Patent Publication Number: US-2020289314-A1

Title: Methods and apparatuses for manipulating temperature

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 15/555,677, filed on Sep. 5, 2017, which is a National Stage filing under 35 U.S.C. § 371 of International Application No. PCT/US2016/022105, filed Mar. 11, 2016, which claims the benefit under 35 U.S.C. 119(e) to U.S. Provisional Application Ser. No. 62/132,981, filed Mar. 13, 2015, each of which are incorporated herein by reference in its entirety for all purposes. 
    
    
     FIELD 
     The present disclosure relates generally to methods and apparatuses for manipulating temperature of a surface. 
     BACKGROUND 
     Substantial amounts of energy are used each year by heating, ventilation and air conditioning (HVAC) systems, for keeping spaces within homes, offices, buildings, and other enclosures within comfortable temperature ranges. Despite the significant amounts of energy expended, thermal discomfort still remains a major cause of dissatisfaction within building environments, largely due to wide variance in personal preference. In many cases, an indoor space considered to be optimally conditioned might only be satisfying to about 80% of the occupants at a given time. Conventional HVAC systems are incapable of providing the spatial and temporal variation in temperature that would be necessary for each occupant to feel comfortable, focused, and productive in his/her respective environment. 
     Existing wearable devices for thermal regulation (e.g., clothing) are generally passive in that they do not generate or absorb heat but merely serve to insulate the wearer from the outside temperature. Despite rapid improvements in the field of active wearable devices, including watches, accelerometers, motion sensors, etc., there is a gap in the understanding of wearable devices that actively work to enhance the thermal comfort of the wearer. 
     SUMMARY 
     Methods and devices for manipulating the temperature of a surface are provided. 
     In an illustrative embodiment, a device for manipulating a temperature of a surface is provided. The device includes at least one thermoelectric material constructed and arranged to be disposed adjacent the surface. The device also includes a controller in electrical communication with the at least one thermoelectric material, the controller configured to cause the at least one thermoelectric material to generate a thermal pulse at a region of the at least one thermoelectric material adjacent the surface, the thermal pulse including a first temperature adjustment at the region of the at least one thermoelectric material adjacent the surface from a first temperature to a second temperature at a first average rate of between about 0.1° C./sec and about 10.0° C./sec, and a second temperature adjustment at the region of the at least one thermoelectric material adjacent the surface from the second temperature to a third temperature at a second average rate of between about 0.1° C./sec and about 10.0° C./sec, wherein a difference in magnitude between the first temperature and the third temperature is less than 25% of a difference in magnitude between the first temperature and the second temperature. 
     In another illustrative embodiment, a method for manipulating a temperature of a surface is provided. The method includes positioning a region of at least one thermoelectric material adjacent to the surface; and generating a thermal pulse at the region of the at least one thermoelectric material adjacent the surface. Generating the thermal pulse may include adjusting temperature at the region of the at least one thermoelectric material adjacent the surface from a first temperature to a second temperature at a first average rate of between about 0.1° C./sec and about 10.0° C./sec, and adjusting temperature at the region of the at least one thermoelectric material adjacent the surface from the second temperature to a third temperature at a second average rate of between about 0.1° C./sec and about 10.0° C./sec, wherein a difference in magnitude between the first temperature and the third temperature is less than 25% of a difference in magnitude between the first temperature and the second temperature. 
     In yet another illustrative embodiment, a device for manipulating a temperature of a surface is provided. The device includes a thermal adjustment apparatus constructed and arranged to be disposed adjacent the surface, the thermal adjustment apparatus configured to generate a thermal pulse over a time period of less than 120 seconds at a region of the temperature adjustment apparatus adjacent the surface, the thermal pulse including a first temperature adjustment at the region of the thermal adjustment apparatus adjacent the surface from a first temperature to a second temperature at a first average rate of between about 0.1° C./sec and about 10.0° C/sec, and a second temperature adjustment at the region of the thermal adjustment apparatus adjacent the surface from the second temperature to a third temperature at a second average rate of between about 0.1° C./sec and about 10.0° C./sec, wherein a difference in magnitude between the first temperature and the third temperature is less than 25% of a difference in magnitude between the first temperature and the second temperature, and a magnitude of the first average rate is greater than a magnitude of the second average rate. 
     In a further illustrative embodiment, a method for manipulating a temperature of a surface is provided. The method includes positioning a region of a thermal adjustment apparatus adjacent to the surface; and generating a thermal pulse over a time period of less than 120 seconds at the region of the thermal adjustment apparatus adjacent the surface. Generating the thermal pulse may include adjusting temperature at the region of the thermal adjustment apparatus adjacent the surface from a first temperature to a second temperature at a first average rate of between about 0.1° C./sec and about 10.0° C./sec, and adjusting temperature at the region of the thermal adjustment apparatus adjacent the surface from the second temperature to a third temperature at a second average rate of between about 0.1° C./sec and about 10.0° C/sec, wherein a difference in magnitude between the first temperature and the third temperature is less than 25% of a difference in magnitude between the first temperature and the second temperature, and a magnitude of the first average rate is greater than a magnitude of the second average rate. 
     In an illustrative embodiment, a device for manipulating a temperature of a surface is provided. The device may include at least one thermoelectric material constructed and arranged to be disposed adjacent the surface, a power source configured to provide energy to the at least one thermoelectric material, and a controller in electrical communication with the at least one thermoelectric material and the power source. The controller may be configured to cause the at least one thermoelectric material to generate a plurality of thermal pulses in succession at a region of the at least one thermoelectric material adjacent the surface such that an average power consumption of the power source during the thermal pulse generation is less than 10 Watts, or less than 6 Watts. 
     In another illustrative embodiment, a method for manipulating a temperature of a surface is provided. The method may include positioning a region of at least one thermoelectric material adjacent to the surface, and generating a plurality of thermal pulses in succession at the region of the at least one thermoelectric material adjacent the surface such that an average power consumption of a power source providing energy to the at least one thermoelectric material during the thermal pulse generation is less than 10 Watts, or less than 6 Watts. 
     In yet another illustrative embodiment, a device for manipulating a temperature of a surface is provided. The device may include at least one thermoelectric material constructed and arranged to be disposed adjacent the surface, a controller in electrical communication with the at least one thermoelectric material, and a housing including a thermally conductive material forming an enclosure at least partially surrounding the controller on multiple sides. The controller may be configured to cause the at least one thermoelectric material to generate a thermal pulse at a region of the at least one thermoelectric material adjacent the surface. 
     In an illustrative embodiment, a device for manipulating a temperature of a surface is provided. The device may include at least one thermoelectric material constructed and arranged to be disposed adjacent the surface, a controller in electrical communication with the at least one thermoelectric material, and a housing providing an enclosure at least partially surrounding the controller. The controller may be configured to cause the at least one thermoelectric material to generate a thermal pulse at a region of the at least one thermoelectric material adjacent the surface. A portion of the housing may be constructed and arranged for coupling and decoupling with a complementary portion of a detachable support structure. 
     In yet another illustrative embodiment, a method of using a device for manipulating a temperature of a surface is provided. The method may include coupling a portion of a housing of the device to a complementary portion of a wearable support. The housing may provide an enclosure at least partially surrounding a controller in electrical communication with the at least one thermoelectric material. The method may further include positioning a region of the at least one thermoelectric material adjacent to the surface, generating a thermal pulse at the region of the at least one thermoelectric material adjacent the surface, and removing the housing of the device from the complementary detachable support structure. 
     In another illustrative embodiment, a device for manipulating a temperature of a surface is provided. The device may include at least one thermoelectric material constructed and arranged to be disposed adjacent the surface, a controller in electrical communication with the at least one thermoelectric material, and a thermally conductive material located adjacent to the at least one thermoelectric material. The controller may be configured to cause the at least one thermoelectric material to generate a thermal pulse at a region of the at least one thermoelectric material adjacent the surface. The thermally conductive material may have a substantially flat surface profile extending between a first end region of the device and a second end region of the device, the second end region located opposite the first end region. 
     In a further illustrative embodiment, a device for manipulating a temperature of a surface is provided. The device may include at least one thermoelectric material constructed and arranged to be disposed adjacent the surface, a controller in electrical communication with the at least one thermoelectric material, and a thermally conductive material located adjacent to the at least one thermoelectric material. The controller may be configured to cause the at least one thermoelectric material to generate a thermal pulse at a region of the at least one thermoelectric material adjacent the surface. The thermally conductive material may have a surface profile substantially free of protrusions extending greater than 1 mm away from the surface, between a first end region of the device and a second end region of the device, the second end region located opposite the first end region. 
     In another illustrative embodiment, a device for manipulating a temperature of a surface is provided. The device may include at least one thermoelectric material constructed and arranged to be disposed adjacent the surface, a controller in electrical communication with the at least one thermoelectric material, and a thermally conductive material located adjacent to the at least one thermoelectric material. The thermally conductive material may be a heat dissipation unit adapted to undergo a temperature change of greater than 10 degrees C. per Watt of power applied to the thermally conductive material at standard ambient temperature and pressure (SATP) conditions. The controller may be configured to cause the at least one thermoelectric material to generate a plurality of thermal pulses in succession at a region of the at least one thermoelectric material adjacent the surface. 
     In yet another illustrative embodiment, a device for manipulating a temperature of a surface is provided. The device may include at least one thermoelectric material constructed and arranged to be disposed adjacent the surface, a controller in electrical communication with the at least one thermoelectric material, and a thermally conductive material located adjacent to the at least one thermoelectric material. The controller may be configured to cause the at least one thermoelectric material to generate a thermal pulse at a region of the at least one thermoelectric material adjacent the surface. A ratio of an externally facing surface area of the thermally conductive material and an externally facing surface area of the at least one thermoelectric material may be less than 10. 
     Various embodiments of the present disclosure provide certain advantages. Not all embodiments of the present disclosure share the same advantages and those that do may not share them under all circumstances. Various embodiments described may be used in combination and may provide additive benefits. 
