Jiajun Gu

Versatile Fabrication of Intact Three‐Dimensional Metallic Butterfly Wing Scales with Hierarchical Sub‐micrometer Structures

properties, which can be modulated by their intrinsicmicrostructures. Such structures, however, are quite difficultto prepare by traditional methods. One promising route tocreate these metallic structures is direct replication fromhierarchical structures of various natural species. Metals havebeen physically deposited onto biological structures tofabricate metallic structures through physical vapor deposi-tion (PVD).

Iridescent large-area ZrO2 photonic crystals using butterfly as templates

Intact ZrO2 (with refractive index of 2.12) replica, which is large in size (about 3×4u2002cm2), has been synthesized by using natural butterfly wings as templates. Microstructure characters of original butterfly wing scales are maintained faithfully in this biomorphic ZrO2. All replicas can reflect iridescent visible lights, which can even be observed by naked eyes. Optical microscope investigations indicate that colors reflected by one single scale are different from those done by the overlapped two or even more scales. Colors are not only determined by materials’ refractive index, observation angle, and the structure of every single scale, but also by its piled number and modes. With the increase in the number of piled scales, the color is not simply redshifted or blueshifted, which is the most direct and powerful evidence for structural colors.

ZnO single butterfly wing scales: synthesis and spatial optical anisotropy

We synthesize ZnO butterfly single wing scales (SWSs) directly templated from original individual SWSs. A 20° departure of the light incidence may drastically reduce the reflectance intensity by ten times. This work helps clarify the mechanism in butterfly replica optical properties, which are hotly being discussed at present.

Morphological Effects on Surface-Enhanced Raman Scattering from Silver Butterfly Wing Scales Synthesized via Photoreduction

Through a simple room-temperature photoreduction process, this letter conformally replicates 3D submicrometer structures of wing scales from two butterfly species into Ag to generate practical surface-enhanced Raman scattering (SERS) substrates. The Ag replicas of butterfly scales with higher structural periodicity are able to detect rhodamine 6G at a low concentration down to 10(-9) M, which is three orders of magnitude lower than the detectable concentration limit of using quasi-periodic Ag butterfly structures. This result presents a way to select suitable scale morphologies from 174,500 species of Lepidopterans to replicate, as consumable SERS substrates with low cost and high reproducibility.

Tunable optical photonic devices made from moth wing scales: a way to enlarge natural functional structures' pool

We use an electric field sensitive hydrogel (EFSH) to embed and fill the wing scales of sunset moth with rich structural colors. The EFSH swells and de-swells with volume transition that modifies the structures of wing scales, resulting in materials reflectance peak shift for visible light. Within several minutes, a total reversible peak shift range reaches as large as 150 nm. Our results broaden the natural species pool for functional structure selection, and provide designable and controllable bio-inspired material solutions according to specific practical demands.

Novel Photonic Crystals: Incorporation of Nano-CdS into the Natural Photonic Crystals within Peacock Feathers

In this investigation, the natural 2D photonic crystals (PhCs) within peacock feathers are applied to incorporate CdS nanocrystallites. Peacock feathers are activated by ethylenediaminetetraacetic/dimethylformamide suspension to increase the reactive sites on the keratin component, on which CdS nanoparticles (nano-CdS) are in situ formed in succession and serve as the seeds to direct further incorporation during the following solvothermal procedure. Thus, homogeneous nano-CdS are loaded both on the feathers surface layer and inside the 2D PhCs. The obtained nano-CdS/peacock feathers hybrids are novel photonic crystals whose photonic stop bands are markedly different from that of the natural PhCs within original peacock feathers, as observed by the reflection spectra.