Medical Grade Freezer for Vaccines and Medications

Abstract

A medical grade cooler or freezer uses a Peltier system without the use of vapor compression refrigeration. An opening may be cut through a wall, for example, a top, bottom, rear or side wall, of the cooler or freezer and the Peltier device sealed within that opening with the hot side exposed outside of the cooler or freezer and the cold side exposed inside the cooler. When a voltage is applied to the Peltier device, the interior temperature of the cooler may be reduced. The Peltier devices can also be reversed by applying voltage in the opposite direction to remove heat from outside of the cooler and pump heat into the cooler or freezer.

Description

BACKGROUND OF THE INVENTION

The present invention relates generally to insulated storage coolers, for example, for safely storing frozen vaccines and other biological samples for clinical applications meeting recommended temperature requirements and, in particular to, an electrical cooling system for such storage coolers eliminating the need for evaporators and condensers.

Medical grade coolers provide a way to properly store vaccines at ultra-cold temperatures. Vaccines that are not stored at the proper temperature may have reduced potency, creating the need for revaccination, and in some situations resulting in vaccine waste.

A temperature controlled supply chain is used to maintain vaccines at proper temperatures from vaccine manufacture to vaccine administration. Manufacturers, distributors, public health staff, and health care providers are responsible for the administration of the “cold chain.” The temperature controlled supply chain starts at the cold storage at the vaccine manufacturing site, next, to the transport and delivery of the vaccine to the provider facility, next, to the cold storage at the provider facility, and finally, ends at the administration of the vaccine to the patient. When vaccines are not stored properly and are exposed to improper temperatures, including heat, cold, and light, their potency is reduced. Potency cannot be restored resulting in wasted drugs.

Proper storage and monitoring equipment for biologics are specifically built to store vaccines at proper temperatures and are sometimes referred to as “pharmaceutical-grade” or “medical-grade” coolers or freezers. It is known in the art to incorporate microprocessor-based temperature control with a temperature sensor, such as a thermocouple, resistance temperature detector (RTD), or thermistor, and fan forced air circulation using powerful fans and cooling air vents promoting uniform temperature and quick recovery from out of range temperatures, for example, when the door is opened.

Refrigerators and freezers may be upright or chest style. The refrigerators and freezers may use two or more vapor compressors using different refrigerants and an inter-stage heat exchanger to cool the freezer to desired temperatures. Refrigerators may maintain temperatures between 2 degrees and 8 degrees Celsius (36 degrees and 46 degrees Fahrenheit) and freezers may maintain temperatures between −50 degrees and −15 degrees Celsius (−58 degrees and 5 degrees Fahrenheit) with ultralow temperature freezers maintaining temperatures between −50 degrees and −80 degrees Celsius (−58 degrees to −123 degrees Fahrenheit).

SUMMARY OF THE INVENTION

A Peltier device is a class of thermoelectric cooler and typically provides a semiconductor plate across which a voltage can be applied. Upon the application of voltage, heat is pumped from one side of the Peltier device (the cold side) to the other side (the hot side). The direction of the current determines the hot side and the cold side.

The present invention provides a Peltier system that can be used with a medical grade cooler or freezer without the use of vapor compression refrigeration. When such a cooling device is incorporated into a cooler or freezer, an opening may be cut through a wall, for example, a top, bottom, rear or side wall, of the cooler or freezer and the Peltier device sealed within that opening with the hot side exposed outside of the cooler or freezer and the cold side exposed inside the cooler. In this way, when a voltage is applied to the Peltier device, the interior temperature of the cooler may be reduced. The Peltier devices can also be reversed by applying voltage in the opposite direction to remove heat from outside of the cooler and pump heat into the cooler or freezer.

Alternatively, the thermal conductive material may pass over a wall of the cooler or freezer to provide a heat pipe communicating between opposed Peltier devices, a first device positioned within the cooler or freezer and pumping heat into the heat pipe and a second device positioned outside the cooler or freezer and removing heat from the heat pipe.

