Patent Description:
<CIT> describes hybrid conductors which may be used in electrical or thermal applications, or combinations of both. One method of fabricating such hybrid conductors includes complexing conductive metal elements (e.g., silver, gold, copper), transition metal elements, alloys, wires, or combinations thereof, with carbon nanotube materials. In the alternative, the hybrid conductors may be formed by doping the carbon nanotube materials in salt solutions.

A carbon nanotube (CNT) cable includes: a pair of plated twisted wires, each wire comprising one or more sub-cores, at least one sub-core comprising CNT yarn; the CNT yarn being chemically pretreated using chlorosulfonic acid; a dielectric surrounding the plated twisted wires; and an electrical layer surrounding the dielectric, the electrical layer shielding the CNT cable.

A method for making a carbon nanotube (CNT) cable includes:, depositing plating using a controlled deposition rate, so as to surround a pair of wires, each wire comprising one or more sub-cores, at least one sub-core comprising CNT yarn; chemically pretreating the CNT yarn using chlorosulfonic acid; twisting the plated wires together; and surrounding the plated twisted wires with an electrical layer that shields the plated twisted wires, thereby creating the CNT cable.

The accompanying drawings provide visual representations which will be used to more fully describe various representative embodiments and can be used by those skilled in the art to better understand the representative embodiments disclosed herein and their advantages. In these drawings, like reference numerals identify corresponding elements.

While the present invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail one or more specific embodiments, with the understanding that the present disclosure is to be considered as exemplary of the principles of the invention and not intended to limit the invention to the specific embodiments shown and described. In the following description and in the several figures of the drawings, like reference numerals are used to describe the same, similar or corresponding parts in the several views of the drawings.

According to embodiments of the invention, a CNT yarn cable is provided. For example, a CNT cable is provided. For example, a strong CNT cable is provided. For example, a lightweight CNT cable is provided. For example, a strong, lightweight CNT cable is provided. For example, a resilient CNT cable is provided.

For example, a cable is provided having low radio frequency (RF) insertion loss. For example, a cable is provided having an RF insertion loss less than or equal to approximately <NUM> decibels per foot at a frequency of approximately <NUM> Gigahertz. For example, a cable is provided having an RF insertion loss less than or equal to approximately <NUM> decibels per foot at a frequency of approximately <NUM> Gigahertz. For example, a cable is provided having an insertion loss equivalent to the insertion loss of a solid copper wire. For example, a cable is provided having high electrical conductivity.

<FIG> is a photograph <NUM> of a plated twisted wire <NUM> comprising one or more sub-cores, at least one sub-core comprising CNT yarn.

<FIG> are a set of four schematic drawings showing components of a CNT cable <NUM>. In <FIG>, the CNT cable <NUM> comprises a <NUM> American Wire Gauge (AWG) high speed CNT cable <NUM>. As depicted, the CNT cable comprises a pair of twisted wires, a first twisted wire 210A and a second twisted wire 210B.

The twisted wires 210A, 210B are shielded by the shield <NUM> that forms an electrical layer <NUM> of the CNT cable <NUM>. For example, the electrical layer <NUM> comprises an external surface <NUM> of the CNT cable <NUM>. For example, the electrical layer <NUM> is surrounded by a physical layer (not shown). For example, the electrical layer <NUM> is surrounded by a braid (not shown), the braid configured to protect the electrical layer <NUM> from abrasion.

At least one of the twisted, shielded wires 210A, 210B comprises a core. For example, the first twisted wire 210A comprises a first core 230A. For example, the second twisted wire 210B comprises a second core 230B. As depicted, the first twisted wire 210A comprises a first core 230A, and the second twisted wire 210B comprises a second core 230B. For example, at least one of the twisted shielded wires 210A, 210B, has a desired number of sub-cores.

