# US 7,947,773 B2 · Electrically conductive composite material > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,947,773 B2 - Document ID: US7947773B2 - Status: Granted - Kind: B2 - Application number: 11/609,113 - Filed: 2006-12-11 - Published: 2009-05-07 - Granted: 2011-05-24 - Earliest claimed: 2002-04-17 - Assignees: Conductive Composites Company, LLC - Inventors: George Clayton Hansen; Lauren Hansen; William C. Jenkin - Web page: https://patentgrep.com/patent/US7947773B2 ## CPC - D04H 5/00: Non woven fabrics formed of mixtures of relatively short fibres and yarns or like filamentary material of substantial length - B29C 70/14: oriented - B29C 70/882: {partly or totally electrically conductive, e.g. for EMI shielding (conductive floors or floor coverings H05F3/025; EMI shielding in general H05K9/00)} - G01K 5/50: arranged for free expansion or contraction - G01K 2211/00: Thermometers based on nanotechnology - Y10S 977/754: Dendrimer, i.e. serially branching or "tree-like" structure - Y10S 977/778: within specified host or matrix material, e.g. nanocomposite films - Y10T 428/249924: Noninterengaged fiber-containing paper-free web or sheet which is not of specified porosity - Y10T 428/249931: Free metal or alloy fiber - Y10T 428/249933: Fiber embedded in or on the surface of a natural or synthetic rubber matrix - Y10T 428/256: Heavy metal or aluminum or compound thereof - D04H: MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL (weaving D03; knitting D04B; braiding D04C; net-making D04G; sewing D05B; tufting D05C; finishing non-woven fabrics D06); FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING {; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION}(non-woven fabrics having an intermediate or external layer of a different kind, e.g. of woven fabric, B32B) - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) - G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00) - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract An electrically conductive composite material includes metallic nanostrands distributed throughout a matrix constructed of a polymer, ceramic, or elastomer. The nanostrands may have an average diameter under four microns and an average aspect ratio over ten-to-one. Larger fibers may also be included to enhance electrical conductivity or other properties. The nanostrands and/or fibers may be magnetically oriented to enhance electrical conductivity along one direction. A pressure sensor may be formed by utilizing an elastomer for the matrix. Electrical conductivity through the composite material varies in proportion to deflection of the elastomer. A composite material may be applied to a surface as an electrically conductive paint. Composite materials may be made by cutting a blank of the nanostrands to the desired shape, inserting the matrix, and curing the matrix. Alternatively, a suspension agent may first be used to dispose powdered nanostrands in the desired shape. ## Claims ### Claim 1 A method for manufacturing a composite material capable of conducting electricity, the method comprising the steps of: (a) forming a plurality of metallic branching nanostrands having an average diameter less than about four microns and an average aspect ratio greater than about ten-to-one; (b) providing a plurality of fibers having an average diameter greater than about four microns; (c) distributing the fibers substantially throughout a matrix formed substantially of a nonmetallic material; and (d) dispersing the metal branching nanostrands substantially throughout the matrix as liberated metallic branching nanostrands by minimal shear mixing, the liberated metallic branching nanostrands retaining substantial lengths, large aspect ratios, and abundant lateral branching. ### Claim 2 (depends on 1) The method of claim 1, wherein the step of distributing the fibers in combination with the step of dispersing the metallic branching nanostrands by minimal shear mixing together result in a total volumetric concentration of the liberated metallic branching nanostrands and the fibers within the matrix sufficient to provide an electrical conductivity of the composite material that is at least ten times an electrical conductivity of the nonmetallic material alone. ### Claim 3 (depends on 1) The method of claim 1, wherein the step of dispersing the metallic branching nanostrands by minimal shear mixing is conducted using a volumetric concentration of the metallic branching nanostrands ranging from about one-half of a percent to about twenty percent of the volume of the matrix. ### Claim 4 (depends on 1) The method of claim 1, further comprising the step of selecting the fibers in such a manner that the fibers cooperate with the liberated metallic branching nanostrands to synergistically improve an electrical conductivity of the composite material. ### Claim 5 (depends on 1) The method of claim 1, further comprising selecting the fibers in such a manner that the fibers enhance a mechanical strength of the composite material. ### Claim 6 (depends on 1) The method of claim 1, wherein the step of forming the metallic branching nanostrands comprises the step of constructing the metallic branching nanostrands substantially of nickel. ### Claim 7 (depends on 1) The method of claim 1, wherein the matrix comprises a nonconductive material selected from the group consisting of elastomers and ceramics. ### Claim 8 (depends on 1) The method of claim 1, wherein the matrix comprises an elastomer, and wherein the step of dispersing the metallic branching nanostrands by minimal shear mixing produces an electrical conductivity