In one embodiment, the Peltier device may be placed within an opening through a top wall of the cooler or freezer such that varied temperature zones are created within the cooler or freezer with colder temperatures toward the bottom of the cooler or freezer and warmer temperatures toward the top of the cooler or freezer. The varied temperature zones may be separated into separate compartments or drawers thereby creating varied temperature compartments. A sharps bin may be incorporated into the cooler or freezer for convenience.

In one embodiment, the cooler or freezer may be lightweight and smaller in size (e.g., internal capacity of 5 to 9 cubic feet or less) than a permanent unit thereby allowing the cooler or freezer to be portable and moveable onto a vehicle for transport from the manufacturer site to the provider facility. The cooler or freezer may include caster wheels to facilitate transport.

In an alternative embodiment, the cooler or freezer is larger in size (e.g., internal capacity of 12-18 cubic feet or more than 18 cubic feet) and serves as a permanent unit not intended to be portable and may be permanently located at the manufacturer site, on a transport vehicle, or at the provider facility during the temperature controlled supply chain. A larger cooler or freezer may contain more than one Peltier device or a larger sized Peltier device.

The present invention provides a medical cabinet for cooling vaccines comprising a cabinet having upstanding front wall and rear wall flanked by upstanding side walls enclosed by a top wall and bottom wall on their top edges and bottom edges, respectively, defining a cabinet volume; at least one shelf dividing the cabinet volume into separate compartments; a first Peltier thermoelectric device providing a first semiconductor plate across which a voltage is applied supported by at least one wall of the cabinet; a second Peltier thermoelectric device providing a second semiconductor plate across which the voltage is applied supported by at least one wall of the cabinet; a heat sink attached to at least one of the first and second Peltier thermoelectric devices; and a fan attached to the heat sink and forcing air through the heat sink.

It is thus a feature of at least one embodiment of the present invention to provide an ultra-low temperature freezer, for example, for storing DNA, RNA, enzymes, and vaccines.

The front wall may have at least one rectangular opening receiving at least one sliding drawer having a bottom wall surrounded by sidewalls terminating upwardly at a rectangular lip surrounding an upwardly exposed opening.

It is thus a feature of at least one embodiment of the present invention to minimize heat transfer into and out of the cabinet when retrieving vials by defining separately accessible cabinet cavities.

Sliding rails may receive the at least one drawer and permit the at least one drawer to slide into and out of the at least one rectangular opening. The sliding rails may be supported on an inner surface of the upstanding side walls.

It is thus a feature of at least one embodiment of the present invention to allow for the storage of temperature sensitive specimens in vials in a manner which is easy to organize and to retrieve different biologics stored at different temperatures.

The at least one shelf may be vented to permit airflow through the at least one shelf.

It is thus a feature of at least one embodiment of the present invention to permit airflow between the separate compartments promoting a more uniform temperature within the cabinet.

At least one of the upstanding front wall, rear wall, and side walls may be covered with an insulation material.

It is thus a feature of at least one embodiment of the present invention to prevent heat transfer into and out of the cabinet to provide more precise temperature control within the cabinet cavity.

The first and second Peltier thermoelectric devices may extend through an opening in the top wall. The heat sink and fan may be positioned on an exterior of the cabinet.

It is thus a feature of at least one embodiment of the present invention to provide low cost and environmentally friendly coolers for cooling its contents.

The hot and/or cold side of the Peltier device may be attached to heatsinks to aid in the transfer of heat between the Peltier device and ambient air.

It is thus a feature of at least one embodiment of the present invention to reach ultra-low temperatures within the cabinet for maintaining biologics at the required temperature range for safety and efficacy.

Electrical wiring may communicate with at least one of the first and second Peltier thermoelectric devices and the fan and terminate at a standard automotive 12-volt connector.

It is thus a feature of at least one embodiment of the present invention to permit the Peltier thermoelectric devices to be powered by mains electricity delivering 12 to 30 volts AC.