     Further features and advantages of the present disclosure, as well as the structure of various embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are not intended to be drawn to scale. For purposes of clarity, not every component may be labeled in every drawing. In the drawings: 
         FIG. 1A  shows a perspective view of a device for manipulating the temperature of a surface worn by a user according to one set of embodiments; 
         FIG. 1B  depicts a side view of the device of  FIG. 1A ; 
         FIG. 1C  illustrates a bottom view of the device of  FIGS. 1A-1B ; 
         FIG. 2  shows a perspective view of another device for manipulating the temperature of a surface according to one set of embodiments; 
         FIG. 3  shows a perspective view of yet another device for manipulating the temperature of a surface according to one set of embodiments; 
         FIG. 4A  is a schematic representation of a thermal pulse generated by a device according to one set of embodiments; 
         FIG. 4B  is a schematic representation of another thermal pulse generated by a device according to one set of embodiments; 
         FIG. 5A  is a schematic representation of yet another thermal pulse generated by a device according to one set of embodiments; 
         FIG. 5B  is a schematic representation of another thermal pulse generated by a device according to one set of embodiments; 
         FIG. 6  is a schematic representation of a succession of thermal pulses generated by a device according to one set of embodiments; 
         FIG. 7  is an example of an electrical signal applied to a device according to one set of embodiments; 
         FIG. 8  is an exemplary plot of the relative change in temperature of a surface in response to a set of voltage profiles applied to a device according to some embodiments; 
         FIG. 9  is an exemplary plot of the relative change in temperature of a surface in response to another set of voltage profiles applied to a device according to some embodiments; 
         FIG. 10  is an exemplary plot of the temperature of a surface for a series of thermal pulses generated by two devices according to some embodiments; 
         FIG. 11A  shows a perspective view of an exemplary device for manipulating the temperature of a surface according to one set of embodiments; 
         FIG. 11B  shows a top-down view of the internal components of the device of  FIG. 11A ; 
         FIG. 11C  shows a face-on view of the exemplary device of  FIG. 11A  configured such that it can be reversibly incorporated into a necklace; 
         FIG. 11D  shows a perspective view of the exemplary device of  FIG. 11A  configured such that it can be reversibly incorporated into a wristband; 
         FIG. 11E  shows a top view of the exemplary device of  FIG. 11A  configured such that it can be reversibly incorporated into a keychain; 
         FIG. 11F  shows a perspective view of the exemplary device of  FIG. 11A  configured such that it can be reversibly coupled and decoupled with a support structure; 
         FIG. 12  shows a cross-sectional view of another exemplary device for the manipulation of temperature according to one set of embodiments; and 
         FIG. 13  depicts a cross-sectional view of another exemplary device for the manipulation of temperature according to one set of embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Methods and apparatuses for manipulating the temperature of a surface are generally provided. The present disclosure relates to a device that includes one or more thermoelectric materials, or other suitable thermal adjustment apparatus(es), placed near a surface, such as the skin of a user. The device may be configured to generate a series of thermal pulses in succession at the surface. This thermal pulsing, when suitably applied, may result in an enhanced thermal sensation for a user which, in some cases, may provide the user with a more pleasurable thermal experience than would otherwise be the case without the thermal pulsing. 
     As further described herein, a thermal pulse may include a transient, reversible temperature change at a surface, where the temperature changes from an initial temperature to another temperature, quickly followed by a return temperature change at the surface from the other temperature back to the initial temperature, or a temperature close to the initial temperature, all over a relatively short period of time (e.g., less than 120 seconds, or shorter). For example, a thermal pulse may include a first temperature adjustment at a surface from a first temperature to a second temperature (e.g., at an average rate of 0.1°-10.0° C./sec), and a second temperature adjustment at the surface from the second temperature to a third temperature (e.g., also at an average rate of 0.1°-10.0° C./sec). In such a thermal pulse, the difference in magnitude between the first temperature and the third temperature may be less than 25% of the difference in magnitude between the first temperature and the second temperature. Further, in some cases, the magnitude of the first average rate may be greater than the magnitude of the second average rate. 
     Under conventional usage, thermoelectric materials, or other temperature adjustment devices, for heating or cooling are generally operated in steady-state, i.e., under constant applied temperature and/or electrical signal modes, so as to maintain long-time scale applications of heating or cooling. For example, such conventional methods are typically used for hot or cold pack compression therapy where it is desirable for the temperature to remain the same for long periods of time. In contrast, aspects of the present disclosure involve generating thermal pulses that are substantially reversible and transient, which may result in continuous thermal stimulation for the human skin. 
     The inventors have recognized, unexpectedly, that varying the temperature at the surface of human skin in a certain manner, for example, by generating thermal pulses according to particular temperature profiles, may give rise to an enhanced heating or cooling effect for the individual. This enhanced thermal effect may be perceived by the individual in a way that is more pronounced when the temperature is pulsed back and forth in a reversible manner at the surface under short time durations (e.g., less than 120 seconds, less than 30 seconds), in comparison to if the temperature is gradually changed from one temperature to another at the surface over longer periods of time (e.g., over several minutes or hours). That is, when subject to thermal pulses in accordance with embodiments of the present disclosure, the perceived strength of this heating/cooling effect is comparable to actual changes in temperature that are much larger in magnitude and which may be applied, for example, at steady state. 
     By generating a suitable series of thermal pulses at the surface of human skin, which may or may not include certain variations between pulses, thermoreceptors of the skin may be continuously stimulated. The inventors have appreciated that, in responding to heating and/or cooling at the surface of the skin, thermoreceptors may have a tendency to adapt and, once accustomed to the immediate environment, become desensitized to the initial stimulus. This is analogous to the desensitization of skin to the touch of an external stimuli, such as clothing or some other stimulus to which the senses may become accustomed. 
     The inventors have discovered, in particular, that by generating thermal pulses at the surface of human skin having particular combinations of parameters, such as rates of temperature change, magnitudes of temperature change, pulse duration, etc., as described in more detail herein, the effects of adaptive desensitization are mitigated or otherwise reduced, and the perceived effects of cooling and/or heating are enhanced. As compared to the desensitization that may occur in a cooled or heated room, the devices described herein may be able to continuously provide a user with an enhanced thermal experience, e.g., a pleasant feeling of cooling and/or heating, according to his/her preferences. As noted above, due to the manner in which the thermal pulse is generated, when the device is in operation, a user may experience, or feel, a temperature sensation that is perceived to be greater in magnitude as compared to the actual magnitude in temperature change of the device at the surface of the skin. 
     In some embodiments, the thermal adjustment apparatus includes one or more thermoelectric materials that may be positioned directly adjacent to the skin of a user. An electrical signal may be applied to the thermoelectric material(s) so as to manipulate the temperature of the surface of the skin, for example, in the form of a thermal pulse, and/or a plurality of thermal pulses in succession, one after another. Though, it can be appreciated that any suitable thermal adjustment apparatus may be employed; for example, a laser-powered device, convective thermal device, or any other suitable apparatus that may be able to generate a series of thermal pulses. 
     In various embodiments, each thermal pulse generated by the device may last for a time period of less than 120 seconds (e.g., 1-30 seconds) and may include a first initial temperature adjustment at a region of the thermoelectric material(s) (or suitable thermal adjustment apparatus) adjacent the surface from a first (initial) temperature to a second (pulsed) temperature, and a second return temperature adjustment at the region adjacent the surface, from the second (pulsed) temperature to a third (return) temperature. 
     For some embodiments, the first temperature adjustment involves a heating step while the second temperature adjustment involves a cooling step. Or conversely, when the first temperature adjustment involves a cooling step, the second temperature adjustment may involve a heating step. That is, the thermal pulse may be characterized by an initial temperature variation followed by a return to a temperature that is substantially the same or close to the initial temperature at the surface. For example, the difference in magnitude between the first (initial) temperature and the third (return) temperature may be less than 25% of a difference in magnitude between the first (initial) temperature and the second (pulsed) temperature. 
     Each of the first and second temperature adjustments may be characterized by an average rate of between about 0.1° C./sec and about 10.0° C./sec. Though, in some cases, the magnitude of the average rate of the first temperature adjustment is greater than the magnitude of the average rate of the second temperature adjustment. That is, the time period under which the surface adjacent the thermal adjustment apparatus to thermally relax or otherwise adjust from the second (pulsed) temperature to the third (return) temperature may be longer than the time period for the surface to initially step from the first (initial) temperature to the second (pulsed) temperature. 
     As noted above, temperature profiles at the surface of the skin, in accordance with various embodiments, may provide a person with an enhanced thermal experience, resulting in a perceived heating or cooling sensation for the person. For example, when the ambient temperature is cooler than is otherwise desirable, a user may set the device to a suitable heating mode where a series of thermal pulses generated at the surface of the user&#39;s skin cause the user to feel warmer within that environment. Conversely, in an uncomfortably warm ambient environment, the user may set the device to a suitable cooling mode, generating a series of thermal pulses at the surface of the skin so as to cause the user to feel cooler. For each of the heating and cooling modes, the user may also adjust various parameters (e.g., magnitude of temperature change, rate of change, duration of each pulse, steady-state temperature, etc.) based on preference. 
     As noted above, existing HVAC systems generally require substantial amounts of energy to heat or cool a commercial building. Embodiments of the present disclosure are estimated to significantly reduce energy consumption related to HVAC usage. For example, outfitting a 1,000 person office building with devices as described herein may consume only 5 kWh a day, as compared to 200 kWh which may be required to adjust a particular region of the building by 1° C. Moreover, methods and devices described herein may provide a user with personal control over his/her level of thermal comfort. By providing a more localized manner of control over a person&#39;s thermal comfort, office buildings are estimated to be able to save up to 40% of their HVAC energy usage through a generally reduced HVAC load. 
     The term thermoelectric material is given its ordinary meaning in the art and refers to materials in which a temperature change is generated at a surface of the material upon application of an electric potential (e.g., voltage and corresponding current), in accordance with the thermoelectric effect (e.g., often referred to by other names such as the Peltier, Thomson, and Seebeck effects). Any suitable thermoelectric may be employed, a number of which are described further below. It should be understood that, while a portion of the description herein describes thermoelectric materials, the present disclosure is not limited to thermoelectric materials, and other thermal adjustment apparatuses may be employed where appropriate. 
     In various embodiments, the overall device construction may be compact and modular in nature. For example, as discussed herein, thermal pulsing of the thermal adjustment apparatus may allow for the device to be more efficient and exhibit a significantly lower overall average power consumption than would otherwise be the case without thermal pulsing. Hence, less heat is generated by the device, resulting in less of a need for thermal dissipation. Accordingly, the use of a large, bulky heat sink may be avoided in certain embodiments. This opens up a number of alternative structural arrangements that would not have otherwise been feasible if a large heat sink were employed, as described further below. 
       FIGS. 1A-1C  depict an embodiment of a device  100  that includes a thermoelectric material  110  that, during use, is configured to be positioned adjacent to the surface of the user&#39;s skin  102 . As explained further below, the device may include multiple thermoelectric materials positioned at the surface of the skin. The device  100  may optionally include a thermally conductive material  120  (e.g., heat sink) located on the side of the thermoelectric opposite the skin in a manner that covers the thermoelectric material  110 . 
     The thermally conductive material  120 , described further below, may dissipate heat to and/or from the thermoelectric material(s), as desired. The thermally conductive material may include any suitable material, such as metal (e.g., aluminum, copper, stainless steel, etc.), thermally conductive polymer, porous ceramic, or another appropriate material. Those skilled in the art would understand that the term “thermally conductive material” generally refers to materials with a relatively high thermal conductivity (e.g., a thermal conductivity of greater than about 1.0 W m −1  K −1 , greater than about 5.0 W m −1  K −1 , greater than about 10.0 W m −1  K −1 , or greater than about 50.0 W m −1  K −1 ). Methods for determining thermal conductivity are known in the art and may include, for example, laser flash analysis. 
     Though, in some embodiments, as described further below and illustratively shown in  FIGS. 2-3 , rather than a thermally conductive material, a thermally insulative material may be located on the side of the thermoelectric opposite the skin, covering the thermoelectric material(s). As also noted herein, and shown in  FIG. 10 , covering the thermoelectric material(s) with a thermally insulative material may enhance the effects of thermal pulsing at the surface of the skin. 
