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.