Classification of ELISA instruments

　　1. Microplate readers can be divided into filter-type microplate readers and grating-type microplate readers based on different filtering methods. The filter-type microplate reader uses filters to select wavelengths. The microplate reader has a built-in filter wheel, which can select filters of different wavelengths required for the test to split the light. Most of the full spectrum light emitted by the light source is filtered after passing through the filter, leaving only the wavelength allowed by the filter itself. In this way, a specific wavelength can be obtained through the filter. The filter wheel generally contains 4-6 filters. Different wavelengths can be obtained by selecting different filters, but the wavelengths obtained are fixed and subject to certain restrictions. Any required wavelength cannot be obtained, and the price of replacing filters is relatively expensive. Generally, filters with fixed wavelengths are 405, 450, 490, and 630NM. The grating microplate reader was first invented and used by the American Molecular Instrument Company (Versamax). Although it has only been around for a short ten years, it has developed very rapidly and is now the mainstream microplate reader. It uses grating for spectrometry. After the full spectrum light emitted by the light source passes through the grating, it can obtain light of any wavelength through a series of slits distributed on the grating. The wavelength is continuously adjustable, and the general increment is 1nm. The grating microplate reader is convenient and flexible to use. You can select any wavelength of light through the software, and you can scan the full wavelength. Through the full wavelength scan, you can obtain the absorption peak of the unknown sample, so as to achieve the purpose of detecting the unknown sample. It is very popular in the laboratory and can be used for more experimental detection. Therefore, it is currently very popular in China.

　　2. According to the function, the microplate reader can be divided into light absorption microplate reader, fluorescence microplate reader, chemiluminescence microplate reader and multifunctional microplate reader. The light absorption microplate reader is used to detect the absorbance of visible light and ultraviolet light. After the light of a specific wavelength passes through the sample in the microplate, the light energy is absorbed, and the absorbed light energy is in a certain proportional relationship with the concentration of the sample, so it can be used for qualitative and quantitative detection. The detection technology of light absorption is mature, low cost, and simple to operate, but the dynamic range is narrow, the sensitivity is relatively low, and the specificity is not strong. Generally, tungsten lamps and deuterium lamps are used as light sources for visible light and ultraviolet light respectively, while the ultraviolet/visible microplate reader can switch between the two light sources to meet the needs of different measurement wavelengths. The fluorescence microplate reader is used to detect fluorescence. After the light of a specific wavelength after the excitation grating is irradiated on the sample calibrated by the fluorescent substance, it will emit emission light with a longer wavelength, which will reach the detector after passing through the emission grating. The intensity of fluorescence is in a certain proportion to the concentration of the sample. Fluorescence detection has high sensitivity, real-time detection, easy use, and diverse detection modes, but it is easily interfered by the outside world. The excitation light and the emission light can easily affect each other and interfere with the detection. Chemiluminescence is a spontaneous luminescence from biochemical reactions, which can be divided into two types: glow type and flash type. The glow type has a long-lasting and stable luminescence that can last for a period of time; the flash type has a short luminescence time, changes quickly, and is not stable, and an automatic sampler is required to be used. The number of photons emitted in chemiluminescence is proportional to the amount of sample. The chemiluminescence microplate reader has a very high sensitivity and a wide dynamic range. The multifunctional microplate reader is a combination of the above three microplate readers. It is also the first invention and production of the American Molecular Instrument Company (Spectramax M5). It integrates two or three microplate readers in one, and can simultaneously perform light absorption, fluorescence and chemiluminescence detection. It has powerful functions and a wide range of use. It can be used as a research platform to avoid repeated purchases and is the first choice for laboratories. In addition, according to the number of channels, the microplate reader can be divided into two types: single-channel and multi-channel. Single channels can be divided into automatic and manual.