High-strength liquid metal composite–hydrogel interfaces enable robust stretchable electronics

. This robust interface prevents liquid metal leakage and ensures stable electrical connection under extreme conditions, including prolonged ultrasonication, 300 MPa impacts, and thousands of stretching cycles. The strategy forms an interpenetrating cross‑linked polymer network through cross-interfacial assembly, fusing the circuit and substrate into an integrated structure. This simple and scalable method enables the fabrication of high‑resolution circuits for a wide range of electronic devices. We demonstrate its performance in applications including stretchable circuits, on-skin biosensors, and underwater soft robots.