The first core 230A is surrounded by first plating 240A. The second core 230B is surrounded by second plating 240B. For example, one or more of the first plating 240A and the second plating 240B comprises copper plating. For example, one or more of the first copper plating 240A and the second copper plating 240B comprises electroplated copper plating. For example, one or more of the first plating 240A and the second plating 240B comprises silver plating. For example, one or more of the first plating 240A and the second plating 240B comprises gold plating. As depicted, the first core 230A is surrounded by a first copper plating 240A. As depicted, the second core 230B is surrounded by a second copper plating 240B. For example, one or more of the first copper plating 240A and the second copper plating 240B has a thickness of up to approximately <NUM> microns.

The first copper plating 240A forms a first plated perimeter that runs around the outside of the surface formed by the three sub-cores 250A, 250B, and 250C. Similarly, the second copper plating 240B forms a second plated perimeter that runs around the outside of the surface formed by the three sub-cores 250D, 250E, and 250F.

For example, one or more of the first core 230A and the second core 230B comprises a multi-component core. For example, as depicted, the first core 230A comprises a triaxial first core 230A comprising three sub-cores 250A, 250B, and 250C. For example, the three sub-cores 250A, 250B, and 250C are twisted together. For example, as depicted, the second core 230B comprises a triaxial second core 230B comprising three sub-cores 250D, 250E, and 250F. For example, the three sub-cores 250D, 250E, and 250F are twisted together.

For example, one or more of the sub-cores 250A-250F comprises yarn. For example, one or more of the sub-cores 250A-250F comprises CNT yarn.

For example, one or more of the first sub-cores 250A-250F comprises chemically stretched CNT yarn (CSY). CSY pretreatment comprises an acid wash that uses chlorosulfonic acid to provide an optimal template to maximize conductivity of the plating layer. CSY pretreatment acid dopes semi-conducting CNT, thereby increasing conductivity. CSY also densifies the yarn. CSY also improves CNT network connectivity.

The three sub-cores 250A, 250B, and 250C are twisted together to form a first twisted wire 210A of a desired gauge. For example, at least one of the three sub-cores 250A, 250B, and 250C has a desired approximate diameter. Alternatively, seven <NUM> tex (<NUM>/Km) sub-cores (not shown) are twisted together to form a <NUM> American Wire Gauge (28AWG [. 08sq mm]) first twisted wire 210A.

<FIG> shows an alternative embodiment of the CNT cable <NUM> in which the first twisted wire 210A comprises one sub-core 250A and the second twisted wire 210B comprises one sub-core 250B. Also shown are the shield <NUM>, the first core 230A, the second core 230B, the first plated perimeter 240A and the second plated perimeter 240B.

<FIG> shows an alternative embodiment of the CNT cable <NUM> in which the first twisted wire 210A comprises four sub-cores 250A-250D and the second twisted wire 210B comprises four sub-cores 250E-<NUM>. Also shown are the shield <NUM>, the first core 230A, the second core 230B, the first plated perimeter 240A and the second plated perimeter 240B.

<FIG> shows an alternative embodiment of the CNT cable <NUM> in which the first twisted wire 210A comprises seven sub-cores 250A-<NUM> and the second twisted wire 210B comprises four sub-cores <NUM>-250N. Also shown are the shield <NUM>, the first core 230A, the second core 230B, the first plated perimeter 240A and the second plated perimeter 240B.

An optimal yarn configuration comprises 28AWG [. 08sq mm] CNT wire comprising four sub-cores. This configuration provides an excellent balance between competing considerations of maximizing plated perimeter and minimizing number of sub-cores.

Embodiments of the invention have a conductivity above approximately <NUM> megasiemens per meter (MS/m). Embodiments of the invention have a conductivity above approximately <NUM>/m. Embodiments of the invention have a conductivity of approximately <NUM>/m to <NUM>/m. Preferably, the fiber is lightweight. Preferably, the fiber has high tensile strength.

<FIG> are a set of four micrographs showing a prior art CNT wire, a CNT wire that is copper plated according to embodiments of the invention, a CNT wire pretreated according to embodiments of the invention by performing an acid wash using chemically stretched CNT yarn (CSY), and a CSY pretreated CNT wire after copper plating according to embodiments of the invention.

