Patent Publication Number: US-2022233003-A1

Title: Systems and methods of passive body temperature management

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     This patent application claims priority to co-pending U.S. Provisional Patent Application Ser. No. 63/134317, filed Jan. 6, 2021. 
    
    
     BACKGROUND 
     The average adult human body emits over 100 watts of latent heat. Blankets are used to regulate personal body temperature by increasing the resistance to thermal diffusion across a barrier. As heat accumulates the local body temperature increases. Passive heating blankets, such as down comforters and wool blankets, as well as active heating blankets, such as electric blankets and electric heating pads, are known in the art. These devices regulate a user&#39;s body temperature by concentrating the thermal energy produced by the user, and in the case of active blankets, adding thermal energy to the consumer through the use of resistive electrical elements. While blankets are efficient at increasing body temperature, few options exist for decreasing body temperature. 
     Conventional strategies for decreasing body temperatures rely on decreasing the temperature of the entire ambient environment, often through air conditioning or open ventilation with the environment. This method is highly energy inefficient where the ambient temperature of an entire room or even house is adjusted for the sake of personal cooling. In addition, environmental changes may adversely affect the comfort levels of other individuals resting in the ambient environment. 
     Previous attempts to make a cooling pads or blankets have relied on open circuit actively recirculating systems where a fluid filled pad or blanket is continuously flushed with fresh fluid provided by a fluid reservoir and pump. While these systems are effective, they are not suitable for passive cooling applications. They also need to periodically change the fluid in the fluid reservoir once the fluid temperature approaches body temperatures. As a result, these systems typically only provide transient benefits of up to a few hours. 
     Other attempts to make cooling blankets have focused on thermal absorption through the use of high heat capacity acrylate gels; however, these systems are also only effective for a short period of time lose their effectiveness once the gel approximates body temperature. While the high viscosity acrylate polymers enable relatively even distribution across the blanket, the high viscosity also limits thermal conductivity and cooling rates. In addition, polymer filled blankets must be shipped as a prefilled structure due to the sealed design and hazardous nature of poly-acrylate gels, or the like. As a result, previous attempts to utilize polymer gel filled chamber to impart cooling have achieved limited success. 
     Thus, there is a need for a more efficient means for decreasing personal body temperature regulation without the need for adjusting the ambient environment. The present invention addresses this need. 
    
    
     
