The fabrication and characterization of fibers that are ultrastretchable and have metallic electrical conductivity are described. The fibers consist of a liquid metal alloy, eutectic gallium indium (EGaIn), injected into the core of stretchable hollow fibers composed of a triblock copolymer, poly[styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene] (SEBS) resin. The hollow fibers are easy to mass‐produce with controlled size using commercially available melt processing methods. The fibers are similar to conventional metallic wires, but can be stretched orders of magnitude further while retaining electrical conductivity. Mechanical measurements with and without the liquid metal inside the fibers show the liquid core has a negligible impact on the mechanical properties of the fibers, which is in contrast to most conductive composite fibers. The fibers also maintain the same tactile properties with and without the metal. Electrical measurements show that the fibers increase resistance as the fiber elongates and the cross sectional area narrows. Fibers with larger diameters change from a triangular to a more circular cross‐section during stretching, which has the appeal of lowering the resistance below that predicted by theory. To demonstrate their utility, the ultrastretchable fibers are used as stretchable wires for earphones and for a battery charger and perform as well as their conventional parts.

This article describes the fabrication of self-healing stretchable wires formed by embedding liquid metal wires in microchannels composed of self-healing polymer. These stretchable wires can be completely severed with scissors and rapidly self-heal both mechanically and electrically at ambient conditions. By cutting the channels strategically, the pieces can be re-assembled in a different order to form complex microfluidic networks in 2D or 3D space.

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Our study of the adsorption of oxygen molecules on individual semiconductiong single-walled carbon nanotubes at ambient conditions reveals that the adsorption is physisorption, that the resistance without O 2 increases by ~two orders of magnitude as compared to that with O 2 , and that the sensitive response is due to the pinning of the Fermi level near the top of the valence band of the tube resulting from impurity states of O 2 appearing above the valence band.

Here, we present the results of the resistive response of tungsten trioxide nanowire (mat-like, nanowire networks) and nanoparticle thin films subjected to N 2 O gas in the temperature range of 373-773 K. The nanowire mats exhibited an order of magnitude higher response in the resistivity change compared to that of nanoparticle films at temperatures above 523 K. Nanowire mats also exhibited relatively faster adsorption and desorption times. Impedance spectroscopy studies showed that the gas sensing mechanism for nanowire mats involves changes in both the nanowire and grain boundary resistances, whereas for nanoparticle films only the grain boundary resistance governs the sensor properties upon exposure to gases.