<FIG> is a micrograph of a prior art bare <NUM> American Wire Gauge (28AWG [. 08sq mm]) CNT wire with a linear density of approximately <NUM> tex (<NUM> grams per kilometer).

<FIG> is a micrograph of a 28AWG [. 08sq mm] CNT wire with a linear density of approximately <NUM> tex (<NUM>/Km) that is copper plated according to embodiments of the invention.

<FIG> is a micrograph of a bare 28AWG [. 08sq mm] CNT wire with a linear density of approximately <NUM> tex (<NUM>/Km) that is pretreated according to embodiments of the invention using CSY.

<FIG> is a micrograph of a 28AWG [. 08sq mm] CNT wire with a linear density of approximately <NUM> tex (<NUM>/Km) that is pretreated using CSY and is copper plated according to embodiments of the invention.

CSY pretreatment according to embodiments of the invention produces yarn with a surface comprising substantially no loose CNT fibers that act as nucleation sites for large-scale surface defects during electroplating. CSY pretreatment of yarn according to embodiments of the invention produces yarn having minimal defects and also minimal surface roughness that does not contribute to a final surface roughness of a plated surface. Surface roughness of plated layer appears to be a function of conditions of an electroplating process used in operating the invention. Pretreatment with CSY according to embodiments of the invention results in an ideal, smooth substrate for electroplating the wire. CSY pretreatment also increases conductivity of the CNT cable.

<FIG> are a set of eight micrographs showing both small-scale surface roughness and large-scale surface defects for both <NUM> American Wire Gauge (24AWG [<NUM>. 25sq mm]) wire with an average grain size of approximately <NUM> microns and <NUM> American Wire Gauge (28AWG [. 08sq mm]) wire with an average grain size of approximately <NUM> microns. For example, the CNT cable comprises a pair of twisted wires, each wire having a grain size less than or equal to approximately <NUM> microns. For example, the CNT cable comprises a pair of twisted wires, each wire having a grain size less than or equal to approximately <NUM> microns.

Small-scale surface roughness means roughness visible using a magnification of approximately <NUM> times. Large-scale surface defects means surface defects visible using a magnification of approximately <NUM> times.

<FIG> is a micrograph of small-scale surface roughness for embodiments of the invention using 24AWG [<NUM>. 25sq mm] [<NUM>. 25sq mm] wire with an average grain size of <NUM> microns and a low current.

<FIG> is a micrograph of small-scale surface roughness for embodiments of the invention using 24AWG [<NUM>. 25sq mm] wire with an average grain size of <NUM> microns and a high current.

<FIG> is a micrograph of large-scale surface defects for embodiments of the invention using 24AWG [<NUM>. 25sq mm] wire with an average grain size of <NUM> microns and a low current.

<FIG> is a micrograph of large-scale surface defects for embodiments of the invention using 24AWG [<NUM>. 25sq mm] wire with an average grain size of <NUM> microns and a high current.

<FIG> is a micrograph of small-scale surface roughness for embodiments of the invention using 28AWG [. 08sq mm] wire with an average grain size of <NUM> microns and a low current.

<FIG> is a micrograph of small-scale surface roughness for embodiments of the invention using 28AWG [. 08sq mm] wire with an average grain size of <NUM> microns and a high current.

<FIG> is a micrograph of large-scale surface defects for embodiments of the invention using 28AWG [. 08sq mm] wire with an average grain size of <NUM> microns and a low current.

<FIG> is a micrograph of large-scale surface defects for embodiments of the invention using 28AWG [. 08sq mm] wire with an average grain size of <NUM> microns and a high current.

It can be seen that plated copper conductivity has a negative correlation with surface roughness. It can be seen that plated copper conductivity has a negative correlation with surface defects. Lowering copper deposition rate during electroplating according to embodiments of the invention maximizes conductivity of the plating layer. According to embodiments of the invention, the copper deposition rate is less than or equal to approximately <NUM> microns per minute.

