采用CO2激光直写烧蚀加工技术在聚甲基丙烯酸甲酯(PMMA)基片表面加工微通道, 分析了CO2激光输出功率和激光束移动速度对加工质量的影响。选用4.5 W输出功率和76.2 mm/s移动速度, 在30 s内加工了水力直径为100 μm的微通道。在进行微通道的大批量、快速加工时, CO2激光直写烧蚀加工技术具有较高的工艺稳定性, 工艺流程简单, 可随时根据实验需要对微通道结构进行调整和再加工。微通道的激光拉曼光谱与PMMA基片相同, 保证了微通道和盖片对聚合酶链式反应(PCR)物化学影响的一致性。虽然微通道边缘存在少量重铸物, 但不会影响热压键合效果, 芯片能够满足PCR扩增中的压力与密封要求。使用这种芯片实现了180 bp拟南芥脱氧核糖核酸(DNA)片段的PCR扩增, 扩增效果与使用常规PCR仪相当, 验证了采用CO2激光直写烧蚀方法加工PMMA基连续流式PCR微流控芯片的可行性。

CO2 laser direct-writing ablation micromachining technique is used to fabricate the microchannel on the polymethyl methacrylate (PMMA) substrate. The correlation between the process parameters (the laser power and the beam translational velocity) and the micromachining quality (the depth and the width of the microchannel) is investigated. A laser power of 4.5 W and beam translational velocity of 76.2 mm/s is used to make ablation of the microchannel with a hydraulic diameter of 100 μm on the PMMA substrate. The time for the ablation process is 30 s. This technique is steady and efficient in the batch production. The microchannel has the same Raman spectra as that of the PMMA substrate. The spectra shows that they have the same chemical effect on the polymerase chain reaction (PCR) mixture. The presence of the bumps of resolidified material on the edges of the microchannel has no influence on the hot-press bonding result and the PCR microfluidic chip could satisfy the pressure and the sealing requirement in PCR process. An amplification of a DNA template with 180 bp fragment of arabidopsis thaliana is successfully performed with this chip, in less than 30 min. This result exhibits the availability of CO2 laser direct-writing ablation technique on the micromachining of the PMMA continuous-flow PCR microfluidic chip.