Abstract: A nanofiber sheet dispenser that houses a nanofiber forest from which a nanofiber sheet can be drawn is described. Using the nanofiber sheet dispenser, a nanofiber forest disposed on a substrate can be moved, transported, and/or shipped with a reduced risk of damage relative to transporting a nanofiber sheet. Techniques are also described for configuring the nanofiber sheet dispenser so that a nanofiber sheet can be conveniently drawn from the forest and, in some cases, drawn so as to form a nanofiber yarn that is continuous with both the nanofiber sheet and the nanofiber forest, the latter of which is within the nanofiber sheet dispenser.

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 torsional fiber actuator includes a first polymer fiber (exhibiting a first polymer fiber diameter) and a torsional return spring in communication with the first polymer fiber. The first polymer fiber is configured to include a first plurality of twists in a first direction to produce a twisted polymer fiber. The first polymer fiber is further configured to include a plurality of coils in the twisted polymer fiber in a second direction each coil having a mean coil diameter.

Abstract: Placement of nanofibers and yarns comprised of nanofibers onto a substrate are described. The nanofiber yarns are difficult to manipulate with precision given that the diameters can be as little as 5 microns or even less than one micron. As described herein, a placement system is described that can place nanofiber yarns on a substrate at pitches less than 100 ?m, less than 50 ?m, less than 10 ?m, and in some embodiments as low as 2 ?m. In part, this precise placement at small pitches is facilitated by the use of coarse and fine adjustment translators, and a guide connected to a compliant flange. The compliant flange and the guide facilitate consistency of location of a nanofiber 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: 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: 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: An insulated nanofiber having a continuous nanofiber collection extending along a longitudinal axis with an outside surface and an inside portion is described. A first material infiltrates the inside portion, where the outside surface of the nanofiber collection is substantially free of the first material. An electrically-insulating second material coats the outside surface of the nanofiber collection. A method of making an insulated nanofiber collection is also disclosed.

Abstract: Techniques are described for infiltrating a nanofiber yarn with an infiltration material and removing a surface layer of the infiltration material on at least a portion of the infiltrated nanofiber yarn. This enables an infiltration method by which the infiltration material is selectively disposed within an interior of a nanofiber yarn and not disposed on an exterior surface of at least a portion of a nanofiber yarn. Electrical connection can be established by mechanically connecting an electrode (e.g., a conductive clamp or fitting) directly to the exposed surface of the nanofiber yarn.

Abstract: A density of a nanofiber sheet can be changed using an edged surface, and in particular an arcuate edged surface. As described herein, a nanofiber sheet is drawn over (and in contact with) an arcuate edged surface. Depending on whether the arcuate surface facing a direction opposite the direction in which the nanofiber sheet is being drawn is convex or concave determines whether the nanofiber sheet density is increased relative to the as-drawn sheet or decreased relative to the as-drawn sheet.

Abstract: A flexible sheet comprising a composite sheet, the composite sheet comprising a binder and an aggregate containing a plurality of carbon nanotubes that is disposed in the binder, wherein the aggregate is formed as a waveform structure travelling along a single direction in a plane of the composite sheet, is provided. The disclosed flexible sheets may be used as thermally conductive components, electrically conductive components, antistatic components, electromagnetic wave shields, and/or heating elements, in addition to other possible uses.

Abstract: Nanofiber based sensors are described that can be used to detect analytes in biological or non-biological contexts. Each sensor includes at least two nanofiber yarns that are spaced apart from one another so as to avoid electrical (or physical) contact. Each nanofiber yarn of the nanofiber sensor includes a sensing region that is in electrical contact with the rest of the corresponding nanofiber yarn. The sensing regions of the at least two nanofibers are treated with complementary sensing agents so that when the sensing regions (and the corresponding sensing agents) are exposed to the analyte to be detected, an electrical response is detected. This response is then communicated through one or more of the nanofiber yarns for interpretation by a processor.

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: 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 flexible sheet comprising a composite sheet, the composite sheet comprising a binder and an aggregate containing a plurality of carbon nanotubes that is disposed in the binder, wherein the aggregate is formed as a waveform structure travelling along a single direction in a plane of the composite sheet, is provided. The disclosed flexible sheets may be used as thermally conductive components, electrically conductive components, antistatic components, electromagnetic wave shields, and/or heating elements, in addition to other possible uses.

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: Techniques are disclosed for producing multilayered composites of adhesive nanofiber composites. Specifically, one or more sheets of highly aligned nanofibers are partially embedded in an adhesive such that at least a portion of the nanofiber sheet is free from adhesive and is available to conduct current with adjacent electrical features. In some example embodiments, the adhesive nanofiber composites are metallized with a conductive metal and in these and other embodiments, the adhesive nanofiber composites may also be stretchable.

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: Methods, systems, and apparatus for fabricating nanofiber yarn at rates at 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. 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.

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 torsional fiber actuator includes a first polymer fiber (exhibiting a first polymer fiber diameter) and a torsional return spring in communication with the first polymer fiber. The first polymer fiber is configured to include a first plurality of twists in a first direction to produce a twisted polymer fiber. The first polymer fiber is further configured to include a plurality of coils in the twisted polymer fiber in a second direction each coil having a mean coil diameter.

Abstract: Actuators (artificial muscles) comprising twist-spun nanofiber yarn or twist-inserted polymer fibers generate torsional and/or tensile actuation when powered electrically, photonically, chemically, thermally, by absorption, or by other means. These artificial muscles utilize non-coiled or coiled yarns and can be either neat or comprising a guest. Devices comprising these artificial muscles are also described.