Study On The Fabrication Of PMMA Microchip Of Capillary Electrophoresis With Electrochemical Detection

PMMA microchip of capillary electrophoresis with electrochemical detection (CE-ECD chip) is the integrated chip to achieve the sample injection, reaction, separation and detection, with units such as micro-channels, react chambers, detection units, and etc. CE-ECD chip was fabricated using MEMS technologies, based on the theory of capillary electrophoresis. The CE chip has many advantages such as remarkable sensitivity, inherent miniaturization, portability, low cost, fast detection and etc. In this thesis, the structure and design of CE-ECD chip were first investigated, then the mass production of CE-ECD chips was studied, at last the fabricated chips were tested through the separating of combined samples. The main work and innovations are described as the following:1) The structure of the capillary electrophoresis chip was first analyzed and designed. The character of micro-fiuidic in the micro-channel was investigated through computer simulation using CFD software such as ANSYS and Fluent. At the same time, the different micro-channels' effect on the fluidic was also investigated. The Electric Double Layer's effect on the distribution of electric field in the micro-channel was studied, and the result shows that sample injection and separation are mainly determined by electric field of separating voltage. In order to archive effective sample injection, the control of voltage was optimized. The micro-channels were designed as for the fabrication of CE chip and the detection of samples. At last, the electrochemical detection system was designed for the CE chip.2) The sample chip of CE-ECD should be investigated before the study of mass production of CE chip. PMMA-SU8-PMMA based CE chip was fabricated as the sample chip. The SU8 micro-channel was fabricated through lithography instead of UV-LIGA process, which also has the high quality of pattern and fast production. The electrodes were fabricated through lift-off process, and the chip was packaged using the thermal bonding method.3) The mass production of CE chips was studied based on the UV-LIGA process. The conventional UV-LIGA process was first optimized and improved for the fabrication of the PMMA micro-channels: (1) The lithography parameters were optimized to obtain good adhesion of SU8 layer; (2) A second electric seed layer was sputtered on the surface of the cross-linked SU8 layer to reduce the line space of the structures before electroforming. The electrodes were fabricated and integrated onto the chip using lift-off process. The CE chip was packaged by the PMMA thermal bonding process based on the surface modification which developed by ourselves, and high...