PCR machine includes ordinary PCR machine, gradient PCR machine, in situ PCR machine, real-time fluorescence quantitative PCR machine, etc. The essence of PCR machine is a fast and stable temperature change device, which can amplify a large number of DNA sequences.

Uniformity is an important index of the PCR system, and the factors causing the uneven temperature of each well are as follows:

1. Inhomogeneity of refrigeration semiconductor chips

Most PCR systems now use semiconductor refrigeration chips to control the temperature. The quality of the semiconductor wafer will affect the uniformity of PCR thermal cycler. The performance of the semiconductor chip will decline after being used for a period of time, but the degree of decline is inconsistent, so it will show a temperature difference.

2. Number of temperature control points

Another advantage of multiple sensors is that they can control different temperatures and create temperature gradients.

3. Edge effects and mitigation methods

In fact, the radiator also has the problem of low edge temperature. Edge-assisted heating techniques are generally used to reduce edge effects. But in reality, the edge effects are not uniform. One is that the temperature at the corner is lower, and the other is also related to the blowing direction of the radiator fan.

4. Heat dissipation uniformity of the radiator

The heat dissipation uniformity of the radiator has a great influence on the temperature uniformity of the module. The semiconductor chip controls the temperature difference between its front and back sides, and each semiconductor chip is controlled as a whole. If the temperature of the radiator on the opposite side is uneven, of course the temperature of the front module is also uneven.

5. Material and shape of the module

In terms of uniformity, silver is the best material for modules, followed by copper and then aluminum alloy.

6. Speed of temperature rise and fall

The heating and cooling rate is another important indicator of the PCR instrument. Excessive heating and cooling rates will also affect the uniformity of temperature.