Patent Application
20060191675
The invention relates to heat exchangers. The invention has particular application to heat exchangers for use in warming or cooling living subjects. The invention may be applied to cooling the brains or other body parts of living subjects. The apparatus and methods generally provide a heat exchange fluid, which is a liquid in some embodiments and a gas in other embodiments, that passes through a heat exchanger to exchange heat with a body to be warmed or cooled.
It has been discovered that quickly inducing hypothermia can significantly improve the recovery prospects of patients who suffer global ischemic brain injury secondary to cardiac arrest and probably focal ischemic brain injury from thrombotic or embolic causes. The latter is referred to as an ischemic stroke. Some trials have placed global and focal ischemic brain damaged victims in whole-body cooling chambers or devices. Intra vascular devices are used for whole body cooling and, secondarily, brain cooling. Such chambers or devices are unwieldy and can be intimidating for the patient. Fletcher, U.S. Pat. No. 6,511,502 discloses methods for cooling a subject's brain by applying heat exchangers to the neck of the subject adjacent the subject's carotid arteries. The heat exchangers cool blood flowing to the subject's brain.
In various other areas of medicine it is desirable to cool or warm body parts. For example, U.S. Pat. Nos. 4,138,743; 5,916,242; 4,566,455; 4,750,493; 4,763,866; 4,020,963; 5,190,032; 5,486,204; 5,643,336; 5,897,581; 5,913,855; 5,057,964; and 6,030,412 relate to cooling or warming body.
Various types of heat exchanger exist. Air cooled heat sinks are structures which take heat from an object and dissipate the heat into ambient air. Such heat sinks typically consist of a finned piece of thermally-conductive material having a face which can be placed in thermal contact with an object, such as an electronic component, to be cooled. Some heat sinks are equipped with fans located to flow air past the fins to improve the rate at which heat is dissipated.
U.S. Pat. No. 6,549,411 B1 discloses a flexible heat sink that can be attached to a generally flat surface of an object. The heat sink can flex to conform to the surface of the object to achieve improved contact with the object, and hence increase the efficiency of heat transfer between the heat sink and the object. U.S. Pat. No. 6,367,541 B2 discloses a heat sink that can be attached to multiple electronic chips which have different heights. The heat sink dissipates heat from the chips into ambient air. The devices disclosed in these patents are not suitable for heating or cooling living subjects.
U.S. Pat. No. 5,368,093 discloses a flexible bag filled with thermal transfer fluid useful for thawing frozen foods. U.S. Pat. No. 4,910,978 discloses a flexible pack containing a gel. The pack can be cooled and applied to a patient for cold therapy. The pack conforms to surface contours of the patient's body. These devices have limited cooling capacities.
More sophisticated heat exchangers use a heat exchange fluid such as a cooling or heating liquid instead of ambient air to carry heat away from or provide heat to an object to be cooled or heated. Golden, U.S. Pat. No. 4,864,176 discloses a thermal bandage. The bandage includes a conforming member adapted to be placed against the skin. A thermal pack includes a chamber through which fluid can be circulated. The thermal pack is separated from the conforming member by a thermally-conductive surface. U.S. Pat. No. 5,757,615 discloses a flexible heat exchanger with circulating water as coolant for cooling a notebook computer. U.S. Pat. No. 5,643,336 discloses a flexible heating or cooling pad with circulating fluid for therapeutically treating the orbital, frontal, nasal and peri-oral regions of a patient's head. U.S. Pat. No. 6,551,347 B1 discloses a flexible heat exchange structure having fluid-conducting channels formed between two layers of flexible material for heat/cold and pressure therapy. U.S. Pat. Nos. 6,197,045 B1 and 6,375,674 B1 disclose a flexible medical pad with an adhesive surface for adhering the pad to the skin of a patient. U.S. Pat. No. 6,030,412 discloses a flexible enveloping member for enveloping a head, neck, and upper back of a mammal for cooling the brain of the mammal suffering a brain injury. All of these heat exchangers require heat to pass through a layer of some flexible material such as rubber, a thermoplastic, or a flexible plastic such as polyurethane. In addition, heat is exchanged between the surface of the flexible material and circulating fluid. Water is the most commonly used circulating fluid.
Rubber and flexible plastics are poor conductors of heat. To provide a high heat transfer efficiency in a flexible heat exchanger in which heat is transferred across a layer of rubber or plastic the layer must be very thin. This makes such heat exchangers prone to damage. In addition, water is a poor heat conductor. Heat exchange between the flexible material and water is largely dependent on convection. Water flowing over a relatively flat surface will often not result in efficient heat exchange.
U.S. Pat. No. 3,825,063 discloses a heat exchanger having metal screens of fine mesh with internal plastic barriers that at least partly penetrate the screens. The screens are stacked to provide transverse heat conduction relative to longitudinal flow paths. U.S. Pat. No. 4,403,653 discloses a heat transfer panel comprising a woven wire mesh core embedded in a layer of plastic material. The mesh and closure layer extend in the same longitudinal direction. U.S. Pat. No. 5,660,917 discloses a sheet with electrically insulating thermal conductors embedded in it. The apparatus disclosed in those patents is not adapted for warming or cooling living subjects.
There remains a need for heat exchangers suitable for warming or cooling living subjects via the surface of the subjects' skin. There is a particular need for such heat exchangers that provide a high ratio of heat-transfer capacity to skin contact area. There is also a need for heat exchangers which can be used in practising the methods described in Fletcher, U.S. Pat. No. 6,511,502 and which avoid at least some disadvantages of prior heat exchangers. In some fields there remains a need for heat exchangers capable of providing high heat transfer rates between the heat exchangers and objects that are not flat, are vibrating or are otherwise difficult to interface to. There is a particular need for such heat exchangers which have high ratio of heat-transfer capacity to contact area.
The invention relates to heat exchangers and has many aspects which may be combined or, in some cases, exploited individually. One aspect of the invention provides a flexible heat exchanger comprising a volume having at least one inlet for receiving a heat exchange fluid and at least one outlet and a flexible sheet essentially impermeable to the heat exchange fluid. The sheet carries a plurality of substantially-rigid members. Each of the members comprises an exposed thermally-conductive surface on a thermally-conductive first body on an outside of the sheet and having a thermally-conductive portion extending from the thermally-conductive first body, through the sheet, and into the volume. Each of the plurality of members comprising opposed gripping surfaces held firmly against opposed sides of the sheet.
