| Summary: | 碩士 === 國立雲林科技大學 === 化學工程與材料工程研究所 === 95 === This study combined self-assembled monolayers (SAMs) sensing material with microcantilever to build microcantilever chemical sensors, by which the sensing behaviors of metal ions in water were investigated.
First, the self-assembled monolayers (SAMs) formed by different n-alkyl thiols (X(CH2)nSH where n is the number of alkyl chains and X is the terminal group) and different incubation times were characterized by the contact angle, FT-IR RAS and ESCA measurements. The contact angle and FT-IR RAS measurements showed that as the chain length increases, the monolayer structure becomes increasingly ordered with higher packing density and coverage. The formation of SAMs reaches saturation in about 1 hr. The ESCA measurement showed that there is about 1eV shift in the binding energy of the sulfur atom after the formation of SAMs, which further confirms that the chemical binding between the gold surface and the thiols.
Then, the metal ion detections in water were carried out using the developed microcantilever sensors functionalized with the self-assembled monolayers (SAMs) of 15-Mercaptopentadecanoic acid (COOH(CH2)14 SH). The results of Pb2+ detections showed that the 15-Mercaptopentadecanoic acid-functionalized cantilever exhibits a reasonable sensing performance with a sensitivity of 0.099 N/m/log[Pb2+] (surface stress change per unit log concentration change), a detection limit of 10-6 M and a detection range of 10-1 M~10-6M.
In order to further improve the sensor performance, two macrocycle molecules, including 18-crown-6-ether and Supramolecular MS-113, were grafted onto the 15-Mercaptopentadecanoic acid-functionalized cantilever to carry out Pb2+ detections. The results showed that the detection limit reaches 10-7 M for both compounds, and the sensitivities are increased to be 0.126 N/m/log[Pb2+] and 0.131 N/m/log[Pb2+] for 18-crown-6-ether and Supramolecular MS-113, respectively. The graft of macrocycle molecules onto the cantilever surface indeed improves the sensing performance significantly.
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