Cryogenic biological preservation unit with active cooling and positive atmospheric seal lid

Abstract

A cryogenic biological preservation unit and method of operation wherein the atmosphere within the unit is sealed from the outside atmosphere by pressure maintenance provided by varying amounts of refrigeration from a cryocooler and by a sealed lid employing pliable polymeric material maintained in compression.

1 . A cryogenic biological preservation unit comprising: 
 (A) an insulated vessel having a vessel interior, a lid positioned within an opening allowing access to the vessel interior, and a seal comprising pliable polymeric material in contact with the lid;    (B) a cryocooler positioned to provide refrigeration to the insulated vessel; and    (C) a pressure relief conduit having a pressure relief valve and being in communication with the vessel interior.    
   
   
       2 . The cryogenic biological preservation unit of  claim 1  wherein the cryocooler is a pulse tube refrigerator.  
   
   
       3 . The cryogenic biological preservation unit of  claim 1  containing at least one biological sample within the vessel interior.  
   
   
       4 . The cryogenic biological preservation unit of  claim 1  further comprising a differential pressure transducer on the pressure relief conduit.  
   
   
       5 . A method for operating a cryogenic biological preservation unit comprising: 
 (A) providing refrigeration from a cryocooler to the interior of an insulated vessel, said insulated vessel having a lid and a seal comprising pliable polymeric material in contact with the lid;    (B) maintaining the pliable polymeric material in compression; and    (C) maintaining the pressure within the interior of the insulated vessel within 2 psi of the pressure outside of the insulated vessel.    
   
   
       6 . The method of  claim 5  wherein the pressure within the interior of the insulated vessel is maintained within 2 psi of the pressure outside of the insulated vessel by varying the amount of refrigeration provided from the cryocooler to the interior of the insulated vessel.  
   
   
       7 . The method of  claim 5  wherein the pliable polymeric material is maintained in compression by engaged mating screw threads on the lid and on an adjacent screw thread ring.