Preparation and Characterization of Photonic Crystals and Their Applications to Chemical Sensors

• Main Authors: Chug-Cheng Chiang, 江竣呈
• Other Authors: Lai-Kwan Chau
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/57826335464788454579

碩士 === 國立中正大學 === 化學所 === 97 === This first part of this thesis reports the use of LB technology to prepare silica opal. Cationic surfactants (e.g.: CTAB, DTAB) that adsorb to the surface of silica spheres by cationic-anion interaction were used to make the surface of the silica spheres more hydrophobic in order to spread the silica spheres at the air/water interface on the LB trough. After a long time compression at a fixed surface pressure, the particulate monolayer was transferred to a glass plate, and thus a monolayer of silica spheres was obtained. Repetition of the steps yielded a silica photonic crystal. Results show that the silica photonic crystal prepared with DTAB have higher reflectance then that with CTAB and both kinds of silica photonic crystals exhibit higher reflectance than results from literatures. Then we attempted to use photonic band gap to enhance fluorescence signal. By controlling the size of silica spheres so that the photonic band gap just falls in the emission wavelength range of a fluorescence dye, we can detect enhanced fluorescence signal. The second part of this thesis reports the fabrication of three types of inverse opal films by three different methods, included SU8 inverse opal (by cell method), SU8 inverse opal/gold nanoparticles (by covalent bond modify), and TiO2 inverse opal (by cell method and dip-coating method). Based on Bragg’s law, these inverse opal films were used as chemical sensors to detect refractive indexes of different organic solutions. The optical sensing properties of these inverse opal films have been compared. Results showed that the sensitivity of these inverse opal films are 409.03 nm/RIU for SU8 inverse opal/gold nanoparticles、383.55 nm/RIU for SU8 inverse opal、317.01 nm/RIU for the TiO2 inverse opal fabricated by the dip-coating method, and 207.10 nm/RIU for TiO2 inverse opal fabricated by the cell method. The third part of this thesis reports the use of the TiO2 inverse opal films fabricated by the dip-coating method for the development of a humidity sensor. Under different humidity conditions, results show that the photonic band gap of sample red shift in a high humidity environment, indicating the use of this structure as a humidity sensor is feasible.