Sensing Chemical Warfare Agent Simulants via Photonic Crystals of the Morpho didius Butterfly

[Image: see text] The rapid and portable detection of trace chemical warfare agents (CWAs) remains a challenge for the international security and monitoring community. This work reports the first use of natural photonic crystals (PhCs) as vapor sensors for CWA simulants. Dimethyl methylphosphonate, a nerve agent simulant, and dichloropentane, a mustard gas simulant, were successfully detected at the parts per million level by processing visible light reflected from the PhC inherent to the wing scales of the Morpho didius butterfly. Additionally, modeling of this natural system suggested several parameters for enhancing the sensitivity of a synthetic PhC toward CWA simulants, including materials selection, structure, and spacing of the PhC, and partial functionalization of the PhC toward the analyte of interest. Collectively, this study provides strategies for designing a sensitive, selective, rapid, and affordable means for CWA detection.