| 초록 |
Periodic nanostructures at length scale of half the wavelength reflect the light of band gap. Such a unique property of photonic crystals makes them appealing for security materials. In this work, we develop a novel method to create inverse opals with micropatterned wettability, which enables the encryption at wide range of length scale. To accomplish this, we make photolithographically-featured micropattern on the top surface of hydrophobic inverse opal, which serves as a shadow mask for reactive ion etching with oxygen gas. Therefore, inverse opal without the mask is rendered to be hydrophilic, whereas one underlying the mask remains intact. The patterned wettability enables the regioselective penetration of water when the whole pattern is subjected to water environment. This makes the encrypted messages appear. This novel technology will provide new opportunity in a wide range of encryption applications. |
