Patent Application
20220015198
Temperature management of one or more parts of the body is a subject of interest for personal comfort, as well as for medical or veterinary heat therapy, such as for joint pain relief or for injury rehabilitation (including athletic rehabilitation). Electrical heaters are also ubiquitous in indoor and automobile climate control systems and portable temporary shelters.
Typical electrical heaters use the concept of joule heating (also referred to as “resistive heating” or “ohmic heating”) in one or more heating elements. In Joule heating, heat is generated when a voltage is applied across the heating element, where inelastic collisions between accelerated electrons and phonons occur as a current passes through a conductive material that forms the heating element. Contemporary commercially-available products have almost-exclusively used copper wires as the Joule heating element or elements. While copper-wire heating elements and the electrical heaters made from them are cheap and widely-available, electrical heaters including copper-wire heating elements are typically heavy and inflexible. Also, copper-wire heating elements cannot be cut, sewn, ironed, or woven like standard threads, such that copper-wire heating elements are not feasible for use in fashioning heated apparel.
The present disclosure describes methods to modify conventional textiles (e.g., fabric, cloth, and the like) or fibers (e.g., threading, yarns, and the like) into an electrically-heatable composite material, as well as the electrically-heatable composite material made by such a process. The electrically-heatable composite materials described herein can be fashioned into a fabric or threading heater (such as by cutting and sewing a fabric heater, or weaving or sewing with a threading heater) to fashion lightweight fabric-based heaters for local climate control and/or personal thermal management.
In an example, described herein, a method includes coating a textile-based or fiber-based substrate with an electrically-conducting polymer coating comprising an electrically-conducting polymeric material. The electrically-conducting polymeric material is coated onto the textile-based or fiber-based substrate via reactive vapor deposition under specified conditions that produce an electrically-conducting polymer coating having a specified thickness and that covers a specified portion of one or more fibers or threads of the textile-based or fiber-based substrate. In some examples, the reactive vapor deposition conditions are such that the electrically-conducting polymer coating substantially conformally coats one or more of the fibers or threads of the textile-based or fiber-based substrate.
The present inventors have recognized, among other things, that a problem to be solved can include textile-based or fiber-based electrode structures having an electrical resistance that is too high for practical application because it would require a voltage input for significant heating that is higher than may be practical for a transportable or wearable article. The present subject matter described herein can provide a solution to this problem, such as by providing for an electrically-conducting polymer coating having sufficient thickness or that coats a sufficient portion of each of the one or more fibers or threads of the textile-based or fiber-based substrate, or both. The present inventors have discovered that having an electrically-conductive polymer coating that is at least 100 nanometers (nm) thick, or that coats at least about 75% of a surface area of the fibers or threads of the substrate, or both, is particularly effective for use as a portable and/or wearable fabric-based or textile-based heating element.
In some examples, a fabric-based or textile-based heating element structure includes an electrically-conductive polymer coating that is at least 1 micrometer (μm) thick, and in some examples is 1.5 μm thick or thicker. In some examples, a fabric-based or textile-based heating element structure includes an electrically-conductive polymer coating that covers at least about 80% of the surface area of the fibers or threads that forms the substrate of the heating element, for example at least about 90% of the surface area, such as at least about 95% of the surface area, for example at least about 99% of the surface area, and in some examples all (100%) or substantially all (e.g., 99.9% or more) of the surface area of the fibers or threads that form the substrate of the heating element.
This summary is intended to provide an overview of subject matter of the present disclosure. It is not intended to provide an exclusive or exhaustive explanation of the invention. The detailed description is included to provide further information about the present disclosure.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.
The following detailed description is provided to describe, by way of illustration, specific embodiments of methods of depositing a coating of an electrically-conductive polymer material onto a textile-based or fiber-based substrate to produce a fiber or textile-based electrically conductive heating element. The following detailed description further describes examples of the resulting textile-based electrically conductive heating elements. The detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments, which are also referred to herein as “examples,” are described in enough detail to enable those skilled in the art to practice the invention. The example embodiments may be combined, other embodiments may be utilized, or structural, and logical changes may be made without departing from the scope of the present invention. While the disclosed subject matter will be described in conjunction with the enumerated claims, it will be understood that the exemplified subject matter is not intended to limit the claims to the disclosed subject matter. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims and their equivalents.
References in the specification to “one embodiment”, “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described can include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.
Values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range of “about 0.1% to about 5%” should be interpreted to include not only the explicitly recited values of about 0.1 wt. % to about 5 wt. %, but also the individual values (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, and 3.3% to 4.4%) within the indicated range.
The term “about” as used herein can allow for a degree of variability in a value or range, for example, within 10%, within 5%, within 1%, within 0.5%, within 0.1%, within 0.05%, within 0.01%, within 0.005%, or within 0.001% of a stated value or of a stated limit of a range, and includes the exact stated value or range.
The term “substantially” as used herein refers to a majority of, or mostly, such as at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or 100%.
In this document, the terms “a” or “an” are used to include one or more than one and the term “or” is used to refer to a nonexclusive “or” unless otherwise indicated. In addition, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. The statement “about X to Y” has the same meaning as “about X to about Y,”” unless indicated otherwise. Likewise, the statement “about X, Y, or about Z” has the same meaning as “about X, about Y, or about Z,” unless indicated otherwise.
In this document, the terms “a,” “an,” or “the” are used to include one or more than one unless the context clearly dictates otherwise. The term “or” is used to refer to a nonexclusive “or” unless otherwise indicated. Unless indicated otherwise, the statement “at least one of” when referring to a listed group is used to mean one or any combination of two or more of the members of the group. For example, the statement “at least one of A, B, and C” can have the same meaning as “A; B; C; A and B; A and C; B and C; or A, B, and C,” or the statement “at least one of D, E, F, and G” can have the same meaning as “D; E; F; G; D and E; D and F; D and G; E and F; E and G: F and G; D, E, and F; D, E, and G; D, F, and G; E, F, and G; or D, E, F, and G.” A comma can be used as a delimiter or digit group separator to the left or right of a decimal mark; for example, “0.000,1”” is equivalent to “0.0001.”
