Endothermic reactions for single-use palmar cooling

Abstract

A handheld device configured to lower the core body temperature of a human individual by applying an external interface possessing surfaces cooled by an internally contained endothermic reaction to the glabrous skin of the individual's hands, feet, or face. An outer casing includes an interior chamber having multiple rupturable inner compartments, where at least some of these rupturable inner compartments include reactant chemicals. The rupturable inner compartments are configured to rupture upon application of user-generated mechanical force, thus releasing the reactant chemicals into the interior chamber of the outer casing. These reactant chemicals are chosen to produce an endothermic reaction that cools glabrous skin of the user at configured temperatures that reduce vasoconstriction.

Description

ENDOTHERMIC REACTIONS FOR SINGLE-USE PALMAR COOLINGCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to co-pending U.S. Provisional Patent Application No. 63 / 705,266, filed October 9, 2024, and titled “Endothermic Reactions for Single-Use Palmar Cooling.” The entire contents of the above-identified priority application are hereby fully incorporated by reference herein.TECHNICAL FIELD

[0002] The subject matter disclosed herein relates to systems and methods to lower core body temperature, and, more particularly, to applying an external interface possessing surfaces cooled by an internally contained endothermic reaction to the glabrous skin of a human individual’s hands, feet, or face.BACKGROUND

[0003] Humans and other mammals must regulate their internal physiological body temperature within narrow limits. As a result, humans and other mammals utilize various anatomical and physiological adaptions for thermoregulation, such as perspiration, fur, panting, and heat exchange by modifying blood flow through blood vessels beneath the specific areas of skin (for example, glabrous or “non-hairy” skin), and the like. Humans, also employ shading, ventilation, clothing, and environmental control to achieve proper thermoregulation.

[0004] Conventional systems and methods to transfer heat through glabrous skin include circulating counter-current, heat-exchanging fluid through containers placed in proximity or in contact to glabrous skin, such as in proximity to the palm area of the human hand. However, one drawback of these systems and methods is that electrically driven thermoregulatory devices require an electrical power source to maintain the required mechanical circulation, and thus tend to be expensive or impractical under a variety of use circumstances. Thus, real-world adoption of such conventional devices has been, at best, very limited. Other conventional designs have attempted to remove the need for immediate access to electricity during the act of palmar cooling but fall short of removing the need for an electrical supply entirely.

[0005] Conventional “icepacks” that provide mobile cooling without electricity do not resolve the deficiencies of the electrical systems. Conventional icepacks typically provide extreme cooling to external surfaces of the body to counteract injury, inflammation, bug bites, or other surface-level or sub-surface condition. The extreme cooling provides direct-contactrelief to the person’s surface area or to a small portion of immediately underlying areas, while providing little internal temperature cooling of the user. For example, conventional icepacks typically use internally contained endothermic reactions sufficiently cold to treat the surface level or sub-surface conditions mentioned above, such as near freezing or slightly above (32°F / 0°C to 40°F / 4.5°C). These colder temperatures provide a reduced internal cooling effect because those temperatures cause the normal physiological response of vasoconstriction, a natural phenomenon where blood vessels constrict in response to low temperatures. Conventional icepacks also have a generally flat shape when a hand is placed thereon. This flat hand posture compresses the underlying blood vessels in the hand, thereby suppressing the blood perfusion required for effective palmar cooling.SUMMARY

[0006] In some aspects, the techniques described herein relate to a palmar cooling device, comprising a flexible outer casing configured for handheld placement against glabrous skin of a user, the outer casing having a curved exterior profile; an interior chamber within the outer casing; and a plurality of rupturable compartments within the interior chamber, at least one rupturable compartment containing a first reactant chemical and at least one other rupturable compartment containing a second reactant chemical, wherein the rupturable compartments are configured to rupture upon application of user-generated mechanical force to release the first and second reactant chemicals into the interior chamber, and wherein the first and second reactant chemicals are selected to undergo an endothermic reaction when mixed that cools an external surface of the outer casing to a temperature between 5°C and 25°C for at least one minute.

[0007] In some aspects, the techniques described herein relate to a device, wherein the curved exterior profile comprises an arc angle between 5° and 80°.

[0008] In some aspects, the techniques described herein relate to a device, wherein the arc angle is between 15° and 45°.

[0009] In some aspects, the techniques described herein relate to a device, wherein the first reactant chemical comprises a solid selected from the group consisting of urea, calcium ammonium nitrate, potassium chloride, and ammonium nitrate.

[0010] In some aspects, the techniques described herein relate to a device, wherein the second reactant chemical comprises water.

[0011] In some aspects, the techniques described herein relate to a device, wherein the first reactant chemical is urea and the mass ratio of urea to water is between 1 :2 and 1 :4.

[0012] In some aspects, the techniques described herein relate to a device, wherein the endothermic reaction cools the external surface to a temperature between 10°C and 15°C.

[0013] In some aspects, the techniques described herein relate to a device, wherein the outer casing is formed from a material selected from the group consisting of polyethylene, polypropylene, polyvinyl chloride, thermoplastic polyurethane, and polylactic acid.

[0014] In some aspects, the techniques described herein relate to a device, wherein the outer casing has a thickness between 0.1 mm and 3 mm.

[0015] In some aspects, the techniques described herein relate to a device, wherein the curved exterior profile is configured to conform to a natural resting curvature of a human hand.

[0016] In some aspects, the techniques described herein relate to a device, further comprising a structural barrier within the interior chamber configured to maintain the curved exterior profile.

[0017] In some aspects, the techniques described herein relate to a device, wherein at least one of the rupturable compartments is perforated to facilitate rupture upon application of mechanical force.

[0018] In some aspects, the techniques described herein relate to a device, further comprising a thermochromic material that changes color at a temperature between 5°C and 25°C to provide visual indication of device readiness.

[0019] In some aspects, the techniques described herein relate to a device, wherein the thermochromic material is incorporated into the outer casing.

[0020] In some aspects, the techniques described herein relate to a device, wherein the thermochromic material is disposed within the interior chamber.

[0021] In some aspects, the techniques described herein relate to a device, further comprising multiple rupturable compartments each containing water, wherein the multiple compartments are configured for sequential rupture to extend cooling duration.

[0022] In some aspects, the techniques described herein relate to a device, wherein the first reactant chemical comprises a solid in powdered form and in pelleted form to provide initial rapid cooling followed by extended cooling duration.

[0023] In some aspects, the techniques described herein relate to a chemical cooling device, comprising a flexible outer compartment configured for placement against glabrous skin; and an interior chamber comprising a first reactant and at least one rupturable compartment comprising a second reactant, the reactants selected to produce an endothermic reaction maintaining an outer surface of the outer compartment between 5-25°C for at least 1 minute.

[0024] In some aspects, the techniques described herein relate to a method of cooling glabrous skin to reduce core body temperature, comprising providing a handheld cooling device comprising an outer casing with an interior chamber containing separated reactant chemicals configured to undergo an endothermic reaction; applying mechanical force to the device to mix the reactant chemicals and initiate the endothermic reaction; placing an external surface of the device against glabrous skin of a palm, foot, or face of a user; and maintaining the external surface at a temperature between 10°C and 25°C for at least one minute to cool the glabrous skin while reducing vasoconstriction.

[0025] In some aspects, the techniques described herein relate to a method, wherein the external surface is maintained at a temperature between 10°C and 15°C.

[0026] In some aspects, the techniques described herein relate to a method, wherein the reactant chemicals comprise urea and water, and wherein the method further comprises holding the device against a palm of the user’s hand for at least three minutes during exercise or physical activity to reduce core body temperature.

