The patent's assignee is
News editors obtained the following quote from the background information supplied by the inventors: "The latent heat absorption property of material phase change has been used as a means for absorbing heat influx and maintaining the temperature of objects in close contact or local proximity within a desired range. The phase change of water, due to the relatively large latent heat of fusion of the material, provides an excellent means of maintaining temperatures near 0.degree. Celsius. As the presence of liquid water produced by the phase change can be inappropriate for many applications, enclosing both the solid and liquid phase in a sealed container provides a simple means of preventing water damage. To enhance container security, the container may be constructed from robust materials; however, due to the approximate ten percent volume expansion of water upon solidification, containers need to be constructed from flexible materials that do not rupture or fracture under the high expansion pressure.
"Materials such as plastics and rubbers are used to construct such expandable containers. To reduce the container thickness while managing the risk of a rupture spill, water is often absorbed into materials such as gels, foams, and fibers, and enclosed in sealed bags or containers. Such options are frequently applied where costs and weight reduction is desired, as in shipping and transport applications.
"Unfortunately, however, such containment options are also typically associated with insulating properties that restrict the flow of thermal energy to the phase change medium. Plastic and rubber container materials have a low thermal conductivity and effectively insulate the phase change material contained therein. Absorptive materials also present an insulating feature in that the materials will thaw from the outside inward as heat is absorbed. The thawed material restricts the transfer of thermal energy to the solid remaining core, thereby imposing an increasingly thicker insulation barrier as the phase change progresses. Placing an insulation barrier between the solid phase of the phase change material and the object that is to be thermally regulated increases the dynamic effective temperature of the material or device. As the effective insulation barrier thickens, the temperature of the object will rise and may exceed the desired temperature range.
"While a variety of devices and materials require cooling or maintenance at a cool (below ambient room temperature, i.e., around 0.degree. Celsius), biological materials (organs, tissues, cells, cellular components, proteins, nucleic acids, and the like) are frequently maintained at cool temperatures, because the natural breakdown of biological materials can be significantly delayed by refrigeration. While many types of biological specimens can be preserved for an even greater duration by freezing the material, freezing is inappropriate for many biological samples. Tissue structures can be disrupted by ice crystal formation, thereby desegregating labile and degradative components. For example, specimen solutions can be damaged by ice crystal formation, as well, and concentrated solutes may impose conditions of pH and salt tonicity that alter molecular structures. As a result it is desirable to maintain biological specimens at a temperature that is above 0.degree. Celsius and below 4.degree. Celsius. Although this temperature range can be easily achieved by placing specimens into crushed ice or into ice water, safety, energy management, ergonomic, clinical protocol, space restriction, and sterility concerns have created a significant need for portable cooling solutions without exposed ice. Aqueous gels, contained water, and absorbed water-based phase change solutions currently fulfill the need for thermal sinks on which portable passive cooling solutions can operate. However, due to the construction of the thermal sink units, a steady temperature near the phase-change temperature of the thermal sink medium is difficult to maintain.
"Numerous substances with temperature sensitivities, including biological samples, chemicals, and drugs are subject to degradation when shipped by common methods using gel packs and insulated containers. Unless the payload of the package is in intimate contact with the phase change medium, thermal gradients inside the package can result in significant elevations in temperature in addition to temperature fluctuations as package contents rearrange during shipment. As the gel packs thaw during normal use, the added thawed material on the gel pack boundary adds more separation from the frozen core, further increasing the temperature differential thereby.
"Therefore, there is a need for a phase-change container that will isolate the phase change material, allow for expansion upon solidification of the contained material, provide a thermally conductive interface with the object to be thermally regulated, and ensure close proximity of the solid phase of the phase change material to the thermally conductive barrier, thereby cooling an object and/or maintaining the cooled object in a narrow temperature range close to phase change media transition temperature. The present invention meets these needs."
As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "The present invention provides methods and devices for cooling and maintaining a temperature of an object. In particular, the present invention relates to a thermal sink cooling cartridge which includes an expandable base container having a thin, thermoconductive cover, wherein an aqueous medium is stored in the base container and in contact with the thermoconductive cover. The expandable base container generally comprises a non-porous material that is durable at low temperatures. In some instances, the expandable base container may include a polymer material that remains flexible or pliable at low temperatures, such as polyethylene, polypropylene, Santoprene.TM., Titan.TM., Engage.TM., ethylene vinyl acetate, PETG, silicone, and other weatherable polymer materials. The expandable base container may further include one or more plasticizers to improve the flexibility and durability of the container.
"In various embodiments, the cartridge module of the invention comprises a base container which accommodates an expanding volume of the aqueous medium upon solidification without rupture, failure of container seams, or significant distortion of overall dimensions of the base container. For example, in some implementations the expandable base container comprises at least one expansion panel, whereby the interior volume of the base container may expand in response to increased pressure within the container. The expansion panel may include a fold, a crimp, a recessed surface, or other integrated shape or contour which allows for expansion of the aqueous medium within the expandable base container.
