Superior Stretchable Conductors by Electroless Plating of Copper on Knitted Fabrics

Stretchability is critical to wearable devices to afford a large amplitude strain. Herein, a uniformly nanoscale copper layer was successfully deposited onto the surface of a knitted fabric by a facile electroless deposition (ELD) approach for the construction of stretchable electrodes that had low and stable resistivity. A polymerized dopamine layer was pre-decorated onto the fiber surface for capturing a Pd 2+ catalyst that was also partially reduced to nanoparticles by polydopamine. This process improved the electrical conductivity and stability. As a result, an initial surface resistivity R 0 as low as ∼0.32 Ω sq –1 (σ ≈ 2.83 × 10 5 S m –1 ) and a stretched R of ∼2.0 Ω sq –1 ( R / R 0 ≈ 6) under 500% tensile strain were obtained. Prolonging the ELD process led to better mechanical performance and electrical conductivity of the as-made fabrics. The deformation mechanism of such e-fabrics was particularly emphasized on the “contact junction shift” principle, providing a reconstruction of the conductive networks under a large amplitude strain. Finally, two electronic prototypes with such e-fabric elements demonstrated great mechanical and chemical stability as well as washing fastness. This was the first report about the e-fabric with such high stretchability, which enabled it to be integrated efficiently with garments as a stretchable electrode or as an element of a physiotherapy device to afford perspiration evaporation and large-area stretchability and to minimize discomfort.