聚合酶链式反应微流控芯片的准分子激光制备和应用研究

摘要采用价格便宜的聚甲基丙烯酸甲酯(PMMA)代替价格昂贵的硅或玻璃作为聚合酶链式反应(PCR)微流控芯片的基片材料,采用柔性大且自动化程度高的准分子激光微加工方法代替加工工艺复杂的光刻化学腐蚀方法,在19 kV和18 mm/min的优化加工参数下,在48 mm×67 mm×1 mm的PMMA基片上制备出20个循环的PCR微流控芯片. 芯片微通道横截面呈梯形,底面光滑. 微通道宽104 μm,深56 μm,长2 060 mm,加工耗时约110 min. 该芯片和相同尺寸的盖片在160 N和105 ℃条件下通过热压经20 min键合在一起,键合强度为0.85 MPa. 键合后的芯片和温控系统集成在一起,采用比例积分微分(PID)方法得到的控温精度为±0.2 ℃,采用红外热像仪得到的相邻温区间的温度梯度分别为16.5和22.2 ℃,最后利用该芯片在对170 bp的DNA片段实现了体外扩增.     

两种高聚物生物芯片材料的光学透过及激光加工性能分析

用准分子激光对高聚物材料进行微加工制作,可以获得比较理想的高聚物基生物芯片.根据对制作生物芯片材料的性能要求,比较了聚甲基丙烯酸甲酯(PMMA)和聚碳酸酯(PC)对不同波长激光的光波透过率,测量了高聚物材料经准分子激光微加工后的微结构,并得出准分子激光对不同髙聚物材料的刻蚀速率与入射激光能量密度之间的关系.     

基于牺牲层工艺的微流控亚微米粒子计数器研究

设计了一种基于微机电系统表面微加工工艺的亚微米粒子计数器微流控芯片。该芯片具有可大规模生产、价格低廉的优势,相比于纳米粒子跟踪分析技术和动态光散射技术,具有体积小、便于集成和在线检测的优点。芯片的检测区域尺寸为高700 nm、宽1μm,可以检测到粒径300 nm的聚苯乙烯微球,具有良好的信噪比。该芯片可以提供一种新的价格低廉的亚微米颗粒物在线检测方法,且采用微机电加工技术,和半导体加工工艺兼容,具有形成芯片实验室的潜力。     

3D打印微流控芯片技术研究进展

近年来,微流控技术在生命科学和医学诊断等领域得到广泛的应用,显示出了其在检测速度、精度以及试剂损耗等方面相比传统方法的显著优势.然而,使用从半导体加工技术继承而来的微加工技术制作微流控芯片具有比较高的资金和技术门槛,在一定程度上阻碍了微流控技术的推广和应用.近年来随着3D打印技术的兴起,越来越多的研究者尝试使用3D打印技术加工微流控芯片.相比于传统的微加工技术,3D打印微流控芯片技术显示出了其设计加工快速、材料适应性广、成本低廉等优势.本文针对近年来国内外在3D打印微流控芯片领域的最新进展进行了综述,着重介绍了采用微立体光刻、熔融沉积成型以及喷墨打印等3D打印技术加工制作微流控芯片的方法,以及这些微流控芯片在分析化学、生命科学、医学诊断等领域的应用,并对3D打印微流控芯片技术未来的发展进行了展望.     

激光技术在聚合酶链式反应微流控芯片中的应用

评述了激光技术在聚合酶链式反应(polymerase chain reaction,PCR)微流控芯片领域中的应用进展,包括激光技术在PCR微流控芯片微加工、微流体物理参数测量、温度循环控制以及芯片上在线产物检测(包括荧光实时定量/终点和毛细管电泳检测)中的应用。最后,展望了激光技术在未来基于PCR的微全分析系统(micro-total analysis system,μTAS)中的新应用。     

CO2激光直写加工聚合物微流体芯片的建模研究

在CO2激光直写聚合物(PMMA)微流体芯片加工原理基础上,对激光直写PMMA微流道的数学模型进行了研究.采用能量守恒原理对激光直写PMMA微流道成型进行分析,结果表明,其微流道的形状呈高斯函数型分布,并获得了微流道深度和激光功率、加工速度的函数关系及微流道截面形状的数学模型.实验数据较好地验证了所建模型的正确性,该模型对CO2激光直写聚合物(PMMA)微流体芯片的加工工艺具有很好的指导作用.     