"In various embodiments, the cooling cartridge of the invention comprises a thermoconductive cartridge cover that provides a thermally conductive interface. In general, the aqueous medium is positioned within the base container such that contact remains constant between the thermoconductive cover and the aqueous medium throughout various phase changes of the aqueous medium. Thus, in some implementations the expandable base container is completely or almost completely filled with the aqueous medium such that there are no, or only minimal, air pockets between the aqueous medium and the thermoconductive cover. As used herein, minimal air pockets means that less than 20% of the upper plate surface area is in contact with air pocket(s), including less than 10%, less than 5%, less than 3%, and less than 1%.
"As the aqueous medium changes from liquid to solid, the solid phase of the aqueous medium becomes buoyant within the base container and forms an interface directly with the thermoconductive cover. Heat from the solid phase of the aqueous medium is therefore transferred to the thermoconductive cover throughout the duration of the medium's solid phase. The buoyant nature of the solid phase ensures constant contact between the solid phase and the thermoconductive cover as the aqueous medium changes from solid to liquid phase. Thus, heat transfer between the solid phase of the aqueous medium and the thermoconductive cover is maximized by various implementations of the present invention.
"In some aspects of the invention, the expandable base container comprises flared or tapered side walls to encourage separation between the base container and the solid phase of the aqueous medium. As the aqueous medium becomes solid and therefore buoyant within the base container, the flared or tapered sides walls reduce any compressive or shear forces between the solid phase the side walls. As such, the solid phase aqueous medium is released from the side walls and permitted to rise within the base container to contact the thermoconductive cover.
"In some implementations, an external object is cooled by placing the object in direct contact with the thermoconductive cover. Heat from the aqueous medium is transferred to the object via the thermoconductive cover. Thus, in some aspects of the invention the thermoconductive cover comprises a thermoconductive material, such as aluminum, copper, silver, gold, an aluminum alloy, a copper alloy, a silver alloy, a gold alloy, a titanium alloy, stainless steel, and/or a magnesium alloy.
"In some implementations, the thermoconductive cover further comprises one or more magnets whereby to facilitate coupling of the thermoconductive cover to an external object. In some instances, the one or more magnets are imbedded within the material of the thermoconductive cover. In other implementations, the one or more magnets are attached to any surface of the thermoconductive cover, wherein the one or more magnets magnetize the remaining surfaces of the thermoconductive cover.
"In some implementations, the thermoconductive cover further comprises a temperature sensor and indicator coupled to a portion of the thermoconductive cover. The temperature sensor and indicator may monitor and display the temperature of the thermoconductive cover. In some implementations, the temperature sensor and indicator comprises a temperature sensitive strip that is applied to the thermoconductive cover via an adhesive.
"In some instances, the thermal sink cooling cartridge further includes a fluid tight seal interposed between an opening of the expandable base container and the thermoconductive cover. The fluid tight seal prevents leakage of the aqueous medium within the base container. The fluid tight seal further prevents leakage of the aqueous medium due to increased pressure within the base container. Accordingly, in some implementations of the present invention a fluid tight seal includes at least one of an adhesive, a silicone-based adhesive, a compressed gasket, an o-ring, a compression band, a clamp, a crimped seal, and a fusion weld. Further, in some instances a fluid tight seal includes a rim channel molded into a base portion of the expandable base container.
"The thermal sink cooling cartridge of the present invention may further include various features and surfaces to facilitate handling of the device. For example, the expandable base container may include a contact surface having a feature, a texture, a contour, and/or a shape to assist a user in handling and transporting the cartridge device. The cartridge may further include at least one of a ridge, a groove, a peg, a hole, a texture, a feature, a protrusion, an encasement and/or an indent to accommodate or receive an external object.
"An external object may include any object for which cooling is desired. An external object may further include any object capable of transferring heat to the thermoconductive cover, the expandable base container, or the aqueous medium of the cartride device. Non-limiting examples of external objects may include a biological sample, an organic material, an inorganic material, a food, dry ice, an electronic component, an automated machine, a stand, a refrigeration device, a computer chip, a sample tray, a sample tube, a container, an adapter for a container, and a sample rack.
"In some implementations, the thermal sink cooling cartridge is connected to an external object via a thermoconductive channel. For example, in some aspects the cooling cartridge is connected to an external object via a heat tube. The cooling cartridge may further be connected to an external object via a heat sink, a conduit, a refrigeration line, and a water bath.
"The thermal sink cooling cartridge of the present invention may further include various features and surfaces to accept or compatibly receive an external storage housing. For example, an external surface of the cooling cartridge may include a feature, a texture, a contour, and/or a shape which engages or interlocks with a feature, texture, contour, and/or shape of an interior surface of a storage housing. A storage housing may include a container comprising an insulating material, such as polyethylene foam, polypropylene foam, styrene foam, urethane foam, and evacuated containers. In some implementations, the storage housing comprising a shipping container.
