Ultralow-Loading Multilayer Liquid Metal Conductors with Leakage Immunity and Uncompromised Electro-Mechanical Performance.

Liquid-metal (LM)-based stretchable conductors are promising for soft electronics, yet their practical use is limited by high material costs and susceptibility to leakage. Here, we report a multilayer architecture comprising a top Cu layer, a Cu-SEBS hybrid layer, a Cu-GaCu2-SEBS-LM composite layer, and a micron-scale SEBS layer, which decouples mechanical strain from electrical conduction. This design couples strain-induced microcracked Cu films with strain-isolated out-of-plane and in-plane conductive pathways, eliminating strain-dependent resistance variations. Remarkably, the conductor achieves strain-invariant high conductivity (on the order of 107 S m-1) over 0-920% strain with an ultralow LM loading of only 5 vol %. Critically, it exhibits exceptional leakage resistance across the entire stretching range, addressing a longstanding challenge in LM-based electronics. As a proof of concept, we demonstrate its applicability as stretchable electrodes for real-time physiological signal monitoring and machine-learning-assisted gesture recognition, highlighting its potential for next-generation wearable bioelectronics.