[0027] These and other aspects, objects, features, and advantages of the examples described herein will become apparent to those having ordinary skill in the art upon consideration of the following detailed description.BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figures 1A and IB are perspective and cross-sectional views, respectively, of a palmar cooling device.

[0029] The figures herein are for illustrative purposes only and are not necessarily drawn to scale.DETAILED DESCRIPTIONOverview

[0030] The technology described herein provides cooling at the palmar interface without the need for an external power source thus, reducing the bulk and complexity of the system. These electricity-free methods and devices provide practical use in many real-world circumstances. The technology described herein also provides palmar cooling at temperatures that provide cooling of internal blood vessels without compression and without causing vasoconstriction, which provides an enhanced cooling effect on body temperature.

[0031] Conventional endothermic reactions have often been used for cooling purposes, such as in instant icepacks, but the packaging in which they are contained, the shape of thepackaging, as well as the concentrations and quantities in which their reagents are present are sub-optimally suited for cooling glabrous skin. Conventional instant icepacks are rather flat and / or lack the pronounced curvature needed to appropriately complement the curved, relaxed anatomy of the hand when held in the palms. Extending a glabrous skin surface, such as the hand, into the flat posture needed for application to the surface of a conventional instant icepack can compress the underlying blood vessels, thereby suppressing the blood perfusion required for effective palmar cooling. The technology described herein provides a curved surface for application to the general, natural curvature of the hand, thereby enhancing the cooling effect on body temperature.

[0032] Conventional instant icepacks are often designed to use internally contained endothermic reactions to maintain temperatures sufficiently cold to treat surface level or subsurface conditions, such as near freezing or slightly above (32°F / 0°C to 40°F / 4.5°C). As a result, such conventional instant icepacks, when brought into contact with glabrous skin, elicit the normal physiological response of vasoconstriction, a natural phenomenon where blood vessels constrict in response to low temperatures. This normal physiological reaction in response to extreme cold is sub-optimal and contraindicated when excess heat removal is desired. Thus, the technology described herein provides palmar cooling at temperatures that do not cause (or that reduce the amount of) vasoconstriction, thereby enhancing the cooling effect on body temperature. The technology described herein provides packageable, endothermic reactions that can cool the surface of its outer casing to temperatures that are warmer than a conventional instant icepack to avoid triggering (or to reduce) vasoconstriction yet at the same time be capable of absorbing significant amounts of excess body heat from a human user (who will typically have a core temperature near 37°C or higher). For example, a desired surface temperature is in the range of about 5 to about 25°C, about 10 to about 20°C, and about 10 to about 15°C, including 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, and 25°C. These temperature ranges can avoid, reduce, or limit palmar vasoconstriction experienced by individuals at the lower temperature ranges while also providing a temperature on the surface of the device having a sufficient differential from the user’s core body temperature to provide a cooling effect to the user. As the surface temperature of the device increases to the upper temperatures in the ranges, the temperature differential between the surface of the device and the core body temperature of the user still provides a cooling effect, although a reduce efficiency of cooling, about 25 degrees C the delta T between core temperature and the interface is great enough to show some (although reduced efficiency ofcooling). In some examples, temperatures of 10-15°C (and those between 5-25°C) provide effective cooling while reducing vasoconstriction compared to temperatures below 5°C.

[0033] The endothermic reactions described herein have energetic characteristics that provide cooling in the desired temperature ranges. Such reactions include, but are not limited to, the dissolution of many salts in water, such calcium ammonium nitrate (Ca(NO3)2 • NH4NO3) and potassium chloride (KC1), as well as the dissolution of organic solids in water, such as urea (CC NBL)?). The concentration and quantity of these reactants can be varied to create and calibrate an internally contained, endothermic reaction capable of maintaining the desired temperature range for palmar cooling on the outer surface of the device (the same surface intended to contact glabrous skin). The same procedure can be used to adjust the technology’s minimum surface temperature as well. In some examples, calcium ammonium nitrate and water, potassium chloride and water, or solid urea and water can be used as reagents for the internally contained endothermic reaction.

[0034] Such reagents and reactions produce environmentally safe and friendly end products. The quantity, type, and shape or configuration of reagents and reactions can be manipulated to create a cooling temperature range that can extract heat from a glabrous surface for a minimum of 1 minute up to 18 or more minutes, for example, by maintaining an internal device temperature within the effective ranges described herein.

[0035] In some examples, the technology described herein is a chemical cooling device comprising a flexible, impermeable, hand-held outer casing comprising a biocompatible polymer that is configured for placement against the glabrous skin of a human subject. This flexible, hand-held outer casing comprises an interior chamber comprising multiple rupturable inner compartments, where at least some of these rupturable inner compartments include reactant chemicals. At least some of these rupturable inner compartments are configured to rupture upon application of user-generated mechanical force, thus releasing the reactant chemicals into the interior chamber of the impermeable hand-held outer casing. These reactant chemicals are chosen to produce an endothermic reaction that cools the glabrous skin of the human subject at configured temperatures within the effective ranges described herein.

[0036] Advantages of the technology herein include one of more of providing a mobile cooling device without requiring electricity, providing a surface temperature of the device that provides cooling to the palm of a user without causing (or with limited or reduced) vasoconstriction of the blood vessels in the user’s palm, and providing a device shape based on the natural curvature of the hand to reduce vessel compression caused when the hand is more flat.Examples

[0037] Now having described the technology of this disclosure in general, the following examples describe some additional embodiments, features, and attributes of this disclosure.

[0038] The examples will now be discussed in more detail with reference to Figure 1. Figures 1 A and IB are perspective and cross-sectional views, respectively, of a palmar cooling device 100. In Figure 1 A, internal components are shown via hidden lines. The palmar cooling device 100 comprises an outer casing 102 configured for placement against the glabrous skin of a human subject. The outer casing 102 comprises a top side 102a, a bottom side 102b, and two ends 102c, 102d. The outer casing also comprises an interior chamber 104 formed therein comprising one or more rupturable components 106a, 106b therein. The rupturable components 106a, 106b include reactant chemicals. The rupturable components 106a, 106b are configured to rupture upon application of user-generated mechanical force, thus releasing the reactant chemicals contained therein into the interior chamber 104 of the outer casing 102. These reactant chemicals produce an endothermic reaction when mixed that cools the glabrous skin of the human subject at configured temperatures. The interior compartment 104 of the outer casing 102 also can comprise a barrier 108. The barrier 108 can include apertures therein. The barrier 108 can provide internal support to maintain the curved shape of the outer casing 102 and / or the barrier 108 can separate reactant chemicals instead of, or in addition to, using the rupturable components 106a, 106b. In the latter case, the barrier 108 is configured to rupture upon application of user-generated mechanical force, thus allowing the reactant chemicals on opposite sides thereof to mix and react. Alternatively, the barrier 108 can include slots, holes, or other apertures therein to allow the reactants on either side of the barrier 108 to flow therethrough and mix together. In certain examples, a first reactant chemical is disposed within the interior chamber 104, and a second reactant chemical is included therein in one or more of the rupturable components 106a, 106b. When a rupturable component 106a, 106b is ruptured, the second reactant chemical is released into the first reactant chemical and a reaction occurs. When multiple rupturable components 106a, 106b are used, rupturing the components in a serial manner can allow multiple reactions to occur sequentially, thereby allowing the device 100 to be reused and / or to provide longer reaction times that increase the usable cooling time of the device. In certain examples, a solid reactant chemical can be provided in the interior compartment 104 (such as by using solid reactant chemical crystals or powder) in place of the rupturable components 106a, and a second reactant chemical is included therein in one or moreof the rupturable components 106b. When a rupturable component 106b is ruptured, the second reactant chemical is released into the first reactant chemical and a reaction occurs.OUTER CASING: Material

[0039] In use, the outer casing 102 is applied to the glabrous skin of a human, such as the face or palms. Either before or after this application, various internal compartments (such as the barrier 108 and / or the rupturable components 106a, 106b) that separate the reactants are ruptured by mechanical force. The separated reactants now mix freely, creating an endothermic reaction that lowers the temperature of the glabrous skin.

