Cryopreservation without dry ice-induced acidification during sample transport: CO2 free and sustained cryofreeze transport

Dry ice (solid CO₂) remains highly useful when temperature-sensitive biological samples need to be cryogenically transported. CO₂ released during the sublimation of dry ice can diffuse through gas permeable receptacle material or any defective seals resulting in potential sample acidification and compromised integrity. In addition, the quality of cryopreservation can be undermined once the dry ice is exhausted. The dry ice carrier design described here has been demonstrated to prevent sublimated CO₂ from reaching the samples while maintaining storage temperature below −60 °C for 19 h. It is also equipped with microcontroller-based temperature monitoring for traceability and CO₂ gas monitoring for safety.