An inner surface of at least one of the front wall, rear wall, and sidewalls may be lined with a conductive material.

It is thus a feature of at least one embodiment of the present invention to eliminate heat from the system through conduction.

At least one temperature sensor may communicate with a microcontroller controlling a temperature of the cabinet volume. Separate temperature sensors may be disposed within each compartment.

It is thus a feature of at least one embodiment of the present invention to provide precise temperature control of each individual cavity and to use temperature gradients to cool vials at different temperatures.

A method of cooling vaccines includes providing a cabinet having upstanding sidewalls enclosed by a top wall and bottom wall on their top edges and bottom edges, respectively, defining a cabinet volume, and at least one shelf dividing the cabinet volume into separate compartments, a first Peltier thermoelectric device providing a first semiconductor plate across which a voltage is applied supported by at least one wall of the cabinet, a second Peltier thermoelectric device providing a second semiconductor plate across which the voltage is applied supported by at least one wall of the cabinet, a heat sink attached to at least one of the first and second Peltier thermoelectric devices, and a fan attached to the heat sink and forcing air through the heat sink. Vials of biologics are inserted into the cabinet volume. A voltage is applied across the first and second Peltier thermoelectric devices.

The method comprises cooling the cabinet volume to a temperature of less than room temperature (i.e., 20 to 22° C.). The method comprises cooling the cabinet volume to a temperature of less than 10 degrees Celsius.

The method comprises inserting the vials into at least one sliding drawer having a bottom wall surrounded by sidewalls terminating upwardly at a rectangular lip surrounding an upwardly exposed opening removably insertable into the cabinet volume.

The method comprises applying 12 to 30 volts AC across the first and second Peltier thermoelectric devices.

The advantages of the use of a Peltier device over vapor compression refrigeration include lack of moving parts or circulating liquid, very long life, invulnerability to leaks, small size, and flexible shape.

These particular objects and advantages may apply to only some embodiments falling within the claims and thus do not define the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a medical grade cooler with a Peltier system of the present invention attached thereto showing the external Peltier device;

FIG. 2 is a cross-section taken along line 2-2 of FIG. 1; and

FIG. 3 is a simplified elevational view with the front wall removed showing the air flow and temperature zones within separate compartments of the medical grade cooler of FIG. 1 and holding vials of vaccines.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1, a medical cooler system 10 of the present invention may use a cabinet 12 providing an insulated container having four upstanding sidewalls 14 positioned about a rectangular bottom wall 16 and a rectangular top wall 18. The bottom wall 16 may be supported on caster wheels for mobility. The internal capacity of the cabinet may be 5 to 9 cubic feet or less. In an alternative embodiment the internal capacity of the cabinet may be 12-18 cubic feet or more than 18 cubic feet.

The front wall 14a has one or more front rectangular openings 20 receiving one or more corresponding drawer boxes 21. The one or more front rectangular openings 20 may be spaced apart to define vertically spaced apart compartments, as further described below.

Each of the drawer boxes 21 may include four upstanding sidewalls 22 positioned about a rectangular bottom wall 23 of the drawer boxes 21. The drawer boxes 21 provide an open top opening 27 allowing for the insertion of vials 32 of vaccine or other biologics into the drawer boxes 21.

A drawer front wall 22a of each of the drawer boxes 21 may be removably positioned in front of the openings 20 so as to move away from the openings 20 when open and to cover the openings 20 when closed to provide an enclosed insulated volume within the upstanding sidewalls 14.

The drawer boxes 21 may be slid on corresponding interior rails 25 of the cabinet 12 attached to an inner surface of the sidewalls 14. The outer surface of the sidewalls 22 of the drawer boxes 21 may support corresponding rails 29 that mate with the rails 25 of the cabinet 12 and, for example, may be roller slides.