[0040] The outer casing can be constructed out of materials that are thin (such as 0.1mm to 3 mm or similar), flexible, and readily permit heat transfer between the internal components and the glabrous skin surface to which it is applied. The outer casing also can be constructed of two or more layers of materials that are laminated together. Each layer of material can be formed from the same material or different materials to provide desired mechanical properties. In one example, two layers of 1.5mm thick materials are laminated together to form the shell of the outer casing. The outer casing is also strong enough to withstand typical user generated forces needed to mix the contents held within the casing or to otherwise activate the device. Suitable materials for the outer casing include, but are not limited to, polymeric materials, such as plastics like polyethylene terephthalate (PET), polylactic acid (PLA), polyvinyl chloride (PVC), polypropylene (PP), thermoplastic polyurethane (TPU), and high and low density polyethylene (PE), such as linear low-density polyethylene (LLDPE); and natural or synthetic rubbers, such as ethyl ene-propylene diene monomer (EPDM) styrene-butadiene, butadiene, isoprene, nitrile, or silicone rubbers. Composite films, metal foils, and textile based materials, such as nylon and polyester, can also be used to construct the outer casing. Hydrophobic / other water proofing coatings can be applied to the outer casing (internally and or externally) to minimize degradation from internal reagents, improve its ability to seal reagents inside, or otherwise improve the efficacy. Materials can be chosen to provide sufficient durability while also providing a desired heat transfer between the endothermic reaction inside the casing and the user’s palm (or other body part) touching the exterior surface of the casing.

[0041] The outer casing also can be constructed out of thermochromic materials (materials that change color in response to temperature) to provide visual temperature indication. This inclusion can allow the user to assess the temperature of the device as the color of a thermochromic outer casing can change to indicate the temperature or the temperature range of the surface of the outer casing. Such thermochromic material can be used to wholly constructthe outer casing or to simply construct a part thereof. These materials also can be calibrated to indicate when the device temperature is below the usable range, within the usable range, and / or above the usable range, and can be formulated to have dichromatic, trichromatic, or polychromatic properties.

[0042] For example, one potential example can include thermochromic materials that change when the temperature range to start glabrous skin cooling is achieved, such as 5 to 25°C (depending on the use case). Other possible examples include thermochromic materials that change when the temperature range exceeds that which can effectively cool glabrous skin, such as greater than 25°C, depending on the use case.

[0043] The outer casing’s material also can be used to facilitate temperature indication when constructed out of transparent or translucent materials, both in whole or in part, and used in conjunction with internally held thermochromic pigment. Such transparent or translucent materials provide a means of visually assessing the internal temperature as the thermochromic pigment in the interior can be viewed through the transparent or translucent casing, or through a window placed within an otherwise opaque or poorly translucent outer casing. Such an example provides insulating capacity which increases the functional time where the surface temperature when in contact with the surface of the palm is within the desired range and also increases the duration of functional use by minimizing parasitic heat loss for non-contact areas of the device.

[0044] In an alternative example, a material with greater thickness, relatively higher thermal resistivity, or otherwise more insulating can be used to construct the outer casing in the event that the internal endothermic reaction absorbs more heat than is needed to cool the surface of the device to a temperature below the minimum usable temperature, which in, many examples, can range between 5 and 10°C for exercise related palmar cooling applications, and extend as high as 15 to 25°C for medical applications, such as reducing multiple sclerosis tremors in older individuals. Similarly, protective sleeves constructed out of fabrics, such as neoprene or cotton, rubbers, such as silicone rubber, plastics, and / or other thermally insulating materials can be created and placed over or on top of the device to provide a buffer between the applied glabrous skin surface and surface of the device. Such insulating materials can be used to control heat transfer to the interface with the skin or to modulate the functional capacity for cooling from the endothermic reaction. Such insulation materials also can be used to cover at least a portion of the device not in contact with the palm (or other part of the body) to prevent heat absorption of the internal reaction through the outer casing and thereby prolonging the cooling reaction inside.OUTER CASING: Exterior Geometry & Design

[0045] In one example of the invention, the outer casing 100 is shaped to complement the natural curvature of a human hand, foot, or other glabrous skin surface. This design allows the bodily surface to which the device is applied to maintain a relaxed posture, increasing blood perfusion to the glabrous skin surface, thereby increasing the palmar cooling effects of the device.

[0046] The curved geometry is configured to accommodate the natural resting position of the hand, which can reduce vessel compression. Viable device shapes include, but are not limited to, teardrops, squircles, cylinders, ellipsoids, chip bag-like shapes, spheres, semispheres, semi-cylinders, contoured wedges, and other three-dimensional shapes that have rounded or curved edges or faces or can be beveled or otherwise smoothed to have rounded or curved edges or faces. More specifically, potential examples of the device designed for application to the glabrous skin of the palmar hand can complement the hand’ s natural, relaxed, and curved anatomy by employing geometries with arc angles between 5° and 80°. As shown in Figure 1 A, the arc angle a is measured between a plane tangent to the top side 102a at the center and face of the top side 102a. A similar angle can be measured on the bottom side 102b if the device is curved on both sides. Arc angles of 15-45° accommodate the natural curvature of a large portion of adult hands. The curved geometry of the device 100 is designed to accommodate the natural resting position of the hand as described above. This accommodation allows the hand to maintain a relaxed posture with reduced compression of blood vessels compared to a flat hand posture. In some examples, the arc angle a ranges from 5° to 80°, preferably 15° to 45°. Such custom shapes can be achieved by molding or welding plastics or other viable materials during the manufacturing process. Examples of the device can also be developed in non-curved or more planar shapes that resemble the geometries, including, but not limited to, those of flat pouches, rectangular prisms, cubes, and wedges. Additional potential examples can also assume geometries containing a gusset or other compressible element that can allow users to readily circulate or otherwise manipulate the material held within the outer casing.

[0047] In one example as shown in Figures 1A and IB, the outer casing 102 comprises a top side 102a, a bottom side 102b, and two ends 102c, 102d. The ends 102c, 102d are curved to provide the curved profile to the device. The shape of the ends 102c, 102d can be contoured to provide the desired curved profile for the top side 102a or bottom side 102b of the device.The height of the barrier 108, if used, can be sized to support the desired curved profile to the device. However, as discussed below, the reagents or other liquids or air inside the device 100 can be included in sufficient quantities such that the internal pressure of the device maintains the desired shaped defined by the profile of the casing.

[0048] In another example, the two ends 102c, 102d are omitted from the device 100. In this case, all four edges of the top side 102a and the bottom sides 102b are coupled together to create the interior compartment(s) 104. An amount of reagents, air, water, and or other material in the device are controlled to provide the desired curvature of the top and / or bottom sides 102a, 102b of the device 100. A larger volume of these items increases a curvature of the device 100, while a smaller volume of these items decreases the curvature of the device. In examples where water is a reactant (such as the water / urea example), the quantity of the water can be increased or decreased to provide a desired shape of the device, where increasing the amount of water causes the device to expand and create a more curved geometry and decreasing the amount of water causes the device to deflate and create a less curved geometry.

