Apparatus, system, and method for a conformal heater in a wearable device

Abstract

The present invention provides an apparatus, system, and method for a flexible heater suitable for embedding in a wearable device. The flexible heater includes: a conformable substrate; a set of matching functional inks printed onto at least one substantially planar side of the substrate to form the following layers: at least one conductive layer capable of receiving current from at least one power source; a resistive layer electrically associated with the at least one conductive layer and comprising a plurality of heating elements capable of generating heat upon receiving the current; and a dielectric layer capable of at least partially insulating the at least one resistive layer, wherein the set of matching inks is matched to exclude detrimental interactions between the printed inks of each of the at least one conductive layer, the at least one resistive layer, and the dielectric layer, and to exclude detrimental interactions with the conformable substrate.

Description

[0001] This application is a divisional application of the Chinese invention patent application with the application date of August 28, 2018, application number 201880063625.9, and invention name “Apparatus, system and method for providing conformal heaters in wearable devices”. Background Art

[0002] public domain

[0003] The present disclosure relates generally to printed electronics and, more particularly, to conformal heaters for use, for example, in wearable devices.

[0004] Background

[0005] Printed electronics uses printing or "additive" methods to create electrical (and other) devices on a variety of substrates. Printing typically defines patterns on a variety of substrate materials using, for example, screen printing, flexographic printing, gravure printing, lithographic printing, and inkjet printing. Using one or more of these printing techniques, electrically functional electronic or optical inks are deposited onto the substrate, creating active or passive devices such as transistors, capacitors, resistors, and inductors.

[0006] Printed electronics can use inorganic or organic inks. These ink materials can be deposited using solution-based, vacuum-based, or other processes. Ink layers can be applied one on top of another. Printed electronics can feature or include semiconductors, metallic conductors, nanoparticles, nanotubes, and more.

[0007] Rigid substrates (such as glass and silicon) can be used for printed electronics. Poly (ethylene terephthalate) - foil (PET) is a common substrate, partly due to its low cost and appropriate high temperature stability. Poly (ethylene naphthalate) (PEN) and poly (imide) - foil (PI) are alternative substrates. Alternative substrates include paper and textiles, although the high surface roughness and high absorbency in such substrates may be problems in the printed electronics thereon. In short, typically, suitable printed electronics substrates preferably have minimum roughness, suitable wettability and low absorbency.

[0008] Printed electronics offer low-cost, high-volume manufacturing. This lower cost enables their use in many applications, but typically with reduced performance compared to conventional electronics. Furthermore, manufacturing methods on a variety of substrates allow electronics to be used in previously unknown ways, at least substantially without increasing costs. For example, printing on flexible substrates allows electronics to be placed on curved surfaces without the additional expense that would be associated with conventional electronics in such situations.

[0009] Furthermore, conventional electronics typically have lower limits on feature size. In contrast, printed electronics can provide higher resolution and smaller structures, thereby offering circuit density, precise layering, and variability in functionality that cannot be achieved using conventional electronics.

[0010] In printed electronics, controlling thickness, pores, and material compatibility is essential. In practice, the choice of the printing method(s) used may be determined by requirements related to the properties of the printed layers, layer characteristics, and printed materials (e.g., thickness, pores, and material type as mentioned above), as well as by economic and technical considerations of the final printed product.

[0011] In general, sheet-based inkjet and screen printing are best for printing electronics in small quantities with high precision. Gravure, lithographic, and flexographic printing are more common for high-volume production. While lithographic and flexographic printing are commonly used for inorganic and organic conductors and dielectric materials, gravure printing is highly suitable for quality-sensitive layers, such as those found in transistors, due to the high quality they offer.

[0012] Inkjet is very versatile, but generally offers lower throughput and is better suited for low-viscosity, soluble materials due to potential nozzle clogging. Screen printing is often used to produce patterned, thick layers from paste-like materials. Aerosol jet printing atomizes the ink and uses an airflow to focus the printed droplets into a tightly collimated beam.

[0013] Evaporation printing combines high-precision screen printing with material evaporation. The material is deposited through a high-precision template that is "aligned" with the substrate. Other printing methods can be used, such as microcontact printing and photolithography (e.g., nanoimprint lithography).