Referring momentarily to FIG. 2, each upstanding sidewall 14 may provide a plastic shell 24 forming opposed inner and outer sides of the upstanding sidewalls 14 defining a space therebetween filled with a foam polymer material 26 for added insulation. The bottom wall 16 and top wall 18 may be constructed similarly. The inner sides of the upstanding sidewalls 14 may be lined with a conductive material such as an aluminum sheet, e.g., 1/16 inch thickness. This conductive material permits heat to be removed from the cabinet 12 through conduction rather than convection.

Referring again to FIGS. 1 and 2, a rectangular opening 28 may be formed within the top wall 18 of the cabinet 12 to support a Peltier system 30 therein. An exterior broad surface of a Peltier thermoelectric device 40 may be attached to an extruded aluminum heatsink 42 having multiple fins 44 extending vertically for exchanging heat with the ambient air. The fins 44 may be alternatively oriented horizontally.

Positioned over the heatsink 42 is a fan 46 forcing air through the fins 44 for improved heat transfer. Electrical wiring 48, for example, terminating at a standard 12-volt connector 50 to deliver converted 12 to 30 volt electricity to the fan 46 and the Peltier thermoelectric device 40, biasing the latter so that the cold side of the Peltier thermoelectric device 40 extends inside the cabinet 12 and the hot side is outside the cabinet 12 and faces the heatsink 42. It is understood that the electrical wiring 48 may connect the fan 46 and the Peltier thermoelectric device 40 to a mains electricity delivering an input voltage of 120 volt AC and converting it to 12 to 30 volt electricity.

The Peltier thermoelectric device 40 includes semiconductor elements 36 including alternating n-type and p-type elements that are of different type but have complementary Peltier coefficients. The semiconductor elements 36 are connected to two nickel plated copper conductor plates 37 (hot side), 39 (cold side), one on each side of the semiconductor elements 36, to electrically connect the semiconductor elements 36 to each other. The semiconductor elements 36 are electrically connected in series but thermally connected in parallel. The semiconductor elements 36 and two nickel plated copper conductor plates 37, 39 form an array that are further affixed to two ceramic substrates 41 (hot side) and 43 (cold side), one on each side of the nickel plated copper conductor plates 37, 39, to conduct heat to and from the array.

As understood in the art, heat is absorbed at the cold side of the n- and p-type elements, and heat is released at the hot side of the Peltier thermoelectric device 40. The heat pumping capacity of a module is proportional to the current and is dependent on the element geometry, number of n-type and p-type elements, and material properties.

The array of semiconductor elements 36 may extend through the top wall 18 of the cabinet 12 so that the hot side and ceramic substrate 41 of the Peltier thermoelectric device 40 is positioned outside the cabinet 12 and the cold side and ceramic substrate 43 of the Peltier thermoelectric device 40 is positioned inside the cabinet 12.

Referring momentarily again to FIG. 1, the Peltier thermoelectric device 40 may be surrounded by an outer shell housing 45 with air vents 47 that allow air to flow in and out of the Peltier thermoelectric device 40 but allow the Peltier thermoelectric device 40 to be protected from the environment. Thermal insulation 53 may cover the exposed surfaces of the ceramic substrates 41, 43 and air gaps may be sealed between the Peltier thermoelectric device 40 and the rectangular opening 28.

It will be appreciated that the cabinet 12 may support more than one Peltier thermoelectric device 40 and the multiple Peltier thermoelectric devices may be of different sizes. It will be appreciated that more than one Peltier thermoelectric devices may be of the same size running at a lower voltage. The more than one Peltier thermoelectric devices may extend through different sidewalls 14 of the cabinet 12 including through additional rectangular openings 28 in the rectangular top wall 18 and any of the four upstanding sidewalls 14.

The cabinet 12 may further include microprocessor-based temperature control with a temperature sensor 61, such as a thermocouple, resistance temperature detector (RTD), or thermistor, communicating with a controller, for example, a microcontroller 66 having one or more processors 68 executing programs and communicating with an associated memory 69, holding an operating program 72 controlling temperature within the cabinet 12.

