Abstract:
A system for local thermal treatment includes a solid-state heat pump, a controller, a power supply, a heat sink, a thermal conductor, and a thermal pack. The solid-state heat pump may increase or decrease the temperature of the thermal pack to a desired temperature for providing heat or cold treatment. The controller provides control of the solid-state heat pump and its associated components. The heat sink may include an air heat exchanger with fins and a fan, and a liquid heat exchanger with a coolant loop and pump. The coolant loop may allow the heat sink to be separated from the thermal pack for convenient use in constrained spaces. The thermal conductor and thermal pack may be flexible and may be configured specifically to conform to individual body parts. The thermal pack provides local thermal treatment to a subject&#39;s body for an extended duration.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation of International Application No. PCT/US15/46284, filed on Aug. 21, 2015, which claims priority to U.S. Provisional Application No. 62/040,536, filed Aug. 22, 2014. The entire content of the aforementioned applications is hereby incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to the field of solid state heat pumps used for temperature control. Solid state heat pumps consist of two types of semiconductor material, such as a p-type and an n-type, aligned in parallel. When an electrical junction connects one end of the materials, and a voltage is applied across the opposite end, flow of electrical current through the dissimilar materials causes a temperature difference between the two ends. As a result, heat moves from one end of a solid state heat pump to the other. If the applied voltage polarity is reversed, heat flows in the opposite direction. This enables heating and cooling from a single device, which is useful for versatile temperature control. 
       BACKGROUND 
       [0003]    Self-heating devices that produce heat through exothermic chemical reactions are known to the art, as well as devices for producing heat or cold by heat of dilution rather than by chemical reaction. Typically, these devices are not reusable and the duration for which they can provide heating or cooling is limited. 
         [0004]    There is a need in the art for a heating or cooling device that is portable, but also able to provide heating or cooling for an extended time period. 
       SUMMARY OF THE INVENTION 
       [0005]    A system for local thermal treatment includes a solid-state heat pump, a controller, a power supply, a heat sink, a thermal conductor, and a thermal pack. The thermal pack provides local thermal treatment to a subject&#39;s body for an extended duration. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0006]      FIG. 1  is a block diagram showing one system for local thermal treatment, in an embodiment. 
           [0007]      FIG. 2  is a block diagram showing one system for local thermal treatment, in another embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0008]    The disclosure provides an electrical cooling and heating pack. The electrical cooling pack is capable of cooling body parts for various therapies and treatments. The electrical cooling pack can be portable and/or hand held. It can also be installed into furniture, for example a seat or chair for the application of cold to the body of a subject. It can also be installed in clothing including a hat or helmet. 
         [0009]    The disclosure further provides a system for local thermal treatment, wherein the system operates from electrical power in order to provide heating or cooling that can be applied to a part of the body of a subject. The systems described herein can be used to apply thermal treatments for a variety of reasons including muscle therapy, stiffness, pain, strains, sprains or muscle tears. The systems described herein can be used to apply thermal treatments for reducing symptoms associated with insomnia and central nervous system disorders. The systems described herein can also be used for medical and surgical purposes. For example, surgeries where the application of cold using the systems described herein could be used post surgically include abdominal surgeries like Caesarean section, appendectomy, hernia surgery and abdominoplasty (tummy tuck); head and neck surgeries like vocal cord surgery and tumor removal in the oral cavity; orthopedic surgeries like meniscus tear repair surgery, knee surgery, shoulder surgery, hand surgery, hip surgery and foot surgery; as well as cardiac surgeries like coronary stent implantation, cardiac ablation and bypass surgery. The systems described herein can also be used to provide heat in cool environments or cold in hot environments, thereby keeping a subject in a relatively moderate temperature. In certain embodiments, the system for local thermal treatment is portable. In these embodiments, the system can be small enough to be carried by hand or it can be installed into a seat of a vehicle. In other embodiments, the systems described herein are intended to be stationary. In these embodiments, the systems are installed into furniture or other appliances for the application of heat or cold to a subject. 
