RESUMEN
A key aspect of the use of conventional fabrics as smart textiles and wearable electronics is to incorporate a means of electrical conductivity into single polymer fibres. We present the transformation of thin polymer fibres and fabrics into conductive materials by in situ growth of a thin, optically transparent gold-silver nanowire (NW) mesh with a relatively low metal loading directly on the surface of polymer fibres. Demonstrating the method on poly(lactic-co-glycolic) acid and nylon microfibres, we show that the NW network morphology depends on the diameter of the polymer fibres, where at small diameters (1-2 µm), the NWs form a randomly oriented network, but for diameters above several micrometers, the NWs wrap around the fibres transversally. This phenomenon is associated with the stiffness of the surfactant templates used for the NW formation. The NW-decorated fibres exhibit a significant increase in conductivity. Moreover, single fibres can be stretched up to â¼15% before losing the electrical conductivity, while non-woven meshes could be stretched by about 25% before losing the conductivity. We believe that the approach demonstrated here can be extended to other polymeric fibres and that these flexible and transparent metal-coated polymer fibres could be useful for various smart electronic textile applications.
RESUMEN
We utilize time-domain Terahertz (THz) reflectivity measurements for characterizing the surface conductivity of Polyethylene-terephthalate coated with nanowire (NW) films to form novel transparent electrodes (TE). We find good correspondence between the film conductivity and the THz-field reflectivity that provide uniquely desirable means for non-destructive, contactless conductivity measurements of large area NW-based-TEs. We demonstrate the robustness of THz reflectivity measurements to deviations invoked on NW film composition and film uniformity. The dependence of THz reflectivity on area NW coverage follows an anisotropic effective medium model for the dielectric constant.
RESUMEN
This article describes a unique combination of inkjet printing of functional materials with an intricate self-assembly process. Gold-silver nanowire (NW) mesh films were produced by a sequential deposition process, in which small metal seed nanoparticle film was deposited at desired areas by inkjet printing, followed by coating with a thin film of NW growth solution. Two different types of NW growth solutions were used: the first, based on benzylhexadecyldimethylammonium chloride, exhibited a bulk solution growth mode and was thus suitable for coverage of large uniform areas. The second type was based on hexadecyltrimethylammonium bromide, which induced NW growth confined to the substrate-solution interface and thus enabled patterning of small transparent electrode features, which have the same dimensions as the deposited seed droplets. A selective silver plating bath was used to thicken the ultrathin NWs, stabilize them, and reduce the sheet resistance, resulting in films with sheet resistance in the range of 20-300 Ω/sq, 86-95% light transmission, and a relatively low haze. This simple patterning method of the NW film works at ambient conditions on many different types of substrates and has the potential to replace the conventional photolithography used for indium tin oxide patterning for applications such as touch sensors and flexible/stretchable electronics.