Fabrication Of Optical Fiber Probes And Eletodes Based On Self-Assembled Techniques

Optical fiber probes with various shapes and gold electrodes modified with histidine for determining copper in water have been fabricated based on self-assembled technology in this dissertation. It is consists of the following aspects.1 Fabrication of optical fiber probes by dynamic chemical etching based on siphon principleA simple dynamic chemical etching device based on siphon principle has been developed for fabrication of optical fiber probes, which widely used in near-field optical microscopy, scanning electrochemical/optical microscopy and optical nanobiosensors. Probes with various shapes have been fabricated because the tape length and tape angle of the probe could be efficiently controlled through adjusting the speed and direction of water flux while etching. Compared with traditional static chemical etching, this method has some obvious advantages, such as reproducibility, controllability, convenience, less cost, and making probe surface smooth. Probes with apex diameter from 20nm to 300nm and taper angle varied from 12°to 65°have been achieved by this method. Moreover, double-tape probes with apex diameter less than 50nm also could be obtained by selecting appropriate water level difference. Furthermore, the mechanism of the chemical etching has been discussed.2 Electroless silver plating for metallization of optical fiber probesElectroless silver plating based on self-assembled monolayers has been developed for metallization of optical fiber probes and the experiments conditions have been optimized. Compared with traditional vacuum deposition techniques, this method has advantages such as free-pinholes, controllability, convenience, less cost, and making tip surface smooth. The metallized probes were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and optical microscopy. The mechanism of deposition is discussed.3 Glutaraldehyde modified gold electrodes for subsequent histidine attachment and determination of copper A new chemically modified gold electrode was prepared by glutaraldehyde modified electrode for sunsequent histidine attachment. A new approach was developed for sensitive and selective determination of copper by the electrode. A complex of copper with the modifier was formed and accumulated on surface of the electrode while immersed the electrode into copper-containing solution. In a NaH2PO4-Na2HPO4 buffer solution, the electrode has good electro-activity. While adding copper, the current increase and potential remains same. The value of peak current is linear with the copper concentration in range 1×10-12～1.8×10-11 mol/L and 5×10-7～2.1×10-5mol/L. The detection limits is 0.5×10-12mol/L and an indirect mechanism of determination is proposed.