         [0010]    In certain embodiments, the system weighs between 0.5 and 15 pounds. In other embodiments, the system weighs between 0.25 and 10, 1 and 8, 3 and, 4 and 5 or 0.25 and 1 pounds. In certain embodiments, the system has a length of between 2 inches and 4 feet. In other embodiments, the system has a length of between 3 inches and 3 feet or 6 inches and 2 feet. In certain embodiments, the system has a width of 2 inches and 4 feet. In other embodiments, the system has a length of between 3 inches and 3 feet or 6 inches and 2 feet. In certain embodiments, the system has a depth of between 2 inches and 4 feet. In other embodiments, the system has a length of between 3 inches and 3 feet or 6 inches and 2 feet. 
         [0011]    In certain embodiments, the system could include two or more thermal treatment devices that are worn on distinct parts of the body or are linked together on a single part of the body. In some embodiments, the system could include 2-20 thermal treatment devices. 
         [0012]      FIG. 1  is a block diagram showing one system  100  for local thermal treatment, in an embodiment. A power supply  110  provides electrical power to system  100 . A controller  120  provides control of system  100  components. A solid-state heat pump  130  pumps heat in response to an applied voltage. Solid state heat pump  130  includes a p-type and an n-type semiconductor material aligned in parallel, and an electrical junction connecting the two materials at one end. When a voltage is applied across the two materials at their opposite end, flow of electrical current through the dissimilar materials causes a temperature difference between the two ends. As a result, heat moves from one end of solid state heat pump  130  to the other, forming a hot end and a cold end. A thermal conductor  140  is thermally connected to one end of solid-state heat pump  130 , such that heat is transferred between solid-state heat pump  130  and thermal conductor  140  by conduction. Thermal conductor  140  may be made of any material with sufficient thermal conductivity, such as a metal. A thermal pack  150  is thermally connected to thermal conductor  140 , such that heat is transferred between thermal conductor  140  and thermal pack  150  by conduction. A heat sink  160  is thermally connected to solid-state heat pump  130  on the opposite end of thermal conductor  140  and thermal pack  150 , such that heat is transferred between solid-state heat pump  130  and heat sink  160  by conduction. 
         [0013]    Thermal pack  150  may apply thermal treatment to a subject&#39;s body. Commonly used hot or cold packs, which do not include a power supply, only remain hot or cold for a limited amount of time. In situations where thermal treatment is desired for longer durations, thermal pack  150  maintains a desired temperature. Another advantage of thermal pack  150  is the option to alternate between heat and cold treatment with the same device. 
         [0014]    Controller  120  has electronic circuitry including relays and switches. In an embodiment, controller  120  includes a small digital computer, such as a programmable controller, a programmable logic controller, or a programmable logic relay. Controller  120  includes non-transitory instructions, stored in non-volatile memory, wherein the instructions, when executed by the computer, perform steps for controlling other components of system  100 . Control of solid-state heat pump  130  by controller  120  maintains thermal pack  150  at a desired temperature. In an embodiment, the desired temperature may be any temperature within a desired range. For example, voltage applied to solid-state heat pump  130 , under control of controller  120 , may cool thermal conductor  140  and thermal pack  150  to a temperature between +4° C. and -20° C. for cold treatment. Alternatively, the voltage polarity may be reversed by controller  120  to heat thermal conductor  140  and thermal pack  150  to a temperature between 40° C. and 50° C. for heat treatment. In an embodiment, temperature control includes applying a voltage to solid-state heat pump  130  for a pre-determined amount of time to achieve a desired temperature, after which, a desired temperature range is maintained by lowering the voltage applied to solid-state heat pump  130  or by cycling the voltage on and off 
         [0015]    A temperature difference across solid-state heat pump  130  is determined by its properties, such as its size, the materials used, and how it was constructed. Solid-state heat pump  130  is appropriately selected and sized to achieve sufficiently high and low temperatures in thermal pack  150 . Solid-state heat pump  130  is also appropriately selected and sized to enable rapid temperature change in thermal pack  150 . The achievable high and low temperatures of solid-state heat pump  130  depend on the ambient air temperature and the ability of heat sink  160  to add or remove heat. In the case where thermal pack  150  is cooled, thermal conductor  140  and solid-state heat pump  130  operate in conjunction to pull heat from thermal pack  150 , thereby lowering the temperature thereof. Any excess heat pulled from thermal pack  150  is then discharged into the surrounding medium via a thermal dissipator like a heat sink  160  thereby increasing the efficiency of the heat pump  130 . Conversely, when thermal pack  150  is heated, solid-state heat pump  130  and thermal conductor  140  operate in conjunction to heat thermal pack  150 . Heat sink  160  operates to discharge any coolness from solid-state heat pump  130  into the surrounding medium, thereby increasing the efficiency of solid-state heat pump  130 . 
