How the microplate reader works
The microplate reader is actually a disguised special photoelectric colorimeter or spectrophotometer. The basic working principle is basically the same as the main structure and photoelectric colorimeter. The illustration is a schematic diagram of a single-channel autosampler microplate reader. The light wave emitted by the light source lamp becomes a bundle of monochromatic light through a filter or a monochromator, and enters the sample to be tested in the microporous pole of the plastic. One part of the monochromatic light is absorbed by the specimen, and the other part is irradiated to the photodetector through the specimen, and the photodetector converts the optical signal with different strengths and weaknesses of the specimen to be tested into a corresponding electrical signal. The electrical signal is processed by preamplification, logarithmic amplification, analog-to-digital conversion, etc., and then sent to the microprocessor for data processing and calculation. Finally, the display is displayed by the display and the printer.
The microprocessor also moves the microplate by controlling the movement of the mechanical drive mechanism in the X and Y directions, thereby implementing an automatic injection detection process. Other microplate readers use manual moving microplates for inspection, thus eliminating the mechanical drive mechanism and control circuitry in the X and Y directions, resulting in a smaller instrument and a simpler structure. The microplate is a transparent plastic plate specially packaged for placing the sample to be tested. The plate has a plurality of rows of small holes of uniform size, and the corresponding antigen or antibody is embedded in the hole. A small hole can hold a few milliliters of solution. The common specifications are 40-well plate, 55-well plate, 96-well plate, etc. Different instruments use different specifications of orifice plates, which can be tested by one hole and one hole or one row and one row.
The monochromatic light used in the microplate reader can be obtained either by a coherent filter or by the same monochromator of the spectrophotometer. When using a filter as a filtering device, like a normal colorimeter, the filter can be placed in front of the microplate or behind the microplate, and the effect is the same. The figure below is the current photosystem diagram of the microplate reader. The light from the light source lamp passes through the concentrating mirror, reaches the mirror after the light bar, is reflected by the mirror for 90o, passes through the colorimetric solution vertically, and then passes through the filter to the photocell.
It can be seen from the working chart of the microplate reader and the optical path diagram that it has the following differences with the ordinary photoelectric colorimeter:
(1) The microplate reader usually uses not only A but also optical density OD to indicate absorbance. The microplate reader can be divided into two types: single channel and multi channel. There are two types of single channel: automatic and manual. The automatic type of instrument has a mechanical drive mechanism in the X and Y directions. The small holes of the microplate L can be sequentially sent to the beam for testing, and the manual type is manually moved by the microplate for measurement. Based on the single-channel microplate reader, multi-channel enzyme labels have been developed. Only such enzyme labels are generally automated. It does not have multiple beams and multiple photodetectors. For example, a 12-channel instrument with 12 beams or 12 sources, 12 detectors and 12 amplifiers, under the action of a mechanical drive in the X direction, sample 12 One is tested for a row. The multi-channel microplate reader has a fast detection speed, but its structure is more complicated and the price is higher.
The microplate reader is actually a disguised special photoelectric colorimeter or spectrophotometer. The basic working principle is basically the same as the main structure and photoelectric colorimeter. The illustration is a schematic diagram of a single-channel autosampler microplate reader. The light wave emitted by the light source lamp becomes a bundle of monochromatic light through a filter or a monochromator, and enters the sample to be tested in the microporous pole of the plastic. One part of the monochromatic light is absorbed by the specimen, and the other part is irradiated to the photodetector through the specimen, and the photodetector converts the optical signal with different strengths and weaknesses of the specimen to be tested into a corresponding electrical signal. The electrical signal is processed by preamplification, logarithmic amplification, analog-to-digital conversion, etc., and then sent to the microprocessor for data processing and calculation. Finally, the display is displayed by the display and the printer.
The microprocessor also moves the microplate by controlling the movement of the mechanical drive mechanism in the X and Y directions, thereby implementing an automatic injection detection process. Other microplate readers use manual moving microplates for inspection, thus eliminating the mechanical drive mechanism and control circuitry in the X and Y directions, resulting in a smaller instrument and a simpler structure. The microplate is a transparent plastic plate specially packaged for placing the sample to be tested. The plate has a plurality of rows of small holes of uniform size, and the corresponding antigen or antibody is embedded in the hole. A small hole can hold a few milliliters of solution. The common specifications are 40-well plate, 55-well plate, 96-well plate, etc. Different instruments use different specifications of orifice plates, which can be tested by one hole and one hole or one row and one row.
The monochromatic light used in the microplate reader can be obtained either by a coherent filter or by the same monochromator of the spectrophotometer. When using a filter as a filtering device, like a normal colorimeter, the filter can be placed in front of the microplate or behind the microplate, and the effect is the same. The figure below is the current photosystem diagram of the microplate reader. The light from the light source lamp passes through the concentrating mirror, reaches the mirror after the light bar, is reflected by the mirror for 90o, passes through the colorimetric solution vertically, and then passes through the filter to the photocell.
It can be seen from the working chart of the microplate reader and the optical path diagram that it has the following differences with the ordinary photoelectric colorimeter:
(1) The microplate reader usually uses not only A but also optical density OD to indicate absorbance. The microplate reader can be divided into two types: single channel and multi channel. There are two types of single channel: automatic and manual. The automatic type of instrument has a mechanical drive mechanism in the X and Y directions. The small holes of the microplate L can be sequentially sent to the beam for testing, and the manual type is manually moved by the microplate for measurement. Based on the single-channel microplate reader, multi-channel enzyme labels have been developed. Only such enzyme labels are generally automated. It does not have multiple beams and multiple photodetectors. For example, a 12-channel instrument with 12 beams or 12 sources, 12 detectors and 12 amplifiers, under the action of a mechanical drive in the X direction, sample 12 One is tested for a row. The multi-channel microplate reader has a fast detection speed, but its structure is more complicated and the price is higher.
(2) The container containing the colorimetric liquid to be tested no longer uses the cuvette, but uses a plastic microplate. The microplate is usually made of transparent polyethylene material and has strong adsorption effect on antigen and antibody, so it is used as a solid phase carrier.
(3) Since the plastic microplates of the sample are multi-row porous, the light can only pass vertically, so the light of the microplate reader passes vertically through the solution to be tested and the microplate, and the light beam can be from top to bottom. Down, it can also be through the colorimetric liquid from bottom to top.
The microplate reader has become an indispensable testing equipment for hospitals, medical institutions, and food and drug safety testing departments!
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