Sheath-Core Fibers for Superelastic Electronics, Sensors, and Muscles

Description:

Summary:

From fitness trackers to smart clothing, wearables are in high demand. Researchers at UT Dallas have invented a new class of elastic wires that can be woven into clothing or made into super-stretchy charger cords. Lighter-than-air, electrically conductive sheets of tiny carbon nanotubes are wrapped around a long rubber core to create conducting fibers that can be reversibly stretched 14 times their initial length while increasing electrical conductivity by 200-fold. By adding a thin overcoat of rubber to the sheath-core fibers and then another carbon nanotube sheath, the researchers made strain sensors and artificial muscles in which the buckled nanotube sheaths serve as electrodes and the thin rubber layer is a dielectric, resulting in a fiber capacitor. These fiber capacitors exhibited a capacitance change of 860% when the fiber was stretched 950%.

Fig. 1. Two-dimensional, hierarchically buckled, sheath-core fibers. (A) Steps in the fabrication of a fiber, where the circular arrow indicates the belt direction. (B) Illustration of the structure of a longitudinal section of a sheath, showing two-dimensional, hierarchical buckling. The fiber direction is horizontal. The yellow color in (A) and (B) represents SEBS rubber and the gray shells are NTSs. (C, D) Low and high resolution SEM images showing long-period and short-period buckles for a fiber at 100% applied strain. The fiber direction, which is the direction of the applied strain, is horizontal and the belt direction is vertical in (C) and (D). The fabrication strain was 1400%.

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