         [0016]      FIG. 2  is a block diagram showing one system  200  for local thermal treatment. A power supply  210 , which provides electrical power to system  200 , includes an AC/DC converter  212  that converts electricity from alternating current to direct current. Power supply  210  for example converts “wall power” into energy that is usable by system  200 . In one embodiment, an optional rechargeable battery  215  provides power to system  200  and is recharged by power supply  210 . Rechargeable battery  215  improves the portability of system  200  and allows it to be used remotely from power supply  210 . Alternately, or in addition to rechargeable battery  215 , controller  220  may connect to power supply  210  via a cord such that system  200  operates when power supply  210  is coupled to an outlet. A controller  220  provides control of electrical power to the components of system  200 . Controller  220  has electronic circuitry including relays and switches. In an embodiment, controller  220  includes a small digital computer, such as a programmable controller, a programmable logic controller, or a programmable logic relay. Controller  220  includes non-transitory instructions, stored in non-volatile memory, wherein the instructions, when executed by the computer, perform steps for controlling other components of system  200 . An optional human input device  225  connects to controller  220  enabling a user to input information. Human input device  225  may include, without being limited to, the following examples: one or more switches, a dial, or a graphic user interface (GUI) manipulated by buttons, a keyboard, a mouse, a touchscreen, a phone or a watch. The GUI may be used remotely from the rest of the system. In certain embodiments, the GUI communicates with the controller via Bluetooth or any other wireless electronic method. A switch may be used to select between on and off, or between hot and cold. A dial may be used to select a temperature range or set point. A GUI may be used to select, via the buttons, a temperature set point or a profile of temperature set points. The GUI may also be used to set a timer for maintaining temperature over a desired interval, or to set a clock for changing temperature at a desired time. An optional temperature sensing device  222  may be electrically connected to provide temperature information to controller  220 . For example, temperature sensing device may be configured to measure temperature inside, and near the surface of, thermal pack  150 . Examples of temperature sensing device  222  include, but are not limited to, a thermocouple or a resistance temperature detector. 
         [0017]    A solid-state heat pump  230  pumps heat in response to an applied voltage. Solid state heat pump  230  includes a p-type and an n-type semiconductor material aligned in parallel, and an electrical junction connecting the two materials at one end. When a voltage is applied across the two materials at their opposite end, flow of electrical current through the dissimilar materials causes a temperature difference between the two ends. As a result, heat moves from one end of solid state heat pump  230  to the other, forming a hot end and a cold end. A thermal conductor  240  is thermally connected to one end of solid-state heat pump  230 , thereby transferring heat between thermal conductor  240  and solid-state heat pump  230  by conduction. Thermal conductor  240  may be made of any material with sufficient thermal conductivity, such as a metal. In an embodiment, thermal conductor  240  is made of a flexible material. A thermal pack  250  is thermally connected to thermal conductor  240 , such that heat is transferred between thermal pack  250  and thermal conductor  240  by conduction. In an embodiment, thermal pack  250  includes a gel encased in a flexible package, wherein thermal pack  250  remains flexible when cold. In an alternate embodiment, thermal pack  250  includes a plurality of beads encased in a flexible package, wherein thermal pack  250  remains flexible when cold. A heat sink  260  is thermally connected to solid-state heat pump  230  on the opposite end of thermal conductor  240  and thermal pack  250 . Thermal pack  250  is used to apply thermal treatment to a subject&#39;s body. In situations where thermal treatment is desired for long durations, and power supply  210  is unavailable, rechargeable battery  215  provides power for thermal pack  250  to maintain a desired temperature. Thermal pack  250 , including flexible thermal conductor  240 , may be sized and shaped for specific thermal treatments. This may include, but is not limited to, applying thermal treatment to an ankle, knee, elbow, wrist, finger, shoulder, lower back, upper back, neck, head, or any body part or group of body parts. 
