Rate-controlled freezer and cooling methods thereof

Abstract

The disclosure provides a freezer system including a temperature and cooling-rate controlled freezer having a rack system having a tray adapted for freezing and preserving temperature-sensitive items. The disclosure also provides methods for cooling and preserving items in the freezer system.

1 . A freezer system comprising: 
 a freezer to cool items;    a thermo-sensor to monitor temperature within the freezer;    at least one tray having apertures to hold the items within the chamber of the freezer and to provide uniform cooling of the items;    a programmable controller to receive and process signals from the thermo-sensor and to control the temperature of the freezer and the cooling-rate of the items; and    a baffle within the freezer.    
   
   
       2 . The freezer system of  claim 1  wherein the baffle is part of a tray.  
   
   
       3 . The freezer system of  claim 1  wherein the baffle is situated so that the baffle disturbs laminar refrigerant flow and causes turbulent refrigerant flow.  
   
   
       4 . The freezer system of  claim 1  wherein the at least one tray comprises from two to ten trays.  
   
   
       5 . The freezer system of  claim 1  wherein at least one thermo-sensor monitors the temperature of one or more locations on a tray, monitors the temperature of one or more of the items in the tray, monitors the temperature within the freezer, or combinations thereof.  
   
   
       6 . The freezer system of  claim 1  wherein at least one thermo-sensor is situated within the chamber of the freezer and away from the freezer's refrigerant source.  
   
   
       7 . The freezer system of  claim 1  wherein the items comprise from 10 to about 500 sample items.  
   
   
       8 . The freezer system of  claim 1  wherein the programmable controller signals a cooling-rate of from about −0.1 to about −5° C. per minute.  
   
   
       9 . The freezer system of  claim 1  wherein the programmable controller signals a cooling-rate of about −1° C. per minute.  
   
   
       10 . The freezer system of  claim 1  wherein programmable controller signals a cooling-rate of from about −0.1 to about −1° C. per minute over a temperature range of from about 40° C. to about −100° C.  
   
   
       11 . A freezer system comprising: 
 a freezer comprising a housing having a cooling chamber therein;    a rack system comprising one or more trays in the chamber, the trays being adapted to receive and hold items for cooling;    at least one baffle associated with the rack system or chamber; and    a temperature controller adapted to measure temperatures within the freezer, adapted to control the temperature, and adapted to provide a constant cooling-rate for the items in response to the measured temperatures.    
   
   
       12 . The freezer system of  claim 11  wherein the temperature controller comprises a plurality of thermo-sensors adapted to measure the temperature of the chamber, the rack system, and items in the rack system.  
   
   
       13 . The freezer system of  claim 11  wherein the freezer further comprises a liquid refrigerant source, a valve and solenoid adapted to regulate the liquid refrigerant admitted to the housing, a coil adapted to vaporize the liquid refrigerant, and a fan adapted to circulate the vaporized refrigerant through the chamber.  
   
   
       14 . The freezer system of  claim 13  wherein the temperature controller is adapted to control the solenoid and the fan.  
   
   
       15 . The freezer system of  claim 11  wherein each tray has at least one baffle attached to or integral therewith.  
   
   
       16 . The freezer system of  claim 11  wherein each tray is adapted to stackably engage another tray.  
   
   
       17 . The freezer system of  claim 11  wherein the rack system comprises a frame adapted to slidably receive the trays.  
   
   
       18 . The freezer system of  claim 11  wherein the freezer system provides a relatively constant cooling rate of about −1 centigrade per minute over from about 35° C. to about −90° C.  
   
   
       19 . The freezer system of  claim 11  wherein the freezer system provides a temperature variation within an item of less than from about 0.01 to about 0.5° C.  
   
   
       20 . The freezer system of  claim 11  wherein the freezer system provides a temperature variation between or among two or more items of less than from about 0.1 to about 5.0° C.  
   
   
       21 . The freezer system of  claim 11  wherein the freezer system provides a temperature variation between any two locations in the rack system of less than-from about 0.1 to about 5.0° C.  
   
