Abstract: A multilayer composite is disclosed comprising a heat shrinkable polymer layer and a nanofiber layer. Methods of forming the composite and uses thereof are also described.

Abstract: Actuators (artificial muscles) comprising twist-spun nanofiber twist-inserted polymer fibers generate tensile actuation when powered electrically, photonically, chemically, thermally, by absorption, or by other means. These artificial muscles utilize coiled polymer fibers and can be either neat or comprising a guest. In some embodiments, the coiled polymer fibers actuator can be incorporated into an article, such as a textile, braid, clothing, smart packaging, or a mechanical system, and the coiled polymer fiber in the coiled polymer fiber actuator can have a stroke amplification factor of 5 or greater.

Abstract: Actuators (artificial muscles) comprising twist-spun nanofiber yarn or twist-inserted polymer fibers generate torsional actuation when powered electrically, photonically, chemically, thermally, by absorption, or by other means. These artificial muscles utilize coiled yarns/polymer fibers and can be either neat or comprising a guest. In some embodiments, the actuator system includes a twisted and coiled polymer fiber actuator, and at least one of (i) wire connections that enable electrical heating of the twisted and coiled polymer fiber actuator, (ii) a radiation source and radiation pathway that enables photothermal heating of the twisted and coiled polymer fiber actuator, and (iii) a delivery system for delivering chemicals whose reaction produces heating of the twisted and coiled polymer fiber actuator.

Abstract: Systems for fabricating nanofiber yarn at rates of at least 30 m/min (1.8 kilometers (km)/hour (hr)) using a “false twist” nanofiber yarn spinner and a false twist spinning technique are disclosed. In a false twist spinning technique, a twist is introduced to nanofibers in a strand by twisting the nanofibers at points between ends of the strand. This is in contrast to the “true twist” technique where one end of a strand is fixed and the opposing end of the strand is rotated to introduce the twist to intervening portions of yarn.

Abstract: Techniques are described for controlling widths of nanofiber sheets drawn from a nanofiber forest. Nanofiber sheet width can be controlled by dividing or sectioning the nanofiber sheet in its as-drawn state into sub-sheets as the sheet is being drawn. A width of a sub-sheet can be controlled or selected so as to contain regions of uniform nanofiber density within a sub-sheet (thereby improving nanofiber yarn consistency) or to isolate an inhomogeneity (whether a discontinuity is the sheet (e.g., a tear) or a variation in density) within a sub-sheet. Techniques for dividing a nanofiber sheet into sub-sheets includes mechanical, corona, and electrical arc techniques.

Abstract: One or more nanofiber yarns can be placed in contact with one or more nanofiber sheets. The nanofiber yarns, which include single-ply and multi-ply nanofiber yarns, provide added mechanical stability to a nanofiber sheet that decreases the likelihood of a nanofiber sheet wrinkling, folding, or otherwise becoming stuck to itself. Furthermore, the nanofiber yarns integrated with the nanofiber sheet can also act as a mechanism to prevent the propagation of tears through the nanofiber sheet. In some cases, an infiltrating material can be infiltrated into interstitial spaces defined by the nanofibers within both the nanofiber yarns and the nanofiber sheets. The infiltrating material can then form a continuous network throughout the nanofiber yarns and the nanofiber sheet.

Abstract: Examples described include composite nanofibers sheets that have been “infiltrated” with a polymer (i.e., the polymer has flowed past a surface of the nanofiber sheet and into at least some of spaces within the sheet defined by the nanofibers). An adhesive nanofiber tape is formed when the infiltrating polymer is an adhesive and the adhesive infiltrates the nanofiber sheet from a one major surface of the nanofiber sheet. In other described examples, some portions of nanofibers in the sheet have been conformally coated with at least one metal layer.

Abstract: A dispenser is described for dispensing nanofiber yarns that includes a housing that defines an inlet, an outlet, and a chamber. A spool, around which is wound a length of nanofiber yarn, is disposed within the chamber defined by the housing. The nanofiber yarn is threaded from the chamber through the outlet and can be dispensed in a controlled way that reduces the likelihood of developing knots within the nanofiber yarn, and which facilitates convenient application of the yarn onto an underlying surface. In some cases, the dispenser can be used to concurrently dispense an adhesive or other polymer along with the nanofiber yarn.

Abstract: Techniques are described for controlling widths of nanofiber sheets drawn from a nanofiber forest. Nanofiber sheet width can be controlled by dividing or sectioning the nanofiber sheet in its as-drawn state into sub-sheets as the sheet is being drawn. A width of a sub-sheet can be controlled or selected so as to contain regions of uniform nanofiber density within a sub-sheet (thereby improving nanofiber yarn consistency) or to isolate an inhomogeneity (whether a discontinuity is the sheet (e.g., a tear) or a variation in density) within a sub-sheet. Techniques for dividing a nanofiber sheet into sub-sheets includes mechanical, corona, and electrical arc techniques.

Abstract: A carbo nanofiber nerve scaffold includes a cylindrical helix, a bundle of aligned carbon nanofiber yarns, and a carbon nanofiber sheet. The cylindrical helix includes a surgical suture material, and the cylindrical helix defines an interior of the carbon nanofiber nerve scaffold. The bundle of aligned carbon nanofiber yarns is disposed within the interior of the cylindrical helix. The carbon nanofiber sheet is disposed around the cylindrical helix on a side of the cylindrical helix opposite of the interior.