     It can be appreciated that it is not required for the thermoelectric material(s) to be covered by a thermally conductive or insulative material. For example, a thermal dissipation apparatus may be spaced from or located adjacent to the thermoelectric material(s), without covering the thermoelectric material(s). Or, the thermally conductive or insulative material may be arranged so as to cover a portion of the thermoelectric material(s). 
     The thermoelectric may be connected to a power source  130  (e.g., battery, plug-in outlet, etc.) and a controller  140 , for applying appropriate signals to the thermoelectric, for manipulating the temperature at the surface of the skin. In some cases, the controller may have, one or more inputs and/or outputs to accommodate user control of the device in a suitable and convenient manner. 
     Each of the elements of the device, i.e., the thermoelectric material  110 , thermally conductive material  120 , power source  130  and controller  140 , may be suitably held together by an appropriate band  150 . In some cases, the band  150  may be flexibly adjustable so as to allow for the thermoelectric material  110  to be comfortably and suitably positioned against or otherwise adjacent the surface of the skin such that thermal pulses generated by the thermoelectric are effective to provide the user with a preferred thermal sensation. Though, for some embodiments, the band  150  may exhibit relatively rigid mechanical behavior, providing support for the overall device. It can be appreciated that the band  150  may have any suitable structure and, in some cases, may have stylistic aspects which may lend the device to be worn as a bracelet, anklet, necklace, etc. The band may include any suitable material, such as, but not limited to, metal, plastic, rubber, leather, synthetic leather, or combinations thereof. 
     It can be appreciated that while the thermoelectric material(s) may be positioned directly adjacent to a surface of the user&#39;s skin, in accordance with aspects of the present disclosure, the thermoelectric material(s) are not required to be in direct contact with the user&#39;s skin; for example, an additional layer (not shown in the figures) may be placed between the thermoelectric material(s) and the surface of the skin. For example, a thermally conductive or insulative layer, a protective layer, a support layer (e.g., for added comfort), or another appropriate material. 
       FIGS. 2-3  show embodiments where the device  100  includes a thermally insulative material  122  located on the side of the thermoelectric opposite the skin, covering the thermoelectric material(s). As a result, the thermally insulative material  122  substantially maintains the overall level of heat generated by the thermoelectric material(s), located at the surface of the skin. In some cases, as discussed further below, the thermally insulative material enhances the effect of the thermal pulses generated by the thermoelectric material(s). The thermally insulative material may include any suitable material, for example, polymer, plastic, elastomer (e.g., rubber, neoprene, etc.), and/or another appropriate material. Such insulative materials may also lend themselves to a device that is less bulky and more flexibility than, for example, if a large heat sink were placed over the thermoelectric material(s). Accordingly, covering the thermoelectric material(s) with a suitable insulative layer such as neoprene, other rubbers or cloth or textile-based materials may allow the device to be more desirable to wear. Those skilled in the art would understand that the term “thermally insulative material” generally refers to materials with a relatively low thermal conductivity (e.g., a thermal conductivity of less than about 1.0 W m −1  K −1 , less than about 0.5 W m −1  K −1 , less than about 0.1 W m −1  K −1 , or less than about 0.01 W m −1  K −1 ). Methods for determining thermal conductivity are known in the art and may include, for example, laser flash analysis. For some embodiments, the thermoelectric material(s) may be exposed to air, without a covering or other material located thereon. 
     In some embodiments, the device  100  may include a number of thermoelectric materials. For example, as illustrated in  FIGS. 2-3 , rather than a single slab of thermoelectric material, the device  100  may include a plurality of smaller thermoelectric materials  110 A,  110 B,  110 C,  110 D located adjacent to one another. The thermoelectric materials  110 A,  110 B,  110 C,  110 D of  FIGS. 2-3  may be sized and arranged in a manner so as to accommodate flexing of the device, for example, around a wrist or other part of the body. Similar to a watch having small rigid components (e.g., metallic parts) that are mutually connected, yet able to flex with respect to one another along the wristband, the plurality of thermoelectric materials may be relatively small, yet arranged in a manner that allows for flexibility and overall wearability of the wristband  150 . Accordingly, the relatively small thermoelectric materials may be arranged so as to accommodate the curvature of certain body parts. Thus, the wristband, together with the thermoelectric materials may provide the ability for the device to be adjustably and, hence, snugly fit to the user. 
     The device may include any suitable number of thermoelectric materials. For example, the device may include 2 or more, 3 or more, 4 or more, 5 or more, 10 or more, etc. such thermoelectric materials. The thermoelectric materials may be arranged in any appropriate pattern along the surface of the device, for example, aligned along a row, arranged in a grid-like formation, positioned in an irregular pattern, arranged to form a particular shape (e.g., ellipse, circular, quadrilateral, hexagonal, etc.), or may be configured in another appropriate way. It may be preferable for the thermoelectric materials to be located in relatively close proximity to one another, so that the cluster of thermoelectrics is able to generate thermal pulses in a suitable manner, for example, thermal pulses that are more concentrated at the surface, so as to elicit a more pronounced response, than if the thermoelectrics are spaced further apart from one another. 
     In some cases, the thermoelectric materials may be in electrical communication with one another. For example, the thermoelectric materials may be arranged so as to have an electrical connection in series with each other. Accordingly, an electrical signal applied to one of the thermoelectric materials may also be applied to the others to which it is connected. Or, the thermoelectric materials may be electrically isolated from one another, for example, so as to be separately stimulated by a controller, with electrical signals appropriately tailored for each thermoelectric material, for example, at preferred times, magnitudes, and/or rates, as desired. 
     As noted above, the device may include a controller that is in electrical communication with the thermoelectric material(s), or other appropriate thermal adjustment apparatus. In some embodiments, the controller is configured to apply a series of electrical signals to the thermoelectric material(s) to cause a thermal pulse to be generated at a region of the thermoelectric material(s) adjacent the surface. In some cases, as described further below, the controller may be configured to cause the thermoelectric material(s) to generate a plurality of thermal pulses in succession (e.g., at the region of the thermoelectric material(s) adjacent the surface of the skin of a user). For example, in some embodiments, the thermoelectric material(s) may generate at least one thermal pulse, or at least 2, at least 5, at least 10, at least 20, at least 50, at least 100, at least 200, at least 300, at least 400, or at least 500 thermal pulses in succession, one after another. It can be appreciated that the device may be configured to operate continuously, as there is no limit to how many thermal pulses may be generated at the surface of the skin. 
     In some embodiments, as noted above, the controller may be in separate electrical communication with each of the thermoelectric materials. As a result, the controller may be configured to cause two or more thermoelectric materials to generate two or more thermal pulses, respectively, that are separate and distinct from one another; for example, a first thermoelectric material generating a first thermal pulse and a second thermoelectric material generating a second thermal pulse. It can be appreciated that various characteristics of the respective thermal pulses may be the same or different. In some embodiments, respective thermal pulses may be generated in a substantially simultaneous manner. Alternatively, for certain embodiments, the first thermal pulse and the second thermal pulse may be generated at different times. Or, as described above, the controller may be configured to cause the thermoelectric material(s) to generate a plurality of respective thermal pulses in succession, in any suitable pattern. 
     As discussed herein, for some embodiments, the controller is configured to cause the thermoelectric material(s) to produce a number of suitable time-varying, temperature profiles at the surface of human skin, so as to provide an enhanced thermal sensation to the user, which may be tailored to provide the user with a greater degree of thermal comfort and pleasure. Without wishing to be bound by theory, in some cases, the use of multiple thermal pulses may be particularly effective in applying continuous thermal stimulation to the thermoreceptors associated with the skin, as compared to applying a thermal adjustment over a longer steady-state period of time. As noted above, the application of thermal pulses may provide a continuous level of stimulation, which decreases the likelihood for thermoreceptors to become desensitized to thermal variations. As a result, such thermal pulsing may allow the user to experience an overall enhanced perceived thermal feeling. Accordingly, by modulating and/or adjusting the thermal pulses in an appropriate manner, the overall thermal comfort, or perceived comfort, of a user may be manipulated, as desired. 
     In accordance with aspects of the present disclosure, the device may be configured to generate thermal pulses having appropriate characteristics. For example, the thermal pulse(s) may include a thermal change (e.g., at the region of the thermoelectric material(s) adjacent the surface of the skin) that is substantially reversible over a short period of time. In some embodiments, as noted above, the thermal change includes a first temperature adjustment of the surface from a first initial temperature to a second pulsed temperature, followed by a second temperature adjustment of the surface from the second pulsed temperature to a third return temperature. In some cases, as discussed above, in keeping with pulses that exhibit thermal reversibility, the magnitude difference between the first and third temperatures may be less than 25% of a magnitude difference between the first and second temperatures. 
       FIGS. 4A-5B  depict schematic examples of a thermal pulse which may, in some cases, include a number of regimes. As illustratively shown, the thermal pulse may include a first regime I, an optional second regime II and a third regime III. 
     In various embodiments, the first regime I may involve an initial temperature adjustment at a surface from a first temperature T 1  to a second temperature T 2 . The optional second regime II may involve a slight change in temperature at the surface from the second temperature T 2  to a modified second temperature T′ 2 . The third regime III may involve a subsequent temperature adjustment at the surface from the second temperature T 2 , or a modified second temperature T′ 2  (as shown), to a third temperature T 3 . 
     As depicted in the schematic of  FIGS. 4A-5B , the first temperature T 1  and the third temperature T 3  at the surface are shown to be the same, though, it should be understood that the first temperature T 1  and the third temperature T 3  may differ, though, not significantly. For example, the third temperature T 3  may be greater or less than the first temperature T 1 , yet the difference between the first and third temperatures may be less than 25%, or less. It should understood that the regimes described herein are merely examples of the profile of a thermal pulse, and that other profiles having different behavior and/or regimes may be possible. 
     As noted above, for the examples provided, the optional second regime II may involve an additional adjustment of the second temperature T 2  to a modified second temperature T′ 2 . While  FIGS. 4A-5B  depict the (initial) second temperature T 2  and the modified second temperature T′ 2  to be the same, it can be appreciated that the second temperature T 2  and the modified second temperature T′ 2  may also differ, as discussed further below. For instance, the modified second temperature T′ 2  may be greater or less than the (initial) second temperature T 2 . Or, the modified second temperature T′ 2  may arise during the optional second regime (rather than at the end), as the temperature profile within this regime may be non-linear. That is, the maximum temperature of the surface during the thermal pulse may occur at a time in the middle of the optional second regime II. 
     As discussed herein, a controller may be configured to apply an electrical signal to the thermoelectric material(s), for creating a preferred temperature profile at the surface of the thermoelectric and, hence, the skin. For illustrative purposes,  FIGS. 4A-5B  also show the corresponding electrical signal (i.e., amount of voltage applied over particular period of time, which may have any suitable profile and is not limited by that specifically shown in the figures) that may be applied from the controller to the corresponding thermoelectric material, variations of which will be discussed in more detail below. 
