Halftone-encoded 4D printing of stimulus-reconfigurable binary domains for cephalopod-inspired synthetic smart skins

Cephalopods exhibit versatile control over their optical appearance, texture, and shape for adaptive camouflage and signaling. Achieving such multi-feature dynamic control in synthetic materials remains a significant challenge. Here, we introduce a halftone-encoded 4D printing method that enables simultaneous and programmable control over optical appearance, mechanical properties, surface texture, and shape transformation within a single smart hydrogel film in response to various external stimuli (e.g., temperature, solvents, and mechanical stress)—a capability beyond existing synthetic materials. By encoding halftone binary patterns composed of highly crosslinked (“1”) and lightly crosslinked (“0”) domains, we spatially regulate localized polymer-solvent interactions and microstructural heterogeneities. The interplay, arrangement, and integration of these binary domains collectively dictate macroscale multifunctionality within a single material system. This binary encoding approach offers a simple yet powerful platform for designing multifunctional synthetic materials with complex, reconfigurable behaviors, unlocking opportunities in soft robotics, adaptive surface engineering, and secure information storage.