According to embodiments of the invention, minimizing surface roughness can be achieved by using a lower copper deposition rate during the electroplating process.

According to embodiments of the invention, substantially eliminating surface defects can be achieved by using a lower copper deposition rate during the electroplating process.

Table <NUM> presents experimentally obtained data (electroplating current and conductivity [MS/m] of resulting embodiment of invention) extracted from <FIG> in tabular form.

Embodiments of the invention have a conductivity above approximately <NUM>/m. Embodiments of the invention have a conductivity above approximately <NUM>/m. Embodiments of the invention have a conductivity of approximately <NUM>/m to <NUM>/m. Preferably, the fiber is lightweight. Preferably, the fiber has high tensile strength.

<FIG> are a set of two graphs showing computer simulated data regarding insertion loss (decibels [dB]) of a CNT yarn cable using a twisted wire comprising four different numbers of sub-cores. <FIG> each present insertion loss for a CNT cable comprising <NUM>, <NUM>, <NUM>, and <NUM> sub-cores in each twisted wire. relative to insertion loss for prior art unplated CNT wire for different frequencies in Megahertz (MHz). <FIG> also each present measured insertion loss as a function of frequency for prior art solid copper wire.

<FIG> presents computer simulated data regarding insertion loss for a CNT cable comprising <NUM>, <NUM>, <NUM>, and <NUM> sub-cores and using typical copper plating having conductivity of <NUM> megasiemens per meter (MS/m). The CNT cable comprising <NUM> sub-core has a plated perimeter of approximately <NUM>,<NUM> microns. The CNT cable comprising comprising <NUM> sub-cores has a plated perimeter of approximately <NUM>,<NUM> microns. The CNT cable comprising <NUM> sub-cores has a plated perimeter of approximately <NUM>,<NUM> microns.

<FIG> presents computer simulated data regarding insertion loss for a CNT cable comprising <NUM>, <NUM>, <NUM>, and <NUM> sub-cores and using typical copper plating having conductivity of <NUM> megasiemens per meter (MS/m), which represents the highest conductivity achievable with copper plating.

<FIG> is a bar graph showing wire weight for a CNT yarn cable in embodiments using 28AWG [. 08sq mm] wire, 24AWG [<NUM>. 25sq mm] wire, 22AWG [<NUM>. 34sq mm] wire and 20AWG [<NUM>. 50sq mm] wire, and showing comparative wire weights for the same four wires for prior art COTS copper wire.

A typical weight for the CNT cable in an embodiment using 28AWG [. 08sq mm] wire is approximately <NUM> grams per foot (g/<NUM>. 3048meter). A typical weight for the CNT cable in an embodiment using 24AWG [<NUM>. 25sq mm] wire is approximately <NUM>/<NUM>. A typical weight for the CNT cable in an embodiment using 20AWG [<NUM>. 50sq mm] wire is approximately <NUM>/<NUM>.

<FIG> is a bar graph showing a reduction in weight of a CNT yarn cable relative to prior art COTS wire for the embodiments using 28AWG [. 08sq mm] wire, 24AWG [<NUM>. 25sq mm] wire, 22AWG [<NUM>. 34sq mm] wire and 20AWG [<NUM>. 50sq mm] wire. The reduction in weight for a CNT yarn cable relative to copper off the shelf wire of between approximately <NUM>% and approximately <NUM>%.

<FIG> is a graph showing insertion loss (decibels [dB]) of a CNT yarn cable relative to insertion loss for prior art unplated commercial CNT wire for different frequencies in Gigahertz (GHz). The insertion loss for the prior art unplated commercial CNT wire increases significantly for frequencies above approximately <NUM>-<NUM> gigahertz (GHz) whereas the insertion loss for the CNT cable remains relatively steady.

Table <NUM> presents experimentally obtained data (insertion loss [decibels per foot [dB/ft]) of a CNT yarn cable relative to insertion loss (dB/ft) for prior art unplated CNT wire for different frequencies in Gigahertz [GHz]) extracted from <FIG> in tabular form.

