Numerical and experimental study of a droplet-based PCR chip

A two-temperature continuous-flow polymerase chain reaction (PCR) polymer chip has been constructed that takes advantage of droplet technology to avoid sample contamination and adsorption at the surface. Samples contained in aqueous droplets are continuously moved by an oil carrier-fluid through various temperature zones, introducing the possibility of real-time quantitative PCR. In the present paper, we investigate many of the factors affecting droplet-based PCR chip design, including thermal mass, flow rate, and thermal resistance. The study focuses particularly on the fluid and substrate temperature distribution within the PCR chip and the droplet residence times in critical temperature zones. The simulations demonstrate that the flow rate strongly affects the temperature field within the carrier-fluid. Above a critical flow rate, the carrier-fluid fails to achieve the required temperatures for DNA amplification. In addition, the thermal resistances of the different layers in the chip are shown to have a major impact on the temperature profile in the channel.     

Adhesive bonding with SU-8 in a vacuum for capacitive pressure sensors

This paper describes a method for fabricating capacitive pressure sensors through the use of adhesive bonding with SU-8 in a vacuum. The influence of different parameters on the bonding of structured wafers was investigated. It was found that pre-bake time, pumping time, and the thickness of the crosslink layer are the most important factors for successful bonding. Bonding quality was evaluated by inspection through the transparent glass of the sensor and through the use of an SEM photograph, with 90% of the area successfully bonded and an ultimate yield of 70% of the sensors. The measured bonding strength was 17.15 MPa and 19.6 MPa for wafers bonded in 80 °C and 100 °C, respectively. The pressure–capacitance characteristic test results show that this bonding process is a viable micro electro mechanical systems (MEMS) fabrication technology for cavity sealing in a vacuum.     

Micropositioning and microscopic observation of individual picoliter-sized containers within SU-8 microchannels

We describe the fabrication and application of a bioanalytical chip, made of SU-8 photoresist, comprising integrated, high aspect-ratio microfluidic channels, suitable to manipulate and investigate vesicles, cell fragments and biological cells. A central micrometer-sized aperture allows electrical particle counting and planar membrane experiments, microfluids allow (sub)micrometer-sized objects to be transported and addressed with different chemicals. Here we show how lipid vesicles are positioned with micrometer precision within the micro-channels by means of pressure and electrophoretic movement. Our approach is suited for controlling and investigating (bio)chemical synthesis and cellular signalling processes in ultrasmall individual vesicles by electro-optical techniques.     

SU-8胶在深紫外光源下的光强分布模拟

本文根据菲涅尔衍射的原理,在考虑了折射、光刻胶对光的吸收以及硅片对光的反射的情况下,给出了SU-8胶在365 nm光源下经过方孔曝光时,光刻胶中光强的二维分布及三维分布的计算模拟.将试验结果与实际情况相比,表现出了一定的适用性,可以近似作为光刻胶形貌的最后近似.     

基于SU-8和AU-S的光纤传感制备及测试

将SU-8光刻胶涂覆在经过表面处理的锥形光纤表面,其表面的环氧基与MPTMS(3-硫丙基三甲氧基硅烷)发生交联作用。TPTMS表面的-SH基与用种子溶液生长法制备的星形纳米颗粒形成很强的化学键AU-S(其能量为170 kJ/mo1)。此外,我们还用这种光纤传感对不同浓度的酒精和甲胆紫溶液进行了透射谱测量。最后测试结果表明这种表面修饰了星形纳米颗粒的光纤传感对不同的物质和浓度非常灵敏,这种纳米光学传感有望被用于高灵敏度的检测中。     

微型聚合酶反应芯片的精确温度控制

微型PCR反应芯片是生物芯片的一个重要发展方向,是实现快速分子生物学检测的一个新兴技术。在微型PCR芯片中,变性、回火、延伸三个温度区的精确控制直接影响到生成产物的数量和特异性,因此至关重要。本文使用虚拟仪器技术构建温度测控系统,将其应用于微型PCR芯片的精确温度控制,该系统精度高,温度波动较小。通过Labview图形化编程软件和数据采集卡,大大缩短了系统组建时间,使温度数据采集和显示一次性完成。     

Network properties and acid degradability of epoxy-based SU-8 resists containing reactive gamma-butyrolactone

SU-8 is an octafunctional epoxy-based negative resist supplied with a reactive diluent, gamma-butyrolactone (GBL). This paper characterizes the network properties and acid degradability of cured SU-8 resists with varying GBL monomer content and ultraviolet (UV) irradiation time. The SU-8/GBL network structure was characterized by Fourier transform infrared (FTIR) spectroscopy, ¹³C nuclear magnetic resonance (NMR) spectroscopy and gas chromatography–mass spectrometry (GC/MS). GBL was found to copolymerize with epoxy to bridge two neighbouring epoxy groups and does not homopolymerize. The maximum GBL:SU-8 molar ratio whereby all GBL fully reacted with available epoxy functionalities in the network was found to be 8:1. Excess GBL beyond the maximum GBL:SU-8 ratio remains in the network as a plasticizer. GBL content and UV irradiation time affect glass transition temperature (T_g), epoxy conversion and molecular weight between cross-links (M_c) which were measured by dynamic mechanical analysis (DMA) and FTIR. The mechanism of cross-linked network acid degradation was found to be surface erosion. Lower epoxy conversion, higher M_c and higher GBL content resulted in a higher dissolution rate, which can be exploited in applications requiring SU-8 removal. A patterned SU-8 grating with relatively high-GBL content (10%) was successfully used as a template for Cu electroforming.     