   
       22 . The freezer system of  claim 11  wherein the baffle perturbs laminar air-flow patterns which are present in the chamber in the absence of the baffle.  
   
   
       23 . The freezer system of  claim 11  wherein each tray has at least two baffles attached to or integral with.  
   
   
       24 . The freezer system of  claim 11  wherein the baffle is attached to or integral with an interior wall of the chamber.  
   
   
       25 . The freezer system of  claim 11  wherein the rack system is adapted to slidably engage the chamber.  
   
   
       26 . The freezer system of  claim 11  wherein the rack system is adapted to provide an electrical connection to the temperature controller when slidably engaged in the chamber.  
   
   
       27 . The freezer system of  claim 11  wherein the rack system is adapted to slidably engage one or more trays inserted into the rack system.  
   
   
       28 . The freezer system of  claim 11  wherein the rack system is adapted to provide an electrical connection between the temperature controller and one or more trays when inserted into the rack system.  
   
   
       29 . The freezer system of  claim 11  wherein each tray has a plurality of apertures there through, the apertures being adapted to receive and hold items, and adapted to permit cross-flow refrigerant circulation if unoccupied.  
   
   
       30 . A tray comprising: 
 a base sheet adapted to support items, the base sheet having an optional array of apertures there through, the base sheet apertures when present being adapted to be vacant to permit cross-flow refrigerant circulation in a freezer;    a top sheet having an array of major and minor apertures there through, the top sheet array of major and minor apertures being adapted to be non-collinear with the optional array of apertures of the bottom sheet, the each major aperture being adapted to either hold a item or to be vacant and to permit cross-flow circulation of circulating refrigerant in a freezer, the array of minor apertures being adapted to be vacant and to permit cross-flow refrigerant circulation in a freezer; and    a connector adapted to fixably join together and space apart the adjacent sheets of a tray from each other, and optionally adapted to permit two or more trays to be stacked together.    
   
   
       31 . The tray of  claim 30  further comprising a baffle connected to tray or integral with the tray.  
   
   
       32 . The tray of  claim 31  wherein the baffle is connected to at least one of the sheets.  
   
   
       33 . The tray of  claim 32  wherein two baffles are connected to opposite ends of the tray, the ends being oriented perpendicular to the main flow path of circulating refrigerant when the tray is placed in a freezer.  
   
   
       34 . The tray of  claim 30  wherein the connector comprises a baffle, the baffle optionally having apertures there through, the baffle apertures being adapted to selectively permit refrigerant circulation through the baffle or to be plugged.  
   
   
       35 . The tray of  claim 34  wherein the connector further comprises a leg member adapted to elevate the base sheet to afford an air-way beneath and traversing the base sheet and optionally adapted to permit tray stacking.  
   
   
       36 . The tray of  claim 30  wherein the connector comprises two baffles connected to opposite ends of the tray, the ends being oriented perpendicular to the main flow path of circulating refrigerant when the tray is placed in a freezer.  
   
   
       37 . The tray of  claim 36  wherein the connector further comprises a peg member adapted to elevate the base sheet to afford an air-way beneath and traversing the base sheet and optionally adapted to permit tray stacking.  
   
   
       38 . The tray of  claim 30  wherein the connector comprises a connector rod, an optional spacer, an optional nesting washer, and a fastener.  
   
   
       39 . The tray of  claim 38  wherein the optional nesting washer is adapted to stack and electrically interconnect two or more trays.  
   
   
       40 . The tray of  claim 30  wherein the connector is further adapted to permit electrical interconnection of the tray to another tray and to permit electrical connection of the resulting tray to a temperature measurement system.  
   
   
       41 . The tray of  claim 30  further comprising a middle sheet interposed between the top sheet and bottom sheet, the middle sheet having an array of major and minor apertures there through substantially identical and co-linear to the top sheet apertures.  
   
   
       42 . The tray of  claim 30  further comprising a baffle member attached to a surface of a tray sheet.  
   
   
       43 . A rack system comprising a tray of  claim 30  adapted to receive and hold items.  
   
   
       44 . The rack system of  claim 43  comprising 1 to 10 trays.  
   
