MACHINE-KNITTABLE CONDUCTIVE HYBRID YARNS
20210277544 · 2021-09-09
Inventors
- Clare King (Providence, RI, US)
- Anjali Khemani (Providence, RI, US)
- Birgit Leitner (Providence, RI, US)
Cpc classification
A61B2562/18
HUMAN NECESSITIES
D02G3/441
TEXTILES; PAPER
D10B2403/02431
TEXTILES; PAPER
A61B2562/125
HUMAN NECESSITIES
D02G3/443
TEXTILES; PAPER
D02G3/045
TEXTILES; PAPER
A61B5/256
HUMAN NECESSITIES
A61B5/266
HUMAN NECESSITIES
A61B2562/14
HUMAN NECESSITIES
International classification
D02G3/44
TEXTILES; PAPER
D02G3/04
TEXTILES; PAPER
Abstract
A machine knittable hybrid yarn for providing conductive traces through a textile is disclosed. The hybrid yarn includes conductive wires coated with an insulating material and twisted together with a nonconductive yarn. The nonconductive yarn is from a strong, inelastic, and nonconductive fiber, such as a meta-aramid or para-aramid that protects the integrity of the conductive wire during knitting. The conductive wire can be copper-clad stainless steel or copper wire is coated with polyurethane, and the nonconductive yarn can have no-drip and no-drip properties to allow ablation of the hybrid yarn to remove the conductive yarn and insulating coating on the wire such that the ablated region becomes externally conductive and suitable for making an electrical contact. The hybrid yarn can be bonded with nylon or similar polymer after twisting.
Claims
1. A machine-knittable hybrid yarn, comprising: a non-conductive yarn; and a conductive wire twisted with the nonconductive yarn, the conductive wire having an exterior layer of an insulating material.
2. The hybrid yarn of claim 1, wherein the non-conductive yarn is twisted together with the conductive wire.
3. The hybrid yarn of claim 2, wherein non-conductive yarn and the conductive wire are twisted together with Z twist or an S twist from the single twisting process.
4. The hybrid yarn of claim 1, wherein the conductive wire is twisted with the conductive yarn at between 1 and 15 twists per inch.
5. The hybrid yarn of claim 4, wherein the conductive wire is twisted with the conductive yarn at between 5 and 12 twists per inch.
6. The hybrid yarn of claim 1, wherein the conductive wire defines a continuous strand of metal along the hybrid yarn.
7. The hybrid yarn of claim 1, wherein the hybrid yarn is bonded with a polymer layer.
8. The hybrid yarn of claim 7, wherein the hybrid yarn is bonded with Nylon.
9. The hybrid yarn of claim 1, wherein the insulating layer comprises a polymer coating.
10. The hybrid yarn of claim 1, wherein the nonconductive yarn is 1500 denier or finer.
11. The hybrid yarn of claim 1, wherein the conductive wire is approximately 10 to 100 microns thick.
12. The hybrid yarn of claim 1, wherein the non-conductive yarn has an elasticity less than that of the twisted conductive wire such that the conductive wire does not break before the non-conductive yarn under tensile loading of the hybrid yarn.
13. The hybrid yarn of claim 1, wherein the non-conductive yarn is fire retardant and self-extinguishing.
14. The hybrid yarn of claim 10, wherein the non-conductive yarn is no-melt and no-drip according to the ASTM D6413/D6413M Standard Vertical Test Method for Flame Resistance of Textiles.
15. The hybrid yarn of claim 1, wherein the non-conductive yarn has a tensile strength higher than the conductive wire.
16. The hybrid yarn of claim 1, wherein the nonconductive yarn has a Young's modulus of at least 60 GPa.
17. The hybrid yarn of claim 1, wherein the nonconductive yarn has a break elongation percentage of 4.2 or less.
18. The hybrid yarn of claim 1, wherein the non-conductive yarn comprises at least one of an aramid, meta-aramid, or para-aramid polyamide fiber.
19. The hybrid yarn of claim 1, wherein the non-conductive yarn comprises at least one: Ultra High Molecular Weight Polyethene (UHMWPE), Polybenzimidazole (PBI), Polyphenylene Benzobisoxazole (PBO), High Strength Polyester, Liquid-Crystal Polymer (LCP), or spider silk.