Another aspect of the invention provides a flexible heat exchanger comprising a volume having at least one inlet for receiving a heat exchange fluid and at least one outlet. The volume has a flexible wall essentially impermeable to the heat exchange fluid. The wall carries a plurality of substantially-rigid members. Each of the members comprising a thermally-conductive surface on an outside of the wall and has a thermally-conductive portion extending from the thermally-conductive surface, through the wall and into the volume. The thermally-conducting surface is supported at a location spaced outwardly apart from an outside surface of the wall.
Another aspect of the invention provides a flexible heat exchange surface for use in a heat exchanger. The flexible heat exchange surface comprises a flexible sheet essentially impermeable to the heat exchange fluid. The sheet carries a plurality of substantially-rigid members sealed to the sheet. Each of the members comprises first and second thermally-conductive bodies exposed on first and second sides of the sheet. The first and second thermally-conductive bodies are connected by a narrowed thermally-conductive portion having a cross sectional area smaller than a cross sectional area of either of the first and second bodies. The thermally-conductive portion extends through an aperture in the sheet.
Another aspect of the invention provides a flexible heat exchanger comprising a volume having at least one inlet for receiving a heat exchange fluid and at least one outlet. The volume has a flexible wall essentially impermeable to the heat exchange fluid. The wall carries a plurality of substantially-rigid members. Each of the members comprises a thermally-conductive surface on an outside of the wall and has a thermally-conductive portion extending from the pad, through the wall and into the volume. The thermally-conducting surface is either flush with or projects outwardly from an outside surface of the wall.
Another aspect of the invention provides a method for making a heat exchange surface for use in a heat exchanger. The method comprises providing a sheet, the sheet being essentially impervious to a heat exchange fluid to be used in the heat exchanger; inserting thermally-conductive members through the sheet; and, deforming at least one end of each of the thermally-conductive members to cause the thermally-conductive member to sealingly engage the sheet.
Another aspect of the invention provides a method for cooling or warming a plurality of thermally-conductive heat exchange surfaces suitable for placement against the skin of a living subject to cool or warm the living subject. The method comprises: establishing a turbulent flow of a heat exchange fluid through a volume; allowing the heat exchange fluid to contact and exchange heat with a plurality of thermally-conductive members projecting into the volume through a flexible wall of the volume, the thermally-conductive members each in direct thermal contact with at least one of the heat exchange surfaces by way of an unbroken path of a material or materials having a thermal conductivity of at least 50 Wm−1K−1; and, allowing heat to flow between the heat exchange surfaces and the thermally-conductive members along the paths.
Another aspect of the invention provides a flexible heat exchanger for warming or cooling a living subject. The heat exchanger comprises a volume having at least one inlet for receiving a heat exchange fluid and at least one outlet; and, a flexible heat exchange plate essentially impermeable to the heat exchange fluid, the plate comprising a plurality of substantially rigid thermally-conductive members extending through a flexible material of the plate from an outside surface of the plate into the volume, the thermally-conductive members each projecting into a volume by a distance of at least 2 mm.
Another aspect of the invention provides a flexible heat exchanger comprising a volume having at least one inlet for receiving a heat exchange fluid and at least one outlet; and, a flexible plate essentially impermeable to the heat exchange fluid. The plate comprises an array of closely-spaced apart substantially rigid metal thermally-conductive members extending through a flexible material of the plate, substantially at right angles to inner and outer surfaces of the plate, from an outside surface of the plate into the volume wherein a total area of the thermally-conductive members exposed on the outer surface of the plate exceeds a total cross sectional area of the thermally-conductive members at a point where the cross sectional members are extending through the flexible material.
Another aspect of the invention provides apparatus for warming or cooling a living subject, the apparatus comprising a plurality of heat exchangers and a mechanism for independently regulating a supply of cooling or warming fluid circulated through each of the heat exchangers. One aspect of the invention provides a flexible heat exchanger for warming or cooling a living subject. The heat exchanger comprises a volume having at least one inlet for receiving a heat exchange fluid and at least one outlet. A heat exchange fluid may be circulated through the volume. The heat exchanger comprises a flexible heat exchange plate essentially impermeable to the heat exchange fluid. The plate comprises a flexible fluid-impervious membrane supporting a plurality of substantially rigid thermally-conductive members. The thermally-conductive members extend through the membrane from an outside surface of the plate into the volume. Each of the thermally-conductive members comprises a body, a portion extending through the membrane from the body and a retainer member on a side of the membrane opposite to the body. The membrane is gripped between the body and the retainer member.
Another aspect of the invention provides a flexible heat exchanger. The heat exchanger comprises a volume having at least one inlet for receiving a heat exchange fluid and at least one outlet. A heat exchange fluid, for example, water, can flow through the volume. A flexible heat exchange plate essentially impermeable to the heat exchange fluid has a plurality of substantially rigid thermally-conductive members. The thermally-conductive members extend through a flexible material of the plate from an outside surface of the plate into the volume. The thermally-conductive members conduct heat between a subject and the heat exchange fluid.
Another aspect of the invention provides systems for heating or cooling a subject. The systems have a reservoir holding heat exchange fluid and a pair of feed pumps. One feed pump is connected to deliver the heat exchange fluid to a heat exchanger. Another feed pump is connected to withdraw the heat exchange fluid from the heat exchanger. The rate at which the heat exchange fluid is introduced into the heat exchanger by the first feed pump is balanced with the rate at which fluid is withdrawn from the heat exchanger by the second feed pump to maintain a pressure within a volume in the heat exchanger within a desired range of an ambient pressure.
One aspect of the invention provides a flexible heat exchanger. The heat exchanger comprises a volume having at least one inlet for receiving a heat exchange fluid and at least one outlet. A heat exchange fluid may be circulated through the volume. The heat exchanger comprises a flexible heat exchange plate essentially impermeable to the heat exchange fluid. The plate comprises a flexible fluid-impervious membrane supporting a plurality of substantially rigid thermally-conductive members. The thermally-conductive members extend through the membrane from an outside surface of the plate into the volume. Each of the thermally-conductive members comprises a body, a portion extending through the membrane from the body and a retainer member on a side of the membrane opposite to the body. The membrane is gripped between the body and the retainer member.