In methods described herein, the acts can be carried out in any order without departing from the principles of the disclosed method, except when a temporal or operational sequence is explicitly recited. Furthermore, specified acts can be carried out concurrently unless explicit language recites that they be carried out separately. For example, a recited act of doing X and a recited act of doing Y can be conducted simultaneously within a single operation, and the resulting process will fall within the literal scope of the process. Recitation in a claim to the effect that first a step is performed, then several other steps are subsequently performed, shall be taken to mean that the first step is performed before any of the other steps, but the other steps can be performed in any suitable sequence, unless a sequence is further recited within the other steps. For example, claim elements that recite “Step A, Step B, Step C, Step D, and Step E” shall be construed to mean step A is carried out first and steps B, C, D, and E can be carried out in any sequence between steps A and E, and that the sequence still falls within the literal scope of the claimed process. A given step or sub-set of steps may also be repeated. Furthermore, specified steps can be carried out concurrently unless explicit claim language recites that they be carried out separately. For example, a claimed step of doing X and a claimed step of doing Y can be conducted simultaneously within a single operation, and the resulting process will fall within the literal scope of the claimed process.
It is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. Any use of section headings is intended to aid reading of the document and is not to be interpreted as limiting, and information that is relevant to a section heading may occur within or outside of that particular section. All publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. In the event of inconsistent usages between this document and those documents so incorporated by reference, the usage in the incorporated reference should be considered supplementary to that of this document; for irreconcilable inconsistencies, the usage in this document controls.
All publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. In the event of inconsistent usages between this document and those documents so incorporated by reference, the usage in the incorporated reference should be considered supplementary to that of this document; for irreconcilable inconsistencies, the usage in this document controls.
As noted above, the present disclosure describes systems and method of producing fiber or textile-based electrically conductive heating elements (referred to hereinafter simply as “textile heating elements” for brevity). As described in more detail below, one or more of the resulting textile heating elements can be used to produce a wearable garment or other apparel (e.g., a joint brace) with the one or more textile heating elements integrated therein, which can provide for local heating of a specific part of the wearer's body. Lightweight, breathable and body-conformable electrical heaters have the potential to change traditional approaches to personal thermal management, medical heat therapy, joint pain relief, and athletic rehabilitation.
An absence of seamless and imperceptible integration into everyday objects and garments has, thus far, relegated electrical heaters to a category of special-purpose electronics. For wearable devices to be broadly adopted, issues of comfort, aesthetics, haptic perception, and weight may require addressing. The systems and methods described herein provide for the fabrication of textile heating elements that can be easily and inconspicuously incorporated into everyday objects and garments.
To replace conventional-but-cumbersome copper wires, designer fibers that include nanocarbon materials, fabric mimics made of conductive nanowires or meshes, or conducting polymer-impregnated cloths have been attempted as alternative Joule heating elements. While many of these designer fabrics have shown excellent electrical properties, they have been unable to also comprehensively address issues such as breathability, haptic perception, bare skin compatibility, stable conductivity under frequent mechanical deformation, and straightforward integration into demanding textile and garment manufacturing processes.
Returning to
The deposition chamber 26 is also configured to deliver an oxidant (e.g., FeCl3), such as in the form of an oxidant vapor cloud 32. In an example, an oxidant heater 34 (e.g., a Luxel crucible heater) heats an oxidant feed to sublime or vaporize the oxidant to form the oxidant vapor cloud 32 which is then delivered to the deposition stage 24. In an example, the deposition stage 24 is positioned so that the textile substrate 12 is downward facing toward the oxidant heater 34 such that the oxidant vapor cloud 32 floats up to the textile substrate 12 on the deposition stage 24. The one or more reactive precursor compounds 28 (e.g., EDOT molecules) are delivered to the deposition stage 24 via a precursor feed line. The temperature of the deposition stage 24 and the textile substrate 12 are maintained at a specified deposition temperature, which can be from about 30° C. to about 200° C., such as about 120° C.
An in situ quartz crystal microbalance sensor 36 (also referred to herein as a “QCM sensor 36”) can be included at or proximate to the deposition stage 24 to monitor flow rates of the one or more precursor compounds 28 and the oxidant to the deposition stage 24 and the thickness of the resulting conductive polymer coating film on the textile substrate 12 in real time. A flow controller (not shown in
Further details regarding example systems and example methods of depositing EDOT as a PEDOT conductive polymer coating on textile substrates are provided in Zhang et al., “Transforming Commercial Textiles and Threads into Sewable and Weavable Electric Heaters,” ACS Applied Materials & Interfaces, p. 32299, published on Aug. 30, 2017, DOI 10.1021/acsami.7b10514; in Zhang et al., “Rugged Textile Electrodes for Wearable Devices Obtained by Vapor Coating Off-the-Shelf, Plain-Woven Fabrics,” Advanced Functional Materials, p. 1700415, published on May 2, 2017, DOI 10.1002/adfm.201700415; and in Nongyi et al., “Vapor phase organic chemistry to deposit conjugated polymer films on arbitrary substrates,” Journal of Materials Chemistry C, p. 5787, published on Aug. 30, 2017, DOI 10.1039/c7tc00293a; Nen.
A parameter that can be of particular importance for electric heaters that use conductive Joule heating elements is the amount of electrical power required to heat the heating element to an acceptable and effective heating temperature. This is particularly true for heating devices that are intended to be portable—an importance that can be even more pronounced for wearable portable heating structures because of limitations on battery life and electrical power delivery for a device that is to be worn close to a person's or animal's body. In order to achieve an electrical heater that consumes low power (e.g., the wattage that can be delivered at a voltage of from about 1 V to about 3 V, with an upper limit of about 120 V, at a desired heating temperature), it is desirable to use a heating element that, overall, is highly conductive, e.g., a heating element with a relatively low resistance to electrical current. For the present disclosure, the concept of sheet resistance is being used to analyze the overall resistivity of the textile heating elements produced by the systems and methods described herein. As used herein, the term “sheet resistance” refers to a measure of the electrical resistance of thin film or layer of material that has a uniform or substantially uniform thickness (as is typically the case with the coating of a conductive polymer that is coated via reactive chemical vapor deposition, like the example of PEDOT described above). “Sheet resistance” can be defined as the resistivity of the material per unit of thickness of the material (e.g., Rs=ρ/t, where Rs is the sheet resistance, p is the resistivity, and t is the thickness of the material). Resistivity (ρ) is measured in SI units of ohm-meters (Ω⊕m), while the thickness (t) is measured in SI units of meters (m), so that Rs=ρ/t would have SI units of ohms (Ω). However, in order to avoid confusion with the overall electrical resistance (which also is measured in SI units of Ω), sheet resistance is referred to in units of “ohms per square,” which is denoted herein as “Ω/□.”