       BRIEF DESCRIPTIONS OF THE DRAWINGS 
         FIG. 1 . is a diagrammatic representation of a horizontal cross section of a first embodiment of the present invention. 
         FIG. 2 . is a perspective view the embodiment of  FIG. 1 . 
         FIG. 3 . is a diagrammatic view of a first weld patter according to a second embodiment of the present invention. 
         FIG. 4 . is a diagrammatic view of a second weld patter according to a second embodiment of the present invention. 
         FIG. 5 . is a diagrammatic view of a third weld patter according to a second embodiment of the present invention. 
         FIG. 6 . is a diagrammatic view of a fourth weld patter according to a second embodiment of the present invention. 
         FIG. 7  schematically illustrates introducing a fluid having surfactants and active cooling agents through a port into a cooling blanket of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Before the present methods, implementations, and systems are disclosed and described, it is to be understood that this invention is not limited to specific synthetic methods, specific components, implementation, or to particular compositions, 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 implementations only and is not intended to be limiting. 
     As used in the specification and the claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed in ways including from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another implementation may include from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, for example by use of the antecedent “about,” it will be understood that the particular value forms another implementation. 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. 
     “Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not. Similarly, “typical” or “typically” means that the subsequently described event or circumstance often though may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not. 
     A cooling blanket  10  according to one embodiment of the present disclosure comprises a body  35  with an internal, fluidically isolated volume defined by the blanket wall  20 . The body  35  may form a bulk volume  25 , a series of channels  30  mechanically fixed to a predetermined orientation, or a series of isolated chambers  15  mechanically fixed to a flexible structure (such as the wall  20 ). The body  35  and/or respective chambers  15  may further include baffles  40  to regulate the movement of fluids  45  between channels  30  within the chamber  15 . The cooling blanket  10  may also include a cooling fluid  45  (typically a cooling liquid), at least one access port  50  to enable fluidic communication between the body  35  and/or the respective chambers  15  and the external environment. The cooling fluid  45  may contain wetting agents or surfactants  65  and/or active cooling agents  70 . The cooling blanket  10  may also contain ventilation channels  85 , fasteners  90 , and /or covers  75 . 
     Cooling blankets  10  may be constructed of a single layer  55  material where the chamber wall  20  also defines the external contact surface, or multiple layers  55 , where a non-permeable layer is protected by an external fabric or material, such as nylon reinforced polyethylene, wherein a polyethylene material defines the non-permeable internal boundary of the chamber  15 , and the nylon provide mechanical support and abrasion resistance to environmental surfaces during normal use. Layers  55  may be formed utilizing molding processes such as blow-molding of plastic preforms, or heat-sealing of multiple layers together to form internal hollow cavities. While blow-molded structures are capable of producing seamless structures that are molded to access ports, they are typically costly at low volumes due to the mold expense. Hot sealed structures are preferred for low volume and multilayer construction. Hot seal seams  60  are typically formed by heating one or more layers  55  to the plastic softening point thereby forming a multi-layer union. The seams  60  are typically 3 mm to 6 mm wide and form a flat seal that surrounds the chamber walls  20  and defines the edge of the chamber volume. A three-dimension chamber  15  may then be formed by filling the chamber  15  with a fluid  45  through the access port  50 . 
     A chamber  15  may be formed by a flexible, non-permeable material such as vinyl, polypropylene, mylar, polyester, polyethylene, such as high-density polyethylene (HDPE) or low-density polyethylene (LDPE), or nylon reinforced polyethylene, or the like. Multiple layers  55  may be pre-bonded together, as in the case of nylon reinforced polyethylene or polyurethane reinforced polyethylene, to form a single film prior to sealing. To layer of multilayer film may then be layered such that their non-permeable surfaces are facing one another, and sealed using conventional techniques. Non-permeable surfaces may further be modified by wetting agents or surface modifiers  65  (such as by conventional surfactants, such as alkoxylate surfactants, silicone surfactants, polysiloxanes, sulfosuccinates, polyacrylates, fluorinated polyacrylates, or star shaped polymers) so as to prefer to remain in certain predetermined portions of the body  35 . A multilayer structure may also contain one or more metalized layers  55  (such as aluminized polyester or aluminized mylar) or metal foil layers  55  (such as aluminum or copper foil) to further enhance thermal transmission and reflect infrared radiation. In some embodiments, a metalized or metal foil layer  55  is only used on one side of a multi-layer, hot sealed cooling blanket  10  intended to enhance thermal transmission away from the user. 
     An access port  50  may be constructed of an open portion of the chamber  15  left exposed during initial construction, and used to fill with a fluid  45  prior to permanently sealing, or may be made of a separate mechanical structure such as a fill tube  50 , which may be sealed permanently through conventional techniques or temporarily through a pinch valve or like technology, a check valve, a screw cap, or any combination thereof. The access port  50  may be used to fill the blanket  10  prior to packaging and be permanently sealed, or sealed by the end user. 
     A fluid  45  may fill or partially fill a chamber  15  to further enhance thermal communication across the cooling blanket  10 . The fluid  45  is preferably a low viscosity fluid with typical viscosity of less than 1,000 Centipoise (CP), more typically less than 500 CP, still more typically less than 100 CP, yet more typically less than 50 CP, and still more typically less than 15 CP. In one embodiment, the chamber  15  may be filled with water, such as deionized water or tap water. A wetting agent or surfactant  65  as previously described may be added to the fluid  45  to improve thermal communication or applied to the chamber walls  20  prior to filling with a working fluid  45 . The fluid  45  may enter the chamber through access port  50 . The volume of fluid  45  typically added to a chamber  15  is less than the maximum chamber volume, and more typically less than  50  percent of the maximum volume, and still more typically less than  35  percent of the maximum chamber volume. Air is typically removed from the chamber  15  prior to filling and residual air is typically removed once the chamber  15  is sufficiently filled. The residual air forms a head space in the chamber  15 , which is typically less than 10 percent of total chamber volume, more typically less than 2 percent of total chamber volume, and still more typically less than 1 percent of total chamber volume. 