     In some embodiments, the device (e.g., controller in electrical communication with thermoelectric material(s)) may be configured to generate a heating pulse that gives rise to a perceived heating experience for the user. That is, the user may feel the sensation of being heated (e.g., locally heated at the surface to which the thermal pulsing is applied, or at other regions of the body), while the actual temperature of the body is generally maintained. Such a heating pulse may involve an increase in temperature at the surface of the skin of the user (e.g., region of the thermoelectric material(s) adjacent the surface of the skin), and a subsequent decrease in temperature at the surface of the skin, over a short period of time (e.g., less than 30 seconds, less than 10 seconds). As illustratively shown,  FIGS. 4A-4B  depict schematic representations of a heating pulse generated at the surface of the skin where the second temperatures T 2 , T′ 2  are greater than the first temperature T 1  and the third temperature T 3 . 
     Conversely, for some embodiments, the device may be configured to generate a cooling pulse for inducing a perceived cooling effect to the user. Here, similar to the heating experience, the user may feel the sensation of being cooled locally or in other areas of the body, while the actual temperature of the body is generally maintained. The cooling pulse may involve a decrease in temperature at the surface of the skin of the user, quickly followed by an increase in temperature.  FIGS. 5A-5B  depict schematic representations of a cooling pulse generated at the surface of the skin where the second temperatures T 2 , T′ 2  are less than the first temperature T 1  and the third temperature T 3 . 
     The temperature at a surface may fall within any appropriate range. For example, the first temperature T 1  may be room temperature (e.g., ambient temperature), or normothermia (e.g., resting body temperature). In some embodiments, the first temperature T 1  is greater than or equal to about 0° C., greater than or equal to about 5° C., greater than or equal to about 10° C., greater than or equal to about 15° C., greater than or equal to about 20° C., greater than or equal to about 22° C., greater than or equal to about 23° C., greater than or equal to about 24° C., greater than or equal to about 25° C., greater than or equal to about 27° C., greater than or equal to about 29° C., greater than or equal to about 30° C., greater than or equal to about 32° C., greater than or equal to about 34° C., greater than or equal to about 35° C., greater than or equal to about 36° C., greater than or equal to about 37° C., greater than or equal to about 38° C., or greater than or equal to about 40° C. In some embodiments, the first temperature T 1  is less than about 45° C., less than about 40° C., less than about 38° C., less than about 37° C., less than about 36° C., less than about 35° C., less than about 34° C., less than about 32° C., less than about 30° C., less than about 29° C., less than about 27° C., less than about 25° C., less than about 24° C., less than about 23° C., less than about 22° C., less than about 20° C., less than about 15° C., less than about 10° C., or less than about 5° C. Combinations of the above referenced ranges are also possible (e.g., between about 22° C. and about 29° C., between about 34° C. and about 38° C.). Other temperatures are also possible. 
     The difference in magnitude between two temperatures (e.g., between the first initial temperature and the second pulsed temperature, between the second pulsed temperature and the third return temperature) may fall within a suitable range. In some cases, where T 2  is greater than T 1 , the difference in magnitude is determined by taking the magnitude of the difference after subtracting T 1  from T 2 . For cases where T 1  is greater than T 2 , the difference in magnitude is determined by taking the magnitude of the difference after subtracting T 2  from T 1 . 
     In some embodiments, the difference in magnitude between the second (pulsed) temperature T 2 , or modified second (pulsed) temperature T′ 2  (whichever is further from the first temperature T 1 ), and the first (initial) temperature T 1  is between about 1° C. and about 10° C. As noted above, it can be appreciated that the modified second temperature T′ 2  is not required to be reached at the end of the optional second regime II. That is, in some cases, the modified second temperature T′ 2  may be characterized as a temperature within the profile that is furthest from the initial temperature T 1 . In certain embodiments, the difference in magnitude between whichever of the second temperatures T 2 , T′ 2  that is greater in value and the first temperature T 1  is greater than or equal to about 1° C., greater than or equal to about 1.2° C., greater than or equal to about 1.4° C., greater than or equal to about 1.5° C., greater than or equal to about 1.6° C., greater than or equal to about 1.8° C., greater than or equal to about 2° C., greater than or equal to about 2.5° C., greater than or equal to about 3° C., greater than or equal to about 4° C., greater than or equal to about 5° C., greater than or equal to about 6° C., greater than or equal to about 7° C., greater than or equal to about 8° C., or greater than or equal to about 9° C. In some embodiments, the difference in magnitude between whichever of the second temperatures T 2 , T′ 2  that is greater in value and the first temperature T 1  is less than about 10° C., less than about 9° C., less than about 8° C., less than about 7° C., less than about 6° C., less than about 5° C., less than about 4° C., less than about 3° C., less than about 2.5° C., less than about 2° C., less than about 1.8° C., less than about 1.6° C., less than about 1.5° C., less than about 1.4° C., or less than about 1.2° C. Combinations of the above referenced ranges are also possible (e.g., between about 1° C. and about 10° C., between about 1° C. and about 8° C., between about 2° C. and about 8° C., between about 1° C. and about 7° C., between about 1° C. and about 6° C., between about 1° C. and about 3° C.). Other ranges are also possible. 
     The above discussion with respect to the possible differences in magnitude between the first and second temperatures may also be applicable when considering the difference in magnitude between the second temperature T 2 , T′ 2  and the third temperature T 3 . For example, in some embodiments, the difference in magnitude between the second temperature T 2 , or modified second temperature T′ 2  (whichever is further from the first temperature T 3 ), and the third temperature T 3  may fall between about 1° C. and about 10° C., certain ranges disclosed above, or other ranges outside of the ranges disclosed. 
     In some embodiments, the third temperature T 3  at the surface of the skin (at the end of a thermal pulse) may approximate the first temperature T 1  at the surface of the skin (at the beginning of the thermal pulse). As noted above, it can be appreciated that, in some instances, the first temperature T 1  at the surface of the skin, prior to application of a thermal pulse, may be greater or less than the third temperature T 3  at the surface of the skin, after application of the thermal pulse. 
     In some embodiments, the third (return) temperature T 3  varies from the first (initial) temperature T 1  by a relatively small amount. For example, a difference in magnitude between the first temperature T 1  and the third temperature T 3  at the surface of the skin may be less than or equal to about 10° C., less than or equal to about 8° C., less than or equal to about 6° C., less than or equal to about 4° C., less or equal to about than about 2° C., less than or equal to about 1° C., less than or equal to about 0.8° C., less than or equal to about 0.5° C., less than or equal to about 0.2° C., or less than or equal to about 0.1° C., or outside of the above noted ranges. 
     In some embodiments, the third (return) temperature T 3  varies from the first (initial) T 1  by a small percentage, as compared to the difference between the first temperature T 1  and whichever of the second (pulsed) temperatures T 2 , T′ 2  that is further from the first temperature T 1 . For example, the difference in magnitude between the first (initial) temperature T 1  and the third (return) temperature T 3  at the surface of the skin may be less than or equal to about 25% of the difference in magnitude between the first (initial) temperature T 1  and the second (pulsed) temperature T 2 , T′ 2 , i.e. as determined by the equation (T 3 −T 1 )/(T 2 −T 1 )×100%, or (T 3 −T 1 )/(T′ 2 −T 1 )×100% depending on whether the temperature difference between T 2  and T 1 , or T′ 2  and T 1 , is greater in magnitude. If the magnitude of T 2 −T 1  is greater than the magnitude of T′ 2 −T 1 , then the former equation is used; though, if the magnitude of T 2 −T 1  is less than the magnitude of T′ 2 −T 1 , then the latter equation is used. In some cases, the difference in magnitude between the first (initial) temperature and the third (return) temperature may be less than or equal to about 25%, less than or equal to about 20%, less than or equal to about 15%, less than or equal to about 10%, less than or equal to about 5%, less than or equal to about 2%, or less than or equal to about 1% of the difference in magnitude between the first (initial) temperature and the second (pulsed) temperature. 
     In certain embodiments, the first temperature and the third temperature may be about equal (i.e., a reversible thermal pulse) which, in some cases, may occur during steady-state operation of the device. It should be noted that the third temperature T 3  may be determined at a time point at which the temperature adjustment between the second temperature T 2 , T′ 2  and the third temperature T 3  has stopped (e.g., the temperature at the surface of the skin reaches a substantially steady state, or when a new pulse has been initiated). For example, in some embodiments in which the controller is configured to cause the thermoelectric material(s) to generate a plurality of thermal pulses in succession, the third temperature T 3  may be determined at the time point when the next thermal pulse begins. Or, in certain embodiments, the third temperature T 3  may be determined at a time point at which the temperature has reached a substantially steady state (e.g., the third temperature does not change in magnitude by more than about 5% over 5 seconds). 
     It can be appreciated that the device may adjust the temperature at the surface of the skin so as to change during various regimes of a thermal pulse, according to a preferred shape or profile. For example, at any given time during the thermal pulse, the temperature profile may exhibit a behavior that is substantially linear, non-linear, exponential (e.g., exponential growth, exponential decay), polynomial (quadratic, cubed, etc.), irregular (e.g., following a piecewise function), or another suitable behavior. 
     Referring to  FIGS. 4A-5B , for some embodiments, the first regime I of the thermal profile may exhibit a substantially linear behavior. That is, for these embodiments, the controller is configured to apply an electrical signal (e.g., square wave voltage) that results in a substantially linear temperature profile over time, for the first regime I. Though, it can be appreciated that other temperature profiles are possible. 
     In some embodiments, the third regime III of the temperature profile may also exhibit substantially linear behavior, such as that shown in  FIGS. 4A and 5A . That is, in some embodiments, the thermal pulse generated by the thermoelectric material(s), or other thermal adjustment apparatus, may be characterized by at least a portion of the temperature adjustment at the surface of the skin exhibiting a behavior between one of the second temperatures T 2 , T′ 2  and the third temperature T 3  that is substantially linear over time. 
     Though, for certain embodiments, the temperature adjustment at the surface of the skin between one of the second temperatures T 2 , T′ 2  and the third temperature T 3  may exhibit a behavior that is not substantially linear over time. For example, as illustrated by  FIGS. 4B and 5B , at least a portion of the temperature adjustment at the surface of the skin from the thermal pulse between the second temperature T 2 , T′ 2  and the third temperature T 3  may exhibit a substantially exponential decay behavior over time. The phrase “exponential decay” generally refers to a behavior in which the parameter (e.g., temperature) reasonably fits an equation such as T(t)=T 0 e −λt , where T(t) is the temperature at a given time, t, T 0  is the initial temperature, and λ is a constant. 
     In accordance with aspects of the present disclosure, the duration of time of each thermal pulse may suitably vary. The degree of the enhanced thermal sensation and, hence, overall thermal comfort, of a user may depend, at least in part, on the particular duration of the thermal pulse(s), which may be tailored as appropriate. That is, in some cases, a thermal pulse that is too long or too short might not result in a desired level of thermal sensation for a user. The time period may be measured as the time elapsed during a thermal cycle at the surface of the skin from the first temperature T 1  to the third temperature T 3 , as illustrated in  FIGS. 4A-5B . For example, as illustrated in  FIG. 6 , the time period may be measured as the difference between a time point at the start of a first pulse t 1  and a time point at the start of a second pulse t 2 . 