电位无标型糖化血红蛋白免疫微传感器

研制了基于标准CMOS工艺和微加工技术的电位无标型免疫微传感器,可实现糖化血红蛋白浓度与血红蛋白浓度的简便检测。该微传感器包括含有信号读出电路的场效应型微传感集成芯片和一次性测试试条。微传感集成芯片由本实验室设计并经新加坡Chartered半导体公司流片制备。一次性测试试条采用微加工技术制备于柔性塑料片上,包括敏感电极阵列和三维微结构测量池。基于自组装单层膜并引入纳米金颗粒的方法,在测试试条电极表面固定抗体。采用循环伏安法和交流阻抗法对电极表面的修饰过程进行了测试和分析。该传感器对糖化血红蛋白和血红蛋白检测的线性范围分别为4～24mg/L和60～180mg/L。     

微圆盘电极技术测定表面化学微加工时的约束刻蚀剂浓度分布

利用微圆盘电极技术, 测定了KBr、L-胱氨酸和硫酸组成的刻蚀溶液体系中Pt电极表面电化学氧化产生的刻蚀剂Br2浓度分布, 为约束刻蚀剂层技术(CELT)中刻蚀体系的选择和优化提供更直观的依据. GaAs表面CELT微加工实验证明了用微圆盘电极测得的表面刻蚀剂的浓度分布趋势与微加工实验所得到的结果一致     

不同类型GaAs上应用约束刻蚀剂层技术进行电化学微加工

应用约束刻蚀剂层技术(CELT)对GaAs进行电化学微加工. 研究了刻蚀溶液体系中各组成的浓度比例、GaAs类型、掺杂以及阳极腐蚀过程对GaAs刻蚀加工过程的影响. 循环伏安实验表明, Br-可以通过电化学反应生成Br2作为刻蚀剂, L-胱氨酸可作为有效的捕捉剂. CELT中刻蚀剂层被紧紧束缚于模板表面, 模板和工件之间的距离小于刻蚀剂层的厚度时, 刻蚀剂可以对GaAs进行加工. 利用表面具有微凸半球阵列的导电模板, 可以在不同类型GaAs上加工得到微孔阵列. 实验结果表明: 在相同刻蚀条件下, GaAs的加工分辨率与刻蚀体系中各组分的浓度比例有关, 刻蚀结构的尺寸随着刻蚀剂与捕捉剂浓度比的增加而增大; 在加工过程中, p-GaAs相对于n-GaAs和无掺杂GaAs受到阳极氧化过程的影响较为显著, p-GaAs表面易生成氧化物层, 影响电化学微加工过程. X射线光电子能谱(XPS)和极化曲线实验也证明了这一点.     

基于纳米金修饰的两种无汞型重金属微传感器的对比研究

采用微加工技术制备了集成有工作电极和对电极的两种重金属微传感电极芯片,工作电极表面采用电沉积法修饰纳米金(Gold nanoparticles,GNPs),由半胱氨酸(L-cysteine,Cys)和天冬氨酸(L-aspartic acid,Asp)修饰制备Asp/Cys/GNPs/微传感电极芯片,并利用原位镀锡膜(Sn film)的方法,制成Sn/GNPs/微传感电极芯片。采用方波伏安法和方波溶出伏安法考察了两种微传感电极芯片对重金属离子Cu2+,Pb2+和Zn2+的响应特性。Asp/Cys/GNPs/微传感电极芯片可有效识别Cu2+和Pb2+,线性范围为5～2000μg/L,检出限为1μg/L;Sn/GNPs/微传感电极芯片可有效识别Cu2+,Pb2+和Zn2+,线性检测范围分别为5～500μg/L,5～500μg/L和10～500μg/L,检出限分别为2,3和5μg/L。相比而言,Asp/Cys/GNPs/微传感电极芯片具有较宽的检测范围,而Sn/AuNPs/微传感电极芯片具有较高的灵敏度,两种传感器绿色环保、制备简单、更新简便、易于集成,在水质在线监测方面具有应用前景。     

XPS-investigations on laser-modified Si3N4 ceramics

For the ultimate use of micro machining in technology, the interaction of laser light and silicon nitride ceramic have been studied. Using X-ray photoelectron spectroscopy (XPS), different effects generated by radiation from Nd:YAG (free running mode) and excimer lasers have been observed. With the Nd:YAG laser (λ = 1.06 μm), reaction zone depths of several 100 nm, apparently caused by melting, were found. The excimer laser treatment with a lower penetration depth of the light (λ = 248 nm) led to very low chemical surface damage. Thus the excimer laser is favored for exact micro machining of nitride ceramics.     

