Electrical Properties of Carbon Nanotube Based Fib

©2014TheAuthors.PublishedbyWILEY-VCHVerlagGmbH&Co.KGaA,Weinheim3661“thematerialofthefuture”.Oneveryinterestingpotentialapplica-tionofcarbonnanotubesisinelectricalwiring.Conventionalelectricalwiresmadeofcopperandaluminiumsufferfromsev-eralproblemsincluding:weight(anissueinaerospaceapplications),skineffect(hinderingtheiruseinmoderntelecommunications),mechanicalperformance(criticalinoverheadpowerlines),andelectromigration(severelydam-agingmicroscopicwiresinelectronicsapplications).Moreover,thegrowingdemandfortheseconventionalmetalconductorsandtheircontinuallyincreasingpricessuggeststhatalow-costmaterialthatcanoutperformconventionalconductorswouldbehighlydesirable.Hence,carbonnanotubesarethematerialofgreatinterest.However,thereareseveralchallengesintheproductionofcarbonnanotubeelectricalwiresandtheirapplication,whichinclude;preparationofmacroscopicstructuresthatretainthepropertiesofindividualnanotubes,controloverthemor-phologyanddimensionsofthesestructures,developmentoflarge-scalecost-effectivemanufacturingprocessesandpro-vidingthewireswithsuitableelectricalinsulationandconnec-tionsforintegrationintoelectricalsystems.Notlessimpor-tant,isthein-depthunderstandingofthephysicsbehindthetransportpropertiesofthesenewcarbonstructuresandpossiblepreparationofnewstandardsfortheuseoftheCNTwires.Someofthesolutionstotheseissueshavebeenalreadysuggested.Severalresearchgroupshavealreadysucceededinthepro-ductionofmacroscopicCNTfibers(alsoreferredtoasyarnsorthreads)whicharelongassembliesofaxiallyalignednano-tubes,ofdiametersinthemicrometerrange.[2–4]ThetheoreticalandexperimentalresearchonCNTfiberspredictthatpropercontrolofthemorphologyofthesemacro-scopicassembliesofCNTsshouldproducethematerialofexcellentelectricalconductivitycomparabletotheconductivityofindividualnanotubes.[5]ElectricalPropertiesofCarbonNanotubeBasedFibersandTheirFutureUseinElectricalWiringAgnieszkaLekawa-Raus,JeffPatmore,LukaszKurzepa,JohnBulmer,andKrzysztofKoziol*Theproductionofcontinuousfibersmadepurelyofcarbonnanotubeshaspavedthewayfornewmacro-scaleapplicationswhichutilizethesuperiorpropertiesofindividualcarbonnanotubes.Thesewire-likemacroscopicassembliesofcarbonnanotubeswererecognizedtohaveapotentialtobeusedinelectricalwiring.Carbonnanotubewiringmaybeextremelylightandmechanicallystrongerandmoreefficientintransferringhighfrequencysignalsthananyconventionalconductingmaterial,beingcost-effectivesimul-taneously.However,transferoftheuniquepropertiesofindividualCNTstothemacro-scaleprovestobequitechallenging.ThisFeatureArticlegivesanoverviewofthepotentialofusingcarbonnanotubefibersasnextgenerationwiring,stateoftheartdevelopmentsinthisfield,andgoalstobeachievedbeforecarbonnanotubesmaybetransformedintocompetitiveproducts.1.IntroductionTheeverincreasinguseoftechnologyinallareasofourdailylifehashadanimmenseeffectonourdemandforelectricalenergy,andthishasresultedintheurgentneedtofindmoreefficientmethodsforitsgenerationanddistribution.Thisneedhasstimu-latedthequestfornewmaterialsandhighlyefficientdevices,whichhavesignificantlybetterperformancethanthosecurrentlyinuse,aswellbeingcost-effective,safe,andenvironmentallyfriendly.Inthisperspective,carbonisaverypromisingmaterial.Therecentsynthesisoffullerenes,carbonnanotubesandseparationofgraphenehasgeneratedenormousinterestinthesecarbonmaterials.[1]Carbonallotropesofthistypeoffernotonlyahighlyexcitingandvastareaforscientificexplorationbutalsothepotentialforawidespectrumofnovelengineeringapplicationsduetotheirproperties.Carbonnanotubesareparticularlyattractive,duetotheirtubularshape,lowdensity,tuneableelectricalproperties,ballisticDOI:10.1002/adfm.201303716Dr.A.Lekawa-Raus,L.Kurzepa,J.Bulmer,Dr.K.KoziolDepartmentofMaterialsScienceandMetallurgyUniversityofCambridgeCB30FS,UKE-mail:[e-mail]mbridgeCB21RF,UKThisisanopenaccessarticleunderthetermsoftheCreativeCommonsAttribution-NonCommercialLicense,whichpermitsuse,distributionandreproductioninanymedium,providedtheoriginalworkisproperlycitedandisnotusedforcommercialpurposes.Adv.Funct.Mater.2014,24,3661–3682FEATUREARTICLE3662©2014TheAuthors.PublishedbyWILEY-VCHVerlagGmbH&Co.KGaA,WeinheimMoreover,thefibersshouldconsiderablyexceedtheperfor-manceofanymetalsusedcurrentlyinelectricalengineeringintermsofmechanicalandthermalproperties,whilekeepingthedensityverylow.Thebestas-madeCNTfibershaveindeedexcellentmechan-icalperformance,whichissuperiortoanyconventionalcon-ductivemetalsandtheyhaveverylowdensity.[2,3,6]However,theelectricalconductiv