【作者】 郝振霞；

【导师】 陈恒武；

【作者基本信息】 浙江大学 ， 分析化学， 2010， 博士

【摘要】 近年来,高聚物材料以其成本低、易加工复制等优势在微流控芯片系统中得到了广泛的应用。微流控系统集成化、微型化、便携化的特点决定了在芯片上制备集成化的金属微器件以用于各种不同的功能单元是微流控发展的必然需要。利用传统的LIGA技术在微流控芯片上集成金属微器件需要洁净实验室和复杂的设备,价格昂贵,制作难度较大,且用传统LIGA技术制备金属微器件的过程中不可避免地需要使用对高聚物材料表面具有腐蚀作用的有机溶剂(光胶稀释剂、显影剂等),不适于高聚物芯片上金属器件的制备。所以目前为止文献报道的带有金属微器件的芯片大多为玻璃/PDMS杂交芯片。这样的杂交芯片通道内壁由两种完全不同的材质构成,而不同材质表面所支持的电渗流大小不同,在电泳分离中会可能响分离效果。本文利用化学镀方法分别在两种微流控芯片常用的高聚物材料聚对苯二甲酸乙二醇酯(PET)和聚二甲基硅氧烷(PDMS)表面研制金属微器件,对金属器件的物理和化学性质进行研究,在此基础上制作均一材质的带有金属电极的全塑微流控芯片,并应用全塑芯片进行微流控化学和生化分析的试验。全文共分四章：第一章,评述了近年来高聚物芯片和微流控芯片上集成化金属微器件的研究进展。主要涉及高聚物芯片中微通道的加工和芯片的封合方法、微流控芯片上集成化金属器件的种类、应用和加工方法等。第二章,主要目标是制作全PET的带有集成化金微电极的微流控芯片。在本章中采用无定形PET材料,研究了紫外光与空气等离子体对无定形PET材料表面改性效果,研究发现,紫外光和空气等离子体两种处理方法对PET表面亲水性均有明显提高,并能显著提高芯片的热封合强度和通道的电渗流水平。等离子体改性在这两方面的效果优于紫外光改性。另外我们还研究了254 nm紫外光诱导的选择性光化学改性与化学镀相结合在PET表面制作金膜微器件的方法、技术及相关原理。在以上研究的基础上,我们在PET表面集成了金膜微器件,并利用空气等离子体处理待封合的PET表面,在较低的温度(65℃)下实现了无辅助黏合层的全PET芯片的热键合,制备了带有金微电极的全PET微流控芯片。所制备的芯片应用于芯片毛细管电泳—安培检测(μCE—AD),分离检测了神经递质多巴胺(DA)和儿茶酚(CA)。分离效率分别为3.2x104和4.3×104塔板/m,检测限(3σ)分别为0.87和1.28μmol/L,五次连续进样分离测定,迁移时间的RSD分别为0.5%和0.3%。与使用黏合层封合的PET同类芯片相比,分析性能明显改善。第三章,由于PDMS表面自由能低、高度疏水的性质,在其表面制备金属微器件的难度很大,本章对在PDMS表面和通道内集成精细且稳定的金属器件的方法进行了研究和探索。本章工作中,我们对比讨论了不同紫外光处理、表面活化方法对PDMS表面区域选择性化学镀金属层质量的影响,并最终选择利用紫外光诱导的丙烯酸(AA)聚合反应对PDMS表面进行区域选择性活化,结合化学镀技术建立了一种在PDMS表面简单而低成本地制备高精度、高结合强度的金属微器件的方法。应用此方法在PDMS表面制备的金膜微器件与基底之间的附着力非常强,具有很好的电化学活性,并且可以通过自组装的方法进行表面修饰。在现有的实验条件下,本方法在PDMS材料表面对金膜微器件的制作精度至少可以达到10μm。我们将此方法制备的金膜微电极应用于μCE—ED,对DA和CA的标准溶液进行分离检测。在对100μM的DA和CA混合样品的分析中,连续21次分离检测的峰高RSD分别为2.1%和2.4%；308V/cm的分离场强下,DA的柱效达21,237塔板/m(H=4.7x10-5m),比文献报道的同类型PDMS/玻璃杂交芯片柱效高。我们认为全PDMS通道内均一的电渗流是柱效得以提高的重要因素。另外我们还将制备的带状金膜作为电加热器考察了其在芯片中对溶液直接加热的性能。第四章,在第三章的基础上,初步考察了PAA接枝—化学镀法在PDMS表面制备的金膜作为细胞培养基底的可能性。考察了一种贴壁细胞COS-7在所制备的金膜表面的生长及增殖状态,结论是PAA接枝—化学镀法在PDMS表面制备的金膜表面可用于贴壁细胞的正常培养。此初步研究为PDMS微流控芯片细胞培养过程中的电刺激诱导分化奠定了一定的基础。本论文的主要创新点：1.通过等离子体改性,实现了无定形PET芯片在较低温度下热封合；结合UV选择性改性为基础的化学镀在PET芯片上集成了可用于电化学检测的金微电极,所制备的全PETμCE—ED芯片显示出良好的分离和检测性能。2.建立了在PDMS表面以光诱导聚合接枝PAA为基础的区域选择性化学镀技术制备集成化金属膜微器件的方法和工艺。与文献报道相比,此方法操作简单、成本低,且所制备金属器件具有令人满意的机械性能、电化学性能以及良好的生物兼容性,可以用于微流控芯片中电流传导、电化学检测和传感、电加热以及细胞培养等各种用途。3.对研制的PDMS-Au表面应用于细胞培养做了初步试验,为在PDMS-Au表面进行细胞的培养和电刺激诱导分化建立了初步的技术平台。更多还原