Another aspect of the invention provides a flexible heat exchanger. The heat exchanger comprises a volume having at least one inlet for receiving a heat exchange fluid and at least one outlet. A heat exchange fluid, for example, water, can flow through the volume. A flexible heat exchange plate essentially impermeable to the heat exchange fluid has a plurality of substantially rigid thermally-conductive members. The thermally-conductive members extend through a flexible material of the plate from an outside surface of the plate into the volume. The thermally-conductive members conduct heat between a subject and the heat exchange fluid.
Another aspect of the invention provides systems for heating or cooling an object. The systems have a reservoir holding heat exchange fluid and a pair of feed pumps. One feed pump is connected to deliver the heat exchange fluid to a heat exchanger. Another feed pump is connected to withdraw the heat exchange fluid from the heat exchanger. The rate at which the heat exchange fluid is introduced into the heat exchanger by the first feed pump is balanced with the rate at which fluid is withdrawn from the heat exchanger by the second feed pump to maintain a pressure within a volume in the heat exchanger within a desired range of an ambient pressure.
Another aspect of the invention provides a heat exchanger comprising front and rear sheet portions substantially impermeable to a heat exchange fluid. The front sheet portion supports a plurality of substantially rigid thermally-conductive members extending through the front sheet portion and having inner portions projecting into a volume between the front sheet portion and the rear sheet portion. The thermally-conducting members have exposed thermally-conducting surfaces on a front side of the front sheet portion. The rear sheet portion is formed with indentations receiving each of the inner portions of the plurality of thermally-conductive members.
Other aspects of the invention provides flexible heat exchange interfaces. The interfaces have plates or membranes penetrated by substantially rigid thermally-conductive members. The thermally-conductive members have enlarged pads on at least one side of the plate or membrane. The flexible material allows the interfaces to flex while the thermally-conductive members are operative to channel heat from a higher-temperature side of the interface to a lower-temperature side of the interface.
Another aspect of the invention provides a flexible heat exchanger comprising a volume having an inlet and an outlet. The volume can receive a heat exchange fluid, for example, water or a water-based coolant. The heat exchanger includes a flexible plate. Substantially rigid thermally-conductive members extend through a flexible material of the flexible plate from an outside surface of the flexible plate into the volume.
In preferred embodiments the thermally-conductive members each have a thermal conductivity of at least 50 Wm1K1 and preferably at least 100 Wm1K1. The thermally-conductive elements may be made of materials such as aluminum, copper, gold, silver, alloys of two or more of aluminum, copper, gold, or silver with one another, alloys of one or more of aluminum, copper, gold, or silver with one or more other metals, carbon, graphite, diamond, or sapphire.
The thermally-conductive members may cover a substantial portion of the outer surface of the flexible heat exchange plate in some embodiments. For example, the thermally-conductive members may be exposed in an area of 30% or 40% or more of an area of the flexible heat exchange plate. In some embodiments, at least 50%, at least 70% or even at least 80% of an area of the flexible heat exchange plate is covered by the thermally-conductive members. Because of the very high rate at which heat can be carried through a thermally- conductive member, in some cases a coverage of 20% or even less by the thermally-conductive members is sufficient.
The flexible material of the plate sheet or membrane may comprise, for example, a suitable grade of polyurethane or other suitable thermoplastic polymer. Examples of other materials that may be suitable for use as the plate of membrane include: styrenic copolymers; suitable grades of: polyvinyl chloride (PVC); polyolefins such as polyethylene or polypropylene; styrenics such as polystyrene; polyesters such as polyethylene terephthalate (PET); polyethers such as polyetheretherketone (PEEK); polyamides (e.g. NYLON™); silicone; cellophane; cellulose acetates; natural or synthetic rubbers; ethylene-vinyl acetate; neoprene; polytetrafluoroethylene (PTFE e.g. TEFLON™); plasticized metallic films; a combination of two or more of these materials; coated or impregnated fabrics; and the like. In some embodiments the flexible material has a thermal conductivity not exceeding 5 Wm−1K−1.
A further aspect of the invention provides a temperature control system comprising a heat exchanger according to the invention, a reservoir containing a heat exchange fluid; a first feed pump connected to feed heat exchange fluid from the reservoir into the heat exchanger and a second feed pump connected to withdraw the heat exchange fluid from the heat exchanger.
Further aspects of the invention and features of specific embodiments of the invention are described below.
In drawings which illustrate non-limiting embodiments of the invention:
Throughout the following description, specific details are set forth in order to provide a more thorough understanding of the invention. However, the invention may be practised without these particulars. In other instances, well known elements have not been shown or described in detail to avoid unnecessarily obscuring the invention. Accordingly, the specification and drawings are to be regarded in an illustrative, rather than a restrictive, sense.
One aspect of this invention relates to pads useful for transferring heat between a body and a heat exchange fluid. Where the heat exchange fluid is warmer than the body, the pad facilitates heat flow from the heat exchange fluid into the body and the pad serves to warm the body. When the heat exchange fluid is cooler than the body then the pad facilitates heat flow from the body into the heat exchange fluid and the pad serves to cool the body.
The heat exchange fluid may comprise a liquid, of which water is an example, or a gas, of which air is an example. The heat exchange fluid is provided at a suitable temperature by a suitable temperature control system.
Some embodiments of this invention provide flexible heat exchangers suitable for use in warming or cooling living subjects. Heat exchangers according to the invention have a flexible heat exchange plate. A plurality of thermal channels pass through the flexible heat exchange plate. The flexible heat exchange plate has a plurality of thermally-conductive members projecting through a flexible medium that is essentially fluid-impermeable. The thermally-conductive members provide effective means to accept heat from a higher-temperature side of the medium, channel the heat through the medium, and release the heat on a lower-temperature side of the medium.
An outer side of the flexible heat exchange plate can be brought into contact with a living subject. The thermally-conductive members contact the skin of the subject. In preferred embodiments, an inner side of the flexible heat exchange plate forms one side of a channel which carries a heat exchange fluid. Heat can be exchanged between the heat exchange fluid and the subject's skin at a high rate by way of the thermally-conductive members which extend directly from the subject's skin into the heat exchange fluid.
The thermally-conductive members may be made of any suitable thermally-conductive materials including thermally-conductive metals, for example, aluminum, copper, gold, silver, or alloys of these metals with one another and with other metals. The thermally-conductive members may also be made of non-metals which have high thermal conductivities such as carbon, suitable grades of graphite, diamond, sapphire or the like. Preferably the thermally-conductive members are made from materials having thermal conductivities, k, of at least 50 Wm−1K−1 and preferably at least 100 Wm−1K−1. All other factors being equal, it is desirable that the material from which the thermally-conductive members is made be relatively low in density to reduce the weight of heat exchangers according to the invention. Where a heat exchanger is made in a way that involves deforming the thermally-conductive members, the material of the thermally-conductive members is chosen to be malleable. For many applications, aluminum is a good choice for the material of thermally-conductive members. For many embodiments, soft 1300 series aluminum is a good choice of material for the thermally-conductive members.