[0049] In addition to the reagents residing within the internal, rupturable compartments, non-reagent liquids, gasses, and / or other additives can also be pumped or otherwise inserted into the outer casing during manufacturing to dispose the outer casing to hold a specific geometry through pressurization and / or other forms of mechanical support, such as the barrier 108. In one potential example of the device, the outer casing can be constructed out of thin, polyethylene plastic and molded in a manner that allows its faces to assume a curved geometry when inflated with a non-reagent gas, such as regular air, nitrogen (N2 gas), or carbon dioxide (CO2 gas), before being sealed during the manufacturing process. In such an example, a nonreagent liquid, such as water, oils, or another organic liquid, can be used in place of or in addition to the non-reagent gas. Examples of the device can thus possess a range of volumes (50 mL to 1 L) to accommodate a range of shapes, sizes, cooling lifetimes, and / or other specifications.

[0050] The shape of the outer capsule can also be controlled by modulating rigidity of the material used. For example, the ratio of hard and soft components used to create the TPU used to construct one potential example of the device’s outer casing can be adjusted to increase the casing’s rigidity / flexibility .

[0051] The desired shape of the curve of the device that contact’s a user’s palm can follow the “natural curvature” of the hand, which is a fundamental concept in anatomy and rehabilitation, often referred to as the resting hand posture or the position of rest. This posture provides the minimal compression of the blood vessels of the hand and therefore provides themaximum cooling effect on body temperature when the device 100 is applied to the hand in its naturally curved position. As the hand is stretched, either more curved or more flat relative to the hand’s natural curvature, the blood vessels of the hand are compressed, and the cooling effect of the device 100 applied to the hand is reduced. As the hand is moved farther from its naturally curved position, the blood vessel compression increases and the cooling effect decreases.

[0052] The shape of the natural curvature of the hand is often referred to as the “Position of Rest” or Intrinsic Plus Position. When the hand is completely relaxed (for example, during sleep or under anesthesia), the hand assumes a characteristic posture that demonstrates its natural curvature, comprising the following:• Wrist: Slightly extended (dorsiflexed) by about 10-20 degrees.• MCP Joints (Knuckles): Flexed to about 40-45 degrees.• PIP Joints (Middle knuckles): Flexed to about 30-40 degrees.• DIP Joints (End knuckles): Flexed to about 10-20 degrees.• Thumb: In a position of slight abduction and opposition, resting away from the palm.

[0053] This posture permits the maximal length of the collateral ligaments of the metacarpophalangeal and interphalangeal joints, which prevent joint stiffness. The shape of the top surface 102a and the bottom surface 102b, or both, can be designed to have a curved profile corresponding to this naturally curved shape of the hand in its position of rest. Since the natural curve of each user’s hand can be different, the device 100 can be designed to have a curvature of its top side 102a that conforms to an average hand shape or other metric designed to capture a configured portion of likely users of the device.

[0054] Although described herein as the device having a shape corresponding to the natural curvature of the palm of the hand, the device can be designed with any desired shape, such as shapes corresponding to other glabrous skin surfaces (for example, the soles of the feet or the face).INTERNAL COMPARTMENT: Material, Geometry, and Design

[0055] Examples of the device can be constructed to contain a single internal compartment, or two or more internal compartments. In a single internal compartment example, the outer casing is simply sealed to create an airtight or watertight internal compartment. This single compartment can be used to hold the reagents necessary for facilitating the endothermic reaction used to imbue the device with its cooling power, as well as any additional substancesintended to create additional functionality, such as thermochromic pigment which can be used for creating a means of visual temperature indication.

[0056] In an example with two or more internal compartments, the outer casing can be extended interiorly to create one or more internal barriers 108 that divide the internal compartment into two or more discrete compartments. This barrier can be perforated or otherwise weakened so that it can be ruptured, and the contents of the two compartments mixed, through the application of a user generated force, including but not limited to shear, compressive / squeezing, and / or tensile forces. This multi-compartment design can be useful in device examples that desire to ensure reagents remain separate before use to avoid a premature reaction. Additional device examples can also construct the internal barriers out of materials that differ from the outer casing but can still be made easily rupturable through thinness, perforation, or other forms of preemptive weakening, upon the application of a user generated force.

[0057] Device examples can also construct internal barriers out of a material that can be weakened or dissolved by a reagent that is released at the time of reaction. For instance, the internal barriers can be constructed from materials that are soluble in solvents such as water, acids, and / or bases. When exposed to the intended solvent stored in a discrete storage capsule prior to the application of user generated force / activation of the device, the solvent-soluble barrier can be weakened or disintegrated, allowing its contents within its chamber to mix with the water and / or other reagents from additional chambers. Perforation or other forms of physical weakening can also be applied to internal barriers of this kind.

[0058] Alternative examples of the device can also contain internal barriers that are secured to the internal compartment with an adhesive that is degraded, dissolved, or otherwise weakened by a reagent that is released upon activation of the device. For example, internal barriers can be secured to the walls of the internal compartment during manufacturing through the use of adhesives that degrade in the presence of water, acids, bases, and / or other potential solvents. Once activated, solvents freed from another internal chamber or storage capsule can contact the seal between the barrier and degrade the adhesive to erode the barrier’s seal with the internal surface of the outer casing and allowing the reagents to mix and the endothermic reaction to proceed. Perforation or other forms of physical weakening can also be applied to internal barriers of this kind and the barriers themselves can also be made soluble by a reactant, as previously described.

[0059] When separation of the reagents is not needed before rupture of the rupturable components containing the reagents, the barrier 108 can include slots, holes, or other aperturestherein to allow the reactants on either side of the barrier 108 to flow therethrough and mix together.INTERNAL COOLING REACTION: General Specifications

[0060] Research has shown that glabrous skin subjected to temperatures below approximately 5°C triggers vasoconstriction responses that reduce blood flow. Conversely, temperatures above approximately 25°C provide reduced temperature gradient for effective cooling from a typical body core temperature of 37°C. The device described herein is configured to maintain external surface temperatures of the device in the range of 5-25°C, and preferably 10-15°C, which provides a balance between sufficient cooling gradient and reduced vasoconstriction response.

[0061] Meaningful palmar cooling effects can be achieved by cooling glabrous skin surfaces between the temperatures of about 5 to about 25 °C, about 10 to about 20°C, and about 10 to about 15°C. In many use cases, 15°C provides maximum cooling effect for a majority of users of the device, as the best temperature for individual users may vary. Thus, to be an effective palmar cooling device, the device utilizes endothermic reactions that render the surface of the outer casing of the device (the portion of the device intended to contact the user’s glabrous skin) within the 5 to 25°C range during use.

[0062] Many endothermic reactions can be prepackaged and placed within the devices internal compartment(s) to cool the device’s surface to within the usable temperature range when activated. Spontaneous endothermic reactions that can be used include but are not limited to the reaction of solid barium hydroxide octahydrate (Ba(OH)2 • 8 H2O) and dry ammonium chloride (NH4C1), baking soda (NaHCO3) and vinegar (CH3COOH), cobalt (II) chloride hexahydrate (CoC12 • 6 H2O) and liquid thionyl chloride (SOC12). Viable endothermic dissolution reactions also include, but are not limited to, the endothermic dissolution of salts in water, such as the dissolution solid ammonium nitrate (NH4NO3) in water (H2O), the dissolution of potassium chloride (KC1) in water, the dissolution of barium hydroxide octahydrate in water, and the dissolution of the solid, hydrated double salt, calcium ammonium nitrate (5Ca(NO3)2 • NH4NO3) in water. Other dissolution reactions, such as the dissolution of solid urea (CO(NH2)2) in water can be used to cool the surface of the device as well.