Previously reported structures that included PEDOT films on substrates were found to have sheet resistances that were greater than 200Ω/□, which the inventors have found was typically too high for a desirable minimum voltage input (e.g., around 5 V) that can affect noticeable Joule heating in these electrodes. As discussed in more detail below, the inventors have determined more optimal processing parameters for the system and method of coating fiber-based or textile-based substrates with a conducting polymer film via reactive vapor deposition. Prior reported studies on the reactive vapor deposition of PEDOT identified the temperature of the substrate stage as a parameter that affected the conductivity of resulting conductive polymer films. In those studies, a stage temperature of 120° C. was found to produce the highest conductivity for PEDOT films produced on glass substrates. However, the inventors found that sheet resistances textile heating elements only decreased nominally between a heating element with a PEDOT coating deposited with a stage temperature of 80° C. compared to a heating element with PEDOT deposited onto a stage with a temperature of 120° C.
Rather, the inventors have found that the selected deposition pressure within the deposition chamber 26 can have a significant impact on the resulting film of the conductive polymer (e.g., PEDOT) that is formed on the textile substrate 12. For example, TABLE 1 below lists the lateral resistance measured across a one (1) inch length (about 2.5 centimeters (cm)) for PEDOT films having a thickness of about 100 nanometers (nm) that were deposited on a woven pineapple fiber textile substrate 12A (shown in
As shown in TABLE 1, a seven (7) fold decrease in the lateral resistance (e.g., from 73 kiloohms (kΩ) to 11 kΩ) was observed for the pineapple fiber textile substrate 12A when the PEDOT film was coated at a chamber pressure of 300 mTorr compared to a corresponding pineapple fiber substrate 12A where the PEDOT was deposited in a 100 mTorr chamber. A further five (5) fold decrease in the lateral resistance (e.g., from 11 kΩ to 2 kΩ) was observed when the chamber pressure during deposition of the PEDOT onto the pineapple fiber substrate 12A was increased to 500 mTorr. Similar reduction in lateral resistance was also observed for PEDOT-coated cotton fiber substrates 12B (e.g., an almost four (4) fold decrease in lateral resistance between a 100 mTorr and a 300 mTorr deposition pressure (e.g., from 195 kΩ to 50 kΩ) and an almost three (3) fold decrease between 300 mTorr and 500 mTorr chamber pressures (e.g., from 50 kΩ to 18 kΩ)).
In some examples, the deposition pressure in the chamber 26 is tuned to a specified pressure that is at least about 100 mTorr, such as at least about 200 mTorr, for example at least about 250 mTorr, such as at least about 300 mTorr, for example at least about 400 mTorr, such as at least about 500 mTorr. A pressure of about 100 mTorr or more was found to be beneficial to provide for a coating of the conductive polymer that is thick enough and that covers a sufficient potion of each fiber (e.g., a substantial portion of a circumference of each fiber) to provide for good electrical conductivity and that has an overall sheet resistance that is low enough to provide for good Joule heating at an acceptable voltage input requirement for efficient heating. In some examples, a chamber pressure of about 200 mTorr or more, such as about 250 mTorr or more, and in particular about 300 mTorr or more were found to be particularly beneficial for more complete coverage of the fibers or threading of the textile substrate with a coating of the conductive polymer that is of sufficient thickness. In some examples, it was found that while higher deposition pressures (e.g., at or proximate to 500 mTorr or greater) yielded textile electrodes with the highest conductivities (e.g., the lowest resistance), the higher pressure could tend to cause the FeCl3 oxidant to diffuse into and clog the precursor feed. Therefore, in some examples, a chamber pressure of 300 mTorr or less was chosen to maintain chamber longevity.
In some examples, the systems and methods described herein, e.g., with the relatively high pressure in the deposition chamber 26, are able to produce a final textile heating element with a sheet resistance that is from about 2Ω/□ to about 200Ω/□, such as from about 25Ω/□ to about 150Ω/□, for example from about 40Ω/□ to about 100Ω/□. As noted above, when the sheet resistance is too high (e.g., greater than 200Ω/□), than the voltage and power requirements tend to be too high for a wearable device with currently-existing battery and portable power supply technology. Conversely, if the sheet resistance is too low (e.g., less than 2Ω/□), then the textile heating element will not experience sufficient heating when current is supplied to the textile heating element, at least not current from currently-existing battery and power supply technology that can be used in a portable or wearable device. In some examples, the systems and methods described herein produce a textile heating element with a sheet resistance of about 200Ω/□ or less, for example any one of about 190Ω/□ or less, about 185Ω/□ or less, about 180Ω/□ or less, about 175Ω/□ or less, about 170Ω/□ or less, about 165Ω/□ or less, about 160Ω/□ or less, about 155Ω/□ or less, about 150Ω/□ or less, about 145Ω/□ or less, about 140Ω/□ or less, about 135Ω/□ or less, about 130Ω/□ or less, about 125Ω/□ or less, about 120Ω/□ or less, about 115Ω/□ or less, about 110Ω/□ or less, about 105Ω/□ or less, about 100Ω/□ or less, about 95Ω/□ or less, about 90Ω/□ or less, about 85Ω/□ or less, about 80Ω/□ or less, about 75Ω/□ or less, about 70Ω/□ or less, about 65Ω/□ or less, about 60Ω/□ or less, about 55Ω/□ or less, about 50Ω/□ or less, about 45Ω/□ or less, about 40Ω/□ or less, about 35Ω/□ or less, about 30Ω/□ or less, or about 25Ω/□ or less.
The inventors have found that the higher chamber pressure described above results in a significantly thicker coating of the conductive polymer and more complete coverage of the of the fibers or threading that forms the textile substrate 12. For example, it was found that a relatively high pressure in the deposition chamber 26 (e.g., about 100 mTorr or more, such as about 200 mTorr or more, for example about 300 mTorr or more) can achieve a film thickness of the conductive polymer that is significantly more than would be expected compared to earlier reported reactive vapor deposited coatings at lower pressures.
The present inventors believe that a larger thickness for the layer of the conductive polymer that is deposited onto the fibers or threads of the textile substrate 12 can provide for a more efficient textile heating element 14 because the thicker coating can carry a higher current density along the coated fibers or threads. In some examples, the system of
The inventors have found, however, that there is usually a practical limit to how thick the coating of the conductive polymer can be before gains in the potential current density are countered by undesirable properties of the resulting textile heating element 14. In particular, when the thickness of the conductive polymer coating is too thick, the final textile heating element 14 can become undesirably inflexible, the textile heating element 14 can begin to lose the tactile feel of the underlying textile substrate (e.g., the final textile heating element 14 might feel unacceptably different compared to the underlying textile substrate), or the conductive polymer can begin to reduce breathability of the textile heating element 14 below that which is desired. In some examples, the thickness of the conductive polymer on the fibers or threads of the textile substrate are no more than about 10 μm, such as no more than about 9 μm, for example no more than about 8 μm, such as no more than about 7.5 μm, for example no more than about 7 μm, such as no more than about 6 μm, for example no more than about 5 μm, such as no more than about 4 μm, for example no more than about 3 μm, such as no more than about 2.5 μm, for example no more than about 2 μm. In some examples, the thickness of the conductive polymer coating on the fibers or threads of the textile substrate is from about 100 nm to about 10 μm, such as from about 250 nm to about 5 μm, for example from about 500 nm to about 2.5 μm, such as from about 1 μm to about 2 μm.