     In some embodiments, the thermal adjustment apparatus, or controller configured to apply an electrical signal to the thermoelectric material(s), may generate a thermal pulse over a time period of less than or equal to about 120 seconds. In certain embodiments, the time period of an entire thermal pulse from an initial temperature to another, pulsed temperature and substantially returning to the initial temperature (with negligible difference between the initial temperature and the final temperature of the pulse) is less than or equal to about 90 seconds, less than or equal to about 75 seconds, less than or equal to about 60 seconds, less than or equal to about 50 seconds, less than or equal to about 45 seconds, less than or equal to about 40 seconds, less than or equal to about 30 seconds, less than or equal to about 20 seconds, less than or equal to about 15 seconds, less than or equal to about 10 seconds, less than or equal to about 7 seconds, less than or equal to about 5 seconds, less than or equal to about 4 seconds, less than or equal to about 3 seconds, less than or equal to about 2 seconds, or less than or equal to about 1 second. In some embodiments, the time period of a thermal pulse is greater than about 2 seconds, greater than about 3 seconds, greater than about 4 seconds, greater than about 5 seconds, greater than about 6 seconds, greater than about 7 seconds, greater than about 10 seconds, greater than about 15 seconds, greater than about 20 seconds, greater than about 30 seconds, greater than about 40 seconds, greater than about 50 seconds, greater than about 60 seconds, greater than about 75 seconds, or greater than about 90 seconds. Combinations of the above-referenced ranges are also possible (e.g., between about 2 seconds and about 5 seconds, between about 3 seconds and about 10 seconds, between about 10 seconds and about 30 seconds, between about 10 seconds and about 60 seconds, or between about 15 seconds and about 90 seconds). Other ranges are also possible. 
     Within a thermal pulse, the initial temperature adjustment of the thermal pulse (e.g., regime I shown in  FIGS. 4A-5B and 8-9 , period in which the temperature at the surface of the skin undergoes a sharp, continuous increase or decrease) may last for a suitable duration. In some embodiments, the initial temperature adjustment of a thermal pulse may last for less than or equal to about 60 seconds, less than or equal to about 50 seconds, less than or equal to about 40 seconds, less than or equal to about 35 seconds, less than or equal to about 30 seconds, less than or equal to about 25 seconds, less than or equal to about 20 seconds, less than or equal to about 15 seconds, less than or equal to about 10 seconds, less than or equal to about 5 seconds, less than or equal to about 4 seconds, less than or equal to about 3 seconds, or less than or equal to about 2 seconds. In some embodiments, the time period of the initial temperature adjustment of a thermal pulse is between about 1 second and about 30 seconds, between about 1 second and about 10 seconds, between about 2 seconds and about 5 seconds, or between about 2.5 seconds and about 4 seconds. Other ranges are also possible. 
     The temperature adjustment of the thermal pulse on return (e.g., regime III shown in  FIGS. 4A-5B and 8-9 , period in which the temperature at the surface of the skin undergoes a gradual increase or decrease back toward the initial temperature) may last for a suitable period of time. In some embodiments, the temperature adjustment of the thermal pulse on return may last for less than or equal to about 60 seconds, less than or equal to about 50 seconds, less than or equal to about 40 seconds, less than or equal to about 30 seconds, less than or equal to about 20 seconds, less than or equal to about 10 seconds, or less than or equal to about 5 seconds. In some embodiments, the time period of the temperature adjustment on return may be between about 1 second and about 60 seconds, between about 1 second and about 5 seconds, between about 2 seconds and about 3 seconds, between about 5 seconds and about 30 seconds, between about 5 seconds and about 20 seconds, or between about 5 seconds and about 10 seconds. Other ranges are also possible. 
     Temperature adjustments of the thermal pulse may exhibit a suitable rate of change of the temperature over time. In some embodiments, the temperature adjustment (e.g., the temperature adjustment from the first initial temperature to the second pulsed temperature, the temperature adjustment from the second pulsed temperature (or the optional modified second pulsed temperature to the third return temperature), the optional temperature adjustment from the second temperature to the modified second temperature) occurs over a particular period of time. 
     In certain embodiments, the first temperature adjustment (e.g., thermal change on the initial pulse, between the first initial temperature and the second pulsed temperature) occurs over a shorter period of time than the second temperature adjustment (e.g., thermal change on return, between the second pulsed temperature (or the optional modified second pulsed temperature) and the third return temperature). That is, in some embodiments, the magnitude of the average rate of the first temperature adjustment at the beginning of the thermal pulse may be greater than the magnitude of the average rate of the second temperature adjustment at the end of the thermal pulse. 
     As provided herein, the magnitude of the average rate may be determined by calculating the difference in magnitude between temperature limits (e.g., magnitude of the difference between the first initial temperature and the second pulsed temperature for the first adjustment, magnitude of the difference between the second pulsed temperature and the third return temperature for the second adjustment) and dividing this difference in magnitude between temperature limits by the time over which the temperature is adjusted. As an example, when applying a cooling pulse, if the duration of the first temperature adjustment upon initiation of the pulse is 5 seconds, where the first initial temperature is 28° C. and the second pulsed temperature is 23° C., the magnitude of the average rate of temperature change for this portion of the pulse is 1° C./sec. For the same cooling pulse example, if the duration of the second temperature adjustment upon return of the pulse is 10 seconds, where the second pulsed temperature is 23° C. and the third return temperature is 28° C., the magnitude of the average rate of temperature change for this portion of the pulse is 0.5° C./sec. 
     In various embodiments, the average rate of the first temperature adjustment, upon initiation of the thermal pulse, between the first initial temperature and the second pulsed temperature, may range between about 0.1° C./sec and about 10.0° C./sec. In some embodiments, the average rate of temperature adjustment on initiation of the thermal pulse is greater than or equal to about 0.1° C./sec, greater than or equal to about 0.2° C./sec, greater than or equal to about 0.3° C./sec, greater than or equal to about 0.5° C./sec, greater than or equal to about 0.7° C./sec, greater than or equal to about 1.0° C./sec, greater than or equal to about 1.5° C./sec, greater than or equal to about 2.0° C./sec, greater than or equal to about 3.0 ° C./sec, greater than or equal to about 5.0° C./sec, or greater than or equal to about 7.0° C./sec. In certain embodiments, the average rate of the temperature adjustment on initiation of the thermal pulse is less than about 10.0° C./sec, less than about 7.0° C./sec, less than about 5.0° C./sec, less than about 3.0° C./sec, less than about 2.0° C./sec, less than about 1.5° C./sec, less than about 1.0° C./sec, less than about 0.7° C./sec, less than about 0.5° C./sec, less than about 0.3° C./sec, or less than about 0.2° C./sec. Combinations of the above-referenced ranges are possible (e.g., between about 0.1° C./sec and about 10.0° C./sec, between about 0.1° C./sec and about 5.0° C./sec, between about 0.3° C./sec and about 3.0° C./sec, between about 0.3° C./sec and about 1.0° C./sec, between about 0.3° C./sec and about 0.8° C./sec, between about 0.5° C./sec and about 3.0° C./sec). Other ranges are also possible. 
     The average rate of second temperature adjustment, upon return of the thermal pulse, between the second pulsed temperature and the third return temperature, may fall within a similar range as that of the first temperature adjustment. For example, the average rate of the second temperature adjustment, on return of the thermal pulse, may range between about 0.1° C./sec and about 10.0° C./sec. In various embodiments, the average rate of temperature adjustment on return of the thermal pulse is greater than or equal to about 0.1° C./sec, greater than or equal to about 0.2° C./sec, greater than or equal to about 0.3° C./sec, greater than or equal to about 0.5° C./sec, greater than or equal to about 0.7° C./sec, greater than or equal to about 1.0° C./sec, greater than or equal to about 1.5° C./sec, greater than or equal to about 2.0° C./sec, greater than or equal to about 3.0° C./sec, greater than or equal to about 5.0° C./sec, or greater than or equal to about 7.0° C./sec. In certain embodiments, the average rate of the temperature adjustment on return of the thermal pulse is less than about 10.0° C./sec, less than about 7.0° C./sec, less than about 5.0° C./sec, less than about 3.0° C./sec, less than about 2.0° C./sec, less than about 1.5° C./sec, less than about 1.0° C./sec, less than about 0.7° C./sec, less than about 0.5° C./sec, less than about 0.3° C./sec, or less than about 0.2° C./sec. Other ranges as well as combinations of the above-referenced ranges are also possible. 
     As discussed herein, in some cases, the average rate of temperature change upon initiation of the pulse may be greater in magnitude than the average rate of temperature change on return of the pulse. In certain embodiments, the magnitude of the average rate of the first temperature adjustment is greater than the magnitude of the average rate of the second temperature adjustment by at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, or at least 80% of the first average rate. In some embodiments, a user may experience an overall increase in thermal sensation, hence, an enhanced level of thermal comfort, as compared to embodiments wherein the first average rate is equal to, or less than, the second average rate of temperature adjustment. 
     The inventors have recognized that generating thermal pulses that incorporate the above-referenced ranges of average rates of temperature change, and rate differences at certain portions of the thermal pulse, are able to enhance the effects of the thermal pulsing, resulting in the ability to increase levels of localized thermal comfort to the average user. This is in stark contrast to the use of large scale heating or cooling systems (e.g., HVACs, or the like), which are non-localized, and longer term heating or cooling systems (e.g., cold packs, hot packs, or the like), which fail to provide the desired thermal sensation. 
     As discussed above, the thermal adjustment apparatus may include a controller that applies an appropriate electrical signal to the thermoelectric material(s), for generating the appropriate thermal pulse(s). The electrical signal may include a suitable step up/down in voltage, current, etc. 
     In some embodiments, the controller includes a voltage source, for generating a suitable electrical signal. In certain embodiments, the voltage source applies a voltage to the thermoelectric material(s) suitable to create a thermal pulse at the surface of the skin of a user. For example, as illustrated in  FIGS. 4A-5B , the controller may be configured to apply a first voltage V 1 , a second voltage V 2 , and/or a third voltage V 3 . Though, it can be appreciated that other voltages may be applied in accordance with any appropriate signal pattern. For instance, rather than applying a constant voltage, the electrical signal may employ pulse width modulation, where the width of the pulse is modulated according to a suitable duty cycle (e.g., 10-50% duty cycle), for example, for modulating (and conserving) the power provided to the device. In some cases, pulse width modulation may be applied using suitable duty cycles having relatively short timescales (&gt;100 Hz). Any suitable form of pulse width modulation may be employed. 
