Scalable Hydrogel-Based Nanocavities for Switchable Meta-Holography with Dynamic Color Printing

Devices used for meta-optics display are currently undergoing a revolutionary transition from static to dynamic. Despite various tuning strategy demonstrations such as mechanical, electrical, optical, and thermal tunings, a longstanding challenge for their practical application has been the achievement of a conveniently accessible real-life tuning scheme for realizing versatile functionality dynamics outside the laboratory. In this study, we demonstrate a practical tuning strategy to realize a dynamic color printing with a switchable meta-holography exhibition based on hydrogel-based nanocavities. On the basis of the inflation sensitivity of a hydrogel to humidity alteration, its transmissive color was notably tuned from 450 to 750 nm. More intriguingly, by controlling the sample dry/immersed states in real time, we successfully enabled dual-channel switchable meta-holography. With the advantages of facile architecture, daily stimulus with large-area modulation, and high chromaticity, our proposed hydrogel-based nanocavities provide a promising path toward tunable display/encryption, optical sensors, and next-generation display technology.