PCR machine, also known as thermal cycler, is an instrument that uses PCR technology to rapidly amplify specific DNA in vitro. Ordinary PCR machines that are often used in laboratories always have their covers open when they are turned off. What's the reason?

Today's PCR machines basically have a "hot cover" function. That is to say, in addition to heating the bottom of the sample tube placed in the PCR machine, the tube cover also has an independent heating function, and the temperature of the "hot cover" is generally higher than the bottom. Since what in PCR reaction system is liquid, steam will be generated during the temperature rise process, and the rising steam will condense on the tube cover. The function of the hot cover is to prevent the evaporated reaction solution from condensing on the tube cover, thereby changing the PCR reaction volume and affecting the experimental results.

PCR machine is equipped with a refrigeration system, which will cause a hot and cold temperature difference between the temperature inside and the air. The temperature just after finishing work is generally 4℃. Therefore, when air with higher temperature comes into contact with the inside of the instrument, the moisture in the air will liquefy, forming small water droplets that adhere to the inside of the instrument. Turning off the machine with the cover open at this time is actually to allow these water droplets to slowly evaporate. Water mist not only requires additional wiping, which is time-consuming and laborious, but also can easily cause the instrument to rust.