[0014] Electronic functionality and printability are traded off against each other, forcing optimization to achieve optimal results. For example, higher molecular weight in a polymer improves conductivity but reduces solubility. Furthermore, viscosity, surface tension, and solids content must be carefully selected and controlled during printing. Interlayer interactions, as well as post-deposition steps and layers, also influence the characteristics of the final product.

[0015] Printed electronics can provide patterns with features ranging in width from 3-10 μm or less, and layer thicknesses ranging from tens of nanometers to greater than 10 μm or more. Once printing and patterning are complete, the substrate may need to be post-processed to achieve the final electrical and mechanical properties. Post-processing can be driven more by the specific ink and substrate combination.

[0016] Typical heaters for use in wearable devices (e.g., clothing or accessories) are manufactured using conventional electronics techniques and manual labor. For example, rigid, thick, and bulky heaters are typically provided, such as in association with printed circuit boards or the like. Wiring that allows these thick, bulky heaters to operate is typically sewn into the wearable device (e.g., between layers of fabric) to enclose the heating element within the fabric.

[0017] Furthermore, smaller heaters manufactured using atypical types of processing are often expensive, in part due to the complex manufacturing steps required to produce such heaters. Consequently, these heaters are not suitable for wearable applications. Furthermore, if, for example, the wearable device associated with the heater is to be cleaned, then both atypical and conventional types of heaters must have an extremely high level of packaging. This is particularly true if the wearable device is to be cleaned multiple times during its lifecycle. That is, the limiting factor in the lifecycle of a wearable device should not be the heater provided in connection with the wearable device.

[0018] Thus, heaters for wearable devices can be assembled using in-line and / or high-throughput processes (e.g., additive printing processes) and are therefore less complex to manufacture, resulting in more cost-effective manufacturing, longer lifespans for the heater and wearable device, and other significant advantages. Such heaters should be formed in a thin, less bulky, more conformable and flexible form, and on a wearable-moldable substrate to not only address the aforementioned issues but also allow integration into a wider variety of wearable device types. Summary of the Invention

[0019] Therefore, the present disclosure provides at least one apparatus, system, and method for a flexible heater suitable for embedding in a wearable device. The flexible heater includes: a conformable substrate; a set of matching functional inks printed onto at least one substantially planar side of the substrate to form the following layers: at least one conductive layer capable of receiving current from at least one power source; a resistive layer electrically associated with the at least one conductive layer and comprising a plurality of heating elements capable of generating heat when receiving current; and a dielectric layer capable of at least partially insulating the at least one resistive layer, wherein the matching ink set is matched to exclude detrimental interactions between the printed inks of each of the at least one conductive layer, the at least one resistive layer, and the at least one dielectric layer, and to exclude detrimental interactions with the conformable substrate.

[0020] The flexible heater may additionally include an encapsulation that at least partially seals at least the compliant substrate having the matching functional ink set thereon from environmental factors. The flexible heater may additionally be integrated into a wearable device having the compliant substrate having the matching functional ink set thereon.

[0021] The flexible heater may further include a drive circuit connectedly associated with the at least one conductive layer. The drive circuit may include a control system, and wherein the amount of heat delivered by the heating element is controlled by the control system.

[0022] Thus, the present disclosure provides a heater for a wearable device that can be assembled using in-line and / or high-throughput processes (e.g., additive printing processes) and, therefore, is less complex to manufacture, resulting in more cost-effective manufacturing, longer service life of the heater and wearable device, and other significant advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Exemplary combinations, systems, and methods will now be described with reference to the accompanying drawings, which are given by way of non-limiting example only, in which:

[0024] Figure 1 is a schematic block diagram illustrating a heater according to an embodiment;

[0025] Figure 2 is a schematic block diagram illustrating a heater according to an embodiment;

[0026] Figure 3 is an illustrative example of an embodiment having a conductor layer with contact points at the upper right and lower left of the heating system;

[0027] Figure 4 is an illustrative example of a conductive layer and resistive layer heating system;

[0028] Figure 5 is an illustrative example of an embodiment having a conductive layer of increased size associated with contact pads on top of the device;

[0029] Figure 6 An illustrative example of a heating system enclosed in an encapsulation layer is shown;

[0030] Figure 7 An exemplary example is shown in which a heating system is laminated to a textile;

[0031] Figure 8 is a flow chart illustrating an exemplary method of providing a conformable heater, for example, for a wearable device; and