The thermally-conductive members are sized and located to permit the thermally-conductive plate to be flexed sufficiently to conform substantially to a part of a body of a living subject. The thermally-conductive members are dimensioned and distributed in a manner so that the thermally-conductive members cover a large proportion of the area of the outer side of the flexible heat exchange plate. In certain embodiments of the invention a plurality of the thermally-conductive members cover more than 30% of an area of the outer side of the flexible heat exchange plate. In some embodiments 50% or more of an area of the outer side of the flexible heat exchange plate is covered by the thermally-conductive members.
In preferred embodiments of the invention a plurality of the thermally-conductive members have thermally-conductive pins, fins, bars or the like that project into the volume of a heat exchanger to form an efficient heat exchange interface with heat exchange fluid in the volume. The projecting pins, fins, bars, plates or the like that form a heat exchange interface with the fluid inside the volume of a heat exchanger may or may not be similar in shape or other physical characteristics to the pins, fins, bars, plates or the like that extend through the flexible medium to form a thermal channel through the medium.
The following example embodiments of the invention will be described in the context of cooling a living subject. Embodiments of the invention could also be applied to warming a subject. As noted below, embodiments of the invention could also be applied to heating or cooling objects in other fields.
Thermally-conductive members 14 pass through the material 30 of plate 12. Inside ends 26 of thermally-conductive members 14 project into volume 20. Ends 26 preferably project significantly into volume 20. In the illustrated embodiment, ends 26 are cut away to provide increased surface area for heat transfer with fluid in volume 20. Each inner end 26 comprises a number of prongs 27. Outer faces 28 of thermally-conductive members can be placed against the skin of a subject. Outer faces 28 may be outer faces of thermally-conductive bodies (which may be called “bases”) 29. Bases 29 are separated sufficiently to permit heat exchanger 10 to flex in a desired degree but are preferably closely spaced to maximize the area of outer faces 28 that can be placed against a desired region on a subject. For example, in some embodiments, bases 29 are spaced apart from one another by spacings in the range of 0.5 mm to 5.0 mm.
In some embodiments, each base 29 has a thickness in the range of 0.5 mm to 5 mm. For example, in some embodiments base 29 has a thickness in the range of 1 mm to 2.5 mm. The size and dimensions of base 29 in the plane of plate 12 may be chosen to suit the application, and particularly depends on the contour of the object to be cooled or heated. Thermally-conductive members 14 according to some embodiments of the invention for use in cooling/warming pads for human subjects, have bases 29 having areas in the range of 1 mm2 to 400 mm2. For such cooling/heating pads the area is preferably in the range of 10 mm2 to 100 mm2.
Thermally-conductive members 14 may have reduced cross sectional areas in their portions inward from bases 29. The cross-sectional area of thermally-conductive members 14 at the point that thermally-conductive members 14 emerge from material 30 on the inside face of plate 12 may, for example, be in the range of 20% to 100%, and preferably 35% to 65%, of the area of base 29.
Plate 12 comprises a flexible sheet or membrane through which thermally-conductive members 14 project. The membrane may be made of a flexible material or materials 30. Thermally-conductive members 14 have lengths sufficient to pass through material 30. In preferred embodiments, members 14 project into volume 20. Thermally-conductive members 14 may, for example, project into volume 20 for a distance in the range of 0 mm to 20 mm. In some embodiments intended for warming or cooling a living subject, thermally-conductive members 14 project into volume 20 for a distance in the range of 2 mm to 10 mm. In some embodiments members 14 project past material 30 by at least 3 mm. The portions of members 14 which project into volume 20 may also function as supports to maintain a minimum spacing between rear wall 24 and plate 12.
It is not necessary that all thermally-conductive members 14 be identical or that all thermally-conductive members 14 have equal-sized bases 29 although it is convenient to make heat exchanger 10 with thermally-conductive members 14 substantially the same as one another.
Material 30 constitutes a flexible membrane through which thermally-conductive members 14 extend. In some embodiments, rear wall 24 is made of material 30. Substantially all of heat exchanger 10, except for thermally-conductive members 14, may be made of the same material or materials 30. Material 30 is preferably flexible and/or elastically stretchable. Material 30 may, for example, comprise any of a variety of suitable flexible polymers such as natural rubber, polyurethane, polypropylene, polyethylene, ethylene-vinyl acetate, polyvinyl chloride, silicone, a combination of these materials, a coated fabric, or the like. Material 30, or portions of material 30 may optionally be loaded with particles of one or more thermally-conductive materials such as metal or graphite. However, since material 30 is not required to play a significant role in conducting heat, material 30 may be a material having a low thermal conductivity not exceeding 5 Wm−1K−1 without significantly impairing the function of heat exchanger 10. In some embodiments, material 30 has a hardness in the range of 10 to 80 on the Shore A hardness scale.
One specific example embodiment of the invention is constructed as shown in
Two such heat exchangers may be dimensioned so that they can be applied to a subject's neck respectively over the left and right carotid arteries to cool the subject's brain by cooling blood flowing to the subject's brain. The heat exchangers are sufficiently flexible to conform substantially to the curvature of the subject's neck without causing unacceptable pressure spots. The heat exchangers may be held in place under a collar, such as a foam collar.
Plate 12 may be fabricated using any suitable process. For example, plate 12 may be made by making holes in a sheet of material 30 and inserting thermally-conductive members 14 through the holes. The holes may initially have dimensions smaller than corresponding dimensions of thermally-conductive members 14 so that material 30 seals around thermally-conductive members 14 sufficiently to prevent any significant loss of heat exchange fluid from volume 20. Additionally, or in the alternative, a sealant, such as a suitable glue may be provided to enhance the seal between thermally-conductive members 14 and material 30. Plate 12 may also be made by a suitable plastic manufacturing process such as thermal injection molding, reaction injection molding, compression molding, vacuum forming or casting. In this case, thermally-conductive members 14 may be molded into plate 12.