Abstract: Methods, systems, and apparatus for fabricating nanofiber yarn at rates of at least 30 m/min (1.8 kilometers (km)/hour (hr)) using a “false twist” nanofiber yarn spinner and a false twist spinning technique are disclosed. In a false twist spinning technique, a twist is introduced to nanofibers in a strand by twisting the nanofibers at points between ends of the strand. This is in contrast to the “true twist” technique where one end of a strand is fixed and the opposing end of the strand is rotated to introduce the twist to intervening portions of yarn.

Abstract: Nerve scaffolds are described that include a tubular outer housing fabricated from a biocompatible polymer, within which are disposed a plurality of carbon nanofiber yarns. The carbon nanofiber yarns, which can be separated by distances roughly corresponding to an average nerve fiber diameter, provide surfaces on which nerve fibers can regrow. Because the proximate carbon nanofiber yarns can support individual nerve fibers, a nerve can be regenerated with a reduced likelihood of undesirable outcomes, such as nerve pain or reduced nerve function.

Abstract: A dispenser is described for dispensing nanofiber yarns that includes a housing that defines an inlet, an outlet, and a chamber. A spool, around which is wound a length of nanofiber yarn, is disposed within the chamber defined by the housing. The nanofiber yarn is threaded from the chamber through the outlet and can be dispensed in a controlled way that reduces the likelihood of developing knots within the nanofiber yarn, and which facilitates convenient application of the yarn onto an underlying surface. In some cases, the dispenser can be used to concurrently dispense an adhesive or other polymer along with the nanofiber yarn.

Abstract: A fabric of nanofibers that includes an adhesive is described. The nanofibers can be twisted or both twisted and coiled prior to formation into a fabric. The adhesive can be selectively applied to or infiltrated within portions of the nanofibers comprising the nanofiber fabric. The adhesive enables connection of the nanofiber fabric to an underlying substrate, even in cases in which the underlying substrate has a three-dimensional topography, while the selective location of the adhesive on the fabric limits the contact area between the adhesive and the nanofibers of the nanofiber fabric. This limited contact area can help preserve the beneficial properties of the nanofibers (e.g., thermal conductivity, electrical conductivity, infra-red (IR) radiation transparency) that otherwise might be degraded by the presence of adhesive.

Abstract: A fabric of nanofibers that includes an adhesive is described. The nanofibers can be twisted or both twisted and coiled prior to formation into a fabric. The adhesive can be selectively applied to or infiltrated within portions of the nanofibers comprising the nanofiber fabric. The adhesive enables connection of the nanofiber fabric to an underlying substrate, even in cases in which the underlying substrate has a three-dimensional topography, while the selective location of the adhesive on the fabric limits the contact area between the adhesive and the nanofibers of the nanofiber fabric. This limited contact area can help preserve the beneficial properties of the nanofibers (e.g., thermal conductivity, electrical conductivity, infra-red (IR) radiation transparency) that otherwise might be degraded by the presence of adhesive.

Abstract: A composite including a heat conformable polymer and a nanofiber sheet is disclosed. The heat conformable polymer can be a hot melt adhesive, and the combination can provide an electrically conductive hot melt adhesive composite. The nanofiber layer is protected and the composite is conformable and/or can be adhered to a variety of surfaces.

Abstract: Actuators (artificial muscles) comprising twist-spun nanofiber yarn or twist-inserted polymer fibers generate torsional actuation when powered electrically, photonically, chemically, thermally, by absorption, or by other means. These artificial muscles utilize coiled yarns/polymer fibers and can be either neat or comprising a guest. In some embodiments, the actuator system includes a twisted and coiled polymer fiber actuator, and at least one of (i) wire connections that enable electrical heating of the twisted and coiled polymer fiber actuator, (ii) a radiation source and radiation pathway that enables photothermal heating of the twisted and coiled polymer fiber actuator, and (iii) a delivery system for delivering chemicals whose reaction produces heating of the twisted and coiled polymer fiber actuator.

Abstract: Actuators (artificial muscles) comprising twist-spun nanofiber twist-inserted polymer fibers generate tensile actuation when powered electrically, photonically, chemically, thermally, by absorption, or by other means. These artificial muscles utilize coiled polymer fibers and can be either neat or comprising a guest. In some embodiments, the coiled polymer fibers actuator can be incorporated into an article, such as a textile, braid, clothing, smart packaging, or a mechanical system, and the coiled polymer fiber in the coiled polymer fiber actuator can have a stroke amplification factor of 5 or greater.

Abstract: One or more nanofiber yarns can be placed in contact with one or more nanofiber sheets. The nanofiber yarns, which include single-ply and multi-ply nanofiber yarns, provide added mechanical stability to a nanofiber sheet that decreases the likelihood of a nanofiber sheet wrinkling, folding, or otherwise becoming stuck to itself. Furthermore, the nanofiber yarns integrated with the nanofiber sheet can also act as a mechanism to prevent the propagation of tears through the nanofiber sheet. In some cases, an infiltrating material can be infiltrated into interstitial spaces defined by the nanofibers within both the nanofiber yarns and the nanofiber sheets. The infiltrating material can then form a continuous network throughout the nanofiber yarns and the nanofiber sheet.

Abstract: A fabric of nanofibers that includes an adhesive is described. The nanofibers can be twisted or both twisted and coiled prior to formation into a fabric. The adhesive can be selectively applied to or infiltrated within portions of the nanofibers comprising the nanofiber fabric. The adhesive enables connection of the nanofiber fabric to an underlying substrate, even in cases in which the underlying substrate has a three-dimensional topography, while the selective location of the adhesive on the fabric limits the contact area between the adhesive and the nanofibers of the nanofiber fabric. This limited contact area can help preserve the beneficial properties of the nanofibers (e.g., thermal conductivity, electrical conductivity, infra-red (IR) radiation transparency) that otherwise might be degraded by the presence of adhesive.