[0032] Figure 9 is a flow chart illustrating a method of using a conformal heater system in a wearable device. Specific embodiments

[0033] The accompanying drawings and description provided herein can be simplified to illustrate and clearly understand the relevant aspects of device as herein described, system and method, while for clear purpose, eliminating other aspects that can be found in typical similar equipment, system and method. Therefore, those of ordinary skill in the art will recognize that other elements and / or operations can be desired and / or necessary for realizing device as herein described, system and method. But because these elements and operations are known in the art, and because they are not conducive to a better understanding of the present disclosure, so for the sake of brevity, this paper may not provide discussion of these elements and operations. However, the present disclosure is considered to still include all these elements, variations and modifications of the described aspects known to those of ordinary skill in the art.

[0034] Provide embodiment throughout the whole text so that the present disclosure is thorough enough and the scope of the disclosed embodiment is fully conveyed to those skilled in the art. Many specific details (such as the example of specific components, equipment and methods) are set forth to provide a thorough understanding of the embodiments of the present disclosure. However, it will be apparent to those skilled in the art that it is not necessary to adopt certain specific disclosed details, and the embodiments can be embodied in different forms. Therefore, the embodiments should not be construed as limiting the scope of the present disclosure. As mentioned above, in some embodiments, well-known process, well-known device structure and well-known technology may not be described in detail.

[0035] The terms used herein are only used for the purpose of describing particular embodiments and are intended to be non-restrictive. For example, as used herein, the singular forms "one", "an", and "the / said" may also be intended to include the plural forms unless the context clearly indicates otherwise. The terms "comprise", "include", "contain", and "have" are inclusive and therefore specify the presence of the features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Unless expressly indicated as a preferred or required order of execution, the steps, processes, and operations described herein should not be interpreted as necessarily requiring them to be performed individually in the specific order discussed or described. It should also be understood that additional or alternative steps may be employed in place of the disclosed aspects or in combination with the disclosed aspects.

[0036] When an element or layer is referred to as being "on" (or "above"), "connected to" or "coupled to" another element or layer, unless expressly stated otherwise, it may be directly on (or on), connected to or coupled to another element or layer, or there may be intervening elements or layers. Conversely, when an element or layer is referred to as being "directly on," "directly connected to" or "directly coupled to" another element or layer, there may be no intervening elements or layers. Other words used to describe the relationship between elements should be interpreted in a similar manner (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.). Further, as used herein, the term "and / or" includes any and all combinations of one or more of the relevant listed items.

[0037] Furthermore, although the terms first, second, third etc. can be used herein to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or part from another element, component, region, layer or part. Unless the context clearly states otherwise, when used in this article, the terms such as "first", "second" and other numerical terms do not imply order or sequence. Therefore, without departing from the teachings of the embodiments, the first element, component, region, layer or part discussed below can be referred to as the second element, component, region, layer or part.

[0038] Historically, and as discussed throughout this document, the formation of many small aspects of devices or small devices has typically integrated deposition and etching processes. That is, traces (e.g., conductive traces, dielectric traces, insulating traces, etc.) that form device features such as waveguides, vias, connectors, etc., are typically formed by subtractive processes, that is, by preparing layers that are later etched to remove portions of those layers to form the desired topology and features of the device.

[0039] Additive printing processes have been developed whereby device features and aspects are formed additively, i.e., by "printing" desired features at desired locations and in desired shapes. This has allowed many devices and elements of devices previously formed using subtractive processes to be formed by additive processes, including but not limited to printed transistors, carbon resistive heating elements, piezoelectric and audio elements, photodetectors and emitters, and devices for medical uses (e.g., glucose strips and ECG bands).

[0040] In short, the printing of such devices depends on many factors, including matching the deposited material (e.g., ink) to the substrate used for a specific application. This ability to use a variety of substrates can provide unique properties to the printed device that were previously unknown in etching devices, such as the ability of the device to stretch and bend, and can be used in previously unknown or difficult environments, such as as a conformal heater in a wearable device to be washed. As a non-limiting example, the ability to print electronic traces on plasticized substrates allows those substrates to be conformed after printing occurs.