"In some instances, an aqueous medium comprises purified water. In various embodiments, the liquid phase change medium is water, water admixed with a dye (to facilitate identification of ruptures or leaks), or water admixed with another substance that changes the freezing point of the aqueous medium. For example, in some instances the aqueous medium comprises water containing an additive selected from glycerol, a salt, polyethylene glycol, an alcohol, a simple sugar, a complex sugar, and a starch. The aqueous medium may further include an antimicrobial material to prevent growth or colonization of microbes within the aqueous medium. Accordingly, some implementations of the invention further include one or more ports that can be used to access an interior of the expandable base container, wherein the one or more ports is used to add, modify, or replace the aqueous medium or an additive of the aqueous medium.
"The aqueous medium is placed in the expandable base container such that a portion of the aqueous medium is in contact with the thermoconductive cover. Thus, heat from the aqueous medium is transferred to an external object via the thermoconductive cover. Accordingly, in some instances, the aqueous medium is separated from the external object only by a thin thermoconductive barrier or cover which greatly improves temperature stability and control for the external object while providing a temperature approximate to 0 degrees Celsius. Some implementations further provide cooling of an external object while avoiding the danger of freezing.
"In some implementations, the present invention provides a passive thermal sink cooling cartridge, consisting of an expandable base container filled with an aqueous medium and having a cover that provides a thermally conductive interface, with said cover attached to the top of the sides of the container by a fluid tight seal that prevents leakage of the aqueous medium, which cartridge can sustain an influx of thermal energy while providing a conductive interface temperature that remains constant over the duration of a phase transition of the aqueous medium contained therein (i.e. from a solid to a liquid). Some aspects of the invention further include a compressible element in contact with the aqueous medium. The compressible element comprises a volume which may be reduced in response to external pressures exerted by the aqueous medium during change of the medium from a liquid to a solid phase. For example, the compressible element may include a closed cell, foam material.
"The cartridges of the invention can be of any size and can be used in any application where one desires to maintain an object (and its contents) at a temperature that is the temperature at which the aqueous medium undergoes a phase change. For example, and without limitation, if one desires to maintain a biological sample at a temperature in the range of 0.degree. Celsius to 4.degree. Celsius, then the cartridges of the invention that contain water as the liquid phase change medium are ideal. Depending on the size of the biological sample (and any container in which it may be located), one selects an appropriately sized cartridge of the invention containing an aqueous phase change medium, subjects the cartridge to conditions that convert some or all of the aqueous phase change medium into ice, and then places the biological sample (or its container) onto the cover of the cartridge. The ice in the cartridge, due to its buoyancy in water, will remain in direct contact with the thermoconductive cover until it completely melts, thus providing optimal temperature maintenance results.
"Thus, in a second aspect, the present invention provides methods for maintaining an object at a desired temperature, said methods comprising placing said objects on the thermoconductive cover surface of a device of the invention.
"These and other aspects, embodiments, and advantages of the invention are described in the attached drawings and following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
"FIG. 1 shows a perspective view of a thermal sink cooling cartridge in accordance with a representative embodiment of the present invention.
"FIG. 2 shows a cross section view of a thermal sink cooling cartridge in accordance with a representative embodiment of the present invention.
"FIG. 3 shows a cross section view of a thermal sink cooling cartridge within a storage housing in accordance with a representative embodiment of the present invention.
"FIG. 4 shows a graph demonstrating the effectiveness of various representative embodiments of the present invention.
"FIG. 5 shows a partial cross section view of a thermal sink cooling cartridge coupled to an external object via a thermoconductive channel in accordance with a representative embodiment of the present invention.
"FIG. 6 shows a cross section view of a thermal sink cooling cartridge within a storage housing in accordance with a representative embodiment of the present invention.
"FIG. 7 shows a detailed, cross section view of an interface between a thermal sink cooling cartridge expandable base container and a thermally conductive cover in accordance with a representative embodiment of the present invention.
"FIG. 8 shows a cross section view of a thermal sink cooling cartridge within a storage housing in accordance with a representative embodiment of the present invention.
"FIG. 9 shows the dimensions of the thermal sink cooling cartridge container shown in FIG. 8.
"FIG. 10 shows a cross section view of a thermal sink cooling cartridge in accordance with a representative embodiment of the present invention.
"FIG. 11 shows added detail for the embodiment shown in FIG. 10, wherein the thermal sink cooling cartridge includes a port in accordance with a representative embodiment of the present invention. FIG. 12 shows the overall dimensions of the thermal sink cooling cartridge of the invention illustrated in FIGS. 10 and 11.
"FIG. 13 shows a graph demonstrating the effectiveness of various representative embodiments of the present invention.
"FIG. 14 shows a perspective view of a multiple bay thermal sink cooling cartridge having temperature sensitive strips in accordance with a representative embodiment of the present invention.
"FIG. 15 shows the dimensions of the multiple bay thermal sink cooling cartridge displayed in FIG. 14.
"FIG. 16 shows a cross section view of a thermal sink cooling cartridge having a compressed gasket seal in accordance with a representative embodiment of the present invention."
For additional information on this patent application, see: Schryver, Brian; Ganaja, Scott. Phase Change Thermal-Sink Apparatus. Filed
Keywords for this news article include: Alkenes, Polyenes, Hydrocarbons,
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