Method of freeze drying
AssigneeMeta-Dry LLC
InventorMichael Golfetto
Life of this patent
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Abstract
A method of freeze-drying comprising rapidly freezing either liquid or supercritical carbon dioxide in and around a material having pores at a rate of at least 0.2° C./min to limit the size of crystals formed from the carbon dioxide so as to avoid the formation of gas bubbles and damage to the pores and exposure of the material to gas-liquid interfaces. During freezing a solid layer primarily of solid carbon dioxide is formed on and surrounding the material by transferring heat with a cryogenic liquid circulating about the material. This solid layer protects the material from gas-liquid interfaces and surface tension before decreasing pressure about the material by venting carbon dioxide.
Claims17
A method of preserving a material, comprising the steps of:
- replacing a first fluid with a first non-gaseous fluid comprising primarily carbon dioxide, the first fluid being in contact with the material, and the material containing pores, wherein a plurality of the pores have diameters of less than 50 nm;
- and
- cooling the first non-gaseous fluid to cause the first non-gaseous fluid to freeze forming a solid;
- wherein the cooling is performed at a rate of at least 0.2° C./min.
Dependencies are inferred from the claim text.