<FIG> is a graph of total wire weight (grams per foot [g/<NUM> meter]) as a function of shielding conductivity (megasiemens per meter [MS/m]) for a CNT yarn cable using 28AWG [. <NUM> sq mm] plated wire at four different approximate minimum operating frequencies. The approximate minimum operating frequencies presented are <NUM> Megahertz (MHz), <NUM>, <NUM>, and <NUM>,<NUM>. <FIG> also shows the corresponding data points for prior art unplated CNT wire and for prior art commercial copper wire.

Embodiments of the invention improve upon conductivity of prior art unplated CNT wire while maintaining weight savings relative to prior art copper wire. <FIG> also presents measured shielding weight as a function of measured shielding conductivity for prior art copper wire and for prior art unplated CNT wire.

A weight of an embodiment of the invention is approximately inversely proportional to signal frequency. Less plating is required for signal wires operating at higher frequencies according to embodiments of the invention.

Embodiments of the invention provide skin depth confinement of RF signals.

Enhancements according to embodiments of the invention of the electroplating process, include one or more of controlling the deposition rate and pretreatment. The enhancements achieve one or more of increasing wire conductivity and lowering total cable weight. According to embodiments of the invention, the copper deposition rate is less than or equal to approximately <NUM> microns per minute.

<FIG> is a flowchart of a method <NUM> for making a CNT yarn cable. The order of the steps in the method <NUM> is not constrained to that shown in <FIG> or described in the following discussion. Several of the steps could occur in a different order without affecting the final result.

In step <NUM>, controlling a deposition rate, plating is deposited so as to surround each of a pair of wires, each wire comprising one or more sub-cores, at least one sub-core comprising CNT yarn. Block <NUM> then transfers control to block <NUM>.

In step <NUM>, the plated wires are twisted together. For example, the twisting step comprises twisting together a plurality of sub-cores, thereby creating the pair of twisted wires, each comprising the plurality of sub-cores. For example, the twisting step comprises controlling a number of sub-cores. For example, the twisting step comprises controlling an approximate diameter of at least one of the plurality of sub-cores. Block <NUM> then transfers control to block <NUM>.

In step <NUM>, the plated twisted wires are surrounded with an electrical layer configured to shield the plated twisted wires, thereby creating the CNT cable. Block <NUM> then terminates the process.

Optionally, the method includes an additional step, performed after the depositing step and prior to the surrounding step, of placing a dielectric around the plated twisted wires.

Optionally, the method includes an additional step, performed before the creating step, of chemically pretreating the CNT yarn cable.

For example, the pretreating step comprises chemically pretreating the CNT yarn cable by performing an acid wash using chlorosulfonic acid.

For example, depositing comprises depositing plating at a rate less than or equal to approximately <NUM> microns per minute.

For example, the pretreating step comprises treatment of the CNT yarn cable with a solvent.

For example, the solvent comprises one or more of acetone, isopropyl alcohol (IPA), and methanol.

In step <NUM>, using chlorosulfonic acid, at least one of a plurality of sub-cores comprising CNT yarn is chemically pretreated. Block <NUM> then transfers control to block <NUM>.

In step <NUM>, controlling a deposition rate, plating is deposited so as to surround each of a pair of wires, each wire comprising a sub-core. Block <NUM> then transfers control to block <NUM>.

In step <NUM>, a dielectric is placed around the plated twisted wires. Block <NUM> then transfers control to block <NUM>.

In step <NUM>, controlling a number of sub-cores, and controlling an approximate diameter of at least one of the plurality of sub-cores, the plated wires are twisted together. Block <NUM> then transfers control to block <NUM>.

In step <NUM>, the dielectric is surrounded with an electrical layer configured to shield the plated twisted wires, thereby creating the CNT cable. Block <NUM> then terminates the process.

Embodiments of the invention provide numerous benefits. Enhancements according to embodiments of the invention of the electroplating process, including one or more of controlling the deposition rate and pretreatment, achieves one or more of increasing wire conductivity and lowering total cable weight.