[0041] However, known additive properties do place limitations on properties previously achievable using subtractive processes. For example, conductive traces formed using additive processes typically have more limited conductivity than conductive traces previously formed using subtractive processes. This is in part because the pure copper traces provided by subtractive processes cannot currently be printed using modern additive processing. Consequently, some devices and their components (e.g., heaters) may require substantial modification compared to conventional electronic product formation techniques to accommodate the modified properties achievable using printed traces in additive processes.

[0042] In embodiments, a number of factors must be balanced in each unique application to best achieve properties that most closely approximate those previously achievable only in subtractive processes. For example, in the disclosed devices and methods of making these devices, compatibility must be evaluated between the printing substrate and the receptivity of such substrate, the ink used and its conductivity, the fineness of the printed traces used, the spacing, density, and consistency of the printed inks, the type of printing performed (i.e., screen printing versus other types of printing), the thickness of the printed layer, and the like. Furthermore, because a variety of inks can be used to prepare the disclosed heating elements, compatibility of the inks used with each other is also an aspect of the embodiments. For example, for all inks in a given ink set, the chemical reactions between the inks, the different curing methods between the inks, and the deposition methods between the inks must be evaluated. It is also worth noting that, based on the discussion herein, those skilled in the art will appreciate that different inks in an ink set can have different characteristics even after deposition. For example, certain inks may experience a valley effect at the center of the deposited trace of that ink, while using other inks may produce peaks at the outer portions of the trace. Therefore, in embodiments, the manner and consistency with which each ink in an ink set is applied is noteworthy, as the thickness of traces deposited using such inks may allow for mitigation or enhancement of the aforementioned effects.

[0043] In known techniques for incorporating heaters, the printed circuit board needs to be mechanically integrated, and therefore consideration needs to be given to mechanically integrating the printed circuit board into each product. However, the ability to use printed electronics with flexible substrates and substrates with non-uniform topology can allow the printed electronics to be integrated as part of the product, rather than having to mechanically integrate the electronics into the finished product. Needless to say, this can include using printed electronics on substrates that are not suitable for receiving electronics prepared using subtractive processes, such as fabrics, plastics that do not provide a "sticky" surface, organic substrates, etc. This can occur, for example, because additive processes allow for different print types in each subsequent printed layer of the printing device, and therefore the functionality provided by each layer (e.g. mechanical, electrical, structural or other functionality) can vary between printed layers throughout the deposition process.

[0044] Additional processes can be used to provide various solutions to balance the above factors. For example, a flexible substrate can be provided where printing is performed on one or both sides of the substrate. Thus, traces can be created on one or both sides of the substrate to form a single heater, a series heater, or a parallel heater. In this case, one or more through-holes can be created between the sides of the substrate, thereby creating a single heating system or multiple heating systems on opposite sides of the substrate that can be connected through the substrate.

[0045] More particularly, in embodiments, flexible heaters for wearable devices can be printed onto flexible and conformable organic or inorganic substrates, for example using a "matching function" ink set. The flexible heater can be composed of multiple layers of inks or substrates forming a matching function set. For example, Figure 1 As shown in the heater 10 in FIG, a conductive layer 12 can be printed onto a substrate 14 to allow current 16 to flow to the heater. A resistive layer 18 can also or subsequently be printed to allow a thermal effect 20 to occur when the resistor heats up due to the current 16 flowing therethrough. Further, a dielectric layer 22 can be printed to insulate the resistive elements 18a from shorting to each other due to the conformable and flexible nature of the substrate 14, and to insulate the heat generated by the heating element 18a to avoid local overheating.

[0046] The substrate 14 onto which the layers 12, 18, 22 are printed may include organic and inorganic substrates, subject to the constraints that the substrate may be flexible and / or conform to the wearable device in or on which the heater 10 is placed. Suitable substrates may include, but are not limited to, PET, PC, TPU, nylon, glass, fabric, PEN, and ceramic.

[0047] As described above, various inks and ink sets can be used to form layers 12, 18, 22 or other aspects of the heater 10, and the inks in the set can be matched to each other to avoid undesirable chemical interactions during deposition, curing, etc., and / or the inks can be matched to the substrate on which the inks are to be printed. As non-limiting examples, the conductive and resistive inks used can include silver, carbon, PEDOT:PSS, CNTs, or various other printable, conductive, dielectric, and / or resistive materials, which will be apparent to those skilled in the art based on the discussion herein.