of the composite material that varies generally in proportion to a magnitude of deformation of the elastomer. ### Claim 9 (depends on 1) The method of claim 1, further comprising the step of applying magnetic flux to the liberated metallic branching nanostrands and the matrix to orient the liberated metallic branching nanostrands generally parallel to each other and thereby enhance an electrical conductivity of the composite material along one direction. ### Claim 10 (depends on 9) The method of claim 9, further comprising the step of applying magnetic flux to orient the fibers generally parallel to the liberated metallic branching nanostrands. ### Claim 11 (depends on 1) The method of claim 1, wherein the step of dispersing the metallic branching nanostrands by minimal shear mixing produces an electrically conductive mixture capable of being applied to coat at least a portion of a surface of a body, the liberated metallic branching nanostrands in the electrically conductive mixture acting to convey electric current through the matrix to enhance the electrical conductivity of the surface of the body. ### Claim 12 (depends on 1) The method of claim 1, wherein forming the metallic branching nanostrands comprises utilizing a process selected to provide a comparatively high degree of branching of the metallic branching nanostrands. ### Claim 13 (depends on 1) The method of claim 1, further comprising applying a surfactant to the branching nanostrands to reduce surface tension of the matrix against the branching nanostrands. ### Claim 14 (depends on 1) The method of claim 1, further comprising applying an additive to the matrix to reduce a viscosity of the matrix. ### Claim 15 (depends on 1) The method of claim 1, further comprising disposing the matrix and the metallic branching nanostrands in a shape through which electricity is to be conducted. ### Claim 16 (depends on 15) The method of claim 15, wherein disposing the metallic branching nanostrands in a shape through which electricity is to be conducted comprises creating a preform of the metallic branching nanostrands, the preform having the shape, wherein distributing the metallic branching nanostrands substantially throughout the matrix comprises directing the nonmetallic material into the preform such that the nonmetallic material substantially fills interstices between the metallic branching nanostrands. ### Claim 17 (depends on 15) The method of claim 15, wherein disposing the metallic branching nanostrands in a shape through which electricity is to be conducted comprises: breaking up the metallic branching nanostrands by minimal shear mixing; performing the minimal shear mixing of the metallic branching nanostrands with a suspension agent such that the metallic branching nanostrands and the suspension agent receive the shape; and removing the suspension agent; wherein distributing the metallic branching nanostrands substantially throughout the matrix comprises directing the nonmetallic material into the metallic branching nanostrands such that the nonmetallic material substantially fills in interstices between the metallic branching nanostrands. ### Claim 18 (depends on 1) The method of claim 1, further comprising curing the matrix. ### Claim 19 A method for measuring deformation in an article made substantially of a nonconductive material, the method comprising the steps of: (a) forming a plurality of metallic branching nanostrands having an average diameter less than about four microns; (b) dispersing the metallic branching nanostrands by minimal shear mixing substantially throughout a matrix of the nonconductive material as liberated metallic branching nanostrands, the liberated metallic branching nanostrands dispersed by minimal shear mixing retaining substantial lengths, large aspect ratios, and abundant lateral branching, the step of dispersing by minimal shear mixing thereby producing a composite material comprising the liberated metallic branching nanostrands and the nonconductive material; (c) forming the composite material into an article; (d) causing deformation to the article to produce a deformed article, the deformation comprising at least one of the group of deformations consisting of tension and compression; and (e) measuring the electrical conductivity of the deformed article to determine a magnitude of the deformation thereof, the deformation of the article causing the electrical conductivity of the article to increase. ### Claim 20 (depends on 19) The method of claim 19, further comprising the steps of: (a) observing the electrical conductivity of the article prior to the step of causing deformation; and (b) determining the magnitude of the deformation by comparing the electrical conductivity in the deformed article with the electrical conductivity of the article prior to the step of causing deformation. ### Claim 21 (depends on 19) The method of claim 19, wherein the nonconductive material comprises an elastomer. ### Claim 22 (depends on 19) The method of claim 19, wherein the step of forming the metallic branching nanostrands comprises the step of constructing the metallic branching nanostrands substantially of nickel. ### Claim 23 (depends on 19) The method of claim 19, wherein the article formed from the composite material is a component of a pressure sensor. ### Claim 24 (depends on 19) The method of claim 19, wherein the article formed from the composite material is a component of a temperature sensor, the temperature sensor determining the temperature of the article by sensing thermal expansion and contraction of the composite material in the article.