Synergistic Mechano-Fluidic Self-Fusion of Poly(Vinyl Alcohol)-Modified Liquid-Metal Particles for Post-Treatment-Free Soft Electronics.

Liquid metals (LMs) are promising candidates for soft and stretchable conductors; however, their high surface tension and poor wettability pose significant challenges for high-resolution printing. To address these limitations, LMs are commonly processed into liquid metal particles (LMPs), which improve printability. Nevertheless, the insulating oxide shell surrounding each particle persists, typically necessitating additional post-treatment steps to achieve electrical conductivity. Here, we report synergistic mechano-fluidic self-fusion of poly(vinyl alcohol) (PVA)-modified liquid-metal particles (PmLMPs) for post-treatment-free soft interconnects. A sprayable PmLMP ink is formulated in which an ultrathin PVA shell stabilizes the particles and enhances substrate adhesion through hydrogen bonding. Direct electrical interconnection is achieved via a two-stage process: spray-induced mechanical impact ruptures the oxide shells to initiate metallic contact, followed by binary-solvent-driven Marangoni convection (deionized (DI) water/ethanol = 3:1 v/v) that promotes particle rearrangement and metallic neck growth. This mechano-fluidic sequence enables rapid formation of conductive networks without post-treatment. The printed films exhibit an initial conductivity of 1.5 × 106 S m- 1, maintain electrical continuity under monotonic strains exceeding 200% and during approximately 1,400 stretch-release cycles at 100% strain, and support 50 µm-scale patterning with large-area scalability. This work establishes a flow-assisted metallic fusion approach for scalable, instantly conductive soft interconnects.