[0048] In certain wearable devices, particularly those that are exposed to the elements and / or intended for washing, the heating system 10 may preferably be encapsulated to increase durability. In such cases, isolation from environmental conditions 30 (e.g., wet conditions, including rain, snow, or moisture), and / or insulation from wash and dry cycles and / or general robust handling may be provided. In such cases, a packaging system 32 (e.g., a laminated bag) may optionally be provided to enclose the heating system 10, and in such cases, the packaging system 32 may include connections and / or feedthroughs to allow a power source 40 to be provided to the heating system 10 through the packaging system 32. Finally, the heating system 10 (e.g., including the packaging system 32) may be integrated into the wearable device 50 via any known method (e.g., by sewing, lamination, etc.).

[0049] Thus, the encapsulation system 32 can provide waterproofing, moisture resistance, etc. to protect the heating system and related systems from any adverse environmental factors 30. In order to provide the encapsulation system 32, various known techniques can be used. For example, acrylic can be laminated to each side of the heater substrate 14 to create a sealed laminate lip around the substrate 14, wherein the only protrusion extending from it has an acrylic laminate seal around it. Further, such a laminate bag can be treated with, for example, ultraviolet radiation so that the laminate is sealed to the heating system 10 and provides maximum protection for the heating system 10. However, it is worth noting that the more layers added to the heating system (for example, including the encapsulation system 32), the less conformable the heating system is to the wearable device, especially when the added layers have a significant thickness.

[0050] In some embodiments, the encapsulation system 32 that protects from environmental conditions 30 may not require any additional effort beyond creating the heating system 10. For example, a submersible and conformable substrate and ink combination may be selected, or, for example, using a single acrylic laminate, the substrate may only have printed electronics thereon to provide partial sealing of the heating system to protect it from environmental conditions.

[0051] As described above, the heating system 10, with or without the packaging system 32, is connected to one or more driver circuits 52. In some embodiments, the interconnects 54 to, for example, the driver circuits 52 and / or the power source 40 may include a high contact surface area to enable the heating system 10 to draw a large current 16 from the power source 40. As also described above, the interconnects 54 may also include or comprise printed electronic surfaces. As non-limiting examples, such interconnects 54 may additionally include classical wiring, microconnection, and / or electromechanical connection technologies.

[0052] Various interconnects 54, including, for example, interconnects from the driver circuit 52 to an external control system and / or to a power source 56 (if provided), may extend outwardly from the heating system 10. These interconnects 54, as well as the data and power requirements, may depend on the unique configuration of a given heating system 10. For example, as a non-limiting example, different carbon inks used in the formulation of the heating system 10 may have different power requirements, such as 5-15 volts, or more particularly 5, 9, or 12 volts.

[0053] Similarly, the interconnect 54 may also be or include one or more universal connectors known in the art for connecting to, for example, the aforementioned voltages. Further, such universal connectors may be or include other known connector types, such as USB, micro-USB, mini-USB, Lightning connectors, and other known interconnects. Additionally or alternatively, proprietary interconnects 54 may be provided in conjunction with embodiments.

[0054] The aforementioned driver circuit 52 may or may not be directly physically associated with the heating system 10 and the interconnect 54. For example, the driver circuit 52 may be included as a separate system in the electrical path between the power source 40 and the heating system 10. The driver circuit 52 may include a control system 52a or a connection to a control system 52b (e.g., to allow remote and / or wireless control of the heating system 10), and / or provide limits on the heating system (e.g., the amount of heat delivered, the amount of current delivered or power drawn, the difference between different heat delivery levels, etc.). As non-limiting examples, such a remote connection may include a wireless connection (e.g., using NFC, Bluetooth, WiFi, or a cellular connection), such as to link to an app 60 on a user's mobile device 62.

[0055] Notably, as referenced herein, control system(s) 52a, 52b (e.g., a Bluetooth-based control system) may allow for automatic or manual temperature changes. Thus, control system(s) 52a, 52b may communicate with an auxiliary control device (e.g., an app on a mobile device) via, for example, Bluetooth, radio frequency (RF), near-field communication (NFC), or the like. Such changes may only occur within a certain time period (which may be brief), particularly if, for example, the control system indicates that a significant amount of power would be consumed at the desired setting. For example, a user may have preset the heater to heat to 85 degrees Celsius in 90 seconds, perhaps manually or automatically, only when, for example, the user is taking a short walk with the dog in 10-degree weather, since it is understood that the user can fully recharge the system immediately after the short period of use. However, if the user is going on a one-hour jog in the same 10-degree weather, the user may prefer the heater to run at 45 degrees Celsius for 50 minutes of the hour before the battery is completely depleted.