【Abstract】 Microfluidic chips made of polymers have been widely employed in the recent years because they are less expensive and easier to fabricate compared to those made of glass or silica. According to microfluidics’property of miniaturization, integration and portability of analytical instruments, metal apparatuses integrated for various functions are obviously required in microfluidic systems.Fabrication of micro metal devices in microchips through LIGA technique requires clean-room conditions and complicated facilities, which makes the process tough and costly. At the same time, organic solvents harmful for polymer surfaces are inevitably employed in the LIGA process, which is not favorable for preparation of metal devices on polymeric chips. As a result, most microchips integrated with metal devices are hybridized of glass and PDMS, the surface properties of which are completely different. The PDMS/glass hybrid chips can only support inhomogeneous electroosmotic flow (EOF), which might deteriorate the separation efficiency.In present work, electroless plating is employed to fabricate micro metal devices on PET and PDMS sheets, both of which are widely used in fabricating microchips. Properties of the fabricated metal devices are characterized, and polymeric microchips with homogeneous channel surfaces properties and integrated micro metal devices are fabricated, which are then used in chemical and biochemical applications.The thesis is composed of four chapters:In chapter 1, recent progress in polymeric microchips and fabrication of micro metal devices on microfluidic chips are reviewed with respect to fabrication of microchannels in polymers, bonding the polymeric microchips, the functions of metal devices on microchips, as well as their applications and fabrication methods. In chapter 2, amorphous PET was exploited to fabricate full-PET microchips integrated with gold microelectrodes. Surface modification via UV light irradiation and air plasma was studied and both of the two methods were found to be able to improve the surface wettability, enhance the supported electroosmotic flow (EOF), and increase thermal bonding strength of PET sheets, with the latter being more efficient and less time-consuming than the former UV light during the surface modification. On the basis of the study mentioned above gold film electrodes were fabricated on PET sheets, and the micro-structured PET sheet was bonded with the PET sheet carrying micro gold electrode was bonded without assistant layers at a low temperature (65℃), forming a full-PET capillary electrophoresis-amperometric detection (μCE-AD) microfluidic chip.The developedμCE-AD PET chip was used for separation and detection of dopamine (DA) and catechol(CA). The separation efficiencies of DA and CA are 3.2×104 and 4.3x104 plates/m, respectively, and detection limits achieved are 0.87 and 1.28μmol/L, respectively. Electropherograms for five consecutive runs of DA and CA show that the RSDs of migration time are 0.5% and 0.3%, respectively. Compared to the PET chips bonding with assistant layers, the analytical performances of present fabricated chip are significantly improved.It is rather difficult to prepare metal devices directly on PDMS substrates because the low surface energy of PDMS renders the adhesion between the deposited metal layer and PDMS substrate quite weak. In chapter 3, protocols for fabrication of fine and reliable metal devices on PDMS surfaces are studied. Different UV induced surface activation methods and their effects on the finally plated gold films are discussed. Among the tested methods, the UV-induced polymerization and grafting of PAA on the PDMS surface is the most effective for region-selective electroless plating. It provides the active carboxylic moieties which can be used as the scaffold for immobilization of metal nano particle catalysts necessary for region-selective electroless plating. The prepared micro gold devices show strong adhesion to the PDMS substrate, excellent electrochemical properties, and allow the SAMs of thiol-compounds to be perfectly formed on their surface. The minimum width of the prepared micro gold devices is no worse that 10μm, which could be improved if finer photo-masks and collimated UV light are used.The full PDMS chip showed good analytical performance. With DA and CA being the model analysts, the RSD of detection signals for DA and CA are 2.1% and 2.4%, respectively (each at 100μM, n=21). The separation efficiency achieved at the applied electric field of 308 V/cm is 21,237 plates/m (H=4.7×10-5 m for DA), which is significantly higher than that (8600 plates/m) obtained at approximately similar electric fields (250V/cm) with a PDMS/glass hybrid chip. The uniform EOF supported by the homogeneous PDMS channels is one of the reasons for the improvement in the separation efficiency.The fabricated gold device is also used d as an electric heater in microchips and its heating performance is examined.In chapter 4, on the basis of chapter 3’s work, the Au-PDMS substrate which can be immobilized in the well-plate is fabricated and the feasibility of using it in cell culture is preliminarily studied. Similar cell growth and proliferation is observed on the Au-PDMS substrate prepared by the method established in chapter 3 as in the control experiment, which suggests the fabricated Au-PDMS could be used in cell culture. This result shows the potential for the Au-PDMS substrate to be used for electrical stimulation induced stem cell differentiation during cell culture process in PDMS microfluidic chips.The main novelty of the present work is summarized as:1. Realizing full-PET microchip thermal bonding at a relatively low temperature with the help of air plasma surface modification and prepared PETμCE-ED chip with integrated micro gold electrode via UV surface modification induced electroless plating. The fabricated PET chip shows good analytical performances inμCE-ED application.2. Developing the protocol of integrating reliable micro metal devices on PDMS substrates on the basis of UV induced PAA grafting. Compared to the reports, this protocol proves its feasibility in ordinary chemistry laboratories without the need of the clean room and expensive facilities, and the prepared micro gold devices show satisfying mechanical behavior, excellent electrochemical properties, and good biological compatibility, which could be used as electric conductors, electrochemical detectors and sensors, electric heater and cell culture containers.3. Preliminarily testing performances of the electrolessly fabricated Au-PDMS substrate in cell culture experiment, and establishing the platform for cell culture and electrical stimulation of stem cell in PDMS microchips.更多还原