Referring now to FIGS. 1 and 3, the cabinet 12 may be separated into three separate compartments 62a, 62b, 62c by the air permeable drawer boxes 21 that slide into and out of the cabinet 12 along the interior rails 25 to drawer closed and drawer opened positions, respectively. The drawer boxes 21 are supported by the interior rails 25 when in the closed position. The interior volume of the cabinet 12 may be a single cavity that is separated by the rectangular bottom wall 23 of the drawer boxes 21. Alternatively, the interior volume of the cabinet 12 may be separated by air permeable horizontal dividing walls that are arranged between each of the drawer boxes 21 but still permit airflow between compartments 62. For example, the horizontal dividing walls may be vented.

It is understood that the cabinet 12 may include any number of compartments 62 separated by corresponding drawer boxes 21. For example, the cabinet 12 may include one, two, three, four or more compartments 62 created by a corresponding number of drawer boxes 21. The number of compartments 62 may generally correspond with the number of drawer boxes 21.

The bottom wall 23 of the drawer boxes 21 are vented to allow air to circulate between drawer boxes 21 and through the interior of the cabinet and to pull heat 64 upward to the Peltier thermoelectric device 40.

The compartments 62 may naturally have colder temperatures toward the bottom of the cabinet 12 and warmer temperatures toward the top of the cabinet 12 where heat is being removed by the Peltier thermoelectric device 40. The varied temperatures of the compartments 62 allow different vaccines or biologics to be stored depending on their unique temperature requirements.

In one embodiment, the top compartment 62a may be at or around room temperature or about 20 degrees to 22 degrees Celsius, the center compartment 62b may be around 10 degrees Celsius to −8 degrees Celsius, and the bottom compartments 62c may be around −20 degrees Celsius to −78 degrees Celsius. In one embodiment, the top compartment 62a may be less than room temperature (20 to 22° C.), the center compartment 62b may be less than 10 degrees Celsius, and the bottom compartments 62c may be less than −20 degrees Celsius. In one embodiment, the cabinet 12 may be appropriate to store vials 32 of vaccines, e.g., Covid-19 vaccines, at −60 degrees to −80 degrees Celsius or at −15 degrees to −50 degrees Celsius.

Referring again to FIG. 1, a sharps bin 70 may be attached to the cabinet 12 or alternatively positioned in close proximity to the cabinet 12 for providing convenient disposal of used vials, needles and other sharps in a safe manner.

It is understood that the cabinet 12 may employ separate compartments 62 but instead of drawer boxes 21, the cabinet 12 may support doors that are hingeably attached to the front wall 22a to swing over and away from the front rectangular openings 20 and when closed to cover the front rectangular openings 20 to provide an insulated volume. Each of the compartments 62 may include a top wall, bottom wall, and sidewalls where the top wall (except for the topmost compartment) and bottom wall (except for the bottommost compartment) of each compartment is vented to allow airflow through the compartments.

Certain terminology is used herein for purposes of reference only, and thus is not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, and “below” refer to directions in the drawings to which reference is made. Terms such as “front”, “back”, “rear”, “bottom” and “side”, describe the orientation of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Similarly, the terms “first”, “second” and other such numerical terms referring to structures do not imply a sequence or order unless clearly indicated by the context.

When introducing elements or features of the present disclosure and the exemplary embodiments, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of such elements or features. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements or features other than those specifically noted. It is further to be understood that the method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

References to “a controller” and “a processor” or “the microcontroller” and “the processor,” can be understood to include one or more microprocessors that can communicate in a stand-alone and/or a distributed environment(s), and can thus be configured to communicate via wired or wireless communications with other processors, where such one or more processor can be configured to operate on one or more processor-controlled devices that can be similar or different devices. Furthermore, references to memory, unless otherwise specified, can include one or more processor-readable and accessible memory elements and/or components that can be internal to the processor-controlled device, external to the processor-controlled device, and can be accessed via a wired or wireless network.

