Integrating plasmonic nanostructures with natural photonic architectures in Pd-modified butterfly wings for sensitive hydrogen gas sensing.

This work reports a bioinspired three-dimensional (3D) heterogeneous structure for optical hydrogen gas (H) sensing. The structure was fabricated by selective modification of the photonic architectures of butterfly wing scales with Pd nanostrips. The coupling of the plasmonic mode of the Pd nanostrips with the optical resonant mode of the biophotonic architectures generated a sharp reflectance peak in the spectra of the Pd-modified butterfly wing, as well as enhancement of light-matter interaction in Pd nanostrips. Exposure to H resulted in a rapid reversible increase in the reflectance of the Pd-modified butterfly wing, and the pronounced response of the reflectance was at the wavelength where the plasmonic mode strongly interplayed with the optical resonant mode. Owing to the synergetic effect of Pd nanostrips and biophotonic structures, the bioinspired sensor achieved an H detection limit of less than 10 ppm. Besides, the Pd-modified butterfly wing also exhibited good sensing repeatability. The results suggest that this approach provides a promising optical H sensing scheme, which may also offer the potential design of new nanoengineered structures for diverse sensing applications.