What is a cryogenic freezer and how does it differ from a standard laboratory freezer?

A cryogenic freezer is a vacuum-insulated storage vessel designed to maintain biological or industrial material at temperatures below -150°C, typically using liquid nitrogen as the cryogenic medium. It is fundamentally different from a standard laboratory freezer or ultra-low temperature (ULT) freezer in both the temperatures it achieves and the mechanism by which it maintains them.

A standard ULT freezer operates mechanically using a refrigeration compressor system and typically reaches temperatures of around -80°C. This is adequate for short to medium-term storage of many biological materials, but it falls well short of the temperatures required for long-term cryopreservation of embryos, oocytes, and sperm. The critical biological preservation threshold is approximately -130°C. Below this point, cellular metabolism stops completely and biological degradation effectively ceases. A ULT freezer at -80°C does not reach this threshold.

A cryogenic freezer achieves temperatures between -150°C and -196°C by using liquid nitrogen either in liquid phase, where samples are submerged in or sit directly above the liquid, or in vapour phase, where samples are held above the liquid surface in the cold nitrogen gas layer. Both approaches provide storage temperatures well below the -130°C biological threshold, with vapour phase offering the additional benefit of eliminating cross-contamination risk between samples.

In an IVF laboratory context, cryogenic freezers range from compact 20-litre bench-top units suited to smaller clinics through to high-capacity 175-litre floor-standing systems designed for busy programmes storing large numbers of embryos, oocytes, and sperm samples. The choice of vessel size, neck design, racking system, and evaporation rate all influence how well the system performs in a specific clinical environment.

Unlike mechanical freezers, cryogenic freezers require no power source to maintain temperature. Their passive insulation design means that samples remain protected even during power outages, which is a significant operational advantage in a clinical setting where power interruptions cannot always be anticipated.

Cryolab supplies a full range of cryogenic freezers and LN2 storage vessels for UK IVF laboratories and research institutions. Browse the full storage vessel range or contact the Cryolab team for guidance on the right vessel for your laboratory.