         [0018]    Heat sink  260  is thermally connected to solid-state heat pump  230  at the end opposite thermal conductor  240  and thermal pack  250 . If thermal pack  250  is cooled, heat sink  260  discharges excess heat into the surrounding medium. If the polarity of the voltage is reversed to heat thermal pack  250 , heat sink  260  discharges excess coolness into the surrounding medium. Heat sink  260  includes an air heat exchanger  270 , which exchanges heat with the ambient air. Air heat exchanger  270  is made of a material with sufficient thermal conductivity, such as a metal. In an embodiment, air heat exchanger  270  is made of anodized aluminum due to its sufficient thermal conductivity, light weight, and durability. Air heat exchanger  270  includes fins  272 , which provide an increased surface area for a given volume. This increased surface area increases the rate of heat exchange with the air. An optional fan  274  blows air across the fins, thereby further increasing the rate of heat exchange. Controller  220  controls the speed of fan  274 , or turns it on or off as needed. 
         [0019]    In addition to air heat exchanger  270 , heat sink  250  may include an optional liquid heat exchanger  280 . Liquid heat exchanger  280  provides increased heat transfer due to the higher density, and thus larger heat carrying capacity, of liquids compared to air. Another advantage afforded by liquid heat exchanger  280  is the option to physically distance heat sink  260  from thermal pack  250  with a sufficiently long coolant loop  282 . Separation from heat sink  260  allows thermal pack  250  to be used in a constrained space, such as between a subject and a seat or bed, while maintaining sufficient air exposure to heat sink  260 . Liquid heat exchanger  280  is thermally connected to air heat exchanger  270  and one end of solid-state heat pump  230 . Liquid heat exchanger  280  includes a coolant loop  282  and a pump  284 . Coolant loop  282  forms a continuous loop that recycles coolant between thermal contact points of air heat exchanger  270  and solid-state heat pump  230 , thereby transferring heat between them. Controller  220  controls the flow rate of pump  284 , or turns it on or off as needed. Pump  284  may be any pump suitable for driving flow of liquid within coolant loop  282 . In an embodiment, pump  284  is a peristaltic pump, which drives flow by squeezing the coolant loop tubing and therefore does not contact the coolant liquid. Coolant loop  282  contains a fluid that remains in a liquid state at both temperature extremes of solid-state heat pump  230 . In an embodiment, the coolant liquid is a mixture of water and propylene glycol. Coolant loop  284  may be constructed of tubes made of any material compatible with the coolant liquid, pump  284 , and the high and low temperature extremes produced by solid-state heat pump  230 . In other words, the tube material must substantially prevent penetration and corrosion by the coolant liquid, and it must be sufficiently flexible for squeezing by a peristaltic pump, at both temperature extremes. In an embodiment, coolant loop  282  consists of platinum-cured silicon tubing. 
         [0020]    In embodiments where the system is installed in a seat or bed, the seat or bed can be installed in a vehicle. In some embodiments, the vehicle is a car, truck, boat, bus, train, airplane or helicopter. The seat or bed can be used by the driver or pilot or by a passenger. In other embodiments, the seat or bed can be furniture that is used in the home or office. 
         [0021]    In an embodiment, controller  220  includes one or more relays for changing voltage polarity and one or more switches for applying voltage. In an embodiment, controller  220  includes an algorithm that controls voltage supplied to solid-state heat pump  230  using the one or more relays and one or more switches. Controller  220  identifies a voltage differential measurement indicating any difference between a desired temperature and a measured temperature from temperature sensing device  222 . The desired temperature may be predetermined or entered by a user via human input device  225 . Based on the temperature difference, controller  220  sends a control signal to solid-state heat pump  230  to adjust the voltage to solid-state heat pump  230  according to the control algorithm, thereby bringing the measured temperature closer to the desired temperature. Controller  220  may also send control signals to adjust power supplied to fan  274  and pump  284  to appropriately transfer heat. Parameters of the control algorithm are tuned to achieve a desired response. Optionally, the control algorithm parameters may be adjusted using human input device  225 . 
         [0022]    Changes may be made in the above methods and systems without departing from the scope hereof. It should thus be noted that the matter contained in the above description or shown in the accompanying drawings should be interpreted as illustrative and not in a limiting sense. The following claims are intended to cover all generic and specific features described herein, as well as all statements of the scope of the present method and system, which, as a matter of language, might be said to fall therebetween.