Dynamic Liquid Metal Interfaces Enabled Strain‐Tolerant Stretchable Capacitors for Robust Elastic Circuits

As indispensable components in modern electronics, capacitors with flexibility and elasticity are increasingly appealing to meet the demands of emerging wearable devices and electronic skins. Nevertheless, strain‐induced electrical instability remains a critical barrier to their practical implementation. This study presents an intrinsically elastic gallium‐based liquid metal /thermoplastic polyurethane capacitor engineered through dynamic interface design. A unique dynamic electrode/dielectric interface structure is constructed via gravity‐assisted deposition, which effectively suppresses the electrode area changes upon stretching through interface flattening. Concurrently, the gradient distribution design of liquid metal particles endows the electrode/dielectric boundary with dynamic migration capability under strain, thereby adaptively compensating for dielectric thickness variations. Leveraging this synergistic interface stabilization mechanism, the fabricated capacitor demonstrates exceptional mechanical robustness and capacitive stability, achieving an ultralow capacitance fluctuation of 1.29% under 50% strain while maintaining stable functionality over 1000 tensile stretching cycles. Successfully integrated as a tuning element in elastic LC oscillator circuits, the device enabled frequency‐stable near‐field communication under large deformations, showcasing its transformative potential for wearable electronics and fully elastic circuit systems.