Non-equilibrium electrokinetic micro/nano fluidic mixer

We propose a new type of micro/nano fluidic mixer based on non-equilibrium electrokinetics and demonstrate its mixing performance. We fabricate the device with two-step reactive ion etching, one for nanochannels and one for microchannels. Mixing is achieved by strong vortex structures formed near the micro/nano channel interface. We expect the proposed device to be beneficial in the development of micro total analysis systems, since it is simple in its design with minimal fabrication complications.     

Size-controlled flow synthesis of metal-organic frameworks crystals monitored by in-situ ultraviolet-visible absorption spectroscopy

Size-controlled flow synthesis of nanoporous particles are of considerable interest for future industrial applications,however,is facing challenges due to lack of in-situ method for size-characterization in fluidic environment.We present that ultraviolet-visible(UV-vis) absorption spectroscopy can be integrated into a flow-synthesis system which was produced by femtosecond laser micro machining.The shift of the absorption peak position of the ex-situ and in-situ UV-vis spectra correlates to variation of size of porous metal-organic frameworks crystals.ZIF-67 crystals with a size in the range from 200 nm to1025 nm are fabricated with the assistance of tri-ethylamine under monitoring of in-situ UV-vis spectra.The ZIF-67 crystals are converted into nanoporous carbons particles with controlled sizes.These materials show size-dependent performance in Na-ion battery and size-independent performance in metal/H_2 O seawater battery.     

Evaluation of the analytical capability of NIR femtosecond laser ablation-inductively coupled plasma mass spectrometry.

A laser ablation-inductively coupled plasma-mass spectrometric (LA-ICPMS) technique utilizing a titanium-sapphire (TiS) femtosecond laser (fs-laser) has been developed for elemental and isotopic analysis. The signal intensity profile, depth of the ablation pit and level of elemental fractionation were investigated in order to evaluate the analytical capability of the present fs-laser ablation-ICPMS technique. The signal intensity profile of (57)Fe, obtained from iron sulfide (FeS(2)), demonstrated that the resulting signal intensity of (57)Fe achieved by the fs-laser ablation was almost 4-times higher than that obtained by ArF excimer laser ablation under a similar energy fluence (5 J/cm(2)). In fs-laser ablation, there is no significant difference in a depth of the ablation pit between glass and zircon material, while in ArF laser ablation, the resulting crater depth on the zircon crystal was almost half the level than that obtained for glass material. Both the thermal-induced and particle size-related elemental fractionations, which have been thought to be main sources of analytical error in the LA-ICPMS analysis, were measured on a Harvard 91500 zircon crystal. The resulting fractionation indexes on the (206)Pb/(238)U (f(Pb/U)) and (238)U/(232)Th (f(U/Th)) ratios obtained by the present fs-laser ablation system were significantly smaller than those obtained by a conventional ArF excimer laser ablation system, demonstrative of smaller elemental fractionation. Using the present fs-laser ablation technique, the time profile of the signal intensity of (56)Fe and the isotopic ratios ((57)Fe/(54)Fe and (56)Fe/(54)Fe) have been measured on a natural pyrite (FeS(2)) sample. Repeatability in signal intensity of (56)Fe achieved by the fs-laser ablation system was significantly better than that obtained by ArF excimer laser ablation. Moreover, the resulting precision in (57)Fe/(54)Fe and (56)Fe/(54)Fe ratio measurements could be improved by the fs-laser ablation system. The data obtained here clearly demonstrate that, even with the fundamental wavelength (NIR operating at 780 nm), the fs-laser ablation system has the potential to become a significant tool for in-situ elemental and isotopic analysis of geochemical samples including heavy minerals and metallic materials.     

