There are four types of commonly-used PCR machines, namely ordinary basic PCR machine, gradient PCR machine, real-time fluorescent quantitative PCR machine and in situ PCR machine. The general principles of these four PCR machines are similar, but there are still some differences in structure and accessories.

Comparison of different types of PCR systems:

1. Ordinary basic PCR machine consists of host, heating module, PCR tube sample base, heating cover, and control software.

2. In addition to the structure of an ordinary PCR machine, the gradient PCR machine also has a special gradient module, which can realize the adjustment of parameters such as gradient temperature and gradient time. Therefore, different annealing temperatures and annealing times can be set for different samples in one experiment, so that the PCR experiment conditions can be optimized in a short time to improve the efficiency of PCR research.

3. Compared with the ordinary PCR machine, the in-situ PCR machine uses slides instead of PCR tubes, and the reaction process is carried out on the surface of the slides.

4. The real-time fluorescence quantitative PCR machine adds a fluorescent signal acquisition system and a computer analysis and processing system on the basis of the ordinary PCR machine. The fluorescence detection system mainly includes an excitation light source and a detector. Excitation light sources include halogen tungsten light source, argon ion laser, and light-emitting diode (LED) light source. The monitoring system includes ultra-low temperature CCD imaging system and PMT photomultiplier tube.