     In some cases, whether the potential that is applied is positive or negative may correspond to whether a heating pulse or cooling pulse is desired. For instance,  FIGS. 4A-4B  correspond to a heating pulse, where the voltage applied results in an increase in temperature at the surface of the skin.  FIGS. 5A-5B , in contrast, correspond to a cooling pulse; here, the voltage applied results in a decrease in temperature at the surface of the skin. Though, it can be appreciated that certain heating or cooling pulses may involve both positive and negative voltages being applied to the thermoelectric material(s) (e.g., via pulse width modulation where voltages are pulsed at an appropriate duty cycle). The average magnitude of a voltage applied to the thermoelectric material(s) at any given point (e.g., first voltage, second voltage, third voltage) may fall within a suitable range. For example, the average magnitude of the voltage applied to the thermoelectric material(s) may be between about 0.1 V and about 10.0 V, between about 1.0 V and about 8.0 V, between about 2.0 V and about 5.0 V, between about 0.1 V and about 5.0 V, between about 0.1 V and about 1.5 V, between about 0.1 V and about 1.0 V, between about 1.0 V and about 3.0 V, between about 3.0 V and about 8.0 V, or any other appropriate range. In some cases, as illustratively shown in  FIGS. 4A-5B , the average magnitude of the first voltage may be greater than respective average magnitudes of subsequent voltages (e.g., second voltage, third voltage, etc.) applied during the thermal pulse, for example, to create a sharp temperature adjustment at the surface of the skin from a first initial temperature to a second pulsed temperature. As further shown, the average magnitude of the step voltage applied may drop off, for example, to a second voltage V 2  and a third voltage V 3 , so as to allow for temperature reversibility of the thermal pulse in a manner that is more gradual on return. 
     As shown in the figures, the third voltage is given by a lack of applied electrical signal, and is depicted to be essentially zero. In some cases, the average magnitude of the third voltage V 3  may be substantially non-zero, for example, while also being less than the average magnitude of the first voltage V 1  and/or the average magnitude of the second voltage V 2 . It can be appreciated that, for some embodiments, a voltage (e.g., step voltage) may also be applied in the opposite direction (e.g., negative voltage on return after a positive voltage on initiation of the pulse), so as to elicit a sharper temperature change during the return portion of the thermal pulse. For example, in some embodiments, the first voltage V 1  applied to the thermoelectric material(s) may be positive (e.g., during a heating thermal pulse) and the second voltage V 2  may be negative (e.g., to cause the temperature at the surface of the skin to decrease more sharply); or vice versa where the first voltage V 1  applied to the thermoelectric material(s) is negative and the second voltage V 2  is positive. 
       FIGS. 8-9  show a number of temperature measurements at the surface of the thermoelectric. As illustrated in these figures, the voltage applied during the second regime II of the thermal pulse is varied, by magnitude (shown in  FIG. 8 ) and duration (shown in  FIG. 9 ). This demonstrates an ability for the thermal pulse(s) generated at the surface of the skin to be controlled and varied as desired. Accordingly, the temperature profile of a thermal pulse may be appropriately tailored to suit the thermal needs of the user. For example, as noted herein, it can be appreciated that any suitable voltage profile may be applied to the thermoelectric material(s), according to any appropriate pattern. 
       FIG. 8  shows a group of waveforms where the duration in which the optional second voltage V 2  was applied was kept constant, and the magnitude of the second applied voltage V 2  was varied. In this example, waveform  200  corresponds to the instance where no second voltage V 2  was applied (i.e., second voltage V 2  applied was zero) and waveform  210  corresponds to the case where the second voltage V 2  is greatest in magnitude amongst the group. As depicted, when the second voltage V 2  is effectively zero, the temperature relaxes in accordance with an exponential decay, as if a single square voltage V 1  was applied. Though, upon application of a non-zero second voltage V 2 , the temperature at the surface may still increase, albeit not as sharply as in the case where the initial voltage V 1  is applied. When the second voltage V 2  is no longer applied, the temperature profile exhibits relaxation decay behavior. 
     As illustrated in  FIG. 9 , the magnitude of the optional second voltage V 2  was kept constant and the duration of the second applied voltage V 2  was varied. In this example, the length of time between the second applied voltage V 2  and the third applied voltage V 3  was varied between 0 seconds and about 10 seconds. As shown, the waveform  300  corresponds to the instance where no second voltage V 2  was applied (applied for 0 seconds) and waveform  310  corresponds to the case where the second voltage V 2  is applied for the longest period of time (applied for 10 seconds) amongst the group. As depicted, as the second voltage V 2  lasts longer, the temperature at the surface may continue to increase or hover around a particular temperature range. And, as application of the second voltage V 2  ceases, the temperature at the surface decays back toward the initial temperature. 
     In some embodiments, the controller includes a current source, for generating a suitable electrical signal. The current source may apply a current to the thermoelectric material(s), for generating a thermal pulse at the surface of the skin of a user. The magnitude of a current applied to the thermoelectric material(s) at any given point may fall within a suitable range. In some embodiments, the magnitude of a current applied to the thermoelectric material(s) may be between about 0.1 A and about 4.0 A, between about 0.1 A and about 3.5 A, between about 0.1 A and about 3.0 A, between about 0.2 A and about 2.5 A, between about 0.5 A and about 2.0 A, between about 1.0 A and about 2.0 A, between about 0.1 A and about 1.5 A, between about 0.1 A and about 1.0 A, between about 0.5 A and about 1.0 A, between about 0.1 A and about 0.5 A, between about 1.0 A and about 1.5 A, or any other appropriate range. The electrical signal(s) may be applied to the thermoelectric material(s) in accordance with any suitable form or pattern. In some embodiments, the electrical signal(s) may be applied to the thermoelectric material(s) as one or more square waves (i.e., a constant voltage/current applied for a period of time), which may result in a particular rate of temperature change, depending on how the electrical signal is applied. Or, the electrical signal(s) may exhibit more complex behavior, for example, the electrical signal(s) may be applied as a linear ramp function, non-linear, exponential, polynomial function, piecewise function, etc. 
     As shown in  FIGS. 4A-5B , for some embodiments, to initiate the thermal pulse, as provided in regime I, a first square wave voltage is applied to the thermoelectric material(s), resulting in a sharp linear temperature adjustment at the surface of the skin from the first temperature T 1  to the second temperature T 2 . In regime II, a second square wave voltage is applied, the magnitude of which is less than the magnitude of the first square wave, resulting in a relatively constant, insubstantial change in the temperature T 2 , T′ 2  at the surface of the skin. In regime III, no voltage is applied, resulting in a thermal adjustment to the third temperature T 3 , which may be different from the first initial temperature T 1  by a small amount/percentage. 
     As noted further above, the inventors have recognized that the use of thermal pulses, as described herein, can significantly reduce energy consumption of the device that would otherwise be much greater when the device is operated without thermal pulsing. For example, typical traditional thermoelectric and/or heat generating devices that do not employ such thermal pulsing, or are operated so as to maintain a continuous temperature state, consume comparatively larger amounts of energy. Thus, the relatively low energy consumption afforded by embodiments of the present disclosure may enable an entirely new class of devices to be constructed, such as in various embodiments described herein. For example, the thermoelectric material  110 , thermally conductive material  120 , power source  130  and/or controller  140  may be provided with unique housings that occupy relatively small volumes and/or are characterized by relatively small surface area. Such housings may provide for the device to be modular, for example, able to be coupled and decoupled with a variety of support structures (e.g., wearable articles). 
     In an example of a traditional macroscopic cooling application (i.e. application that does not involve cooling microelectronic components), a 40×40 mm thermoelectric module typically requires an average power consumption of between about 60 Watts and about 90 Watts during continuous (non-pulsing) operation. In such cases, in order for the heat generated by operation of change caused by a heat pump or other thermal adjustment apparatus to not cause the device temperature to rise excessively during continuous use, the energy consumed by the heat pump is generally dissipated as heat. Under standard operating conditions, traditional thermoelectric modules may require heat dissipation of between about 70 Watts and about 120 Watts. Such large heat dissipation generally requires the use of heat sinks that have relatively large surface areas (e.g., via the incorporation of parallel fins), which can be undesirably large and cumbersome. 
     Furthermore, in traditional macroscopic cooling applications, forced convection (e.g., fans) is generally required to increase the rate at which heat can be dissipated from the high surface area heat sink. Accordingly, the high-power operation modes of previous thermoelectric devices often heavily constrain the geometries of previous thermoelectric devices where heat dissipation requirements have generally driven device design. 
     By contrast, devices in accordance with certain embodiments of the present disclosure require significantly less energy than traditional thermoelectric apparatuses of an equivalent physical size or capacity (e.g., characterized by volume and/or surface area). For example, in some embodiments, a device may employ one or more thermoelectric materials located adjacent a surface (e.g., skin), along with a controller and power source configured to operate the thermoelectric material(s) so as to generate multiple thermal pulses in succession at the surface. Such thermal pulsing may result in the power source having a relatively low power consumption. 
     Certain embodiments of the device may be operated so as to exhibit any of a wide variety of suitable average power consumption by the power source (e.g., the power source generating power for the thermoelectric material, the controller and/or other components of the device). In some embodiments, the average power consumption of the power source, thermoelectric material(s) and/or controller during the thermal pulse generation is less than about 20 Watts, less than about 15 Watts, less than about 10 Watts, less than about 8 Watts, less than about 6 Watts, less than about 5 Watts (e.g., between 1 Watt and 5 Watts, between 2 Watts and 5 Watts, between 3 Watts and 5 Watts, between 4 Watts and 5 Watts), less than about 4 Watts (e.g., between 1 Watt and 4 Watts, between 2 Watts and 4 Watts, between 3 Watts and 4 Watts), less than about 3 Watts (e.g., between 1 Watt and 3 Watts, between 2 Watts and 3 Watts), less than about 2 Watts (e.g., between 1 Watt and 2 Watts), or less than about 1 Watt. As provided herein, power consumption is determined by measuring the current and voltage across the unit of interest and calculating the power according to Ohm&#39;s Law (P=I*V). For example, in determining the power consumption of the power source, leads are placed across the power source, and the power consumption is given by the product of the measured current and the measured voltage. Such a level of power consumption arising from devices described herein (e.g., due in part to thermal pulsing) is significantly lower than the average power consumption of typical traditional thermoelectric devices continuously operating over an equivalent surface area, as described above. Accordingly, the devices described herein may have a lower overall power requirement (e.g., enabling significantly longer lifetimes for a given power source). 
     In addition, devices described herein may in certain embodiments employ heat dissipating units that have relatively small surface area. Such a low power consumption is not typically considered achievable in conventional thermoelectric devices used for macroscopic heating and cooling applications, so, accordingly, such typical, conventional devices do not enjoy the flexibility of sizes and geometries achievable for certain devices designed to function under such low power consumption conditions, as provided in the present disclosure. 
     A dissipation unit (e.g., a heat exchanger) maintained at a temperature different from its surroundings exchanges heat with the surroundings. The performance of a dissipation unit may therefore be defined as the amount that the temperature of the dissipation unit rises per unit power dissipated by the heat sink; the more effective the dissipation unit, the larger amount is the amount of power that it can dissipate while maintaining a given temperature difference between itself and the surroundings, i.e. the less effective the dissipation unit, the larger is the temperature difference with the surroundings required to achieve the same amount of power dissipation. This performance may be measured in degrees Celsius temperature change per watt of heat exchanged, sometimes called the thermal resistance. For certain electronics applications, effective dissipation units may exhibit very low thermal resistances of around 2 degrees Celsius per Watt or less. 
