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Fabrication of Poly(methyl methacrylate) (PMMA) Microfluidic Chips Using CO2 Laser Beam Machining and Hot Bonding
Yishi Huang, Shouxin Wang, Zhuang Tian, Yingzi Mu, Chunming Hou and Xueye Chen

A single, versatile fabrication method for producing microfluidic chips on poly(methyl methacrylate) (PMMA) substrates is described. First, we processed the microchannel using CO2 laser beam machining on the PMMA substrate. In this course the influence of laser power, scanning speed and focal distance on the processing quality of microchannel were investigated by orthogonal experiment. The experimental result shows that the greatest influence factor is focal distance. Based on the experiment, we found a set of optimal parameters to process the microchannel within the set parameters. Next, the substrate with the microchannels and the cover are combined using thermal bonding. Since the previous bonding technology has a low success rate, we have proposed a new bonding termed a pre-bonding technique for bonding chips. The principle of this technology is to first remove the material stress with low pressure, and then use high pressure bonding. Finally, the processing quality of the microchannel and the feasibility of the pre-bonding method were verified successfully by the mixed experiment. This study can help people pay attention to the effect of focal distance on the shape of microchannels when using CO2 laser beam machining to process microchannels.

Keywords: CO2 laser, poly(methyl methacrylate) (PMMA), microfluidic chip, laser machining, hot bonding, focal distance, processing quality

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