     In some embodiments, the fluid  45  includes an active cooling agent  70 . The active cooling agent  70  enhances cooling across the chamber  15  by undergoing a temperature dependent physical change across the chamber  15 . The active cooling agent  70  may be a miscible volatile chemical, such as isopropanol, butanol, or the like, selectively soluble volatile compound, such as butane, a salt with a temperature dependent solubility, such as calcium chloride, potassium nitrate, ammonium nitrate, silver nitrate, cesium sulfate, sodium nitrate, potassium chlorate, or the like, or a magnetically active fluid, such as a ferrofluid. The active cooling agent  70  may be added to the fluid  45 , such as water, such that it forms an undersaturated, saturated, or supersaturated solution, depending on the anticipated environmental conditions. In some embodiments a super saturated salt solution may precipitate or form concentrated solutions on a first surface and dissolve or form more dilute solutions on a second surface, such that thermal transmission is enhanced across chamber volume. 
     The cover  75  may be a cleanable fabrics or film, such as cotton, bamboo cloth, polyesters, percale, sateen, or flannel, expanded polytetrafluoroethylene (PTFE), or the like. The cover  75  may be solid, woven, knit, formed, spun, or the like. The cover  75  may be water permeable or non-permeable, textured or smooth. The cover  75  may further include fasteners  90 , such as buttons, hook and loop connectors, zippers, or the like for mechanically adhering the cover  75  to the cooling blanket  10 . 
     The chamber  15  may form a channel  30  that may be defined as a geometrically restricted structure within the larger cooling blanket  10 . Channels  30  define the fluid path within the chamber  15  and may be used to resist the tendency for a fluid to selectively migrate away from the user during operation. Typically channels  30  represent tubular structures, that may be between 25 mm and 100 mm wide prior to filling with a fluid  45 , and may traverse the length of the blanket  10 . Channels  30  may form interdigitated structures or may weave back and forth across the blanket  10 . Channels  30  are generally formed longitudinally along the length of the blanket  10  such that they are positioned from head to toe during use. Channels  30  may vary in width along their path, which may be typical with a longitudinal of 50 mm to 100 mm connected by to a parallel channel  30  via a side channel  30  of 10 mm to 50 mm. Channels  30  are typically narrower towards their oppositely disposed ends. 
     One or more baffles  40  may be used to regulate and/or retard fluidic communication between one or more channels  30  within a chamber  15 . A baffle  40  may include flaps formed by additional film or fabric, semipermeable plugs, such as nitrocellulose or polyester fabrics, or valves, such as check valves formed by weights, balls, needle valves, access ports, or the like. Baffles  40  may also be formed by capillary channels of less than 25 mm wide. 
     The cooling blanket  10  may also contain non-movable weights  95  made of a dense material, such as lead, tin, aluminum, or iron, that may be bound into the blanket structure to provide greater mechanical stability by providing a constant force on the user during fluidic shifts, which may help to keep the blanket stationary as the user tosses and turns throughout the night. 
     Air-filled bladders  80  may be added to the blanket  10  and maintained fluidically isolated from fluid filled channels  30  to enhance mechanical rigidity along the air-filled bladder  80 . Air bladders  80  may also be used to decrease or modulate the relative cooling efficacy along the blanket  10  and allow for greater comfort. In one embodiment, air bladders  80  are positioned within the blanket  10  in thermal communication with the user&#39;s arms and legs to prevent over-cooling of the user&#39;s extremities. 
     A ventilation hole  85  may be formed by removing excess film formed beyond the hot seal seam  60  during manufacturing; these holes  85  enable direct ambient communication across the sides of the cooling blanket  10  to prevent body moisture accumulation and suffocation during use. In some embodiments, ventilation holes  85  may be small (for example 3 mm to 10 mm across their longest axis) or large (for example 100 mm to 500 mm across their longest axis). 
     In another embodiment, the body  35  may form a bulk volume  25 , further including a series of point welds  100  mechanically fixed to either side of the body  35 , thereby constricting the body&#39;s  35  volumetric expansion. The welds  100  may be solid or rings with hollow centers. The rings may be sonically welded. They may be 5 to 25 mm in diameter, and for hollow rings, may have a weld thickness of at least 5 mm, more typically at least 8 mm, more typically at least 10 mm thick. The chamber  15  may be constructed of poly urethane of at least 60 durometer, more typically at least 70 durometer, and still more typically 80 durometer. Welds  100  of the present embodiment may form an array ranging between 25 to 250 mm apart. The weld pattern  105  may be more constricted on the sides of the blanket  10  resulting in hydrostatic pressure to urge fluids  45  toward predetermined portions of the body portion  35  of the blanket  10 , typically such so as to keep the fluid  45  elevated above the user. Typically, a low viscosity fluid will drain to the sides of the individual, thereby decreasing cooling efficiency and capacity. By restricting the volumetric expansion of the chamber  15 , a hydrostatic pressure is produced due to the elasticity of the chamber walls  20 , resulting in fluid elevation and fluid concentration at higher elevations. Examples of weld patterns may be found in  FIGS. 3-6 . 
     In other embodiment, each respective individual chamber  15  may have welds  100  operationally connected thereto to restrict expansion. 
     While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any inventions or of what may be claimed, but rather as descriptions of features specific to particular embodiments of particular inventions. Certain features that are described in this specification in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination may in some cases be excised from the combination, and the claimed combination may be directed to nigh-infinite subcombinations or variations of a subcombination.