Sample warming during innocent exposures from a liquid nitrogen freezer

Storing samples in liquid nitrogen vapour phase freezers (LN2) is very common and performed throughout the biobanking and cell therapy industries. These freezers are chosen primarily because they maintain a sub -150°C storage environment and thus, keep the samples below -135°C, the glass transition temperature of water (Tg). This cryogenic storage practice preserves sample viability. The concern is what happens to innocent samples (the ones not intended to be thawed) during routine rack exposures. Thousands of innocent samples may be exposed multiple times throughout their storage lifetime. Constant thawing/freezing through the glass transition phase may cause irreversible damage and affect sample functionality when thawed.