The thickness of material 30 in plate 12 can be selected to provide a desired compromise between flexibility and durability. Since heat exchanger 10 does not rely on material 30 to conduct heat, it is not necessary to make material 30 extremely thin to improve heat conduction. Material 30 may, for example, have a thickness in the range of about 0.1 mm to 20 mm. In some embodiments of the invention, material 30 has a thickness in the range of 4 mm to 7 mm in plate 12. When thermally-conductive members of types which grip material 30 from either side (as shown for example in
Projections of material 30 or some other material may optionally extend into volume 20. Such projections may be positioned to support wall 24 relative to plate 12, to direct the flow of fluid 65 within volume 20 and/or to induce turbulence at selected locations in the flow of fluid 65 in order to provide enhanced thermal contact between thermally-conductive members 14 and fluid 65.
Thermally-conductive members 14 may be arranged in a wide range of patterns. For example, as shown in
Flexing of plate 12 may be facilitated by arranging members 14 to provide substantially unbroken lines 31 of material 30 extending generally parallel to one or more axes about which a user may wish to flex heat exchanger 10. The embodiment shown in
Thermally-conductive members 14 may take any of a wide variety of forms which provide the function of carrying heat in either direction between a subject on one side of the flexible plate and a heat exchange fluid 65 or other matter on an opposed side as the flexible plate that is warmer or cooler than the subject. Ideally, members 14 provide:
In the illustrated embodiment, one of the pieces of member 14I has a pin 39 which is received in a corresponding socket 40 (see
Membrane 130 may comprise, for example, a suitable grade of polyurethane or other suitable thermoplastic polymer. Examples of other materials that may be suitable for use as membrane 130 include: styrenic copolymers; suitable grades of: polyvinyl chloride (PVC); polyolefins such as polyethylene or polypropylene; styrenics such as polystyrene; polyesters such as polyethylene terephthalate (PET); polyethers such as polyetheretherketone (PEEK); polyamides (e.g. NYLON™); silicone; cellophane; cellulose acetates; natural or synthetic rubbers; ethylene-vinyl acetate; neoprene; polytetrafluoroethylene (PTFE e.g. TEFLON™); plasticized metallic films; combinations of two or more of these materials; coated or impregnated fabrics; and the like.
Thermally-conductive members 114 penetrate membrane 130. Each thermally-conductive member 114 has a pad (which may also be called a base) 129 on an outer side of membrane 130 and a pin portion 132 which projects into volume 120 and is in thermal contact with a fluid 65 in volume 120. Base 129 may be a body formed in or attached to thermally-conductive member 114. Thermally-conductive members 114 are held in place by retention members 115.
As shown in
In a currently preferred embodiment of the invention, rear sheet 130B is vacuum formed, or otherwise shaped, to provide a dimple corresponding to each of the thermally-conductive members (e.g. 114). Thermally-conductive members 114 project into the corresponding dimples. This can yield a structure which remains highly flexible and resistant to “ballooning” as heat exchange fluid 65 is pumped through it. With this construction the volume surrounding thermally conductive members 114 can be made small, thereby reducing the weight of the fluid-filled heat exchanger. Front and rear sheets 130A and 130B may be affixed together at locations which define one or channels which each have a single row of thermally-conductive members extending along the channels. The locations at which front and rear sheets 130A and 130B are affixed together may be just far enough apart to be on either side of the thermally-conductive members 114. The channels may be straight, serpentine, U-shaped, or follow alternative paths as convenient for the application at hand. One can appreciate that as one moves along the centerline of one of the channels the rear sheet 130B bumps away from the front sheet 130A in each dimpled portion and is close to, even touching or almost touching front sheet 130A in its portions between thermally-conductive members 114.
In some embodiments of the invention, the heat exchanger has “drape”. This means that when the heat exchanger is placed over a horizontal member, such as a thin horizontal dowel or a pencil, the overhanging parts of the heat exchanger hang down substantially vertically from the horizontal member. A heat exchanger which has drape can conform readily to the surface contours of a person or object against which it is brought.
In other embodiments of the invention (not shown), a part of thermally-conductive member 114 projects from an enlarged body in volume 120 through an aperture in membrane 130. The projecting part of thermally-conductive member 114 is subsequently deformed, for example by pressing, to form an enlarged base on the outside of membrane 130. The membrane is held between the body in volume 120 and the enlarged base.
Many variations in the design of a thermally-conductive member 114 and retention member 115 are possible within the scope of the invention. Thermally-conductive member 114 and retention member 115 may be made of the same material. If they are made from different materials then it is desirable that the coefficients of thermal expansion of the materials of thermally-conductive member 114 and retention member 115 be such that retention member 115 does not tend to loosen as a heat exchanger is used. For example, where a heat exchanger is to be used for cooling applications it is desirable that retention member 115 have a coefficient of thermal expansion that is the same as or greater than that of pin 132.
In some embodiments of the invention, retention member 115, base 129, or both have one or more narrow projecting rings 131 or grooves (
Many variations are possible in the embodiments of the invention illustrated in
Some embodiments of the invention provide an extension on one or more of pins 132 which provides additional surface area for thermal contact with fluid 65. The extension may be in the form of a cap affixed to the end of pin 132. Various forms of extension are shown in
FIGS. 13 to 21 show members adapted to be sealed to a membrane or other flexible material and methods for installing such members. A number of the embodiments of FIGS. 13 to 21 are suitable for use as thermally-conductive members in heat exchangers according to the invention.
As shown in
Edge portion 214C of membrane 214 fits closely to shaft 222. The deformation of lower portion 222A of shaft 222 carries edge portion 214C of membrane 214 into groove 224. Continued deformation of shaft 222 moves edge portion 214C deeper into groove 224. Eventually the continued deformation of shaft 222 moves inner wall 224A of groove 224 toward outer wall 224B of groove 224 so that edge portion 214C of membrane 214 becomes gripped between inner wall 224A and at least a portion of outer wall 224B as shown in
It is thought that providing a smooth or even polished surface on the portion of shaft 222 contacted by the edge of a sheet 214 during deformation of shaft 222 will help the edge of sheet 214 to slide down shaft 222 into groove 224. It is also thought that the edges of sheet 214 will be drawn most effectively into groove 224 if the edges of sheet 214 is at least somewhat elastic.
In some embodiments of the invention, membrane 214 is impervious to fluids and pin 210 makes a fluid-tight seal to membrane 214. Membrane may be of any suitable flexible material. In some embodiments of the invention, membrane 214 comprises an elastic material, such as urethane. Membrane 214 could comprise any of a variety of suitable flexible sheet like materials. Some examples are polymers such as natural rubber, polyurethane, polypropylene, polyethylene, ethylene-vinyl acetate, polyvinyl chloride, silicone, a combination of these materials, fabrics, or the like.
