Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, Fribourg, 1700, Switzerland.
Chemistry and Physics of Materials, University of Salzburg, Jakob-Haringer-Straße 2a, Salzburg, 5020, Austria.
Adv Sci (Weinh). 2022 Sep;9(26):e2202145. doi: 10.1002/advs.202202145. Epub 2022 Jul 18.
The bright colors of Pachyrhynchus weevils originate from complex dielectric nanostructures within their elytral scales. In contrast to previous work exhibiting highly ordered single-network diamond-type photonic crystals, here, it is shown by combining optical microscopy and spectroscopy measurements with 3D focused ion beam (FIB) tomography that the blue scales of P. congestus mirabilis differ from that of an ordered diamond structure. Through the use of FIB tomography on elytral scales filled with platinum (Pt) by electron beam-assisted deposition, it is revealed that the red scales of this weevil possess a periodic diamond structure, while the network morphology of the blue scales exhibit diamond morphology only on the single scattering unit level with disorder on longer length scales. Full wave simulations performed on the reconstructed volumes indicate that this local order is sufficient to open a partial photonic bandgap even at low dielectric constant contrast between chitin and air in the absence of long-range or translational order. The observation of disordered and ordered photonic crystals within a single organism opens up interesting questions on the cellular origin of coloration and studies on bio-inspired replication of angle-independent colors.
大兜虫鞘翅上明亮的颜色源自其鞘翅鳞片内复杂的介电纳米结构。与之前展示高度有序的单一网络金刚石型光子晶体的工作相反，本文通过结合光学显微镜和光谱测量以及 3D 聚焦离子束（FIB）断层扫描表明，奇异大兜虫的蓝色鳞片与有序的金刚石结构不同。通过电子束辅助沉积在充满铂（Pt）的鞘翅鳞片上进行 FIB 断层扫描，揭示了这种甲虫的红色鳞片具有周期性的金刚石结构，而蓝色鳞片的网络形态仅在单个散射单元级别上表现出金刚石形态，在更长的长度尺度上存在无序。在重构体积上进行的全波模拟表明，即使在缺乏长程或平移有序的情况下，介电常数对比在甲壳素和空气中较低，这种局部有序也足以打开部分光子带隙。在单个生物体中观察到无序和有序的光子晶体，引发了关于颜色细胞起源的有趣问题，以及对独立角度颜色生物启发复制的研究。