20. The hybrid yarn of claim 1, wherein the conductive wire comprises a copper-clad stainless steel wire or a solid copper wire.
21. The hybrid yarn of claim 1, wherein the non-conductive yarn and the insulating material each have a decomposition temperature less than a melting point of the conductive wire.
22. The hybrid yarn of claim 1, wherein the non-conductive yarn comprises staple fibers.
23. The hybrid yarn of claim 1, wherein the conductive wire is a first conductive wire, and the hybrid yarn further comprises a second conductive wire twisted with the nonconductive yarn.
24. The hybrid yarn of claim 1, wherein non-conductive yarn comprises staple fibers.
25. A machine-knittable hybrid yarn, comprising: a non-conductive yarn; and a conductive wire twisted together with the nonconductive yarn, the conductive wire having an exterior layer of an insulating material, wherein the non-conductive yarn has a tensile strength higher than a tensile strength of the conductive wire, and wherein the non-conductive yarn is fire retardant and self-extinguishing.
26. A method of making a machine-knittable hybrid yarn, the method comprising: twisting, in a single process, a non-conductive yarn with a conductive wire, the conductive wire having an exterior coated with an insulating material.
27. The method of claim 26, further comprising: bonding, after the twisting, the twisted non-conductive yarn and conductive wire with a nonconductive exterior layer.
28. The method of claim 27, wherein the nonconductive layer comprises a polymer.
29. The method of claim 26, wherein the conductive wire is twisted with the conductive yarn at between 1 and 15 twists per inch.
30. The method of claim 26, wherein the non-conductive yarn has an elasticity less than that of the twisted conductive wire such that the conductive wire does not break before the non-conductive yarn under tensile loading of the hybrid yarn.
31. The method of claim 26, wherein the non-conductive yarn is fire retardant and self-extinguishing.
32. The method of claim 26, wherein the non-conductive yarn has a tensile strength higher than the conductive wire.
33. The method of claim 26, wherein the nonconductive yarn has a Young's modulus of at least 60 GPa.
34. The method of claim 26, wherein the nonconductive yarn has a break elongation percentage of 4.2 or less.
35. The method of claim 26, wherein the non-conductive yarn comprises at least one of: an aramid, meta-aramid, or para-aramid polyamide fiber.
36. The method of claim 26, wherein the non-conductive yarn comprises at least one: Ultra High Molecular Weight Polyethene (UHMWPE), Polybenzimidazole (PBI), Polyphenylene Benzobisoxazole (PBO), High Strength Polyester, Liquid-Crystal Polymer (LCP), or spider silk
37. The method of claim 26, wherein the conductive wire comprises a copper-clad stainless steel wire or a solid copper wire.
38. The method of claim 26, wherein the non-conductive yarn comprises staple fibers.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] This disclosure will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
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DETAILED DESCRIPTION
[0029] Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the devices and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present disclosure is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present disclosure.
[0030] Example Textiles with Integrated Conductive Traces
[0031]
[0032] The textile electrodes 130 can be arranged to, for example, pick up or sense electrical signals from the user's body, such as those related to heart rate and heart function (e.g., the signals for use in forming an electrocardiogram EKG). In some embodiments, the garment 100 includes four textile electrodes 130, positioned with respect to the user's body in order to provide a high-quality EKG signal. The conductive traces 120 connect the textile electrodes 130 to the electrical device 199 via the conductive wires integrated into the hybrid yarn from which the conductive traces 120 are knitted. The conductive wire of the hybrid yarn can be coated with an insulating polymer, which is able to be removed at the points of contact with the textile electrodes 130 and the electrical device 199.