[0056] The power source 40, which delivers power to the heating system 10, for example, via the driver circuit 52, may preferably provide a battery life of, for example, 2-10 hours, or more specifically, 4-8 hours. This power may be provided, for example, by a permanent power delivery system embedded in the garment (e.g., which may use a rechargeable, removable, replaceable, or permanent battery, as a non-limiting example), or by an auxiliary power source adapted to be plugged into the driver circuit system (e.g., which may be embedded in or associated with a mobile device or other mobile power source via a dedicated or non-dedicated connector (e.g., via a micro-USB, lightning connector, etc.)). As referenced, a typical power providing element may include a battery, such as a rechargeable battery (e.g., a lithium-ion battery). Such a battery can typically provide a high level of heating very quickly, and then allow a rapid decrease in heat delivery to avoid unnecessary power usage during the ramp-up or ramp-down phases of power delivery.

[0057] Atypical power sources may additionally be used to provide power 40 for heating system 10. For example, a kinetic power source (e.g., one that stores power based on motion) and / or other similar magnetic and / or piezoelectric power systems may be embedded in or connectable to the wearable device to provide primary, auxiliary, permanent, or temporary power to heating system 10 via driver circuit 52. Similarly, primary, auxiliary, and / or atypical power source(s) 40 may work together and in conjunction with the aforementioned system controls, for example, being embedded in or communicatively associated with driver circuit 52 to supply power only upon specific triggering. For example, a wearable device equipped with heaters in multiple locations (e.g., in the elbows and upper back region of a jersey) may only allow activation of each of these locations upon certain events indicated by an onboard system (e.g., a printed electronic sensor 70, which may be additionally associated with substrate 12). For example, a kinetic sensor may sense motion and, during a period of motion, activate the heater in a given location (e.g., the upper back region in the previous example). However, when motion ceases, as sensed by the kinetic sensor, the heating element in the jersey's elbow may be activated. This may be done for any of a variety of reasons understood by those skilled in the art, such as a pitcher who is taking a break from pitching between innings but wishes to keep his / her elbow "warm" to avoid injury.

[0058] Such variations in heating elements may occur not only in wearable devices with multiple heaters, but may also similarly include variable heater designs for different purposes. For example, smaller heaters consume less power than larger heaters and, therefore, require lower levels of power. Thus, in the earlier example of the pitcher's jersey, a small heater located only near the "Tommy John" ligament in his / her elbow may require very little power to activate but still have a significant health impact for the wearer, for example, by keeping this often-injured ligament warm after more than 10 minutes of inactivity.

[0059] Moreover, the variability of the heat level, such as may be indicated by the driver circuit system, may be made manually by the user or automatically based on system characteristics. For example, if the temperature is colder, it may be necessary to reduce the heat in the hand warmer heating system (such as may be embedded in the pocket of a sweatshirt or in the user's gloves), that is, in order for the user to feel "warm", only a specific temperature difference from the ambient conditions may be required. That is, if the user's gloves are heated to 40 degrees Fahrenheit, rather than heating the gloves all the way to the maximum heating level of 65 degrees, a user in an environment with a temperature of 10 degrees Fahrenheit may feel warmer. However, if the ambient temperature is 35 degrees, the user may need the heating element to reach 65 degrees in order for the user to feel the same level of "warmth".

[0060] Depending on the wearable device and the use case of the heater, additional considerations may be required regarding the power delivered to the heater and / or the amount of heat delivered. For example, in situations where the heater may be in substantial direct contact with or very close to the user's skin, the control system associated with the driver circuit 52 discussed herein may need to limit the power so that the heating is insufficient to cause burns, discomfort, or otherwise harm the user. In certain exemplary embodiments, these issues may be partially addressed by providing a heating element using a self-regulating ink.