Regarding the more complete coverage of the fibers or threads of the textile substrate that was observed, without wishing to be bound by any particular theory, the inventors believe that the higher chamber pressure results in shorter reactant mean free paths for the one or more precursor compounds and the oxidant. It is believed that the shorter reactant mean free paths, in turn, produce more complete surface coverage on the fibrous microstructure of the fibers or threading that forms the textile substrate, in particular on rough and textured surfaces that are typical on textile-based substrates. It is further believed that this more complete coverage is due to a higher frequency of surface-restricted reactions occurring over a larger percentage of the surface area of the fibers or threads of the textile substrate (e.g., on both the front and back sides of the textile substrate and around a larger percentage of the circumference of individual threads and/or fibers of the textile substrate), due to improved transport of the reactive precursor or precursors and the oxidant to the surface of the fibers or threads (e.g., more complete diffusion or other transport, or reduced boundary layer formation, or both), and because of suppression of line-of-sight deposition events.
To test the hypothesis that a higher chamber pressure leads to more thorough surface coverage (perhaps even at shallowly buried interfaces), scanning electron micrograph images of the warp-weft intersects of example PEDOT-coated pineapple fiber substrates were taken and examined for substrates that had been coated with a chamber pressure of 100 mTorr (
In some examples, the apparatus 10 of
In some examples, the system or method described above with respect to
The present inventors believe that greater coverage of the fibers or threads of the textile substrate 12 (e.g., with the percentage coverage described above, or with the conformal or substantially conformal coating of the fiber or textile substrate 12 with the conductive polymer, or both) provide for reduced sheet resistance of the resulting textile heating element 14 because the heating element 14 will have more places along each coated fiber or thread where electrical contact can be made between coated fibers or threads of the textile heating element 14, resulting in a greater number of potential electrical pathways for current to travel along when a voltage is applied to the textile heating element 14. It is also believed that more coverage of the surface area of the fibers or threads provides a greater area for current to travel along the coated fibers and, therefore, can support larger current densities along the length of individual coated fibers or threads.
High surface area coverage or conformal or substantially conformal coverage of the fibers or threads of the textile substrate 12, or both, can result in the conductive polymer coating having a minimal or even unnoticeable effect on the porosity and breathability of the final textile heating element 14 compared to that of the original textile substrate 12 (which was not found to be achievable by previously-reported conductive clothes formed by in situ solution polymerization). The high surface area coverage or the conformal or substantially conformal coverage of the fibers or threads, or both, can also result in the final coated textile heating element 14 feeling substantially the same on a wearer's skin as the wearer would feel with the uncoated textile substrate 12, which can be of great benefit to a designer of a piece of apparel that incorporates a textile heating element 14 according to the present description because the designer will be able to select fabrics for the apparel according to his or her existing knowledge of fabrics and according to the desired feel of the final piece of apparel. In other words, a designer will not have to be concerned with the coating process significantly altering the feel of the fabric, which can reduce over design production time because of a reduced need for trial and error of coated fabrics to be used as a textile heating element 14.
A high percentage of coverage and/or conformal or substantially conformal coating with the conductive polymer can also allow for the production of an effective textile heating element 14 with a relatively small increase in mass compared to an uncoated textile substrate 12, even for the relatively larger coating thicknesses that are achieved with the systems and methods described herein. In some examples the mass increase on the textile substrate 12 due to the deposition of the conductive polymer coating (e.g., the difference between the final mass of the textile heating element 14 and the initial mass of the uncoated textile substrate 12) can be 5% or less, such as 2% or less, for example 1% or less. In one specific example, a one (1) cm by one (1) cm square of the cotton fiber substrate 12B of
The inventors also hypothesize that higher number-average molecular weights for the conductive polymer that coats the textile heating element 14 may be obtained at higher chamber pressures due to the increased frequency of oligomer-oligomer couplings compared to the predominance of oligomer-monomer or monomer-monomer interactions at lower chamber pressures. However, this hypothesis was difficult or impossible to prove experimentally because the PEDOT coatings made by the inventors have negligible solubility in most solvents such that accurate molecular weight distributions could not be measured using readily-available instrumentation. For example, a 1 cm×1 cm sample of a textile heating element 14 made from the cotton fiber textile substrate 12B of
In some examples, after the reactive vapor deposition in the deposition chamber 26 of
The examples of coated textile heating elements 14 described herein were found to be biocompatible, e.g., according to ISO 10993-5 standard guidelines. Samples of the example cotton substrate 12B of
The polymer-coated textile heating elements 14 made by the reactive vapor deposition process and with the reactive vapor deposition system described above are sufficiently stable such that they can be handled or manipulated by one or more processes that can be performed on any other commercial fabric without substantially damaging the conductive polymer coating such that the textile heating element 14 can still be used for Joule heating. For example, a polymer-coated textile heating element 14 as described herein can be cut and/or sewn together with another polymer-coated textile heating element 14 according to the present invention without a substantial detriment to Joule heating performance of the sewn-together heating elements 14 compared to a comparably-sized and comparably-coated single textile heating element 14. In some examples, two or more separate textile heating elements 14 can be sewn together with no detrimental effect or with a negligible effect on the Joule heating performance compared to a single heating element 14. In some examples, two or more of the textile heating elements 14 described herein can be sewn with ordinary textile threading. In other words, in some examples, the threading that is used to sew the textile heating elements 14 together need not be a special electrically-conductive material.
The electrothermal stability or ruggedness of the conductive polymer-coated textile heating elements 14 described herein demonstrate that these textile heating elements 14 can be used to form customized garment-based heating elements using conventional textile cutting and textile sewing techniques. This allows the textile heating elements 14 described herein to be tailorable to any part of the body for which conventional textile articles are made, including but not limited to: hands (e.g., fingers or palm, or both), feet (e.g., toes or the main part of the foot), or joints (e.g., elbows, knees, hips, shoulders, angles, or other joint areas that might be treatable with heat therapy).
