Mechanically tunable structural color hydrogel with MXene/PEDOT:PSS conductive networks for dual-channel information encoding.

Flexible optoelectronic materials capable of simultaneously transducing mechanical stimuli into multiple signal modalities are highly desirable for next-generation wearable electronics, intelligent sensing, and secure communication. Herein, a mechanically tunable conductive structural color hydrogel that integrates a MXene/PEDOT:PSS conductive network with an opal-templated photonic crystal (PC) structure is reported, enabling synchronized optical and electrical dual-signal responses under deformation. The hydrogel is constructed by infiltrating a polyacrylamide matrix containing MXene nanosheets and PEDOT:PSS into a periodic PC template, resulting in vivid, reversible structural colors alongside stable electrical conductivity. Owing to synergistic hydrogen bonding, electrostatic interactions, and chelation among MXene, PEDOT:PSS, and polymer chains, the hydrogel exhibits excellent stretchability (up to 650% strain), high strain sensitivity (gauge factor up to 7.16), rapid response (∼100 ms), and outstanding durability over 500 deformation cycles. Mechanical deformation induces reversible lattice spacing variation in the PC structure, producing pronounced color shifts that correlate quantitatively with resistance changes. The hydrogel is further demonstrated as a wearable platform for Morse code-based dual-channel information encoding and transmission driven by finger motion. This work establishes a versatile strategy for integrating PCs with highly conductive hydrogels, offering new opportunities for multimodal sensing, visualized signal readout, and secure optoelectronic communication.