To be precise, the storage of stem cell liquid nitrogen tanks is divided into two types, one is gas-phase liquid nitrogen storage, and the other is liquid-phase liquid nitrogen storage.
The essential difference between them is that in gas phase storage, biological samples are stored in a nitrogen atmosphere in the liquid nitrogen temperature range, rather than directly immersed in liquid nitrogen. The lowest temperature at the top of the freezer shelf can reach -190°C during gas phase storage, which is indirect contact; liquid phase storage means that biological samples are directly stored in liquid nitrogen, which is completely immersed in liquid nitrogen, which is direct contact.
Because liquid-phase liquid nitrogen storage is in direct contact, there is a risk of cross-infection; gas-phase liquid nitrogen storage is currently the mainstream application in international sample banks, and is currently an effective way to prevent cross-infection.
Advantages of gas phase storage over liquid phase storage:
Avoid cross-contamination of stored samples;
Reduce the potential accidental injury caused by liquid nitrogen operation;
Minimize the loss of liquid nitrogen operation;
Fast access to samples, reducing sample access operation time.
Usually in the laboratory, gas-phase liquid nitrogen is used for storage. In the stem cell liquid nitrogen tank, there is a liquid level gauge measuring hole. When the liquid nitrogen reaches the specified value, it will be transmitted to the monitoring terminal, and the input of liquid nitrogen into the tank will be stopped. , which can be stored in the gas phase.