Cryo means “ice cold” in Greek; used to describe the effects of low temperatures or activities carried on at a very low temperature.
Cryobiology is the study of life at low temperatures.
Cryogenics is the branch of physics and engineering that studies the production and use of very low temperatures.
Cryonics is the low temperature preservation of humans and mammals with the intention of future revival. Cryogenics is not cryonics, although people often confuse the two terms. Cryonics is not part of mainstream cryobiology. Cryonics depends heavily on speculative future technology, which may or may not be invented. Cryonics is out of the scope of interest at the Biothermal Technology Laboratory.
Cryopreservation is the preservation of biological cells, tissues, and organs, at low temperatures.
Cryoinjury is tissue injury due to exposure to low temperatures.
Cryosurgery is the controlled destruction of undesired tissues, such as cancerous tumors, by freezing.
A cryoprotectant is a substance that is used to protect the biological tissue from damage associated with water-ice crystallization—the cornerstone of cryoinjury. The terms cryoprotectant and cryoprotective agent (CPA) are interchangeable. Common CPAs are DMSO (dimethyl sulfoxide), ethylene glycol, glycerol, propylene glycol, sucrose, and trehalose.
Vitrification is the transition of a substance from liquid into a glassy state. In a sense, a glass is a liquid that is too cold to flow at any practical time scale due to its high viscosity. Vitrification is promoted by rapid cooling of a highly viscous material, such as the CPA in lower cryogenic temperatures. In the context of cryopreservation, vitrification has the potential of eliminating tissue damage due to ice crystallization. The adverse effects of vitrification are toxicity, due to elevated CPA concentration, and increased thermo-mechanical stress, due to the required rapid cooling rate.
Thermal strain is the normalized volume change of the material as a result of a temperature change (in the context of solid mechanics).
Thermal expansion coefficient is the rate of change of thermal strain with temperature when the material is free of mechanical stress.
Thermo-mechanical stress is the mechanical stress resulting from thermal strain in a constraint material. When the developed stress exceeds the strength of the material, structural damage follows with fracture formation as its most dramatic outcome. The terms thermo-mechanical stress and thermal stress are often interchangeable. In a completely different context, “thermal stress” may refer to overloading the thermal regulation system of the body.