[0033] In some embodiments, the hybrid yarn is constructed from a highly inelastic material, such as meta-aramid or para-aramid (e.g., Kevlar® or Twaron®) or a material with similar material properties to protect the integrated conductive wires from damage or being severed during the knitting process and being damaged or severed during normal wear of the garment 100, such as Ultra High Molecular Weight Polyethene (UHMWPE), Polybenzimidazole (PBI), Polyphenylene Benzobisoxazole (PBO), High Strength Polyester, Liquid-Crystal Polymer (LCP), or spider silk. In some embodiments the hybrid yarn is made with a fire retardant and self-extinguishing material, such as para-aramid or material with similar properties according to the ASTM D6413/D6413M Standard Vertical Test Method for Flame Resistance of Textiles to enable the insulating layer and nonconductive yarn to be removed using ablation. The conductive wire can be, for example copper wire or copper-clad stainless-steel sire. Additionally, the textile electrodes 130 may be knitted or otherwise constructed with a conductive wire, such as silver or copper wire or a nonconductive yarn (e.g., nylon, polyester, cotton, or wool) coated with a conductive material such as silver or copper. In some embodiments, the standard material 110, textile electrodes 130, and conductive traces 120 are knitted together into a single-layer garment 100 without seams.
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[0035] Examples of a Hybrid Conductive Yarn
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[0037] In one example, the hybrid yarn 200 includes two stands of copper-clad stainless steel or copper with between 5 to 12 twists per inch around a Kevlar strand. The 5 to 12 twists per inch construction can be a strand of Kevlar and a 50 micron conductive wire (e.g., 43 micron thick metal and a 3-4 micron thick coating of polyurethane) that when twisted together suitable to knit a textile at 15 gauge. The hybrid yarn 200 in
[0038] Nonconductive yarns 210 made with para aramid or similar materials have many advantages, such as being strong, but relatively light. The specific tensile strength (stretching or pulling strength) of both Kevlar 29 and Kevlar 49 is over eight times greater than that of steel wire. Unlike most plastics it does not melt: it is reasonably good at withstanding temperatures and decomposes only at about 450° C. (850° F.). Accordingly, the hybrid yarn 200 can be laser ablated or burned to remove the nonconductive yarn 210 and the coating on the conductive wire 220.
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[0041] Example Hybrid Conductive Yarn Properties
[0042] Nonconductive yarns 210 made with para aramid or similar materials have many advantages, such as being strong, but relatively light. The specific tensile strength (stretching or pulling strength) of both Kevlar 29 and Kevlar 49 is over eight times greater than that of steel wire. Unlike most plastics it does not melt: it is reasonably good at withstanding temperatures and decomposes only at about 450° C. (850° F.). Similarly, Aramid fibers can be used for the nonconductive yarn 210. Aramid fibers are created with a range of beneficial properties, and come in two types, para-aramid and meta-aramid, both of which are suitable. Kevlar is an example of a para-aramid fiber. These generally have a high strength-to-weight ratio and great tenacity, making them abrasion-resistant. Other advantages include: [0043] High Young's Modulus (i.e., structural rigidity, also known as “elastic modulus,” which defines the relationship between stress and strain in a material) of, for example 60 to 179 GPa. [0044] Low elongation at break point (i.e., the yarn stretches very little under tension). [0045] Nonconductive under normal conditions. [0046] Resistance to abrasion and cutting. [0047] Resistance to organic solvents. [0048] Retain low flammability, resistant to thermal degradation, and self-extinguishing. [0049] Keep fabric integrity at elevated temperatures. [0050] Excellent dimensional stability.
TABLE-US-00001 TABLE 1 Strength- Ultimate to-weight Tensile Strength Density Material KN .Math. m/kg. MPa g/cm3 Kevlar 2514 2757 1.44 Carbon Fiber 2457 4137 1.75 E Glass Fiber 1307 3450 2.57 Carbon Laminate 785 1600 1.5 E Glass Laminate 775 1500 1.97 Nylon 69 75 1.15
TABLE-US-00002 TABLE 2 Young's Modulus Material GPa Aramid (such as Kevlar and Twaron) 70.5-112.4 Nylon 2-4 Polypropylene 1.5-2
[0051] Meta-aramid fibers are another example of a suitable nonconductive yarn 210 for use in the hybrid yarn 200 and they have the following advantages: [0052] Heat resistance: Meta-aramid has long-lasting thermal stability. It can operate for long time at a temperature of 204° C. and it maintains excellent dimensional stability. It is not overly brittle, and does not soften or melt even if it is briefly exposed to temperatures up to about 300° C. [0053] Flame resistance: Meta-aramid is inherently flame resistant. It does not self-burn or melt at regular levels of oxygen. It is self-extinguishing and should carbonize at 400° C. [0054] Electrical insulation: Meta-aramid has excellent electrical insulation properties. The dielectric strength of meta-aramid paper is up to about 20 kv/mm, but varies depending on the particular meta-aramid. [0055] Chemical stability: Meta-aramid has a very stable chemical structure and is resistant to organic solvents. [0056] Radiation resistance: Good resistance to Ultraviolet, α (alpha) and β (beta). [0057] Mechanical properties: Meta-aramid is formable for moldable parts. [0058] Low elongation at break point as well as para-aramid (i.e., it exhibits a minimal stretch under tension).