[0063] Potential examples of the device can use one or more endothermic reactions to reduce the temperature of their outer surface. These examples can also include one or more reaction catalysts or buffers that can be used to accelerate or decelerate reaction velocity.Potential catalysts and buffers include, but are not limited to, acids, bases, and biological enzymes or other proteins.

[0064] Examples of the device can also utilize reagents that minimize the risk posed to the user in the event that the device leaks, breaks, or is otherwise compromised such that the reagents or their products are released from the inner compartment of the sealed outer casing. Such examples can use reagents including, but not limited to, urea and water, which are largely safe to the touch and do not produce fumes or odors.Reaction Examples

[0065] The following examples are provided for a device 100 having top and bottom sides 102a, 102b measuring five inches by seven inches and omitting the two ends 102c, 102d. The amounts of reagents inside the device 100 provide a desirable shape allowing a relaxed hand position for an average user’s natural curvature of the palm:• 100g of water combined with 30g of Urea produces an internal mixture temperature of 13°C (55°F).• 70g of water combined with 60g of Urea produces an internal mixture temperature of 8°C (46°F).• 80g of water combined with 50g of Urea produces an internal mixture temperature of 10°C (50°F).

[0066] Depending on the thickness and type of material used for the outer casing of the device, the external surface temperature of the device can be the same as, or slightly warmer than, than the internal mixture temperature due to heat transfer through the outer casing 102. Thus, in certain cases, the internal endothermic reaction is designed to provide a colder internal temperature such that the external surface temperature of the device is in the desired temperature range. The device utilizes endothermic reactions that render the surface of the outer casing of the device (the portion of the device intended to contact the user’s glabrous skin) within the 5 to 25°C range during use.

[0067] In the following example, 100 milliliters of water was mixed with 30 grams of Urea in a beaker at a room temperature of 24.5°C. The reaction temperature was measured versus time without external warming of the beaker (for example, without a user’s palm placed on an exterior of the beaker). The following results were obtained for the temperature of the mixture in the beaker over time:

[0068] The results show that the internal temperature of the mixture was maintained between 10.9 and 15.4°C for 18 minutes or within the range of 10-15°C for 14 minutes. These internal temperatures provide an external surface temperature of the device within the desired ranges described herein.

[0069] The cooling duration of the device can be controlled by adjusting the ratio of reagents and the total quantity. For urea-based reactions, a ratio of approximately 1 :3 to 1 :4 (urea:water by weight) provides the desired temperature range. Increasing the total quantity extends duration approximately proportionally (for example, doubling reagent quantity approximately doubles cooling duration). Depending on the materials used to construct the outer casing (and the thermal properties of those materials), a colder internal reaction can be desired to provide an external surface temperature within the ranges described herein. In this case, ratios below 1 :3 to 1 :4 can be utilized.INTERNAL COOLING REACTION: Reagent Storage and Mixing of Reagents / Activation of Internal Endothermic Reaction

[0070] The reagents stored inside the device responsible for producing the endothermic reaction used to power the device’ s cooling capabilities are kept separate from each other when the device is not in use, as undesired mixing can cause the endothermic reaction to initiateprematurely. In this case, the device’s cooling abilities will expire prior to the instance when the device is needed for use. However, the method used to separate the reagents possesses a means to be overcome by a user generated force so that the reagents can be mixed, and the device activated (for example, by smashing, squeezing, twisting, shearing, or other application of force) when a user is ready to use it. Additionally, the separation of reagents is designed in manner that also ensures the reagents will remain separate when the device is transported and stored, but easily mixed when intended for use. These concepts are achieved through multiple methods which include, but are not limited to, creating discrete internal compartments for reagents (the barriers (for example, barrier 108) between each can be broken when the device is ready for use) and / or packaging reagents into discrete storage capsules (such as the rupturable components 106a, 106b, which can also be broken when the device is ready for use). Examples of the device can have any combination, permutation, and / or number of internal storage compartments and discrete capsules. Barriers between internal storage compartments and discrete storage capsules can be constructed out of materials different from the outer casing and other barriers and / or packages, the same material, or a combination thereof.Internal Compartment ExamplesBarrier Example

[0071] In one example of the device, discrete internal storage compartments for reagents can be created by barrier(s), such as the barrier 108, within the device’s internal compartment by extending the outer casing material interiorly (see the OUTER CASING: Internal Geometry and Design section) or constructed out of material that is distinct from the outer casing. This barrier can then be perforated to create a weakened tear line along a portion of the barrier that can be ripped open when a shear force is applied to the device, such as the user placing their hands firmly on opposite faces of the device and sliding them in opposite directions, to allow the reactants to mix. Standard perforation can be suitable for separating solid reactants as solid reactants may not require an airtight seal to prevent a premature reaction. Blind perforation (perforation that stops just before fully punching out a hole in the material) can provide a suitable means of containing a liquid or gaseous reactant in an internal compartment as the compartment barrier can remain airtight while still being weakened enough to allow for a usergenerated force to tear it. The compartment barrier can also be constructed out of a material that is weaker, thinner, or otherwise more prone to rupture, than the outer casing. This design can allow the compartment barriers to be ruptured, the reactants to mix, and the device to be activated through the application of a user generated squeezing or other compressive force. Acompartment barrier of this kind can be constructed out of a material significantly thinner than the outer casing and / or weakly secured to the interior walls of the outer casing via a thermal bond, adhesive, or other process.

[0072] Internal storage compartments can also be pressurized (by a liquid or a gas) to better dispose a user generated squeeze to rupturing the compartment barriers and mixing the reagents together to activate the device. In such an example, the compartment barrier can again be perforated or constructed out of an otherwise weakened material, as previously described.Discrete Storage Capsule Examples

[0073] Discrete storage capsules, such as the rupturable components 106a, 106b, can also be employed to separate reagents prior to device activation, and can be utilized with or without the barrier 108. Like the barriers between internal storage compartments, discrete storage capsules can be constructed out of a material that is weaker than the outer casing and / or other storage barriers, depending on intended use, so that it can be easily ruptured when the device is readied for use. Candidate materials for such discrete storage capsules include, but are not limited to, polymeric materials, such as plastics like PET, PLA, PVC, PP, LLDPE and TPU. These materials can also be used in conjunction with hydrophobic and / or protective coatings. If such a storage capsule is used to store a liquid or a gas, care should be taken to ensure that the capsule’s material is taught so that it can be easily ruptured upon the application of a user generated force. An internal storage capsule can also be used to store a solid. In this case, the capsule can be pressurized during manufacturing to ensure that it can be readily ruptured when needed. Pressurization can be used in the storage of gaseous and liquid reagents as well but may not be as necessary. Internal storage capsules can also be perforated in either the typical or the blind perforation fashion to make them more prone to rupturing when needed.

[0074] Capsules can also be made to be soluble by another reagent, such as liquid water, acids, and / or bases that are kept in a compartment separate from the discrete storage capsule. When mixed, the capsule can dissolve to expose its contents inside. In this scenario, the capsule would not need to be pressurized unless doing so might improve the device’s ability to hold its desired shape; however, capsules containing reagent or non-reagent materials can be employed to dispose the device’s shape.

