Size-dependent rupture strain of elastically stretchable metal conductors

Experiments show that the rupture strain of gold conductors on elastomers decreases for conductors that are long and narrow. Rupture is caused by the irreversible coalescence of microcracks into one long crack. A mechanics model identifies a critical crack length ℓcr above which the long crack propagates across the entire conductor width. ℓcr depends on the fracture toughness of the gold film and the width of the conductor. The model provides guidance for the design of highly stretchable conductors.