PCR amplification instrument, also known as PCR gene amplification instrument, PCR nucleic acid amplification instrument, polymerase chain reaction nucleic acid amplification instrument, commonly known as PCR machine, a kind of instrument which uses PCR (Polymerase chain reaction) technology to amplify specific DNA and are widely used in medical and biological laboratories. According to the purpose of DNA amplification and detection standards, PCR machines can be divided into four types: ordinary PCR machine, gradient PCR machine, in-situ PCR machine, and real-time fluorescent quantitative PCR machine.
 
I. Ordinary PCR machine
A PCR machine that can only run a specific annealing temperature for a PCR amplification is called traditional PCR machine, or ordinary PCR machine. If you want to do different annealing temperature, you need to run multiple times. It is mainly used for simple amplification of the annealing temperature of the target gene. This instrument is mainly used in scientific research, teaching, clinical medicine, inspection and quarantine and other institutions.
 
II. Gradient PCR machine
A PCR machine that can set a series of different annealing temperature conditions (temperature gradient, usually 12 temperature gradients) at one time for PCR amplification is called gradient PCR machine. Because different DNA fragments to be amplified have different optimal annealing temperatures, by setting a series of gradient annealing temperatures for amplification, one-time PCR amplification can screen out the optimal annealing temperature with high expression to achieve effective amplification. It is used to study the amplification of unknown DNA annealing temperature, which saves cost and time. Gradient PCR machine can also do ordinary PCR amplification without setting a gradient, which is mainly used in scientific research, teaching institutions, inspection and  quarantine, etc.
 
III. In-situ PCR machine
The intracellular gene amplification instrument used to analyze the location of target DNA in the cell is called in-situ PCR machine. Such as the location of the pathogenic gene in the cell or the location of the target gene in the cell. It is to maintain the integrity of cells or tissues, make the PCR reaction system penetrate into the tissues and cells, and perform gene amplification at the location of the cell's target DNA. Not only can the target DNA be detected, but also the position of the target sequence in the cell can be marked, which has great practical value for studying the pathogenesis, clinical process and pathological changes of diseases at the molecular and cellular level, widely used in clinical and scientific research.
 
IV. Real-time fluorescent quantitative PCR machine
A PCR instrument that adds a fluorescent signal acquisition system and a computer analysis and processing system based on ordinary PCR machine is called fluorescent quantitative PCR machine. Its PCR amplification principle is the same as that of ordinary PCR machine, except that the primers added during PCR amplification are labeled with isotope, fluorescein, etc., and the primers and fluorescent probes are used at same time to specifically bind to the template for amplification. The amplified result is connected to the computer analysis and processing system through the real-time acquisition signal of the fluorescence signal acquisition system to obtain a quantitative real-time result output. This type of PCR machine is called real-time fluorescent quantitative PCR machine (qPCR machine). Fluorescence quantitative PCR machine includes single-channel, dual-channel and multi-channel, which is mainly used in medical clinical testing, biomedical research and development, food industry, scientific research institutions and universities.