[0075] Some examples of the device can employ multiple discrete storages capsules and instruct the user to activate (or rupture) them at different times in order to extend device lifetime. For example, one example can include calcium ammonium nitrate pellets (loose inside the device 100) and two storage capsules, each containing water. Users can be instructed tofirst rupture just one storage capsule (to initiate the endothermic reaction between water and calcium ammonium nitrate and activate the device) and wait until the temperature of the device has noticeably equilibrated with the environmental temperature to rupture the second capsule and reactivate the device by introducing additional water to react with the remaining calcium ammonium nitrate. This technique of progressively rupturing storage capsules to extend the time the device can maintain its palmar cooling capabilities can also be applied to internal storage compartments. It can be used with storage compartments and discrete storage capsules in combination.

[0076] Multiple options exist for mixing the reagents inside the device. For example, water can be provided in the device, and a reagent, such as urea, CAN, or other reagent, can be provided in capsules inside the device. A user then manipulates the device to rupture one of the rupturable components (i.e., the capsule) to start the endothermic reaction. The user can then rupture additional capsules as desired to continue (or restart) the reaction for use. Other options include varying the type of reactants in the capsules or disposed freely in the device. For example, loose pellets of CAN or urea (or other reactant), a capsule (such as a bag) filled with water, and another capsule with more CAN or urea (or other reactant) can be provided in the interior chamber 104 of the device 100. The user first breaks the water capsule to mix the water and the loose reactant, and then later breaks the second reactant capsule to continue / reactivate the device and extend its useful time. In another example, urea pellets (or other loose reactant) are provided in the interior chamber 104 of the outer casing 102 of the device 100. Also provided in the interior chamber 104 is a bag (a rupturable component) of water. The user squeezes the outer casing 102 sufficient enough to break the water bag therein, which allows the components to mix to start the endothermic reaction.

[0077] Potential examples of the device might also include combinations of single or multiple internal storage compartment and / or discrete storage capsules.INTERNAL COOLING REACTION: Reagent Specifications

[0078] Solid, liquid, and gaseous reagents can be stored in the device’s internal storage compartments and / or discrete storage capsules and can be used to create the endothermic reaction responsible for cooling the surface of the device and imbuing it with palmar cooling capabilities. The speed of the device’s internal endothermic reaction, the device’s minimum surface temperature, and the time for which the device can maintain a surface temperature within the range for viable palmar cooling can be controlled and calibrated by modulatingdevice elements including, but not limited to, reagent quantities, reagent concentrations, and the surface area of a reagent exposed to other reagents.

[0079] For examples of the device including one or more solid reagents, the surface area of one or more of the solid reagents can be increased or decreased to control reaction rate. For instance, one potential device example can use urea (a solid reagent) and water (a liquid reagent) to produce the endothermic reaction. The solid urea can be powdered (to increase surface area and thereby accelerate reaction rate and decrease the device’s minimum surface temperature) or used in the form of larger pellets (to lower surface area and thereby decelerate reaction rate and decrease minimum surface temperature). Device properties beyond reaction rate and minimum surface temperature can also be controlled by surface area modulation. Other examples of the device can employ other forms of solid reagents beyond powder and pellets, including, but not limited to, solid reagents in shapes resembling spheres, cubes, discs, strands, sheets, and sponges.

[0080] Other potential examples of the device containing single or multiple solid reagents present in forms with varying surface area can be used to modulate the device’s capabilities. For example, an example that employs one solid and one liquid reagent might contain the solid reagent in both a powdered (high surface area) and pelleted (lower surface area) forms. This can allow the reaction to initially proceed quickly (due to the high reaction rate of the high surface area of the powdered, solid reagent) without rapidly exhausting itself (as the lower surface area, slower reacting pellets can continue the reaction once the powder has been fully dissolved). Examples of the device can employ solid reagents of any single or multiple shape(s), volume(s), and / or mass(es) to modulate reaction rate.

[0081] Alternative examples of the device can also employ binding agents to control the rate at which solid reagents can be exposed to other reagents. Such binding agents (also known as binders, excipients, solution binders, and dry binders) can be organic or inorganic in nature and can be classified metallic, ceramic, or polymeric as well. Potential binding agents include, but are not limited to, bitums, glues or adhesives, lime, calcium carbonate, saccharides and their derivatives (such as disaccharides, polysaccharides, and sugar alcohols), proteins (such as gelatin), and synthetic polymers (such as polyvinylpyrrolidone and polyethylene glycol). Examples of the device can use the binding agents to reduce the surface area of the solid reagent(s) with which they are formulated to increase or decrease reaction rate by modulating the ratio of binding agent to reagent. Potential device examples can employ pure solid reagents, solid reagents formulated with a binding agent (or another inert material), or a combination thereof.

[0082] Device examples employing endothermic reactions with at least one solid and one liquid reagent can also include a quantity of solid reagent that exceeds said reagent’s solubility in the liquid reagent to increase the reaction rate and decrease the device’s minimum surface temperature.INTERNAL COOLING REACTION: Additives for Controlling the Visual Properties of the Internal Reaction Mixture (Thermochromic Pigment, Dyes, and other Colorants)

[0083] Thermochromic materials change color when heated or cooled to a specific temperature. In device examples including a transparent or translucent outer casing or viewing window into the device, thermochromic pigment can be added to the internal reaction mixture to provide users with a visual indication of its temperature. Like the thermochromic material that can be used to construct the device’s outer casing, the thermochromic pigment can also be calibrated to indicate when the cooling surface’s temperature is below the usable range, within, the usable range, and / or above the usable range. It can also be formulated to have dichromatic, trichromatic, or polychromatic properties.

[0084] For thermochromic pigment to be readily soluble in a reaction mixture, both must possess similar polar character. In the event that a thermochromic pigment, dye, or other thermochromic additive and the reaction mixture have incompatible polar character, surfactants or other amphipathic molecules can be included to increase the solubility of thermochromic material in a reaction mixture. If the polar character of the reaction mixture changes significantly after the reaction is initiated, but temperature indication is desired before and after, thermochromic indicators of differing polarities can be used. Similarly, a single thermochromic indicator can be included in a concentration above the saturation point of a surfactant / amphipathic agent so that there is thermochromic indicators available to be dissolved in both the mixture’s polar and non-polar states. Amphipathic thermochromic indicators can be employed as well. The same chemical procedure can be employed to colorants, dyes, or other additives designed to change the visual appearance of the internal reaction mixture.INTERNAL COOLING REACTION: Biological Additives for Controlling Concentration of Reaction Reagents and Products and Improving Biodegradability

[0085] Examples of the device can contain biological additives to improve the device’s functioning. Enzymes can be included to convert products back into reactants to extend the cooling power of the device or to otherwise control the rate of reaction. Enzymes also can beincluded to improve the biodegradability of the device and its contents after use, or to act as catalysts for the device’s endothermic reaction.ACCESSORIES

[0086] Examples of the device can include or be used in conjunction with accessories. Such accessories may intend to secure the device to the user, particularly, but not exclusive to, glabrous skin regions, such as the palms of the hands, soles of the feet, and the face. These accessories include straps, bands, sleeves, mitts, gloves, fasteners, and other means of affixing the device to the user.POTENTIAL USE CASES

[0087] The devices described herein can be used to provide electricity-independent and portable palmar cooling. More specifically, the device can be used to remove excess heat through contact with glabrous skin surfaces. Such applications include, but are not limited to, applying the device to the palms of the hand, soles of the feet, or face during or after exercise, work, or physical activity, to relieve or reduce thermodysregulation (such as menopausal hot flashes), overheating and heat stress, or multiple sclerosis related tremors, or to improve or accelerate the process of falling asleep.