Pretreatment with CSY according to embodiments of the invention results in an ideal, smooth substrate for electroplating the wire.

Relative to metallic wires, embodiments of the invention are more resilient to flexural, tension and other induced mechanical strain during installation, integration, testing, and operation.

Plating thickness is optimized to match a natural skin depth of high-frequency signals, ensuring that signal quality is not substantially affected by use of a strong, lightweight CNT core instead of a prior art copper wire.

Embodiments of the invention provide data transfer rates in a single twisted wire pair of at least approximately <NUM> Gigabits per second (Gbit/s), which is more than <NUM> times the maximum data rate of prior art cables lacking electroplated copper, which are limited to a maximum data rate of approximately <NUM> Mbit/s. The data transfer rate of at least approximately <NUM> Gbit/s is also more than three times the data transfer speed of Universal Serial Bus (USB) <NUM>.

Embodiments of the invention comprise a fibrous CNT core configured to bend more easily than the prior art metallic wire. Moreover, embodiments of the invention comprise a fibrous CNT core having a smaller bending radius than the prior art metallic wire. Additionally, embodiments of the invention are more flexible than prior art alternatives, allowing them to be stored in smaller spaces.

Embodiments of the invention can more effectively transmit power than prior art metal-coated polymer wires. Embodiments of the invention have superior conductivity relative to prior art unplated CNT cables even above frequencies greater than approximately <NUM> Megahertz (MHz). Embodiments of the invention also have superior RF insertion loss relative to prior art unplated CNT cables even above frequencies greater than approximately <NUM>.

Embodiments of the invention using copper-plated CNT yarn provide larger weight savings for comparable electrical performance relative to embodiments of the invention using CNT yarn plated with one or more of silver, gold, and copper. Relative to prior art copper conductors, embodiments of the invention are very lightweight, reducing component weight by approximately <NUM>-<NUM>% and overall cable weight by approximately <NUM>-<NUM>%.

The embodiments of the invention using copper-plated yarn are also significantly more cost-effective due to the higher cost of silver and gold.

Embodiments of the invention using one or more of a quad-axial yarn and a triax yarn provide a total cable surface area that is larger than that of a standard off-the-shelf cable. By limiting the total number of yarns to one or more of three and four, parasitic induction is minimized, allowing for total RF insertion loss of the cable to be minimized. In a departure from conventional stranded cables, pursuant to embodiments of the invention, one or more of triax yarns and quad-axial yarns are only plated on their external surface, thereby providing enhanced scalability of plated wire architecture to larger wire diameters without significantly reducing weight savings. Also, according to embodiments of the invention, CSY pretreatment provides an optimal template to maximize conductivity of the plating layer. According to embodiments of the invention, CSY pretreatment optimally conditions the geometry of the CNT surface for plating, which results in maximized conductivity of the plating layer.

Embodiments of the invention provide a high strength cable having a strength of approximately <NUM> to <NUM> Megapascals-cubic meter per kilogram or <NUM>-<NUM> MPa-m<NUM>/kg.

It will be further understood by those of skill in the art that the number of variations of the invention and the like are virtually limitless. It is intended, therefore, that the subject matter in the above description shall be interpreted as illustrative and shall not be interpreted in a limiting sense.

While the above representative embodiments have been described with certain components in exemplary configurations, it will be understood by one of ordinary skill in the art that other representative embodiments can be implemented using different configurations and/or different components. For example, it will be understood by one of ordinary skill in the art that the order of certain steps and certain components can be altered without substantially impairing the functioning of the invention. For example, the two twisted wires could have different numbers of sub-cores in them.

Claim 1:
A carbon nanotube (CNT) cable, comprising:
a pair of plated twisted wires, each wire comprising one or more sub-cores, at least one sub-core comprising CNT yarn, the CNT yarn being chemically pretreated using chlorosulfonic acid;
a dielectric surrounding the plated twisted wires; and
an electrical layer surrounding the dielectric, the electical layer shielding the CNT cable.