Chiral Plasmonic Metamaterials with Tunable Chirality.

Chiral hollow nanovolcano array (HNVA) film and chiral hollow nanoshells (HNSs) are simultaneously fabricated via a new strategy of colloidal lithography technique. The chirality of both chiral plasmonic nanostructures, which arises from the asymmetric charge oscillation and electric field distributions, can be well controlled by regulating the opening-angle of the nanounits during the metal depositions. The large-area HNVA films exhibit strong chiroptical responses in the ultraviolet-visible region with -factor of 0.15 and possess remarkable transferability for better adaptability of different application situations. The chiral HNSs, which are simultaneously obtained during the deposition, is equipped with adjustable chirality and integrability. The obtained HNVA films were transferred to specific substrates, e.g., polydimethylsiloxane (PDMS), hydrogels, and high-curvature surfaces, maintaining the original chiroptical properties and excellent mechanical strength. Deformable chiral flexible metamaterial is obtained by incorporating the chiral HNSs in the hydrogel, enabling the ultrasensitive detection of water content in the hydrogel. Overall, this work will contribute to the study of chiral metamaterials by providing two kinds of newly developed chiral plasmonic metamaterials with tunable chirality and inspiring progressing ways for the flexible devices of artificial chirality.