[0088] The application of a cold substance is also commonly used to treat injuries such as muscle sprains. However, conventional icepacks / cold packs maintain near-freezing or subfreezing temperatures, making applications to the skin not only painful, but also unsafe as the freezing or near freezing temperatures put the user at risk of cold burns or discomfort. The device described herein can also be used to more safely provide an above freezing cooling solution in a more comfortable temperature range for an injury that eliminates the potential risk of cold bums or discomfort.BIODEGRADABILITY

[0089] Potential examples of the device can seek to maximize biodegradability. In such instances, the outer casing, any discrete storage capsules, and / or any internal barriers can be constructed out of sustainable and / or biodegradable materials including, but not limited to, ecofriendly plastics, such as PLA, polyesters, such as polyhydroxyalkanoates (PHAs), and organic films, such as those derived from starch, seaweed, or cellulose. Such materials can also be used in conjunction with biodegradable and / or environmentally conscious coatings that can aid in creating an airtight or watertight seal. Such coatings include but are not limited to,chitosan coatings, beeswax (or other wax based) coatings or emulsions, and pullulan (or other starch based) coatings. Thus, the outer compartment or any inner capsule or barrier can comprise a biodegradable or compostable polymer selected from the group consisting of polylactic acid (PLA), polyhydroxyalkanoates (PHA), polybutylene succinate (PBS), polybutylene adipate terephthalate (PBAT), polycaprolactone (PCL), thermoplastic starch (TPS), cellulose acetate (CA), chitosan, gelatin, polyvinyl alcohol (PVA), pullulan, and mixtures thereof.

[0090] Examples of the device that improve biodegradability can also employ endothermic reactions utilizing environmentally conscious reagents. Such reagents include, but are not limited to, the endothermic dissolution of naturally occurring compounds, such as urea, or salts, such as potassium chloride, in water.

[0091] Described in the examples herein are chemical cooling devices and methods.

[0092] Clause 1. A palmar cooling device, comprising: a flexible outer casing configured for handheld placement against glabrous skin of a user, the outer casing having a curved exterior profile; an interior chamber within the outer casing; and a plurality of rupturable compartments within the interior chamber, at least one rupturable compartment containing a first reactant chemical and at least one other rupturable compartment containing a second reactant chemical, wherein the rupturable compartments are configured to rupture upon application of user-generated mechanical force to release the first and second reactant chemicals into the interior chamber, and wherein the first and second reactant chemicals are selected to undergo an endothermic reaction when mixed that cools an external surface of the outer casing to a temperature between 5°C and 25°C for at least one minute.

[0093] Clause 2. The device of clause 1, wherein the curved exterior profile comprises an arc angle between 5° and 80°.

[0094] Clause 3. The device of clause 2, wherein the arc angle is between 15° and 45°.

[0095] Clause 4. The device of clause 1, wherein the first reactant chemical comprises a solid selected from the group consisting of urea, calcium ammonium nitrate, potassium chloride, and ammonium nitrate.

[0096] Clause 5. The device of clause 4, wherein the second reactant chemical comprises water.

[0097] Clause 6. The device of clause 5, wherein the first reactant chemical is urea and the mass ratio of urea to water is between 1 :2 and 1 :4.

[0098] Clause 7. The device of clause 1, wherein the endothermic reaction cools the external surface to a temperature between 10°C and 15°C.

[0099] Clause 8. The device of clause 1, wherein the outer casing is formed from a material selected from the group consisting of polyethylene, polypropylene, polyvinyl chloride, thermoplastic polyurethane, and polylactic acid.

[0100]

[0101] Clause 9. The device of clause 1, wherein the outer casing has a thickness between 0.1 mm and 3 mm.

[0102] Clause 10. The device of clause 1, wherein the curved exterior profile is configured to conform to a natural resting curvature of a human hand.

[0103] Clause 11. The device of clause 1, further comprising a structural barrier within the interior chamber configured to maintain the curved exterior profile.

[0104] Clause 12. The device of clause 1, wherein at least one of the rupturable compartments is perforated to facilitate rupture upon application of mechanical force.

[0105] Clause 13. The device of clause 1, further comprising a thermochromic material that changes color at a temperature between 5°C and 25°C to provide visual indication of device readiness.

[0106] Clause 14. The device of clause 13, wherein the thermochromic material is incorporated into the outer casing.

[0107] Clause 15. The device of clause 13, wherein the thermochromic material is disposed within the interior chamber.

[0108] Clause 16. The device of clause 1, further comprising multiple rupturable compartments each containing water, wherein the multiple compartments are configured for sequential rupture to extend cooling duration.

[0109] Clause 17. The device of clause 1, wherein the first reactant chemical comprises a solid in powdered form and in pelleted form to provide initial rapid cooling followed by extended cooling duration.

[0110] Clause 18. A chemical cooling device, comprising: a flexible outer compartment configured for placement against glabrous skin; and an interior chamber comprising a first reactant and at least one rupturable compartment comprising a second reactant, the reactants selected to produce an endothermic reaction maintaining an outer surface of the outer compartment between 5-25°C for at least 1 minute.[OHl] Clause 19. A method of cooling glabrous skin to reduce core body temperature, comprising: providing a handheld cooling device comprising an outer casing with an interior chamber containing separated reactant chemicals configured to undergo an endothermic reaction; applying mechanical force to the device to mix the reactant chemicals and initiate theendothermic reaction; placing an external surface of the device against glabrous skin of a palm, foot, or face of a user; and maintaining the external surface at a temperature between 10°C and 25°C for at least one minute to cool the glabrous skin while reducing vasoconstriction.

[0112] Clause 20. The method of claim 19, wherein the external surface is maintained at a temperature between 10°C and 15°C.

[0113] Clause 21. The method of claim 19, wherein the reactant chemicals comprise urea and water, and wherein the method further comprises holding the device against a palm of the user’s hand for at least three minutes during exercise or physical activity to reduce core body temperature.General Disclosures

[0114] While embodiments of this disclosure are described in connection with examples and the corresponding text and figures, there is no intent to limit embodiments of this disclosure to this description. On the contrary, the intent is to cover all alternatives, modifications, and equivalents included within the spirit and scope of embodiments of this disclosure. The examples described herein are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how to make and use the invention claimed herein. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.), but some errors and deviations should be accounted for.

[0115] It is to be understood that this disclosure is not limited to the particular embodiments described, and as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0116] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of this disclosure, certain methods and materials are now described.

[0117] As will be apparent to those of ordinary skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other described embodiments without departing from the scope or spirit of this disclosure. Any recited method can be carried out in the order of events recited or in any other order that is logically possible.

[0118] Where a range is expressed, a further aspect includes from the one particular value and / or to the other particular value. Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the disclosure. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges and are also encompassed within the disclosure, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the disclosure. For example, where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the disclosure, e.g., the phrase “x to y” includes the range from ‘x’ to ‘y’ as well as the range greater than ‘x’ and less than ‘y’. The range can also be expressed as an upper limit, e.g., ‘about x, y, z, or less’ and should be interpreted to include the specific ranges of ‘about x’, ‘about y’, and ‘about z’ as well as the ranges of Tess than x’, less than y’, and Tess than z’ . Likewise, the phrase ‘about x, y, z, or greater’ should be interpreted to include the specific ranges of ‘about x’, ‘about y’, and ‘about z’ as well as the ranges of ‘greater than x’, greater than y’, and ‘greater than z’. In addition, the phrase “about ‘x’ to ‘y’”, where ‘x’ and ‘y’ are numerical values, includes “about ‘x’ to about ‘y’”.