     In an application where a primary objective is to maintain the temperature of a device below a certain operating temperature, a relatively small maximal temperature rise of the device can be the control set-point. Therefore, according to the present invention, a lower heat dissipation, higher thermal resistance dissipation unit may be used in certain such applications. Certain embodiments of the devices disclosed herein exhibit particularly low energy consumption compared with typical conventional dissipation units for electronics applications in the prior art, advantageously enabling new dissipation unit geometries. More specifically, dissipation unit without the fins and other high-surface-area elements, or reliance on evaporation of a working fluid, conventionally employed in typical existing dissipation unit may be used, thus enabling more compact, wearable designs. Additional advantageous product configurations can be facilitated by the use of a relatively high thermal resistance heat sink. For example, the dissipation unit may also serve as the electronics enclosure to further reduces part count and device volume, significantly enhancing device wearability. 
     Certain devices in accordance with the present disclosure may also be constructed as a compact, self-contained module. In some embodiments, a compact, self-contained module may contain a number of elements, such as a thermal adjustment apparatus, a heat dissipation or heat capacitance unit for the heat modulation unit, a control unit to operate the thermal adjustment apparatus, a power source to power the device, and/or a housing. In some cases, the device may be miniaturized by designing the device such that one or more units serve multiple functions. For example, the housing may function both as a protective support structure/enclosure as well as a heat sink. 
     Accordingly, certain devices may include a housing having a thermally conductive material, which may allow for heat dissipation. In some embodiments, the housing, which may optionally include a thermally conductive material, provides an enclosure which at least partially surrounds one or more functional units of the device, such as the controller and/or the power source. In certain embodiments, the housing forms an enclosure that at least partially surrounds the controller and/or power source on multiple sides of the controller and/or power source. In certain embodiments, the housing has an opening that provides space for a plug-in connection (e.g., such as a USB connection), for example, so that the power source can be suitably charged. 
     In some embodiments, the device includes a thermally conductive material located adjacent to and/or in contact (e.g., thermal contact, direct physical contact) with the thermoelectric material(s). In certain embodiments, at least a portion of the thermally conductive material has a substantially flat surface (e.g., without fins or similar features that extend away from the surface for the purpose of increasing the surface area for heat transfer), allowing the overall device construction to be relatively sleek and/or compact. In some embodiments, the substantially flat surface may have a surface profile that extends between opposing end regions of the device. In certain embodiments, a portion of the thermally conductive material has a surface profile substantially free of protrusions extending greater than 1 mm (or, e.g., greater than 2 mm, greater than 3 mm, greater than 4 mm, greater than 5 mm, etc.) away from the portion of the surface immediately surrounding the protrusion. 
     In an exemplary embodiment,  FIGS. 11A-11E  depict a device  100  that includes a housing  180  having a thermally conductive material  120  (e.g., including heat dissipative fins  124  provided as part of the enclosure) and a cover  402  which may optionally be thermally conductive. That is, the thermally conductive material  120  may include features for dissipating heat, and other portions of the housing, such as the cover  402 , may also include features and/or thermally conductive material suitable for dissipating heat. The device  100  may further include a power source  130  and a controller  140 , each located inside the enclosure. A thermoelectric material  110  is provided underneath the housing so as to be suitably positioned adjacent to and/or in contact with the target surface. The housing may form an enclosure that surrounds the controller and/or the power source on multiple sides. Though, in some embodiments, the housing may also at least partially enclose the thermoelectric material(s). 
     As noted above, for various embodiments, due to the low power consumption and, hence, reduced need for significant heat dissipation, the thermally conductive material of the device may have a relatively small surface area. That is, it is not required in certain embodiments for much of the housing or enclosure to have heat dissipating features, such as protrusions or fins. In some embodiments, a significant portion of the housing or enclosure may exhibit a substantially flat surface profile. For example, as shown in  FIG. 11A , a portion of the enclosure that extends between opposite ends of the device (e.g., end regions  190  and  192 ) may be substantially flat, such that the surface profile is free of protrusions. In some embodiments, the ratio of an externally facing surface area of the thermally conductive material and an externally facing surface area of the thermoelectric material(s) may be small, for example, less than about 20, less than about 15, less than about 10, less than about 8, less than about 6, less than about 5, less than about 4, less than about 3, less than about 2, or less than about 1. The ratio of the externally facing surface area of the thermally conductive material and the externally facing surface area of the thermoelectric material(s) may vary outside of these ranges. 
     In some embodiments, the thermally conductive material may function as a heat dissipation unit that may tolerate relatively large temperature changes given a certain amount of power applied. For example, the heat dissipation unit may be configured to undergo a temperature change of greater than 5 degrees C., greater than 10 degrees C., greater than 15 degrees C., greater than 20 degrees C., greater than 25 degrees C., or more, per Watt of power applied thereto at standard state ambient conditions (i.e. Standard Ambient Temperature and Pressure (SATP) which is an environment with a temperature of 25 degrees C. and an absolute pressure of 100 kPa (0.987 atm).) This characteristic may be determined by placing the heat dissipation unit in contact with a temperature measurement apparatus (e.g., thermocouple) and measuring the temperature change recorded by the temperature measurement apparatus upon application of a Watt of power. It has not been found that the measured temperature change behavior of the thermally conductive material/heat dissipation unit as a function of power consumption, as measured as outlined above, is particularly sensitive to whether the thermally conductive material/heat dissipation unit is in contact with another surface or in a surrounding air environment during testing, so that a suitable screening test to determine whether an article meets such a performance parameter would be to place the heat dissipation unit in contact with a temperature measurement apparatus in a surrounding air environment at and measuring the temperature change under SATP conditions. In some embodiments, the heat dissipation unit may have thermal dissipation characteristics that are suitable to maintain the temperature of the surface adjacent the thermoelectric (e.g., skin) within a desirable operating range (e.g., below approximately 50 degrees C.) that is comfortable to the user and/or safe for any electronic components adjacent the thermally conductive material during operation of the device. That is, the power consumed by the device may be low enough such that the heat dissipating unit is not required to rapidly dissipate heat, reducing or eliminating a need to provide higher surface area heat dissipation units which dissipate heat more rapidly (e.g. so as to exhibit a temperature change of as small as 1 degree C. per Watt of power applied thereto at standard ambient temperature and pressure (SATP) conditions.) 
     During use, the thermoelectric material may be placed adjacent to the skin by the user. In some embodiments, the cover  402 , thermally conductive material  120  and/or other portions of the housing enclosure may be textured, colored, anodized and/or shaped according to any suitable design aesthetic. In certain embodiments, the cover  402  may be detachable, for example, allowing the device to be modular and/or easily customized in appearance. 
       FIG. 11B  depicts the internal geometry of the housing enclosure, according to an illustrative embodiment. In some embodiments a power connector  432  is integrated with the controller  140  such that that power source  130  can be recharged. That is, as discussed above, the housing may include an opening that allows for a plug-in connection for the device. In an exemplary embodiment, a charging unit (e.g., micro-USB) is provided such that an appropriate cable (e.g., USB cable) can be inserted into the device through the opening of the housing. 
     Any suitable controller for operating the thermal adjustment apparatus may be employed. For instance, thermoelectric materials may be configured to operate solely based on electrical input(s) received from a printed circuit board having a suitable microcontroller, motor driver, and/or other components common in the art for modulating input voltages to an external device. It can be appreciated that the type of controller employed will be compatible with the type of thermal adjustment apparatus and energy source used to power the device, for suitable operation thereof. For example, the controller may be appropriate for use in controlling thermoelectric material(s), heat/cooling pump(s) and/or any other suitable apparatus for adjusting temperature at a surface. 
     The device may further include a user interface, for providing input to the controller. The user interface may be configured to provide one or more signals to the controller for appropriately operating the device, allowing a user to control the manner in which thermal pulses are generated by the thermal adjustment apparatus (e.g., thermoelectric material(s)). 
     For example, the user may provide input to the device causing the thermoelectric material(s) to generate a series of thermal pulses so as to result in an enhanced heating or cooling experience for the wearer. 
     The user interface may include a physical interface, such as buttons, sliders and/or knobs which may be used to turn the device on or off, modulate thermal pulsing and/or set the intensity of the heating and cooling experienced by the user. Various physical interfaces can be implemented, such as those involving capacitive touch, slides, and/or levers. Physical interfaces in accordance with the present disclosure may allow for the compact device to be standalone, not requiring the user to use any other form of media to turn the device on or off. As shown, the user interface may include a simple on/off switch  442 , which is shown integrated with controller  140 . 
     In some embodiments, the user interface may be in the form of an app on a phone or computer where any appropriate communications technology may be employed. For example, in such an interface, the device may be remotely controlled through digital communication (e.g., via wireless protocols, Wi-Fi, Bluetooth, data transmission, etc.) such that there is no need for the user to physically touch the device itself. Such a digital interface may be advantageous in that the physical layout of the device can be made relatively compact such that a (larger) physical interface is optional. 
     In some embodiments, a portion of the housing (e.g., including a thermally conductive material) may be constructed and arranged for coupling and decoupling with a complementary portion of a detachable support structure. That is to say, in some cases, the device may be coupled to a detachable support structure such as a wearable article or other support. The device may then be removed from the detachable support structure and subsequently coupled to a different support structure. 
     As noted above, for some embodiments, the detachable support structure is wearable. Non-limiting examples of suitable detachable support structures include an article of clothing (e.g., a shirt, a scarf) a necklace, a bracelet, a wrist band, a keychain, or the like. Those skilled in the art would be capable of selecting additional appropriate detachable support structures based upon the teachings of the specification. In certain embodiments, the size of the device may be selected such that the device fits comfortably on a wrist, on an ankle, within an article of clothing, within the palm of a user&#39;s hand, or the like. 
       FIGS. 11C-11E  demonstrate the incorporation of the modular device into a variety of items, according to some embodiments. In these figures, the device is provided as part of a necklace, a bracelet and a keychain. It can be appreciated that other arrangements are possible, as the manner in which the device can worn or otherwise applied to a user&#39;s skin is not so limited. 
     In  FIG. 11C , the device is provided as a pendant-like component on a necklace chain. As shown, the housing includes an eyelet  160  through which a portion of necklace chain  162  (i.e. a detachable support structure) may extend, for holding the device in place. Hence, as the device hangs from the wearer&#39;s neck, the thermoelectric material(s) may be positioned suitably adjacent to the wearer&#39;s skin, for subsequent operation thereof. 
     In  FIG. 11D , the device is provided as a component of a bracelet. Here, opposite ends of the housing include coupling features that provide for a band  150  to be attached. The housing may be coupled to the band  150  may any suitable manner, such as for example, a snap fit, clamshell configuration, bayonet attachment, adhesive, hook and loop fasteners, or any other appropriate coupling arrangement. Once the device is in an appropriate position, for example, with the thermoelectric material(s) located suitably next to the wearer&#39;s skin, the controller may transmit the signals desired for the thermoelectric material(s) to generate a desirable series of thermal pulses. 
     In  FIG. 11E , the device is attached to a keychain ring  164  which, in turn, is attached to a carabiner  166 . As such, in certain embodiments, the device may have a long axis length of only a few inches and a short axis width on the order of an inch. It can be appreciated that devices in accordance with the present disclosure may have any appropriate shape, particularly given that large, bulky heat sinks are not necessary for suitable operation thereof. For example, the device may have an approximately elliptical, circular, polygonal, or other suitable shape. 
