| An integrated capillary electrophoresis chip (ICEC) is a novel kind of micro total analytical system, it can enhance the performance of chemical analysis with respect to smaller amounts of samples, higher analysis speed, better sensitivity with low cost and, at the same time, it is portable. The ICEC can be used to analyze inorganic molecules, organic molecules, biologic molecules(such as DNA, amino acids and proteins), cells, bacteria and viruses, etc.In this paper, on the basis of deep analyzing and studying domestic and foreign current conditions and existing problems of the ICEC, using PMMA as the chip material, the following four jobs are developed.1. The mechanism of hot embossing microchannels on plastic chips is studied; in order to develop the lifetime of the silicon master used in hot embossing, it is electrostatically bonded to a Pyrex 7740 glass wafer, which improves the device yield from ~20 chips to hundreds of chips per master; the temperature is lower than the glass transition temperature of the PMMA during hot embossing, which shortens the time for the whole embossing, and the accuracy of replication(AOR) still remains good; effects of embossing temperature, pressure and time on the AOR are systematically studied using the orthogonal factorial design; the process of hot embossing is simulated by ANSYS.2. Using the hot embossing machine as the thermal bonding device, effects of the bonding temperature, pressure and time on the deformation of microchannel dimensions are systematically studied using the orthogonal factorial design. After the thermal bonding process parameters are optimized, an ideal experimental model (80℃, 1.05MPa, 12 min) is suggested, correspondingly, the reduction rate of the depth of microchannels before and after thermal bonding is 24.7%, and the bonding strength of the chip is 35 KPa. The process of thermal bonding is simulated by ANSYS. The electrophoresis of Vitamin B2 is successfully preformed on a chip. The experimental results demonstrate that the microchannels on the chip fabricated by hot embossing and thermal bonding have a stable performance and perfectly meet the requirements of the electrophoretic analysis.3. Effects of the dead volume on the electrophoretic separation are simulated and evaluated using CoventorWare software. A novel connecting the PMMA ICEC to a quartz capillary with the minimal dead volume is presented. A hole is drilled into the edge of the chip using a500μm standard drill bit, then a home-made flattened drill bit is used to flatten the conical area, so a flattened-bottom hole is created, and a 375μm-o.d. quartz capillary is inserted into the hole and fixed using epoxy, which decreases the dead volume from 3.9nL to 0.1nL. Because the chip is connected to a quartz capillary, the electrophoresis on the chip can be directly detected by a UV absorption detector. Several medicaments are electrophoretically analyzed on a chip fabricated by this connecting method.4. A novel manufacturing process is studied for fabricating copper electrodes on PMMA, an integrated capillary electrophoresis chip on which the electrophoresis can be detected by the electrochemical detection method is manufactured. Cu is sputtered onto PMMA, and copper electrodes are formed by photolithograph and wet etching; an electrophoresis chip is fabricated by thermally bonding the PMMA with copper electrodes to a PMMA substrate with microchannels. During the course of making electrodes, the temperature and time for pre-bake and hard-bake of positive photoresist on the surface of Cu are studied; the eroding solution of Cu is chosen and its concentration is analyzed; a twice-exposure method is first put forward to remove the photoresist on copper electrodes. The thermal bonding process parameters of PMMA capillary electrophoresis chips integrated copper electrodes are optimized again. Electrophoretic experiments are made on the chip fabricated by this method, and the experimental results demonstrate that the copper micro-electrode has good electrochemical properties.
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