Examples of the textile heating elements 14 described above, e.g., a fiber-based or textile-based substrate 12 coated with an electrically-conductive polymer coating (such as PEDOT) that has been deposited via reactive vapor deposition, were found to maintain stable conductivities even after exposure to warm moisture (e.g., body heat and sweat). However, in some examples, the textile heating element can be further treated to electrically protect or separate the electrically conductive polymer of the heating element from its environment. In some examples, the additional treatment comprises applying a protective material onto the outer surface or surfaces of the conductive polymer of the textile heating element. In some examples, the protective coating completely or substantially completely covers all exposed surfaces of the conductive polymer, and in some examples completely or substantially completely covers all exposed surfaces of the textile heating element. In some examples, the protective coating comprises an electrically insulating material, such as a dielectric material, that electrically insulates the conductive polymer, for example by electrically isolating the heating element from structures or materials that may come into contact with the textile heating element. In some examples wherein one or more of the textile heating elements are part of a wearable or otherwise body-mounted electrical heating garment or other piece of apparel, the protective coating reduces the likelihood that a part of the wearer's body (e.g., the wearer's skin) will electrically contact the conductive polymer, which could potentially lead to the wearer experiencing an electrical shock.
In some examples, the protective coating can comprise one or more fluoroalkyl-based compounds, such as one or more fluoroalkylsiloxane compounds, which have been proposed for biocompatible dielectric coatings. In an example, a fluoroalkylsiloxane-based protective coating is produced by exposing the textile heating element to trichloro(1H,1H,2H,2H-perfluorooctyl) silane (PFOTS), e.g., after the conductive polymer had been deposited onto the fiber or textile substrate 12. In an example, the polymer-coated textile heating element is exposed to PFOTS vapor for a specified amount of time sufficient for the PFOTS to completely or substantially completely contact the exposed outer surfaces of the textile heating element. In an example, the specified amount of time is at least about 30 minutes). After the specified amount of time, the PFOTS-treated textile heating element is thermally annealed in the presence of methanol vapor at a specified temperature sufficient such that PFOTS vapor at the surface of the textile heating element forms a fluoroalkyl-based material on at least the exposed surfaces of the conductive polymer. In an example, the specified temperature is about 100° C.
The formation of the fluoroalkyl-based protective layer results in a packaged heating element, wherein the fluoroalkyl-based protective layer is resistant to humidity invasion onto or into the conductive polymer film (e.g., into or onto the PEDOT film) of the textile heating element. In one example textile heating element, formation of a fluoroalkyl-based coating was confirmed by placing the textile heating element in a water both before and after exposure to the PFOTS. The textile heating element sample that had yet to be exposed to the PFOTS sank into the water, exhibiting hydrophilic properties. After the exposure to PFOTS and heat annealing, the textile heating element, the textile heating element floated on top of the surface of the water, demonstrating it had been changed into a hydrophobic body. Lateral resistances and total weight of the polymer-coated textile did not observably change after the PFOTS packaging treatment.
As shown in
In some examples, the final protective material of the protective coating is a reaction product of a polymerization reaction of the one or more protective precursor compounds 54. For this reason, the one or more protective precursor compounds 54 may also be referred to herein as “monomers 54” because they are polymerized to form the final protective material. In some examples, the polymerization reaction is a chain-reaction type polymerization reaction, which can be initiated by one or more initiator compounds. In an example, the one or more initiator compounds are fed to the deposition chamber 56 via a second initiator feed line 62. In some examples, the one or more initiators are fed to the deposition chamber 56 in a gaseous or vapor state.
As described above, in some examples the protective material is an electrically insulating material that is sufficiently electrically insulating such that the conductive polymer will be electrically isolated from the environment around the packaged heating element. Examples of monomers 54 that can be used to form sufficiently electrically insulating materials included, but are not limited to: acrylic monomers, such as acrylate monomers or methacrylate monomers; cyclophane monomers; and siloxane monomers (including linear or cyclic siloxane monomers). Examples of acrylate or methacrylate monomers include, but are not limited to: methyl methacrylate (also referred to herein as “MMA”); butyl acrylate; 2,2,3,3-tetrafluoropropyl methacrylate (also referred to herein as “fluorinated methyl methacrylate” or “fMMA”); 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl acrylate; 2,2,3,3,4,4,4-heptafluorobutyl acrylate; and 2,2,3,3,4,4,4-heptafluorobutyl methacrylate. Examples of cyclophane monomers include, but are not limited to: [2.2]para-cyclophane and octafluoro[2.2]paracyclophane: Examples of siloxane monomers include, but are not limited to: 1,3-divinyltetramethyldisiloxane and 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane.
Monomers 54 useful for forming an electrically insulting protective coating can be a hydrocarbon “base” monomer or a substituted monomer (e.g., with one or more hydrogen or methyl groups substituted with a halogen or other substitution element or group, which may itself be a group substituted with a halogen or another substitution element). Halogenated compounds, and in particular fluorinated compounds, have been found to be particularly useful for electrical insulation and for preventing or reducing moisture ingress into a fiber-based or textile-based heating element packaged with the resulting protective coating. For example, as shown in
Examples of initiators that can be used to initiate a polymerization reaction of the one or more of the protective precursor compounds 54, such as the precursor monomers described above, include, but are not limited to: di(tert-butyl)peroxide, tert-butyl-hydroperoxide, and hydrogen peroxide.
In an example, the protective coating vapor deposition chamber 56 includes a temperature regulation apparatus 64 within the deposition chamber 56 to maintain a temperature at specified position or region within the deposition chamber 56. In particular, the temperature regulation apparatus 64 is positioned and configured to control a temperature of the one or more protective precursor compounds 54 (i.e., the one or more precursor monomers) to a specified temperature at a position relative to the position of the fiber-based or textile-based heating element 52 positioned on the deposition stage 58. In an example, shown in
In an example, the heating apparatus 64 is configured to ensure that the monomer molecules 68 are vaporized and are at the specified temperature before being deposited and reacted onto the substrate being coated. The heating by the heating apparatus 64 also acts to decompose the monomer into reactive radicals, e.g., via reaction with molecules 68 of the initiator to form the reactive radicals. In some examples, the specified temperature selected to ensure vaporization of the monomer molecules 68 and decomposition of a significant portion of the monomer molecules 68 to reactive radicals if from about 60° C. to about 150° C. In an example, the heating apparatus 64 (e.g., the heating filaments 64) are heated to a temperature of from about 100° C. to about 200° C. so that the monomer molecules 68 will reach the desired specified temperature.
