Papers by Author: Bing Yan Jiang

Abstract: A new bonding method of microfluidic chips, bonding in-mold, was presented. Finite element software simulation was used to study the deformation of microchannels in poly methyl methacrylate (PMMA) bonded chips. Varied temperature and compression thickness have been taken into account. Results showed that bonded microchannel cannot maintain the cross-sectional shape and dimensional accuracy. The area of cross-section was smaller. Its height changes since the substrate’s raised up and the cover plate’s bulged down. But the width dimension of microchannel was essentially unchanged. The deformation caused by thermal expansion is small. Experimental data show that compressed thickness has a greater impact than temperature.

Abstract: In this paper reflow process is integrated into LIGA process in order to realize three dimensional fabrication. The melting and deformation process of photoresist, which has an initial cylindrical shape of D500μm and h66μm, and the influence of various processing parameters on the height of formed microlens, is simulated with Marc. The optimum processing parameters combination is obtained by orthogonal experiment method and the influence of different processing parameters on the height of micro-spherical structure is studied with single factor experiment method. The results showed that the optimum processing parameters combination was 1°C /s for heating rate, 110°C for heating temperature and 45min for holding time; the significance of processing parameters on the micro-spherical structure’s height can be ordered in holding time＞heating rate＞heating temperature.

Abstract: Microfluidic chips have a great prospect in the field of biochemical analysis with advantages of fast processes, high flux and low consumption. Molding and bonding are separated by the conventional procedure of hot embossing and bonding, resulting in low automation and long production cycle. In order to reduce cycle time and achieve mass production, this paper proposed In-mold Bonding technology with precisely controlled bonding pressure by injection molding machine’s movement of core-pulling. So simulation analysis for bonding process of PMMA microfluidic chip was carried out using finite element software to study microchannel distortion at different bonding temperature and pressure. The results show that, at a certain bonding pressure, when bonding temperature was lower than glass transition temperature(Tg), microchannel distortion didn’t change significantly, when bonding temperature was higher than Tg, microchannel deformation increases with increasing temperature. Small microchannel distortion was obtained at a temperature of 108°C,which was recommended as the suitable bonding temperature.

Abstract: The melt fluidity of the two typical plastic, including polypropylene (PP) and polyethylene(PE), are studied in the different mold with the different characteristics of channel cross section and channel profile for the fluidity test of the melt. The relationship among the flow ratio, characteristics of channel cross section and channel profile are analyzed. The modified law of the flow ratio was proposed on the basis of the experiment, and discussed in detail. The results are better based on the experiment analysis, and the checking formula of the melt flow ratio could be used to check the designed mold in production.

Abstract: Melt flow properties in micro cavity play an important role in the micro injection molding (MIM). Based on the point view of improving the melting plastification quality, this study focus on solving the problem of melt filling difficulty in micro cavity of MIM by introducing the ultrasonic vibration field into the polymer plastification process. This paper studied the polymer’s ultrasonic plasitfication process by Theoretical analysis and Polymer ultrasonic plastification experiment.

Abstract: Microfluidic chip has bright application prospect in the field of chemical and biological analysis. PMMA is the best material for microfluidic chip fabrication because of its low cost, prominent electrochemical properties and biological compatibility. In this work, a triple-channel microfluidic chip was designed; a nickel mold insert with microstructure was fabricated by UV-LIGA technology, and then the injection mold was designed and fabricated. The change in cross-section dimensions of microchannel was chosen as evaluating indicator, and micro-injection molding experiments were carried out. Then the influence of process parameters on cross-section dimensions of microchannel was observed with microscope. Experiment results demonstrated that substrate and cover plate could be manufactured in a single injection molding process by "1+1" type mold, and the manufacturing cycle was reduced to less than 20s, so production efficiency was greatly enhanced. Best combination of process parameters was obtained when mold temperature was 80°C, melt temperature was 250°C and injection rate was 297mm/s. Thereby, high quality substrate and cover plate could be manufactured efficiently.

Abstract: The aspheric VCD lens is hard to fabricate by injection moulding due to its small volume and high precision requirement. The processing conditions have critical effects on the quality of the moulded lenses. An optic lens needs precisely controlled surface contours, so determination of the processing conditions for lens moulding becomes very complicated. This study’s purpose is to investigate experimentally some effects of the moulding conditions on the form errors of injection moulded lens. An aspheric VCD lens was moulded using polymethyl methacrylate. Different combinations of moulding conditions were used focusing on moulding process parameters of the ram speed, the mould temperature, the melt temperature and the packing pressure, The predicted model of form errors was formulated by orthogonal and regression analysis. Finally, the predicted model is proven to be valid based on the residual diagnostic plots.