Pin 222 may be of any suitable material which is sufficiently ductile to be plastically deformed by pressing, as described above. Where pin 222 is to operate as a thermally-conductive member in a heat exchanger then the material of pin 222 should be highly thermally-conductive. For example, pin 222 may be made of aluminum, copper, or another plastically deformable metal having good thermal conductivity. Other metals or materials commonly used to make blind or solid rivets could be used. Some examples of such metals include suitable steels, stainless steels; brasses; bronzes; monel (a nickel-copper alloy); and inconel (a nickel-chromium alloy). Some successful prototypes have used 1100 series aluminum having a hardness of about 32 on the Brinell hardness scale for shaft 222. The other materials listed above typically have hardnesses in the range of about 20 and about 200 on the Brinell hardness scale. In applications in which pin 222 is not required to conduct heat, deformable plastics such as suitable grades of polyurethane, polyethylene, polypropylene, PVC or poly carbonate could also be used for shaft 222.
As shown in
It is convenient, although not mandatory, to make head 220 and shaft 222 integral with one another. Head 220, including the outer wall 224B of groove 224 does not need to be deformable as does shaft 222. In some embodiments, shaft 222 and head 220 could comprise separate parts which are suitably affixed to one another. An example of such a construction is depicted in
A through member may be configured as a blind rivet.
The invention could also be embodied in blind rivets of other types which have a shaft which in deforms outwardly when the blind rivet installed in a manner such that a membrane 214 or other material through which the blind rivet passes is moved into and retained in a groove by the deformation of the shaft.
A through member according to the invention may be used to join together two or more sheets of material.
As shown in
Another aspect of the invention provides a method for securing a through member in a membrane. The method begins with providing a through member having a head, a shaft extending from the head and a groove surrounding the shaft. The shaft is inserted through an aperture in a membrane to which the through member is to be secured. The method continues by compressing the shaft of the through member longitudinally and thereby deforming the shaft such that an initial deformation of the shaft moves an edge portion of the membrane into the groove of the through member. The method continues by continuing to compress the shaft longitudinally until the shaft deforms sufficiently to cause the edge portion of the membrane to be gripped between an outer surface of the deformed shaft and an outer wall of the groove.
This method may be used to secure a one-piece through member securely, and in some embodiments sealingly, to a membrane or to multiple membranes or other sheet-like materials in a single operation. It is not necessary to assemble multiple pieces to provide the through member or to perform multiple operations (although the invention could be applied to through members assembled from more than one part or to methods involving additional steps). The through member may be introduced from one side of the membrane (or other sheet like material(s)) to which the through member is being affixed. It is not necessary to introduce different parts of the through member from different sides of the membrane.
Head 220 may carry or be attached to some structure which is to be attached to membrane 214. For example, head 220 may carry a snap and membrane 214 may comprise a cover for something, an article of clothing, or the like. A through member according to the invention may be apertured. A valve, stopper or orifice for allowing air, another gas or a liquid to flow through the aperture may be provided in the aperture. A through member may have a threaded aperture capable of receiving a screw or may have a projecting stud. A through member could carry alternative structures such as electrical connectors. In some embodiments of the invention the through member is electrically conductive or has one or more electrical conductors which join electrical connectors on opposing sides of membrane 214.
Various alterations and modifications are possible in the construction and installation of through-members as illustrated in FIGS. 13 to 20 without departing from the invention. For example:
As shown in
In some embodiments of the invention it is desirable that the outer surface of membrane 130 have different properties than the surface of membrane 130 which faces into volume 120. For example, where a heat exchanger is intended to warm or cool a living subject it may be desirable that the outer surface of membrane 130 be absorbent to absorb any sweat, dirt or condensation from the subject's skin. As shown in
In the embodiment of
Where a membrane has multiple layers, the materials of the layers may be chosen to have characteristics under compression and/or elastic characteristics which differ from one layer to the other. Such membranes may be included to advantage in embodiments of the invention in which the membrane is compressed between parts of a thermally-conductive member (as shown, for example, in
For example, the sealing layer may comprise a sheet of suitable plastic material, such as urethane, while the control layer may comprise a sheet of a woven or unwoven fabric. The fabric may be significantly less elastic than the sealing layer and, in some cases may be substantially non-elastic under the expected conditions of use of the heat exchanger. The sealing layer may be on the inside of membrane 130 facing into volume 120 in which case the sealing layer may be welded to a layer making up the back side of volume 120.
In some embodiments of the invention the membrane has three layers, for example, a compressible elastomer sealing layer; a fabric control layer; and an outer layer of a soft absorbent material that is approved for skin contact.
A suitable circulation system may be used to circulate a heat exchange fluid through the volume 20 of one or more heat exchangers as described herein. For cooling purposes it is desirable that the temperature of circulating fluid 65 be greater than 0° C. to avoid freezing the subject's skin. The desired temperature of the circulating fluid will depend to some degree on the application and the portion of the subject's body to be treated. The desired temperature for cold therapy ranges between 0° C. and 15° C. Water has properties which make it good for use as a circulating fluid 65.
It is generally desirable to maintain the pressure of fluid 65 in volume 20 approximately equal to the air pressure surrounding heat exchanger 10. If the pressure within volume 20 is significantly smaller than the ambient air pressure then pressure differences across the walls of volume 20 will tend to collapse volume 20 although the projecting inside ends 26 of thermally-conductive members 14 may prevent the walls from complete collapse. If the pressure within volume 20 is significantly larger than the ambient air pressure then heat exchanger 10 will tend to balloon.
A first feed pump 70 upstream from heat exchanger 10 delivers fluid 65 from reservoir 62 to heat exchanger 10. A second feed pump 72 is located downstream from heat exchanger 10. Second feed pump 72 draws fluid 65 from heat exchanger 10 and returns the fluid to reservoir 62. First and second feed pumps 70 and 72 are balanced so that within volume 20 of heat exchanger 10 the pressure of fluid 65 is substantially equal to the ambient air pressure.
One or more bypass valves may be provided to provide better control over fluid pressure within volume 20. In system 60, an adjustable bypass valve 74 is connected between the output of first feed pump 70 and reservoir 62. Bypass valve 74 indirectly regulates the pressure within volume 20. When bypass valve 74 is opened, a larger proportion of fluid 65 is returned to reservoir 62 by way of bypass conduit 75 and the amount of fluid 65 flowing into heat exchanger 10 is reduced. Bypass valve 74 may be pressure-operated.