[0061] For example, a positive temperature coefficient (PTC) heater can provide a self-regulating heater. When current flows through the heater, the self-regulating heater stabilizes at a specific temperature. That is, as the temperature increases, the resistance of the self-regulating heater also increases, which causes the current to decrease, thus preventing the heater from further increasing the temperature. Conversely, if the temperature decreases, the resistance decreases, allowing more current to flow through the device. Thus, in typical embodiments, a self-regulating / PTC heater provides a stable temperature that is independent of the voltage applied to the heater.

[0062] Auxiliary system 202 may be provided in conjunction with heating system 10 to, for example, maintain warmth, such as Figure 2 For example, in an embodiment of a jersey having transversely crisscrossing pockets 204, a single pocket across the jersey may be lined on its interior with 202 and may have a heating element disposed within the pocket's lining to retain the heat generated by the heating system 10 within the jersey pocket 204 to the greatest extent possible.

[0063] As discussed throughout, it is advantageous, particularly for certain types of wearable devices, that the heating system and / or other systems associated therewith be conformable. Such conformability can be adapted to forces applied by the user or based on activity, or to conform to the physical contours of the wearable device itself, among other things. Additional considerations may arise due to the conformability of the heating system and / or its associated systems. For example, the level of heat delivered may vary based on the physical configuration of the heating element, i.e., when the heating system is bent or partially folded, it may deliver more or less heat than intended in certain locations. Needless to say, the use of a protective dielectric layer 22, such as referenced above, may address some of this variability.

[0064] As discussed throughout, additional sensors, integrated circuits, memories, and the like may also be associated with the heating system 10 in question, may be printed on its substrate 14, and / or may be formed on or in a system associated therewith, and / or on its substrate. Needless to say, in such embodiments, the associated electronics may be separate from the heating system and those systems associated therewith, but may still be similarly conformable to the wearable device, substrate, etc. of the heating system. Further, those skilled in the art will appreciate that such other electronic circuitry may or may not be formed by a printing process on the same substrate of the heating system or on a physically adjacent substrate.

[0065] Furthermore, embodiments may include additional layers (not shown) to those discussed above. For example, the heater substrate may be provided in the form of a highly viscous sticker that may or may not provide a substrate suitable for receiving printed electronics on one side of the "strip." In this case, a compatible adhesive surface may be applied to the opposite side of the sticker, such as by additional processes such as printing, lamination, deposition, etc.

[0066] Figure 3 、 4 and 5 show exemplary examples of the disclosed embodiments. More particularly, Figure 3 The conductor layer 12 is shown with contact points at the upper right and lower left of the heating system. The discrete heater elements 18a of the resistive layer 18 are further shown, as shown in FIG. Figure 3 As shown in the enlarged figure.

[0067] Figure 4 Additional illustrative examples of conductive layer 12 and resistive layer 18 heating systems are shown. Figure 5 An additional embodiment is shown in which the increase in the size of the conductive layer 12 associated with the contact pads on top of the device is remedied. Figure 4 The current blocking point 502. It is worth noting that Figure 3 、 4 Each of the embodiments of 5 and 7 show a dielectric layer 22 printed over the conductive layer 12 and the resistive layer 18, with contacts extending beyond the dielectric layer 22 to allow for the interconnects 54 discussed herein.

[0068] Figure 6 The encapsulation layer 32 is shown. Figure 5 As described throughout, the encapsulation layer 32 can protect the heating system 10 from environmental conditions.

[0069] Figure 7An illustrative example is shown in which the heating system 10 has been laminated to a textile 702. As non-limiting examples, useful textiles may include nylon, cotton, and the like.

[0070] Figure 8 8 is a flow chart illustrating an exemplary method 800 for providing a conformable heater (e.g., for use in a wearable device). At step 802, ink sets are matched to each other for printing compatible ink layers in the ink sets, and the ink sets are matched to a receiving organic or inorganic conformable substrate. At step 804, a conductive layer formed from at least one ink from the ink set is printed on the substrate.

[0071] At step 806, a resistive layer is printed from the ink set, wherein the resistive layer provides at least a plurality of heating elements in electrical communication with the conductive layer. At step 808, a dielectric layer is printed from the ink set to insulate the conductive layer from the resistive layer.

[0072] At optional step 810, the substrate having at least the conductive layer and the resistive layer printed thereon is at least partially encapsulated.At optional step 812, one or more sensors associated with the operation of the heater may be integrated with and / or printed on the substrate.

