서강대학교

초록/요약

The elytra from dry specimens of the Hercules beetle (Dynastes Hercules) appear khaki-green in a dry atmosphere and turn black passively under high humidity levels. The visible dry-state greenish colouration originates from a widely open porous layer located at 3μm below the cuticle surface. This layer has a three-dimensional photonic crystal structure, that is a network of filamentary strings, arranged in layers parallel to the cuticle surface. In this study, we develop a biomimetic humidity sensor that inspired the cuticle structure of the Hercules beetle. Hydrophilic polyethylene glycol (PEG) is used as the base material for the humidity sensor. The PEG solution is infiltrated into a colloidal silica opal template and consequently photo-polymerized by UV. After polymerization, the photonic crystal (PC) humidity sensor is created by wet etching silica colloids. The color of the fabricated PC humidity sensor is sensitive to humidity; it could reversibly change color in visible range, when it is exposed in wet environment. This could be attributed to the humidity sensitivity of the sample’s photonic band gap (PBG). PC humidity sensor could be an economical alternative to traditional humidity sensors and it also provides a new insight into method for humidity detection.