Diffusion driven optofluidic dye lasers encapsulated into polymer chips

Lab-on-a-chip systems made of polymers are promising for the integration of active optical elements, enabling e.g. on-chip excitation of fluorescent markers or spectroscopy. In this work we present diffusion operation of tunable optofluidic dye lasers in a polymer foil. We demonstrate that these first order distributed feedback lasers can be operated for more than 90 min at a pulse repetition rate of 2 Hz without fluidic pumping. Ultra-high output pulse energies of more than 10 μJ and laser thresholds of 2 μJ are achieved for resonator lengths of 3 mm. By introducing comparatively large on-chip dye solution reservoirs, the required exchange of dye molecules is accomplished solely by diffusion. Polymer chips the size of a microscope cover slip (18 × 18 mm(2)) were fabricated in batches on a wafer using a commercially available polymer (TOPAS(?) Cyclic Olefin Copolymer). Thermal imprinting of micro- and nanoscale structures into 100 μm foils simultaneously defines photonic resonators, liquid-core waveguides, and fluidic reservoirs. Subsequently, the fluidic structures are sealed with another 220 μm foil by thermal bonding. Tunability of laser output wavelengths over a spectral range of 24 nm on a single chip is accomplished by varying the laser grating period in steps of 2 nm. Low-cost manufacturing suitable for mass production, wide laser tunability, ultra-high output pulse energies, and long operation times without external fluidic pumping make these on-chip lasers suitable for a wide range of lab-on-a-chip applications, e.g. on-chip spectroscopy, biosensing, excitation of fluorescent markers, or surface enhanced Raman spectroscopy (SERS).     

Surface analysis of ripple pattern on PS and PEN induced with ring‐shaped mask due to KrF laser treatment

The approach for ripple nanopattern construction on surface of two polymer substrates [polyethylene naphthalate (PEN) and polystyrene (PS)] exposed by a KrF pulse excimer UV laser through a contact lithographic mask with circular slit was proposed in this paper. Thin layer of gold was deposited on samples after the laser treatment. Changes in the morphology of the surface of both the shielded and exposed areas of the substrates, as well as the dimensions of the laser‐induced periodic surface structures, were determined (by atomic force microscopy, laser confocal microscopy and scanning electron microscopy), compared with observations and measurements made on samples treated directly (without a contact mask) under the same conditions. The morphology of the interface between the treated and untreated regions was also closely studied. Surface chemistry of treated samples was studied in detail by X‐ray Photoelectron Spectroscopy. The detailed study of surface chemistry of modified PEN and PS revealed a significant increase of oxygen concentration for laser treated PS and increase of carboxyl groups in case of PEN. The potential application of this research can be found in biotechnology, micro technology and several other fields. Copyright © 2016 John Wiley & Sons, Ltd.     

复合式微流控芯片上阴离子型固相萃取微柱柱性能分析

利用原位聚合法在玻璃微管道内制备阴离子交换型固相萃取(SPE)微柱,以NO2^-为分析对象,针对NaNO2-KI—Luminol发光体系设计微流控芯片,并将SPE微柱与微流控芯片连接起来组建成带有SPE微柱的复合式微流控芯片。分析了SPE微柱对NO2^-的吸附保留与富集作用,在复合式微流控芯片上,实现了NO2^-的进样、分离富集和检测,通过漏点曲线和交换容量两种方法分析了SPE微柱的柱容量。为控制SPE微柱的最大进样体积提供有利保障,并实现了食品中NO2^-的在线分离富集与检测。     

Improved DNA extraction efficiency from low level cell numbers using a silica monolith based micro fluidic device

The evaluation of a micro fluidic system with an integrated silica monolith for performing DNA extraction from limited biological samples has been carried out. Low DNA target concentrations usually require the addition of carrier RNA to ensure desired extraction efficiencies. Here, we demonstrate a micro fluidic extraction system with increasingly efficient extraction performances for biological samples containing <15 ng of total DNA without the need of adding carrier nucleic acids. All extracted DNA showed successful amplification via the polymerase chain reaction demonstrating both the effectiveness of the proposed system at removing potential inhibitors and yielding good quality DNA. The work presented here beneficially identifies reduced sample volumes/concentrations as suitable for processing with respect to downstream analysis by enabling pre-concentration of the biological sample, particularly important when dealing with clinical or forensic specimens.     

Formation of artificial micro‐pits on Al alloy with the photon rupture method and the localized corrosion behavior of the formed pits

An in situ artificial micro‐pit fabrication method with an area selective electrochemical measurement technique was applied to investigate the effect of the geometry of artificially formed pits on their localized corrosion behavior in anodized 1000 series aluminum. This technique enables the fabrication of artificial micro‐pits with different aspect ratios (pit depth/pit diameter) in solutions. The aspect ratios of the fabricated artificial micro‐pits in this experiment could be varied from 0.13 to 1.83 by controlling the irradiation time of the focused pulsed YAG laser beam. By applying a constant potential to the final laser‐beam‐irradiated spot in chloride environments, localized dissolution occurred only at the laser beam irradiated area, because the anodic oxide film acted as an insulator. The corrosion current and charge increase with increasing aspect ratio at any applied potential. Copyright © 2010 John Wiley & Sons, Ltd.