofrequency Conductance Method: Radiofrequency refers to high-frequency alternating electromagnetic waves that change more than 10,000 times per second. Different cell structures have different conductivity. By using a high-frequency electromagnetic probe to penetrate the cell membrane lipid, the cell conductivity can be measured, providing effective characteristic information of cell internal chemical composition, nucleus, cytoplasm, and particle composition (size, density), and thus, cell classification can be carried out. It can be used to differentiate cells or particles with the same volume but different internal structures.

Principle of Light-Scatter Cell Counting

Light-Scatter Method: The basic components include a light source, a sheath flow, a cell suspension, and a light detector. After dilution, staining, and spheroidization treatment, the cells are arranged in a single file at a constant speed along the suspension and the sheath flow to the quartz capillary. When irradiated by a laser beam, scattering light of different cell characteristics can be produced at various angles. By using a signal detector to receive different scattering light information and performing comprehensive analysis, normal cell types can be accurately distinguished.
The following are the meanings of different result angles:
(1) Low-angle scattering light (forward scattering light): reflects the cell quantity and the surface volume size.
(2) High-angle scattering light (side scattering light): reflects the complexity of cell internal particles and nucleus.
(3) Scattering fluorescence: FL1 green, FL2 orange-red, FL3 red.
The laser scattering method is the main testing method of the five-part blood analyzer, which uses the principle of flow cytometry to analyze tens of thousands of cells at high speed and obtain multiple parameters. It is more accurate than the impedance method and is one of the main detection principles of modern five-part blood analyzers.