【作者】 苏奇名；

【导师】 刘世炳；

【作者基本信息】 北京工业大学 ， 光学， 2006， 硕士

【摘要】 微流控生物芯片作为一种重要的分析技术,体现在它能将生化分析的许多过程与步骤,即成微缩在手掌大小的一片固体支撑物上来完成。相对于传统的生化分析方法,生物芯片技术具有消耗样品少、污染小、应用范围广等诸多优点。目前,微流控生物芯片技术已经开始推向应用市场,开始向产业化发展。进样储液池是芯片微通道的重要结构之一,其侧壁粗糙度是直接影响进样效果的重要技术指标。因此,进样储液池的加工制备备受关注。但是,我国目前却仍停留在传统的机械台钻加工工艺上。除加工效率极低外,更重要的是无法满足产业化的需要。针对这一难题,本文采用激光加工技术对芯片储液池的加工制备进行研究。为降低CO₂激光加工PMMA材料储液池侧壁粗糙度,本文根据传统的热传导方程,假定激光强度为高斯分布,对有限厚板状材料的温度场进行分析;并考察侧壁表面熔化层凝固过程的特征;结果表明,侧壁粗糙度形成的主要原因在于侧壁表面熔化层凝固前气泡未及时析出。另一原因是激光和材料相互作用过程中分子键断裂,在切割面形成单体,但是单体的尺寸和气泡相比可以忽略。根据理论分析,在工艺上采用了多种途径,揭示激光加工过程中各种因素对侧壁粗糙度的影响。一方面,通过改变激光加工头的运动速度,考察激光与芯片材料的相互作用时间对侧壁表面粗糙度的影响;另一方面,调整激光的功率和离焦量,找出最优化参数。再一方面,通过升高材料温度的方法,有助于激光加工过程中侧壁熔化层内气泡的有效析出,可以大幅降低侧壁粗糙度。通过将实验参数用曲线拟合的方法,得出侧壁粗糙度与激光功率、切割速度和离焦量之间的关系。针对PMMA材料的特性,采用功率为50W,连续输出的CO₂激光器。实验结果表明:激光功率的最佳变化范围是:28-32W,相对应的最佳速度的变化范围是:0.1-0.6m/min;侧壁粗糙度最低最低可达100nm,最佳升温范围是:70-90℃。本文针对芯片加工所需高效率、高精度的产业化要求,研制了一种新型激光加工平台。使用该平台进行激光加工和机械台钻加工相比,加工速度大大增加,最高速度可达3m/min,加工效率提高20倍以上。新型激光加工平台的采用,使芯片产业化向前迈出一大步。更多还原

【Abstract】 As an important analyzing method, microfluidic chip is capable of integrating many biotic analyses into a solid frame of the size of a human hand. Compared with traditional biotic analyses, microfluidic chip features low consumption of sample, low containment and versatility, etc. Now, microfluidic chips have been commercialized. As the sample-chamber is an critical part of a microfluidic chip, its roughness has an direct influence on the sampling. Being a critical technology, the domestic manufacturing of the liquid pool still depends on traditional machining. Besides low productivity, being unable to be industrialized is a more important disadvantage of traditional machining. So the manufacturing of liquid pool by lasers is studied in this work.Aiming at reducing the roughness of the sidewalls in the manufacturing of the PMMA liquid pool by CO₂ lasers, in the hypothesis that the intensity of the laser has a Guassian distribution, the temperature distribution in slab material with limited thickness is studied according to traditional thermal conductive formulas, and the condensing progress of the melted surface of sidewalls is researched. It is concluded from the discussion of temperature distribution that the air bulbs is the major reason for the roughness of the sidewalls. Yet another reason is the breaking of molecular bonds in the reaction of laser and material that results in the generating of monomers on the surfaces. But the size of monomers can be ignored compared with air bulbs.On the bases of theoretical studies, many technical methods are applied to research the influence of different factors on the roughness of sidewalls. Firstly, the influence of reaction time between laser and material on the roughness is studied by changing the speed of laser beam. Secondaly, the optimized parameters are found by adjusting laser power and defocus. Finally, the roughness of sidewalls is reduced greatly by rising the temperature, which results in more effective discharging of air bulbs in the melted surface. a CW CO₂ laser with a power of 50W is applied to fit the PMMA material and the requirements on the roughness of the sidewalls. The relationship between the roughness of the sidewalls and the laser power, cutting speed and defocus is given by curve fitting the experimental data. The experimental data shows that the optimal range of laser power is from 28 to 32W, and the optimal range of cutting speed is from 0.1 to 0.6 meters per minute. As the reason of the roughness is given, it is found that the roughness can be reduced greatly to 256 nanometers by rising the temperature, and the optimal temperature rising is from 70 to 90℃.更多还原