System 60 has a second bypass valve 76 connected in parallel with second feed pump 72. When second bypass valve 76 is open, second feed pump 72 can draw fluid 65 from reservoir 62 by way of conduit 77. Opening second bypass valve 76 increases pressure at the input of second feed pump 72 and consequently increases the pressure within volume 20.
Many variations of system 60 are possible. Although two bypass valves are shown in
In some cases it may be convenient to provide a single reservoir 62 for providing heat exchange fluid for multiple heat exchangers 10. In such cases it is best to provide upstream and downstream pumps 70 and 72 for each heat exchanger 10. In the alternative, suitable manifolds, such as T-connectors, could be provided to allow a number of heat exchangers 10 to be connected in parallel between a single upstream pump system and a single downstream pump system.
System 60A has a second flow regulator 79 which includes a second flow restrictor 84 and a bypass valve 86. Bypass valve 86 is connected in parallel with restrictor 84.
In system 60A, bypass valves 82 and 86 are adjustable. The fluid pressure within volume 20 can be controlled by adjusting one or both of bypass valves 82 and 86.
Some alternative embodiments of the invention lack one of flow regulators 78 and 79. When system 60A is connected to supply fluid 65 to a plurality of heat exchangers 10 it is preferable to provide for each heat exchanger 10 at least one adjustable flow regulator 78 or 79 located where only fluid going to or from that heat exchanger passes through the flow regulator. This permits the pressure within each heat exchanger 10 to be individually regulated. In the alternative, as described above, suitable manifolds may be provided to split the flow of fluid 65 between a number of heat exchangers 10 connected in parallel.
In the illustrated embodiment, control is accomplished by operating a power splitter 88 (illustrated schematically by a potentiometer). Power splitter 88 can be operated to increase the speed of a motor driving pump 70 and to decrease the speed of a motor driving pump 72 or vice versa.
Systems 60, 60A and 60C may be automatically controlled using any suitable control system. For example, a controller may be provided to operate bypass valves and/or control pump speeds or displacements by way of suitable actuators (not shown) as necessary to control pressure within volume 20 to stay within a desired range. Those skilled in the art are familiar with suitable controllers. The controller may, for example, comprise a suitable programmed programmable controller or a hardware controller. One or more pressure sensors and/or flow sensors (not shown) may be included to provide feedback to the controller.
Any of cooling systems 60, 60A and 60B could be adapted for warming by replacing ice 64 with a suitable heating element which can be operated to raise fluid 65 in reservoir 62 to a desired temperature. Instead of ice 64, any of systems 60, 60A or 60B could cool fluid 65 by way of a refrigeration system. However, a refrigeration system large enough to provide high-rate cooling of a living person is expensive, consumes a large amount of power and is not readily portable. Ice has the advantage that melting a block of ice takes a large amount of heat. A reservoir 62 containing enough ice to apply high rate cooling to a human subject for a significant period can be small enough to be readily portable.
As shown in
As noted above, heat exchangers according to alternative embodiments of the invention may be applied to heating or cooling objects of diverse types. For example,
Bases 29 or 129 of thermally-conductive members of heat exchangers as described herein may be shaped to better conform with a surface of an object to be warmed or cooled. For example,
An object to be heated or cooled may be specially configured to match a heat exchanger according to this invention.
Heat exchangers may also be used to transfer heat between fluids and/or between solid objects.
Path 514 of pad 510 is defined in a chamber 518 between a back sheet 520 and a front sheet 522 that are bonded together along connection lines 523. Connection lines 523 comprise locations along which back sheet 520 and front sheet 522 are affixed to one another by welding, a suitable adhesive, or other suitable affixation means. Thermally-conductive members 524 are disposed along path 514. Each thermally-conductive member 524 penetrates and is sealed to front sheet 522 to prevent heat exchange fluid 513 from leaking around thermally-conductive members 524.
Each thermally-conductive member 524 has an outer face 524A on a front face of pad 510 and an inner face 524B on a part of member 524 that projects into chamber 518. Inner faces 524B of thermally-conductive members 524 are in contact with heat exchange fluid 513. Thermally-conductive members 524 may have, for example, any of the constructions described in the above-noted PCT application.
Rear sheet 520 is formed to provide a cup 530 coinciding with each thermally-conductive member 524. As seen best in
In some preferred embodiments front sheet 522 and rear sheet 520 are very flexible fluid-impermeable sheets such as thin sheets of polyether thermoplastic polyurethane. This material has a temperature range from −60 C to 140 C. Front sheet 522 and rear sheet 520 may also be made of other suitable materials, such as urethane, polyurethane, polyvinylchloride (PVC), rubber, silicone, or the like. Various materials suitable for use as front sheet 522 and rear sheet 520 are described in the above-noted PCT application. The material of rear sheet 520 is preferably somewhat elastic. Urethane having a thickness of approximately 0.015 inches has been found to be a satisfactory material to use for rear sheet 520.
For some applications, the thermal characteristics of the materials are important. For example, some polyvinylchloride materials become quite brittle at temperatures below 5° C. Ethylvinylacetate can also become undesirably rigid at low temperatures. Such materials would not be optimum choices for front sheet 522 and rear sheet 520 in applications where a pad 510 is operated at lower temperatures.
Fluid flowing along path 514 encounters a pattern of alternating constrictions 532 and enlarged areas corresponding to cups 530. Although the inventors do not wish to be bound by any particular theory of operation, this alternating pattern of areas of greater and lesser cross-sectional area is thought to help to prevent chamber 518 from becoming overly inflated and overly rigid as heat exchange fluid 513 flows through pad 510. This pattern may also assist heat transfer between thermally-conductive members 524 and heat exchange fluid 513.
In some embodiments of the invention the cross-sectional area of path 514 in constricted areas 532 is about 50% or less, (in some embodiments 25% or less, or even 10% or less) of the cross-sectional area of path 514 in the vicinity of a thermally-conductive member 524. In all such embodiments, the cross-sectional area in constricted areas 532 can be said to be “substantially less” than the cross sectional areas adjacent thermally-conductive members 524.