[0059] While helpful properties of para-aramid and meta-aramid have been listed above, Table 3 shows the various characteristics of aramid fibers compiled from the Chemical Economics Handbook and Encyclopedia of Chemical Technology, Vol. 19 and Indian Journal of Fiber and Textile Research.
TABLE-US-00003 TABLE 3 Properties of Commercial Aramid Fibers Extension Loop Density to Break Modulus Elongation Fiber Type g/cm3 % GPa % Kevlar29 1.43 3.6 70 2.1 Kevlar49 1.45 2.8 135 1.3 Kevlar119 1.44 4.4 55 2.7 Kevlar129 1.45 3.3 99 Kevlar149 1.47 1.5 143 0.6 Nomex 1.38 22 17 Twaron 1.44 3.3 79 Twaron HM N/a 2 123 Technora 1.39 4.3 70 Technora V106 1.32 3.7 77
[0060] Example Hybrid Conductive Yarn Advantages
[0061] Existing commercial hybrid yarns often incorporate stretch core such as Spandex and a metal wire wrapped around it. When this type of yarn is fed through a knitting machine with tension applied the yarn stretches and appears smooth. However, when the yarn relaxes after the knitting process is complete and goes back to its original length, the wire randomly retracts and potentially kinks. Kinking subsequently can lead to breakage or malfunction, resulting in a failed electrical circuit. As discussed above, hybrid yarns of the present disclosure are stable with little to no elongation and protects the wires during a machine the knitting process. Low elasticity and high tensile strength materials, such as para-aramid yarn, keeps the twisted conductive wires 220 from overstretching or breaking. Additionally, within the knit structure the nonconductive yarn 210 examples disclosed herein also protect the conductive wire 220 from daily wear and tear due to their high tensile strength.
[0062] Because the conductive wires 220 wires are insulated and continuous, power flow is contained throughout the region or structure knitting using the hybrid yarn. This contrasts with most known processes in which e-traces are uninsulated and are later protected by application of external materials such as films etc. This is an additive process. Embodiments of the present disclosure can involve knitting in an integrated method yielding a single textile layer only, without needing to add a conductive layer, film or coating overtop the trace regions. These additional materials not only add additional manufacturing steps, it also adds bulk, rigidity and opportunity for failure.
[0063] Finally, if or when a connection needs to be made to the conductive trace region 120, the hybrid yarn 200 can be ablated at any point chosen to expose the conductive wire 220. In an example process of ablation, nonconductive yarn 210 made using a Para-aramid material and a polymer insulation layer on the conductive wire 220 burns or vaporizes off, leaving access to the metal surface. Embodiments include nonconductive yarn 210 made with self-extinguishing fibers, such as para-aramids, and any ablation is strictly contained to a target area.
[0064] Examples of Manufacturing a Hybrid Conductive Yarn
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[0067] Example Knitted Textile Constructs using Hybrid Conductive Yarn
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[0072] The embodiments of the invention described above are intended to be merely exemplary; numerous variations and modifications will be apparent to those skilled in the art. One skilled in the art will appreciate further features and advantages of the disclosure based on the above-described embodiments. Such variations and modifications are intended to be within the scope of the present invention as defined by any of the appended claims. Accordingly, the disclosure is not to be limited by what has been particularly shown and described, except as indicated by the appended claims. All publications and references cited herein are expressly incorporated herein by reference in their entirety.