In some examples, vapor phase for the monomer molecules 68 and/or decomposition into reactive radicals can be caused by reducing the pressure within the deposition chamber 56, such as with a vacuum apparatus (not shown) that creates a vacuum pressure environment in the deposition chamber 56, e.g., via an effluent port 70. In an example, the vacuum pressure environment comprises an absolute pressure within the deposition chamber 56 of about 2 to about 10 mTorr. Reducing the pressure can be performed in place of or in addition to heating the monomer molecules 68 with the heating apparatus 64 (e.g., heating filaments 64), such as by selecting a combination of a specified temperature and the specified pressure that will provide for the desired polymerization and formation of the protective coating on the heating element 52 and at a specified deposition rate.
In some examples, the deposition stage 58 is cooled to a specified stage temperature in order to create a specified temperature gradient between the gas in the deposition chamber 56 (including the monomer molecules 68, the reactive radicals, and the initiator) and the substrate that is being coated (e.g., the fiber-based or textile-based heating element 52). In an example, the deposition stage 58 is cooled with a cooling fluid that is flow through or past or through the deposition stage 58, such as cooling water or an ethylene glycol-water mixture. In an example, the stage temperature to which the deposition stage 58 is cooled is selected to drive the polymerization reaction of the reactive radicals formed from the monomer molecules 68 (e.g., by heating with the heating apparatus 64 or by reducing pressure in the deposition chamber 56, or both) to form the final polymer of the protective coating on the fiber-based or textile-based heating element 52. Cooling of the deposition stage 58 can also help control where the protective coating material will be deposited, e.g., so that most of the molecule molecules 68 or reactive radicals will be deposited onto the fiber-based or textile-based heating element 52 and the deposition stage 58 rather than onto the inner walls of the deposition chamber 56 or onto other structures within the deposition chamber 56 (such as the QCM sensor 36). In some examples, the walls of the deposition chamber 56 can also be heated, e.g., with a separate heater, to further enhance the temperature gradient between the deposition stage 58 and the inner walls of the deposition chamber 56. In an example, the deposition stage 58 is cooled to a stage temperature of from about 0° C. to about 15° C.
In some examples, the protective coating vapor deposition apparatus 50 is configured to produce a protective coating having a thickness of from about 100 nanometers (nm) to about 1 micrometer (μm). The protective coating thickness can be controlled by controlling the deposition rate (e.g., the growth rate of the protective coating on the fiber-based or textile-based heating element 52). In some examples, the deposition rate can be adjusted by controlling one or more of: the partial pressure of the monomer molecules 68 in the deposition chamber 56 (e.g., by controlling the flow rate of the monomer to the deposition chamber 56 through the protective precursor feed line); the partial pressure of the initiator (e.g., by controlling the flow rate of initiator to the deposition chamber 56 through the initiator feed line); chamber pressure; the temperature of the heating filaments 64, and the stage temperature to which the deposition stage 58 is cooled. In an example, shown in
The vertical distance from the inlet of the monomer molecules 68 (e.g., the inlet port 66) and the heating apparatus 64 to the deposition stage 58 is selected so that the monomer molecules 68 and/or the reactive radicals will sufficiently disperse as they diffuse or float down to the deposition stage 58, and in particular so that the concentration of the monomer molecules 68 and/or reactive radicals will be uniform or substantially uniform across all of or substantially all of the surface area of the fiber-based or textile-based heating element 52 being coated. Uniform concentration of the monomer molecules 68 and/or reactive radicals results in uniform or substantially uniform growth of the protective coating on the fiber-based or textile-based heating element 52, which is desirable to more precisely control the thickness of the protective coating. However, if the distance from the monomer inlet port 66 and/or the heating apparatus 64 to the deposition stage 58 is too large, the monomer/radical concentration may be sufficiently uniform, but the growth rate of the protective coating may be too slow, which increases the time needed to grow the protective coating to a specified thickness. In an example, the distance from the monomer inlet port 66 and/or the heating apparatus 64 to the deposition stage 58 is from about 10 cm (about 4 inches) to about 30 cm (about 12 inches). However, the exact distance selected can depend on many other factors, including the specific monomer or monomers being used, the partial pressure of the monomer and initiator in the deposition chamber 56, the overall pressure in the deposition chamber 56 and/or, the specified temperature to which the monomer molecules 68 will be heated, and the stage temperature to which the deposition stage 58 is cooled.
In some examples, the reactive vapor deposition apparatus 50 described above produces a protective coating that conformally or substantially conformally coats the conductive-polymer coated textile heating element 52 with the protective material. Even if the packaged heating element 52 does not include a fully conformal coating of the protective material on the surface or surfaces of the fabric or textile-based heating element 52, the reactive vapor deposition apparatus 50 of
The primary type of heating element described above is one formed from a textile-based substrate. However, the deposition methods described above can also be used to apply the conductive polymer to a fiber-based or thread-based substrate (e.g., a fiber or threading, which will be referred to hereinafter as a “fiber substrate”) in order to form a fiber-based or threading-based heating element (referred to hereinafter simply as a “heating element thread”). A fiber heating element can be used, for example, to form an embroidered heater or a woven textile heater comprising individual heating fibers.
The primary difference between the example apparatus 100 of
In some examples, this design of deposition stage 114 can accommodate a relatively long length of fiber substrate 102, e.g., as much as 2 meters (about 7 feet) or longer of fiber substrate 102 when carefully wound in different layers of the fiber substrate 102. Of course, more efficient designs of the deposition stage 114 to accommodate different lengths and configurations of fiber substrate 102 can be designed without varying from the scope of the present disclosure.
In some examples, the deposition apparatus 100 for deposition of the conductive polymer onto one or more fiber substrates 102 can be operated at substantially the same operating conditions as described above for the deposition apparatus 10 of
One or more of the coated heating element threads can be used to form a larger textile structure. For example,
In some examples, vapor-deposited coatings of the conductive polymer (e.g., PEDOT) do not become rubbed off during weaving, embroidering, or otherwise handling the coated heating element threads, or only have minimal rubbing off of the conductive polymer material. Other methods of manipulating the coated heating element threads or yarns can include knitting, com, complex weaving operations, embroidering, formation into non-woven textiles, winding onto a spindle structure for further processing, lapping, or any other method known in textile processing or composite structure shaping now known or later discovered. In short, the vapor deposition apparatus 100 of
In some examples, a plurality of sheets of textile heating elements are stacked into a multi-layer heating stack. Each textile heating element of the heating stack can be (a) a textile heating element 14 formed by coating an existing textile substrate 12 (such as the example substrates 12 of
The electrical contact between adjacent textile heating elements 132 in a multi-layer heating stack 130 like the example shown in
The electrical contact between adjacent textile heating elements 132 in a multi-layer heating stack 130, and in some examples the corresponding increase of conduction channel cross-sectional area, can reduce the overall resistance (e.g., lateral and transverse resistance) for the entire heating stack 130 as compared to the individual textile heating elements 132 that form the layers of the multi-layer stack 130. Multi-layer heating stacks 130 can also impede dissipation of generated heat to the ambient environment in cold weather by forming a heat trap 138, e.g., in one or more air layers within or between the layers 132 of the multi-layer heating stack 130 or because of infrared reflection, in much the same way that layered conventional textiles do. Therefore, it would be expected that heating structures comprising a plurality of conductive polymer coated textile heating elements 132 arranged in a multi-layer heating stack 130 will demonstrate both higher electrical efficiency and higher heating temperatures compared to single-layered textile heating elements 132.