It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein and the claims should be understood to include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims. All of the publications described herein, including patents and non-patent publications, are hereby incorporated herein by reference in their entireties.

Claims

1. A medical cabinet for cooling vaccines comprising: a cabinet having upstanding front wall and upstanding rear wall flanked by upstanding side walls enclosed by a top wall and bottom wall on their top edges and bottom edges, respectively, to define a cabinet volume;at least one shelf dividing the cabinet volume into separate compartments;a first Peltier thermoelectric device providing a first semiconductor plate across which a voltage is applied supported by at least one wall of the cabinet;a second Peltier thermoelectric device providing a second semiconductor plate across which the voltage is applied supported by at least one wall of the cabinet;a heat sink attached to at least one of the first and second Peltier thermoelectric devices; anda fan attached to the heat sink and forcing air through the heat sink.

2. The medical cabinet of claim 1 wherein the upstanding front wall has at least one rectangular opening receiving at least one sliding drawer having a bottom wall surrounded by sidewalls terminating upwardly at a rectangular lip surrounding an upwardly exposed opening.

3. The medical cabinet of claim 2 further comprising sliding rails receiving the at least one drawer and permitting the at least one drawer to slide into and out of the at least one rectangular opening.

4. The medical cabinet of claim 3 wherein the sliding rails are supported on an inner surface of at least one of the upstanding side walls.

5. The medical cabinet of claim 1 wherein the at least one shelf is vented permitting airflow through the at least one shelf.

6. The medical cabinet of claim 1 wherein at least one of the upstanding front wall, rear wall, and upstanding side walls of the cabinet are covered with an insulation material.

7. The medical cabinet of claim 1 wherein the first and second Peltier thermoelectric devices extend through an opening in the top wall of the cabinet.

8. The medical cabinet of claim 1 wherein the heat sink and fan are positioned on an exterior of the cabinet.

9. The medical cabinet of claim 1 wherein the heat sink has multiple fins adapted to exchange heat with ambient air.

10. The medical cabinet of claim 1 further comprising electrical wiring communicating with at least one of the first and second Peltier thermoelectric devices and the fan and terminating at a standard automotive 12-volt connector.

11. The medical cabinet of claim 1 wherein an inner surface of at least one of the front wall, rear wall, and sidewalls is lined with a conductive material.

12. The medical cabinet of claim 1 further comprising at least one temperature sensor communicating with a microcontroller controlling a temperature of the cabinet volume.

13. The medical cabinet of claim 1 wherein the cabinet volume is approximately 5 to 9 cubic feet or less.

14. A method of cooling vaccines comprising: providing a cabinet having upstanding sidewalls enclosed by a top wall and bottom wall on their top edges and bottom edges, respectively, defining a cabinet volume, and at least one shelf dividing the cabinet volume into separate compartments, a first Peltier thermoelectric device providing a first semiconductor plate across which a voltage is applied supported by at least one wall of the cabinet, a second Peltier thermoelectric device providing a second semiconductor plate across which the voltage is applied supported by at least one wall of the cabinet, a heat sink attached to at least one of the first and second Peltier thermoelectric devices, and a fan attached to the heat sink and forcing air through the heat sink;inserting vials holding biologics into the cabinet volume; andapplying a voltage across the first and second Peltier thermoelectric devices.

15. The method of claim 14 comprising cooling the cabinet volume to a temperature of less than room temperature (20 to 22° C.).

16. The method of claim 15 comprising cooling the cabinet volume to a temperature of less than 10 degrees Celsius.

17. The method claim 14 further comprising inserting the vials into at least one sliding drawer having a bottom wall surrounded by sidewalls terminating upwardly at a rectangular lip surrounding an upwardly exposed opening removably insertable into the cabinet volume.

18. The method of claim 14 wherein 12 to 30 volts AC is applied across the first and second Peltier thermoelectric devices.