Stretchable Liquid Metal-Based Gas Barrier Films Enabled by Vacuum-Assisted Filling and Internal Post-Support Structures

The increasing demand for stretchable and deformable electronic devices has created a critical need for gas barrier materials that combine high barrier performance with mechanical compliance. Conventional polymeric barrier films often suffer from intrinsically high gas permeability, while inorganic or metallic barrier layers are susceptible to cracking and loss of barrier performance under mechanical deformation. In this work, we present a stretchable liquid metal-based gas barrier film fabricated by vacuum-assisted filling of eutectic gallium–indium (EGaIn) into a structurally designed elastomeric mold. An internal post-support structure enables the formation of a uniform, large-area, and free-standing liquid metal layer with controlled thickness while maintaining structural integrity during mechanical deformation. The fluidic nature of EGaIn allows the barrier layer to accommodate stretching, bending, and twisting without permanent structural damage, thereby suppressing the crack-induced failure commonly observed in conventional rigid barrier layers. The fabricated barrier film exhibited a water vapor transmission rate (WVTR) of 0.09 g m⁻² day⁻¹. These results demonstrate that the synergistic integration of structural design and fluidic liquid metal provides an effective strategy for overcoming the conventional trade-off between gas barrier performance and mechanical deformability. This approach offers promising potential for the encapsulation of stretchable electronics, wearable devices, and flexible energy-storage systems.