     In  FIG. 11F , the device is configured to be reversibly incorporated into a detachable support structure, for example, having a base  168  that includes coupling features that may be attached to complementary coupling features of the housing  180 . As such, in certain embodiments, the housing  180  may be reversibly coupled with the base  168  by any suitable manner. For example, in some embodiments, the base  168  includes one or more clips (e.g., clips, spring clips, latches, or the like) or other appropriate fastening member(s). Thus, the base may be positioned into appropriate alignment with the housing such that the thermoelectric material(s) and the controller are coupled with the base. Once suitably coupled, the thermoelectric material(s) may be suitably positioned next to the wearer&#39;s skin, and the controller may transmit the signals appropriate for the thermoelectric material(s) to generate a desirable series of thermal pulses. 
       FIG. 12  depicts a cross-sectional view of an illustrative embodiment of the device. As shown, the housing includes an enclosure having heat dissipating fins  120  extending away from the housing on opposite sides. In this embodiment, both the enclosure and the heat dissipating fins may be formed of a thermally conductive material. That is, the enclosure itself may act as a heat dissipating unit for the thermoelectric material(s). Though, it can be appreciated that for some embodiments, the enclosure may include or be at least partially formed of a thermally insulative material. 
     The enclosure provides a space for holding a power source (e.g. battery  130 ) and a controller (e.g. printed circuit board  140 ) having input features (e.g., switches, buttons, slides, levers, etc.)  442  for controlling the thermoelectric  110 . In this embodiment, the thermoelectric  110  is located beneath the housing so as to be exposed to the exterior, for example, the surface of a user&#39;s skin. Accordingly, the controller  140  may be appropriately activated to cause the thermoelectric to generate a desirable series of thermal pulses when the thermoelectric  110  is positioned suitably adjacent to the surface of the user&#39;s skin. 
       FIG. 13  shows an embodiment including an enclosure formed of a thermally conductive material that is free of optional heat dissipating protruding features (e.g., fins). In some embodiments, the enclosure includes a thermally conductive material and portions formed of a thermally insulating material. As illustrated, the enclosure may serve as a structural unit that supports and protects the power source  130  and controller  140 . The lack of need for protruding heat dissipating features in the exemplary design may make the modular unit more compact and sleek in appearance. In various embodiments, as described above with respect to the embodiment of  FIG. 2 , incorporating a thermally insulating material into the enclosure may be beneficial, so as to enhance the effectiveness of thermal pulses in producing greater rates/magnitudes of temperature change at the skin than may otherwise be achievable. 
     As discussed herein, for various embodiments, the sensation of warming or cooling may be enhanced by generating a series of asymmetric thermal pulses (e.g., thermal pulses which have a faster average rate of temperature change on initiation than the average rate of temperature change on return) at the surface of the skin of a user. In some embodiments, steady-state operation of the device may also include generating a series of thermal pulses in succession. That is, during steady-state operation, the temperature profile of thermal pulses generated in succession may be substantially identical. 
     Though, for some embodiments, it may be advantageous to generate non-steady state thermal pulses, which may be suitable to enhance thermal sensation and/or comfort of the user and/or prevent desensitization to temperature changes. For example, in certain embodiments, the duty cycle of the applied signal may be varied. In some embodiments, so as to provide a smooth transition for the user to a steady-state mode of operation, the baseline average of the electrical signal may be gradually increased, as illustrated in  FIG. 7 , or may gradually decrease, as desired. During non-steady-state operation, the average baseline signal may be adjusted as desired. In some cases, non-steady state operation (i.e., when operation of the device is first initiated, or when more/less power is applied to the thermoelectric at a given time) may allow for an increased amount of cooling or heating at the surface (e.g., more than the device may be designed to dissipate) for a temporary period of time. 
     In certain embodiments, the controller may apply an electrical signal to the thermoelectric material(s) according to a suitable duty cycle. The term duty cycle as known in the art generally refers to the percentage of a time period in which an electrical signal is active. In various embodiments, the electrical signal applied to the thermoelectric material(s) by the controller may exhibit a duty cycle of between about 10% and about 50%, greater than or equal to about 10%, greater than or equal to about 20%, greater than or equal to about 30%, greater than or equal to about 40%, or greater than or equal to about 50%. In some embodiments, the duty cycle applied by the controller may be less than about 50%, less than about 40%, less than about 30%, less than about 20%, or less than about 10%. Combinations of the above referenced ranges are also possible (e.g., between about 10% and about 50%). 
     As will be understood by those skilled in the art, the particular ranges of electrical signal (i.e., voltages, currents) are non-limiting and may suitably vary depending, in part, on the overall configuration of the device, particular materials selected (e.g., thermoelectric materials, number of thermoelectric materials), intrinsic resistances of various components within the device, or other aspects that may contribute to the functionality of the device. 
     As noted above, the thermal adjustment portion of the device may include one or more thermoelectric materials. The thermoelectric materials may, in some embodiments, be preferable for generating rapid, reversible thermal transients (i.e. thermal pulses). Non-limiting examples of suitable thermoelectric materials may include columns of p-type and n-type doped semiconductor materials, bismuth chalcogenides (e.g., Bi 2 Te 3 , Bi 2 Se 3 ), lead selenide, Si—Ge alloys, skutterudites (e.g., including the formula LM 4 X 12 , wherein L is a rare earth metal, M is a transition metal, and X is a metalloid), or any other suitable thermoelectric materials. 
     The thermoelectric material(s) may have any suitable thickness. For example, in some embodiments, the thickness may be selected such that the thermoelectric material(s) may be comfortably held against the wrist, arm, leg, ankle, neck, or any other suitable part of the body. In some embodiments, the thickness of each of the thermoelectric materials may be between about 1 millimeter and about 5 millimeters (e.g., between about 1 millimeter and about 3 millimeters). Other thicknesses are also possible. 
     In some embodiments, each of the thermoelectric materials, or modules that include the thermoelectric material(s), may have a largest average cross-sectional dimension of between about 10 mm and about 4 cm (e.g., between about 30 mm and about 500 mm). Other average cross-sectional dimensions are also possible. Those skilled in the art would be capable of selecting an appropriate size for the thermoelectric material based upon the configuration of the device. 
     Thermoelectric materials, or modules thereof, may be provided in any suitable configuration. For example, a module may include thermoelectric materials sandwiched between ceramic plates, in some cases, for protection and support, as well as to provide thermal conductivity to the surface of the skin. 
     Referring back to  FIGS. 2-3 , for some embodiments, the device may include a thermally insulative material  122  that is positioned so as to cover the thermoelectric material(s)  110 . In certain embodiments, during use, the thermoelectric material(s) may be located between the thermally insulative material and the surface of the skin. The thermally insulative material may be effective to retain the level of heat (or cooling) generated by the thermoelectric material(s), adjacent the surface. In some embodiments, the thermally insulative material is located adjacent to the thermoelectric material on a side opposite the skin. 
     In some embodiments, the thermally insulative material may increase the overall magnitude of temperature change for a given electrical signal, as compared to the use of thermally conductive materials. As a result, incorporation of a thermally insulative material may give rise to stronger or otherwise enhanced thermal pulsing, for example, increasing the overall sensation of temperature change for a user, and/or a reduction in power consumption by the device. 
       FIG. 10  depicts an example where a series of thermal heating pulses are observed, with the same application of electrical signal, for a thermoelectric material covered by a thermally insulative material (e.g., neoprene), as compared to a thermoelectric material covered by a thermally conductive material (e.g., aluminum, other metal(s)). For the device incorporating the thermally insulative material, the regimes of temperature adjustment are more pronounced than for the device incorporating the thermally conductive material. That is, the rates of temperature change are more abrupt for the device incorporating the thermally insulative material; and the average magnitude of temperature increase is also greater for the device that includes the thermally insulative material. 
     Though, for certain embodiments, it may be preferable for the device to incorporate a thermally conductive material, for example, for thermal dissipation of the generated heating or cooling. For example, it may be desirable to switch rapidly between heating and cooling modes. Accordingly, the ability to dissipate heat may allow for residual heating or cooling to be reduced. 
     Any suitable dissipation unit may be employed, for example, a heat sink, a fan, a phase change material, a heat exchanger, or combinations thereof. In some embodiments, the thermal dissipation unit has a size and/or weight such that it can be mounted comfortably on the device and, in turn, for example, on a wrist, as illustrated in  FIGS. 1A-1C . 
     As described above, in some embodiments, the device includes a suitable power source. The power source may include any appropriate materials, such as one or more batteries, photovoltaic cells, etc. Non-limiting examples of suitable batteries include Li-polymer (e.g., with between about 100 and about 1000 mAh of battery life), Li-ion, nickel cadmium, nickel metal hydride, or the like. In some cases, the battery may output a constant voltage and the controller may be configured to apply an appropriate degree of pulse-width modulation to generate time-varying voltage profiles. 
     The device may be further configured to use relatively low amounts of power, in contrast with HVAC systems or other localized electronic thermal sources such as heaters, fans, or the like. 
     In certain embodiments, the device may include one or more sensors arranged to collect information at the region of the thermoelectric material(s) adjacent the surface. Any suitable sensor(s) may be employed, for example, temperature sensors (e.g., thermistors, thermocouples), humidity and/or moisture sensors, barometers, etc., in any appropriate configuration. In some embodiments, the device includes one or more temperature sensors for monitoring the temperature at the surface of the thermoelectric material(s) and/or skin. For example, if the temperature measured at the surface of the thermoelectric material(s) and/or skin exceeds or is lower than a desired temperature, the sensor may send a signal to the controller to adjust the applied electrical signal (e.g., apply a negative (or lower) voltage to reduce the temperature, apply a positive (or higher) voltage to increase the temperature) to result in a preferred temperature profile. 
     In some embodiments, the temperature sensor may be incorporated with the controller, for monitoring the temperature of the controller. In certain embodiments, one or more temperature sensors may be placed directly adjacent one or more surfaces of the thermoelectric material(s). In some embodiments, the temperature sensor(s) may be arranged for sensing the temperature of ambient air. In some embodiments, the temperature sensor(s) may measure the temperature difference across different components of the device (e.g., between the surface of the skin and the thermoelectric material(s), between the thermoelectric material(s) and ambient air). The temperature sensor(s), in some embodiments, may be configured with the controller to operate in accordance with a feedback loop, for example, to prevent excessive heating or cooling of the device and/or to maintain the temperature at the surface within a preferred range. 
     The device may include additional control features, as desired, for example, wireless capabilities for enabling suitable communication with other devices/systems (e.g., for controlling aspects of the device, controlling/monitoring the temperature at the surface of the skin, etc.). Wireless devices are generally known in the art and may include, in some cases, wifi and/or Bluetooth systems. 
     Having thus described several aspects of at least one embodiment of the present disclosure, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. In some embodiments, the device may be used for therapeutic applications. For instance, the device may be used to alleviate hot flashes (e.g., during pregnancy, during menopause), or provide thermal comfort in humid or arid environments. Such alterations, modification, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the present disclosure. Accordingly, the foregoing description and drawings are by way of example only.