Stretchable interconnect

Metals fracture at a few percent tensile strain, yet soft neural implants and skin-mounted arrays must survive tens of percent of stretch and repeated flexion. Stretchable interconnects decouple applied deformation from conductor strain by geometry: serpentine or horseshoe traces unbend like a spring, self-similar fractal layouts distribute strain across scales, and island-bridge architectures place stiff functional islands (electrodes, chips) connected by compliant bridges so that nearly all strain is taken up in the wiring, not the devices.

Alternatives store the conduction path in materials rather than shape: liquid-metal alloys such as eutectic gallium-indium remain conductive while flowing under deformation, and thin gold films on elastomer develop micro-cracks or wrinkles that open and close reversibly. Each approach trades maximum strain, conductivity, hysteresis, and encapsulation difficulty differently, and the interconnect — not the electrode — is frequently the chronic failure point of a stretchable system.