[0119] It should be noted that ratios, amounts, and other numerical data can be expressed herein in a range format. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. It is also understood that a number of values are disclosed herein, and that each value is also herein disclosed as “about” that particular value in addition to the value itself. For example, if the value “10” is disclosed, then “about 10” is also disclosed. Ranges can be expressed herein as from “about” one particular value, and / or to “about” another particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms a further aspect. For example, if the value “about 10” is disclosed, then “10” is also disclosed.

[0120] It is to be understood that such a range format is used for convenience and brevity, and thus, should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range, as if each numerical value and sub-range is explicitly recited. To illustrate, a numerical range of “about 30 to 135” should be interpreted to include not only the explicitly recited values of about 30 to about 135, but also includeindividual values (e.g., about 30, about 31, about 32, etc.) and the sub-ranges (e.g., about 30 to about 45, about 60 to about 70, etc. and other possible sub-ranges) within the indicated range.

[0121] As used herein, the singular forms “a,” “an,” and “the” include both singular and plural referents unless the context clearly dictates otherwise.

[0122] As used herein, “about,” “approximately,” “substantially,” and the like, when used in connection with a measurable variable such as a parameter, an amount, a temporal duration, and the like, are meant to encompass variations of and from the specified value including those within experimental error (which can be determined by, e.g., a given data set, art accepted standard, and / or with, e.g., a given confidence interval (e.g., 90%, 95%, or more confidence interval from the mean), such as variations of + / - 10% or less, + / -5% or less, + / -1% or less, and + / -0.1% or less of and from the specified value, insofar such variations are appropriate to perform in the disclosed invention. As used herein, the terms “about,” “approximate,” “at or about,” and “substantially” can mean that the amount or value in question can be the exact value or a value that provides equivalent results or effects as recited in the claims or taught herein. That is, it is understood that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and / or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error, and the like, and other factors known to those of ordinary skill in the art such that equivalent results or effects are obtained. In some circumstances, the value that provides equivalent results or effects cannot be reasonably determined. In general, an amount, size, formulation, parameter or other quantity or characteristic is “about,” “approximate,” or “at or about” whether or not expressly stated to be such. It is understood that where “about,” “approximate,” or “at or about” is used before a quantitative value, the parameter also includes the specific quantitative value itself, unless specifically stated otherwise.

[0123] The term “optional” or “optionally” means that the subsequent described event, circumstance, or substituent may or may not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.

[0124] The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within the respective ranges, as well as the recited endpoints.

[0125] Various embodiments are described herein. It should be noted that the specific embodiments are not intended as an exhaustive description or as a limitation to the broader aspects discussed herein. One aspect described in conjunction with a particular embodiment is not necessarily limited to that embodiment and can be practiced with any other embodiment s). Reference throughout this specification to “one embodiment,” “an embodiment,” “an exampleembodiment,” or “an example” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention described herein. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” “an example embodiment,” or “an example” in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner, as would be apparent to a person having ordinary skill in the art from this disclosure, in one or more embodiments. Additionally, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention. For example, in the appended claims, any of the claimed embodiments can be used in any combination.

[0126] The example systems, methods, and acts described in the embodiments presented previously are illustrative, and, in alternative embodiments, certain acts can be performed in a different order, in parallel with one another, omitted entirely, and / or combined between different example embodiments, and / or certain additional acts can be performed, without departing from the scope and spirit of various embodiments. Accordingly, such alternative embodiments are included in the scope of the following claims, which are to be accorded the broadest interpretation so as to encompass such alternate embodiments.

[0127] Various modifications and variations of the inventions described herein will be apparent to those having ordinary skill in the art without departing from the scope and spirit of the invention. Although the invention has been described in connection with specific embodiments, it will be understood that it is capable of further modifications and that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention that are obvious to those having ordinary skill in the art are intended to be within the scope of the invention. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from this disclosure that come within known customary practice within the art to which the invention pertains and may be applied to the essential features herein before described.

Claims

CLAIMS1. A palmar cooling device, comprising: a flexible outer casing configured for handheld placement against glabrous skin of a user, the outer casing having a curved exterior profile; an interior chamber within the outer casing; and a plurality of rupturable compartments within the interior chamber, at least one rupturable compartment containing a first reactant chemical and at least one other rupturable compartment containing a second reactant chemical, wherein the rupturable compartments are configured to rupture upon application of user-generated mechanical force to release the first and second reactant chemicals into the interior chamber, and wherein the first and second reactant chemicals are selected to undergo an endothermic reaction when mixed that cools an external surface of the outer casing to a temperature between 5°C and 25°C for at least one minute.

2. The device of claim 1, wherein the curved exterior profile comprises an arc angle between 5° and 80°.

3. The device of claim 2, wherein the arc angle is between 15° and 45°.

4. The device of claim 1, wherein the first reactant chemical comprises a solid selected from the group consisting of urea, calcium ammonium nitrate, potassium chloride, and ammonium nitrate.

5. The device of claim 4, wherein the second reactant chemical comprises water.

6. The device of claim 5, wherein the first reactant chemical is urea and the mass ratio of urea to water is between 1 :2 and 1 :4.

7. The device of claim 1, wherein the endothermic reaction cools the external surface to a temperature between 10°C and 15°C.

8. The device of claim 1, wherein the outer casing is formed from a material selected from the group consisting of polyethylene, polypropylene, polyvinyl chloride, thermoplastic polyurethane, and polylactic acid.

9. The device of claim 1, wherein the outer casing has a thickness between 0.1 mm and 3 mm.

10. The device of claim 1, wherein the curved exterior profile is configured to conform to a natural resting curvature of a human hand.

11. The device of claim 1, further comprising a structural barrier within the interior chamber configured to maintain the curved exterior profile.

12. The device of claim 1, wherein at least one of the rupturable compartments is perforated to facilitate rupture upon application of mechanical force.

13. The device of claim 1, further comprising a thermochromic material that changes color at a temperature between 5°C and 25°C to provide visual indication of device readiness.

14. The device of claim 13, wherein the thermochromic material is incorporated into the outer casing.

15. The device of claim 13, wherein the thermochromic material is disposed within the interior chamber.

16. The device of claim 1, further comprising multiple rupturable compartments each containing water, wherein the multiple compartments are configured for sequential rupture to extend cooling duration.

17. The device of claim 1, wherein the first reactant chemical comprises a solid in powdered form and in pelleted form to provide initial rapid cooling followed by extended cooling duration.

18. A chemical cooling device, comprising: a flexible outer compartment configured for placement against glabrous skin; and an interior chamber comprising a first reactant and at least one rupturable compartment comprising a second reactant, the reactants selected to produce an endothermic reaction maintaining an outer surface of the outer compartment between 5-25°C for at least 1 minute.

19. A method of cooling glabrous skin to reduce core body temperature, comprising: providing a handheld cooling device comprising an outer casing with an interior chamber containing separated reactant chemicals configured to undergo an endothermic reaction; applying mechanical force to the device to mix the reactant chemicals and initiate the endothermic reaction; placing an external surface of the device against glabrous skin of a palm, foot, or face of a user; and maintaining the external surface at a temperature between 10°C and 25°C for at least one minute to cool the glabrous skin while reducing vasoconstriction.

20. The method of claim 19, wherein the external surface is maintained at a temperature between 10°C and 15°C.

21. The method of claim 19, wherein the reactant chemicals comprise urea and water, and wherein the method further comprises holding the device against a palm of the user’s hand for at least three minutes during exercise or physical activity to reduce core body temperature.

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