Ultra‐Fast Fabrication of Mechanical‐Water‐Responsive Color‐Changing Photonic Crystals Elastomers and 3D Complex Devices

The traditional fabrication of opal‐structured photonic crystals is constrained by the rate of solvent evaporation, a process that is not only time‐consuming but also labor‐intensive. This study introduces a paradigm shift by incorporating silica nanoparticles (SiNPs) with high zeta potentials and hydrogen bonding capabilities into an elastomeric matrix, resulting in a novel non‐close‐packed structure. This innovation circumvents the limitations of conventional methods by enabling the rapid formation of photonic inks (PI) into vibrant and luminous photonic elastomers (PEs) within seconds. These PEs demonstrate remarkable mechanochromic properties, exhibiting dynamic color changes across the visible spectrum in response to tensile and compressive deformations. Furthermore, the presence of hydroxyl groups endows the PEs with superior water‐responsiveness, which can be finely tuned through the ink formulation. The elimination of solvent evaporation dependency facilitates the fabrication of macroscopic photonic crystal devices with complex geometries using digital light processing (DLP)‐based 3D printing. This approach ensures exceptional optical performance and high customization potential. The resulting PEs hold significant promise for applications in smart wearables, soft robotics, and advanced human‐machine interface technologies. This study communicates a novel approach to fabricating photonic elastomers using photonic ink infused with SiNPs. The resulting elastomers demonstrate responsive color changes under mechanical stress and upon water interaction. The fabrication of macroscopic photonic crystal devices with complex geometries is precisely controlled via a DLP‐based 3D printing technique.