[0073] At step 814, the heater is integrated with the wearable device. Integration can be performed by stitching, laminating, bonding, or any similar method. Furthermore, at step 816, the heater can be connected to one or more driver circuits having a control system in communication therewith and to one or more power connections to allow power to be supplied to the heating element via the conductive layer. For example, step 816 can include printing or other means of interconnecting one or more electrical interconnects to the heater.

[0074] Figure 9 is a flow chart illustrating a method 900 for using a conformal heater system in a wearable device. In the illustration, at step 902, a conformal heater may be associated with a power source. The association may include a permanent association (e.g., via charging a permanently embedded battery), or a removable association, for example, where an external power source (e.g., a battery, a mobile device, etc.) may be removably associated with the heater.

[0075] At step 904, power delivery from the power source to the heater's driver circuit can be variably controlled. Optionally, at step 904a, wireless control can be via a wireless connection, such as from a mobile device to the driver circuit. As a non-limiting example, the wireless or wired connection can be controlled using a user interface provided by an "app" on the mobile device. The control provided thereby can be automated based on predetermined triggers or operating limits, manual, or a combination thereof. Wireless control can be provided via any known type of wireless interface.

[0076] Optionally, at step 904b, wired control may be via a wired connection from the mobile device to the driver circuit, for example via a micro USB connected to the heater. As will be appreciated by those skilled in the art, in alternative embodiments, power may also be supplied via this connection.

[0077] Furthermore, the description of the present disclosure is provided to enable any person skilled in the art to make or use the disclosed embodiments. Various modifications to the present disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the examples and designs described herein, but should be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A flexible heater suitable for embedding in a wearable device, comprising: substrate; A set of additional deposited inks, selected in combination to achieve a specific fineness, spacing, density, and consistency relative to one another, the selection being made by matching each additional deposited ink in the set of additional deposited inks by considering: the receptivity of the substrate to each of the additional deposited inks; electrical conductivity between the substrate and each of the additional deposited inks; a chemical reaction between the substrate and each of the additionally deposited inks; as well as Different printing and curing methods of the additional deposited inks relative to each other; Each of the additional deposited inks is printed in successive additional printed layers onto at least one substantially planar side of the substrate to form the following layers: a conductive layer capable of receiving electrical current from at least one power source; a resistive layer electrically associated with the conductive layer and comprising a plurality of heating elements capable of generating heat upon receiving the electrical current; as well as a dielectric layer capable of at least partially insulating the resistive layer; When the substrate is not subjected to a subtractive process, the specified fineness, spacing, density and consistency approximates that of the subtractive process. The flexible heater of claim 1 , wherein the substrate comprises an inorganic substrate.

3. The flexible heater according to claim 1, wherein The substrate includes one selected from the group consisting of PET, PC, TPU, nylon, glass, fabric, PEN, and ceramic.

4. The flexible heater of claim 1 , wherein each of the additional deposited inks comprises one selected from the group consisting of silver, carbon, PEDOT:PSS, and CNT inks.

5. The flexible heater of claim 1, wherein at least one of the additional deposited inks is subjected to environmental factors including at least moisture.

6. The flexible heater of claim 1 further comprising an encapsulation that at least partially seals the substrate having at least said each of said additional deposited inks thereon from environmental factors. The flexible heater of claim 6 , wherein the packaging comprises a laminate bag.

8. The flexible heater of claim 1, further comprising integration into the wearable device of the substrate.

9. The flexible heater of claim 8, wherein the integrating comprises one selected from the group consisting of sewing, laminating, and bonding.

10. The flexible heater of claim 1, further comprising a drive circuit connectively associated with the at least one conductive layer.

11. The flexible heater of claim 10, wherein the drive circuit includes a control system, and wherein the amount of heat delivered by the heating element is controlled by the control system.

12. The flexible heater of claim 11, wherein the control system comprises a wireless receiver.

13. The flexible heater of claim 12, wherein the wireless receiver comprises at least one of a Bluetooth, WiFi, NFC, cellular, and RF receiver.

14. The flexible heater of claim 12, wherein the remote portion of the control system comprises a mobile device application.

15. The flexible heater of claim 12, further comprising at least one power source connectively associated with the drive circuit.

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