In one example, when multiple textile heating elements were layered together, the overall lateral and transverse resistance of the stack linearly decreased with the number of layers in the stack. TABLE 2 shows the effect of the multiple layers in heating stacks made from pineapple-fiber textile substrates (e.g., those shown in
As can be seen in TABLE 2 and
The theoretical equilibrium temperature that can be achieved by a heating element structure due to Joule heating is provided by Equation 1.
where T is the expected equilibrium temperature, V is the supplied voltage, I is the current through the heating element structure, h is the convective heat transfer coefficient, A is the device surface area, and Ta is the ambient air temperature. Equation 1 can be rewritten to Equation 2.
where R is the lateral resistance for the entire heating element, e.g., the resistance across the textile heating element for a single-layer device, or the resistance across the entire multi-layer heating stack. As can be seen by Equation 2, the expected temperature increase due to Joule heating is inversely proportional to the overall lateral resistance across the device.
Therefore, the reduction in lateral resistance for the multi-layer heating stacks is expected to result in a corresponding improvement in the heated temperature achieved. TABLE 2 also includes data for the change in temperatures achieved (over the ambient temperature) for the single-layer textile heating element and for the multi-layer heating stacks at the same applied voltages, which demonstrates that this expected improvement in the achieved temperature does occur. The temperature data relative to the number of heating element layers in the heating stack from TABLE 2 is plotted in
For a single-layer PEDOT-coated cotton fiber heating element, the temperature increase achieved was 4° C., corresponding to a predicted temperature increase, based on Equation 2, of 8° C. and 12° C., respectively, for the double-layered and triple-layered heating stacks (plotted as dashed line 152 in
Because the electrical contact between adjacent layers is necessary for this transfer of electrical current between adjacent layers, each layer of the multi-layer heating stack is not packaged with an electrically-insulating protective coating (such as the PFOTS coating described above or the protective coating deposited by the vapor deposition apparatus 50 described above with respect to
In some examples, the varying lateral resistances for heating stacks having different numbers of heating element layers can be used to fabricate specified temperature gradients in an article by creating “circuits” of combinations of single heating elements or multi-layer heating stacks.
Narrow strips of copper fabric 168 were sewn onto overlapping edges between the first heating section 162 and the second heating section 164 (e.g., along the first or left-most edge of the second heating section 164) and between the second heating section 164 and the third heating section 166 (e.g., along the opposing second or right-most edge of the second heating section 164). Similar strips of copper fabric were also sewn onto the outside edges of the first heating section 162 and the third heating section 164 for connection to a voltage source. The copper fabric strips were included to help ensure a uniform electric field across the junctions between adjacent heating sections 162, 164, 166 and at the voltage source connection points. However, as noted above, because of the conductive nature of the conductive polymer coating as well as the complete or substantially complete coverage of the textile heating elements by the vapor deposition methods described above, a metal-based electrode such as the copper fiber is not necessary for operation of all embodiments of heating fabric circuits.
Response times and heater stability under constant operation were measured an example triple-layered heating stack of cotton fiber heating elements that were not packaged with a protective coating.
Various embodiments of the present invention can be better understood by reference to the following Examples which are offered by way of illustration. The present invention is not limited to the Examples given herein.
For all examples below, the chemicals used were purchased from Sigma-Aldrich (St. Louis, Mo., USA) and used without further purification. Scanning electron microscopy (SEM) was performed using a FESEM Magellan 400, FEI Company (Hillsboro, Oreg., USA). Film thicknesses were measured on a Dektak 150 profilometer, Veeco Instruments, Inc. (Plainview, N.Y., USA). Surface sheet conductivities of conductive polymer-coated substrates, reported in units of Ω/□, were calculated from resistivity measurements made using a custom-built four-point probe test station. Lateral resistances, i.e., the horizontal resistance across the short axis of a textile heating element, reported in units of Ω, was measured using standard stainless steel probe tips of an ohm meter. Joule heating was powered by commercially-available alkaline batteries. Thermal images were taken using an IR imaging camera, FLIR Systems, Inc. (Wilsonville, Oreg., USA).
Vapor phase polymerization of 3,4-ethylenedioxythiophene (EDOT) to form poly(3,4-ethylenedioxythiophene) (PEDOT) coatings on textiles was carried out in a custom-built reactive vapor deposition apparatus comprising a cube-shaped stainless steel deposition chamber. A downwards-facing substrate holder/deposition stage was located on the top of the deposition chamber (e.g., the apparatus 10 shown in
Film thickness was monitored by a quartz crystal microbalance (QCM) located inside the cubic chamber. A corrective tooling factor for the readout obtained from the QCM sensor was obtained as follows. Silicon substrates were coated with films of varying thickness (“QCM reported”) at three different monomer:oxidant flow rate ratios, rinsed with H2SO4/methanol, and the resulting film thickness (“actual thickness”) measured using a profilometer. A tooling factor was obtained by taking the ratio of the actual film thickness after rinsing to the thickness reported by the QCM sensor when the tooling factor was set as 100%. The tooling factor was found to be 0.5 for all monomer:oxidant flow rate ratios.
Textiles used as substrates were used as received, without washing. After vapor deposition, the coated substrates were rinsed with 1 M aqueous HCl for 2 minutes to completely remove trapped iron salts, followed by methanol to remove residual monomer and HCl from the polymer coatings. The coated and washed substrates were then dried overnight in air before electrothermal measurements. The PEDOT coatings thus obtained remained stably doped even after rinsing and storage under ambient conditions. For one example of a 1 cm×1 cm cotton square, the measured mass before coating was 27.664 mg, with a measured mass after coating with a 1.5 micron thick PEDOT film of 27.829 mg, a 0.6% increase in mass.