The configuration of path 514 can be adjusted by altering the manner in which rear sheet 520 is formed. For example, making cups 530 deeper increases the cross-sectional areas of path 514 in its parts adjacent to thermally-conductive members 524. The configuration of path 514 can also be adjusted by altering the paths of connecting lines 523. For example, the cross-sectional area of constricted portions 532 can be made smaller by making the opposing connecting lines 523 closer to one another. Similarly, the cross-sectional area of constricted portions 532 can be made larger by making the opposing connecting lines 523 farther apart from one another.
A number of thermally-conductive members 524 penetrate the material of bladder 552 on at least one face thereof. Thermally-conductive members 524 provide paths of very high thermal conductivity between their outer faces 524A and the heat storage material contained within bladder 552. Thermal reservoirs 550 may be used as ice packs, or may be used to warm or cool a heat exchange fluid, or the like.
Each bladder 552 is made of a suitable material (which may be a material of the same type as used for the pads 510 described above). While bladders 552 are preferably flexible, in some embodiments of the invention, bladders 552 are of a stiffer material, such as a plastic, that holds its shape.
Thermally-conductive members 524 may be arranged in any suitable patterns on thermal reservoirs 550. Thermally-conductive members 524 may be disposed on one or more sides of a thermal reservoir 550.
As shown in
In the embodiment illustrated in
One or more drain ports (not shown) may optionally be provided to allow heat storage material 558 to be added or changed. In some embodiments, a hole is punched through the walls of bladder 557. Heat storage fluid 558 is introduced through the punched hole. The hole is then sealed by a rivet and washer as described in the appended PCT application.
Fluid 513 passes out of pad 510 at outlet 516, along tube 567A to heat exchanger 566. Fluid 513 returns to pad 510 by way of tube 567B, pump 564 and tube 567C. A controller 568 (which may comprise any suitable programmable controller or control circuitry, for example) senses a temperature of heat exchange fluid 513 circulating past a temperature sensor 569 and controls pump 564 to adjust a rate of flow of the heat exchange fluid 513 to maintain a desired temperature. Additional temperature sensors (not shown) may be provided in other parts of fluid circuit 562 (for example at heat exchanger 566) to provide additional inputs to controller 568.
The provision of a pad 510 equipped with thermally- conductive members 524 helps to facilitate transfer of heat from circulating heat exchange fluid 513 into ice pack 565. Apparatus 560 could use a pad of one of the types described in PCT patent application No. PCT/CA2004/001660 in place of pad 510.
In some embodiments of the invention, thermally-conductive members 524 are arranged in complementary patterns on pad 510 and thermal reservoir 555. In some embodiments of the invention, the faces of thermally-conductive members 524 of pad 510 have shapes that are complementary to the shapes of the faces that they contact of thermally-conductive members 524 of thermal reservoir 555. For example, the faces of both sets of thermally-conductive members may be flat so that a large area of contact is made between the thermally-conductive members 524 of pad 510 and the thermally-conductive members 524 of thermal reservoir 555. In some embodiments, magnets or other means may be provided to urge the thermally-conductive members 524 of pad 510 into contact with the thermally-conductive members 524 of thermal reservoir 555 to ensure maximum surface area contact between the thermally-conductive members 524 of pad 510 and the thermally-conductive members of thermal reservoir 555. For example, a small rare-earth magnet may be embedded in a thermally-conductive member 524 of pad 510 and another small magnet of opposite orientation or a piece of ferromagnetic material may be embedded in the corresponding thermally-conductive member of heat reservoir 555.
In alternative systems like those of
Another embodiment of the invention is illustrated by
Heat exchanger 598 may comprise a pad (for example a pad 510) as described herein or a heat exchanger as described in PCT patent application No. PCT/CA2004/001660. The heat exchanger 598 of
A controller 600, which may comprise a programmable controller or another suitable control circuit or mechanism operates control valve 594 in response to a temperature sensed at temperature sensor 602.
System 590 could be used in any of many ways including to cool a subject's body in a case where cooling is required for some medical purpose or to provide comfort for a person in a hot environment, for example.
In lieu of, or in addition to an expansion chamber, system 590 could include a suitable “metering” device to decrease the pressure of the heat exchange fluid without the use of an expansion chamber. For example, system 590 may comprise an expansion valve, capillary line, etc. Such devices are known to those skilled in the fields of air conditioning and refrigeration.
Where a component (e.g. a member, pump, valve, sensor, controller, assembly, element, device, circuit, etc.) is referred to above, unless otherwise indicated, reference to that component (including a reference to a “means”) should be interpreted as including as equivalents of that component any component which performs the function of the described component (i.e., that is functionally equivalent), including components which are not structurally equivalent to the disclosed structure which performs the function in the illustrated exemplary embodiments of the invention.
As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. For example:
This application is a continuation-in-part of PCT patent application No. PCT/CA2004/001660 filed on 22 Sep. 2004 which is a continuation-in-part of U.S. application Ser. No. 10/665,073 filed on 22 Sep., 2003 and entitled FLEXIBLE HEAT EXCHANGERS FOR MEDICAL COOLING AND WARMING APPLICATIONS, Ser. No. 10/665,074 filed on 22 Sep., 2003 and entitled FLEXIBLE HEAT EXCHANGERS pursuant to 35 U.S.C. § 120. PCT patent application No. PCT/CA2004/001660 also claims the benefit of U.S. patent application 60/565,517 filed on 27 Apr. 2004 and entitled FLEXIBLE HEAT EXCHANGERS, 60/565,537 filed on 27 Apr. 2004 and entitled FLEXIBLE HEAT EXCHANGERS FOR MEDICAL COOLING AND WARMING APPLICATIONS, and 60/580,356 filed on 18 Jun. 2004 and entitled METHOD AND APPARATUS FOR AFFIXING THROUGH MEMBER IN MEMBRANE, all of which are hereby incorporated by reference herein. This application claims the benefit of U.S. application No. 60/663,267 filed on 21 Mar. 2005 pursuant to 35 U.S.C. § 119.
| Number | Date | Country | |
|---|---|---|---|
| 60663267 | Mar 2005 | US | |
| 60565537 | Apr 2004 | US | |
| 60565517 | Apr 2004 | US | |
| 60580356 | Jun 2004 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CA04/01660 | Sep 2004 | US |
| Child | 11277078 | Mar 2006 | US |
| Parent | 10665073 | Sep 2003 | US |
| Child | PCT/CA04/01660 | Sep 2004 | US |
| Parent | 10665074 | Sep 2003 | US |
| Child | PCT/CA04/01660 | Sep 2004 | US |
