Cryogenic Storage with Vapor and Liquid Nitrogen

 

 

 

 

Cryogenic Storage with Vapor and Liquid Nitrogen

Cryogenic Freezers have used Liquid Nitrogen (LN2) as the touchstone for long-term cryogenic storage and preservation of biological materials for over sixty years.  Initially, direct submersion of biological materials into liquid nitrogen was the only option but after improvements in cryogenic storage, current LN2 freezers can uphold unchanging temperatures in a vapor phase that forms above liquid phase nitrogen.  Using Liquid nitrogen is still the best way to preserve and keep biological materials in long-term storage.  Using vapor phase nitrogen freezers can provide easier access and can protect researchers from the dangers of working with liquid nitrogen.

Liquid and vapor phase systems each present diverse benefits.  Getting an LN2 freezer that contains both storage space in separate liquid phase and vapor phase sections.  Cryogenic storage freezers that preserve biological materials in liquid phase nitrogen provide a cost-effective and efficient way to maintain the extremely low temperatures needed for cryogenic storage.  LN2 freezers with liquid phase storage will ensure that all biological activity has ceased and placing cells in a state of suspended animation.  This ensures that your samples are kept at a consistent temperature throughout their storage time.  Maintaining a sufficient supply of liquid nitrogen will keep the temperature of the samples remaining at or below -196°C for the foreseeable future.  At temperatures of -196°C or less, all cell activity ceases and samples should theoretically never degrade.

Liquid phase systems has been there since the beginning and because of their ability to maintain the consistent low temperatures LN2 cryogenic technology must remain an vital part of cryogenic sample preservation.  The preservation and long term storage of cell samples at the same condition in the far future as they were at the time they were frozen requires this reliability received from a liquid phase system.  It can be difficult to provide both the long-term storage benefits of liquid phase LN2 freezers and the ease of access of vapor phase LN2 freezers.  Nevertheless, frequent access to samples will expose them to temperature fluctuations but a vapor phase system will make retrieval easier and much safer.  Biological activity ceases at -196°C and submersion in LN2 is required to reach those temperatures but, cell activity effectively stops at -135°C allowing samples to be stored at or below this temperature without any significant deterioration.

That’s where vapor phase LN2 freezers becomes useful, since they operate at specific temperature range between -135°C and -190°C.  To accomplish this requires precise temperature monitoring.  Having the right sensors and alert system set up to maintain the ideal temperatures is crucial.   Dual temperature monitoring is needed with two probes at varying depths, one at the vapor and one at the liquid state.