   
       45 . The rack system of  claim 43  wherein the connector comprises a baffle, the baffle optionally having apertures there through.  
   
   
       46 . The rack system of  claim 43  further comprising a baffle member on a surface of a tray sheet.  
   
   
       47 . The rack system of  claim 43  wherein the tray holds from 60 to 150 items.  
   
   
       48 . The rack system of  claim 43  wherein the item comprises an ampoule having a sample volume of from about 5 to about 150 mL.  
   
   
       49 . The rack system of  claim 43  wherein the tray has a total ampoule sample volume capacity of from about 1,000 to about 15,000 mL.  
   
   
       50 . The rack system of  claim 43  wherein the size of the items are the same or different.  
   
   
       51 . The rack system of  claim 43  wherein the item comprises an ampoule containing a biological material.  
   
   
       52 . The rack system of  claim 43  wherein the item comprises an ampoule containing living cells.  
   
   
       53 . The rack system of  claim 43  wherein the item comprises an ampoule containing antibodies.  
   
   
       54 . The rack system of  claim 43  further comprising a shaker adapted to shake the rack and agitate the items in the tray or trays.  
   
   
       55 . A method of cooling with a freezer system, the freezer system comprising: 
 a freezer adapted to cool items;    a plurality of thermo-sensors adapted to monitor the temperature at points within the freezer;    a programmable controller adapted to receive and process signals from the thermo-sensors and further adapted to send signals to control the temperature and the cooling-rate of the items in the freezer; and    a tray comprising: 
 a base sheet adapted to support items, the base sheet having an optional array of apertures there through, the base sheet apertures when present being adapted to be vacant to permit cross-flow refrigerant circulation in a freezer;  
 a top sheet having an array of major and minor apertures there through, the top sheet array of major and minor apertures being adapted to be non-collinear with the optional array of apertures of the bottom sheet, the each major aperture being adapted to either hold a item or to be vacant and to permit cross-flow circulation of circulating refrigerant in a freezer, the array of minor apertures being adapted to be vacant and to permit cross-flow refrigerant circulation in a freezer;  
 a connector adapted to fixably join together and space apart the adjacent sheets of a tray from each other, and optionally adapted to permit two or more trays to be stacked together; and  
 optionally a baffle connected to an end of the tray;  
   the method comprising:    arranging a plurality of items in a pattern in the tray;    placing the tray in the freezer's chamber and sealing the chamber;    circulating the air and a gaseous refrigerant through the chamber and in contact with the items;    monitoring the temperature at points in the chamber with the thermo-sensors; and    controlling the temperature and the cooling-rate of the items in the freezer with the programmable controller.    
   
   
       56 . The method of  claim 55  wherein the pattern of items comprises having an item occupy an aperture and having adjacent apertures vacant.  
   
   
       57 . The method of  claim 55  wherein the pattern of items comprises having an item occupy the major apertures and having minor apertures vacant.  
   
   
       58 . The method of  claim 55  wherein the cooling-rate is about −1° C. per minute over a temperature range of about 40 to −100° C.  
   
   
       59 . The method of  claim 55  wherein the method provides uniform temperatures within individual items and uniform temperatures among items.  
   
   
       60 . The method of  claim 55  wherein the method provides rate-controlled cooling within individual samples and among items.  
   
   
       61 . The method of  claim 55  wherein the method provides a narrow temperature differential among items of about 0.5° C.  
   
   
       62 . The method of  claim 55  wherein the method provides a temperature differential between the chamber and the items in the chamber of about 5.0° C. to about 50° C. for less than about 10 to about 20 minutes.  
   
   
       63 . The method of  claim 55  wherein the controller controls the temperature and cooling-rate of items by regulating the amount refrigerant admitted to the chamber and the circulation rate of the air and refrigerant in the chamber.  
   
   
       64 . The freezer system of  claim 1  wherein the aperture includes a valve optionally connected to and regulated by the programmable controller.  
   
   
       65 . The freezer system of  claim 1  wherein the baffle is moveable by a mover and the baffle's movement is optionally regulated by the programmable controller.