Author: Site Editor Publish Time: 2022-12-16 Origin: Site
A Coulter counter is an instrument that can count cells and measure their volume.It is based on the fact that cells exhibit great electrical resistance; in other words, they conduct little electricity.In a Coulter counter, cells swimming in a conductive solution are drawn one by one into tiny gaps.On either side of the gap are two conductive electrodes.The current does not weaken when there are no cells in the gap, but is resisted when cells are drawn into the gap.A Coulter counter counts the number of such events and measures the current (and thus resistance),which is directly related to the volume of cells trapped.A similar system is the CASY cell counting technology.Coulter and CASY counters are much less expensive than flow cytometers and are the method of choice for applications that require cell number and size, such as cell cycle studies.Its advantage over the methods described above is that a large number of cells can be processed in a short time, ie: thousands of cells per second. This provides high accuracy and statistical significance.
1.Flow cytometry 
Flow cytometry is by far the most complex and expensive method of counting cells.In a flow cytometer, cells flow in a narrow stream in front of a laser beam.A beam of light hits them one by one, and light detectors pick up the light reflected from the cells.Flow cytometry has many other functions, such as analyzing the shape of cells and their internal and external structures, and measuring the amount of specific proteins and other biochemicals in cells.Therefore, flow cytometers are rarely purchased solely for cell counting.
2.Image analysis
Recent approaches consider the use of high-quality microscopy images on which statistical classification algorithms are used to perform automated cell detection and counting as an image analysis task.As an offline (batch) type process, it is usually performed with a constant error rate.A range of image classification techniques can be employed for this purpose.
3.Stereoscopic cell counting
Currently, manual determination of stereocytometric cell counts for object inclusion based on unbiased stereoscopic counting rules remains the only appropriate method for unbiased cell quantification in histological tissue sections, and thus it is not sufficiently automated,indirect cell counting.
4.Spectrophotometry
The cell suspension is cloudy.Cells absorb and scatter light.The higher the cell concentration, the higher the turbidity.A spectrophotometer can measure the intensity of light very accurately.Cell cultures were placed in clear cuvettes and absorbance was measured relative to medium alone.Optical density (OD) is directly proportional to the biomass in the cell suspension within a given range specific to the cell type.Measuring the turbidity of a culture using spectrophotometry is known as nephelometry.This makes spectrophotometry the method of choice for measuring bacterial growth and related applications. The disadvantage of spectrophotometry is that it cannot provide absolute counts or differentiate between live and dead cells.