As discussed above, significant gains were obtained when the background chamber pressure during deposition was increased using inert argon gas. (See TABLE 1 and discussion above). A seven-fold decrease in resistance was observed when pineapple fiber fabrics were coated with PEDOT at a chamber pressure of 300 mTorr, instead of 100 mTorr. A further five-fold decrease was observed when the chamber pressure was increased to 500 mTorr. Similar effects were also observed for cotton squares coated with PEDOT, with a chamber pressure of 500 mTorr also yielding the lowest measured lateral resistances across the plain-woven swatch. As is also discussed above, at 100 mTorr, the warp and weft threads acted as each other's shadow masks and no PEDOT coating could be found in the buried interfaces where the warp thread crossed over the weft thread (or vice versa) because of inefficient diffusion of reactants. In contrast, at 500 mTorr, these buried interfaces were coated with PEDOT. Indeed, near 360o coverage of all the warp and weft threads of the plain-woven fabric swatch were observed when the vapor coating was performed at 500 mTorr (see comparison of
Two commercially-available textiles were used to produce PEDOT-coated heating elements: pineapple fiber and cotton fiber fabrics (shown in
Surface sheet resistances of 44Ω/□ and 61Ω/□ were measured for the PEDOT-coated pineapple fiber and cotton textile substrates, respectively. A battery was connected to the PEDOT-coated heating elements, using alligator clips, to effect Joule heating. A sample of the PEDOT-coated cotton fiber textile substrate was found to be capable of generating a temperature of 28° C. when the ambient temperature was 19° C. when connected to a 4.5-volt battery and to 45° C. when connected to a 6-volt battery.
As noted above, the PEDOT-coated textile heating elements could be handled like any other commercial fabric in that they could be cut and sewn together (with regular thread) without any detriment to Joule heating performance.
A reactive vapor deposition apparatus similar to the deposition apparatus described above for EXAMPLE 1 was used for vapor phase polymerization of EDOT to form a PEDOT coating on a usable length of one or more stand-alone fibers or threads. The main structural modification to the reactive vapor deposition apparatus for deposition onto stand-alone fibers or threads was a modification to the deposition stage to include a plurality of thread posts (e.g., as shown in
A thick cotton yarn, similar to those typically used to make sweaters, was vapor coated with a 1.5 μm thick PEDOT film with the modified reactive vapor deposition apparatus to form a heating element thread that can be used in a Joule heating element.
Layered PEDOT-coated cotton textile heating stacks were used as part of a prototype thermal glove 180. Cotton fiber textile was chosen to fabricate the textile heating elements of the prototype glove because cotton fabric can be thin, breathable, lightweight, and is readily available.
The inner glove layer 182, e.g., the layer 182 that would contact the wearer's hand, comprised a commercially-available cotton lining glove, which was not coated with PEDOT. The middle heating structure 184 included four separate textile heating elements 188 that were placed over the finger compartments 190 of the inner glove 182. Each textile heating element 188 was made from a double-layered heating stack of cotton textile substrates coated with a 1.5 μm thick PEDOT coating. The two layers of each heating stack heating element were sewn together with conductive copper thread to ensure that there was stable electrical contact between the layers of the heating stack (although as described above, conductive threading is not required). Each double-layered heating stack was curled into a closed cylinder shape corresponding to the size and shape of a corresponding finger compartment 190 of the inner glove 182 (but not the thumb compartment). The heating element cylinders 188 were placed over the finger compartments 190 of the inner glove 182 and were sewn onto the inner glove 182 with conventional, non-PEDOT coated cotton thread. The middle heating structure 184 also included copper fabric contact pads 192 for one or more coin cell batteries (Energizer 1632, weight 1.8 g) were sewn onto the inner glove, one contact pad 192 on the palm side of the inner glove 182 (shown in
Conductive copper thread 194 (represented by dashed red lines in
An outer cover layer 186 in the form of a commercially available black silk glove 186 was placed over the cylindrical heating elements 188 on the finger compartments 190, the contact pads 192, the connecting wires 194, and the inner glove 186 to serve as a heat-retaining layer and as an aesthetically-tunable overall packaging layer. However, the present disclosure is not limited to a silk outer glove 186. Rather, any outer casing material can be selected to tailor the glove to the aesthetic and haptic preferences of a potential wearer. Further, if desired, bulky outer layers can be invoked to improve heat retention and manifest warmer temperatures from the Joule heating elements, for example for use in colder environments.
An equivalent circuit for the four cylindrical textile heating element stacks is shown in
The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention can be practiced. These embodiments are also referred to herein as “examples.” Such examples can include elements in addition to those shown or described. However, the present inventors also contemplate examples in which only those elements shown or described are provided. Moreover, the present inventors also contemplate examples using any combination or permutation of those elements shown or described (or one or more aspects thereof), either with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein.
In the event of inconsistent usages between this document and any documents so incorporated by reference, the usage in this document controls.
In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of “at least one” or “one or more.” In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. In this document, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, device, article, composition, formulation, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.
Method examples described herein can be machine or computer-implemented at least in part. Some examples can include a computer-readable medium or machine-readable medium encoded with instructions operable to configure an electronic device to perform methods as described in the above examples. An implementation of such methods can include code, such as microcode, assembly language code, a higher-level language code, or the like. Such code can include computer readable instructions for performing various methods. The code may form portions of computer program products. Further, in an example, the code can be tangibly stored on one or more volatile, non-transitory, or non-volatile tangible computer-readable media, such as during execution or at other times. Examples of these tangible computer-readable media can include, but are not limited to, hard disks, removable magnetic disks, removable optical disks (e.g., compact disks and digital video disks), magnetic cassettes, memory cards or sticks, random access memories (RAMs), read only memories (ROMs), and the like.
The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments can be used, such as by one of ordinary skill in the art upon reviewing the above description. The Abstract is provided to comply with 37 C.F.R. § 1.72(b), to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter may lie in less than all features of a particular disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description as examples or embodiments, with each claim standing on its own as a separate embodiment, and it is contemplated that such embodiments can be combined with each other in various combinations or permutations. The scope of the invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.
This application is a continuation of U.S. patent application Ser. No. 16/258,165, filed Jan. 25, 2019, which claims priority to U.S. Provisional Application Ser. No. 62/621,887, filed Jan. 25, 2018, the disclosure of which are incorporated herein in their entirety by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62621887 | Jan 2018 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16258165 | Jan 2019 | US |
| Child | 17449187 | US |