自热式连续流PCR芯片的模拟与设计

介绍了一种连续流式的聚合酶链式反应(PCR)芯片,采取主动加热、被动冷却的方式,可实现DNA片断的倍增。用ANSYS有限元分析软件对器件进行温场分布仿真及分析,在此基础上, 设计了一种基于玻璃-玻璃的PCR芯片,芯片上分布着宽90μm,深40μm的迂回微沟道。通过单侧局部区域加热的方法,即可形成3个较宽的恒温区(95, 72, 60℃)与PCR反应相对应,且恒温区内温差在5℃以内,可以满足PCR反应的需要。     

A numerical and experimental study on gap compensation and wavelength selection in UV-lithography of ultra-high aspect ratio SU-8 microstructures

This paper presents a study on UV-lithography of thick SU-8 resist using air gap compensation and optimal wavelength selection for ultra-high aspect ratio microstructures. Both numerical simulations and experiments were conducted to study effects of different lithography conditions: broadband light source with and without air gap compensation, filtered light source with glycerol liquid, and filtered light source with Cargille refractive index matching liquid. A thick PMMA sheet was used as an optical filter to eliminate most of the i-line components of a broadband light source. Using the filtered light source and gap compensation with the Cargille refractive index liquid perfectly matching that of SU-8, patterns with feature sizes of 6 μm thick, 1150 μm tall (aspect ratio of more than 190:1) and high quality sidewalls were obtained. Microstructures with height up to 2 mm and good sidewall quality were also obtained and presented. The study also proved that Cargille refractive index matching liquid is compatible with UV-lithography of SU-8 and may be used as an effective air gap compensation solution.     

基于MEMS技术的SU-8仿昆虫微扑翼飞行器设计及制作

为研制一种轻质仿昆虫微扑翼飞行器,提出了采用微机电系统(MEMS)领域的SU-8光刻胶作为结构材料的制作方案.基于仿生学原理和微机电系统加工技术,设计微扑翼飞行器结构及MEMS 工艺方法.研究结果表明,该种结构设计及制作方案满足设计要求,为仿昆虫微扑翼飞行器的研制提供了一种很好的途径.     

基于微球和微柱阵列芯片的乳滴数字PCR定量方法

BEAMing是一种基于磁珠表面核酸扩增的乳滴数字聚合酶链反应(PCR)技术,具有很高的灵敏度,然而后续检测目标磁珠比较困难.通过修饰链霉亲和素的聚苯乙烯微球捕获BEAMing实验中生物素修饰的目标磁珠并利用微柱阵列芯片拦截微球,可以达到统计磁珠的目的.微柱阵列芯片采用基于尺寸差异的拦截原理.该芯片组装简单成本低,降低了BEAMing技术的磁珠统计难度.利用该方法对不同浓度的特定DNA序列做了检测,验证了该方法的实用性.     

一种用于安全芯片的高性能温度监测传感器设计

基于Global Foundry（GF）0.18μm标准CMOS工艺,设计了用于安全芯片的高性能温度监测传感器。该传感器利用PN结正向偏置电压与温度的近似线性关系监测环境温度变化,其集成度高、可靠性高、功耗低,并且能够在宽温度范围内正常工作。测试结果表明：在一定温度范围（-50-140℃）内,其温度系数为-4.47mV/℃,线性度良好;当电源电压为3.3V时,功耗仅为10.04μW,满足安全芯片的设计要求。     

集成加速度传感器敏感芯片性能影响因素及其仿真分析

从集成加速度传感器敏感芯片结构参数的设计入手,分析了支撑梁厚度、电容初始间隙、质量块等敏感芯片结构参数对传感器灵敏度、非线性等性能的影响.同时利用结构分析软件ANSYS进行仿真分析,并对优化后的敏感芯片结构参数进行验证,结果表明:该结构的敏感芯片使加速度传感器灵敏度能够达到10 mV/gn以上,非线性优于2％.     

An integrated genetic analysis microfluidic platform with valves and a PCR chip reusability method to avoid contamination

Clinical diagnostics and genomic research often require performing numerous genetic tests. While microfluidic devices provide a low-cost alternative to such demands, integrated microfluidic devices are fabricated using expensive technology not always affordable for single use. However, carryover cross-contamination (CXC) concerns (i.e. either false positive or false negative PCR data) in PCR chips prevent reuse, defying much of the advantages of miniaturized systems developed using expensive MEMS processing. In this work, we present an integrated and reusable PCR–CE glass microfluidic chip capable of multi-chamber PCR and sequential CE, with emphasis on a unique chip reusability approach to avoid CXC. For reliable PCR, the surface of the chamber is re-configured from its virgin hydrophilic (CA < 20°) to hydrophobic (CA > 110°) by silanization. To then extend this silanization method as a chip reusability technique, the silanization coating is ‘stripped and re-silanized’ (SRS) to create a fresh coating prior to each successive PCR run. Experimental confirmation of the effectiveness of SRS method in avoiding the CXC is demonstrated using plasmid DNA and HIV-1 infected DNA samples. We also present passive plug microvalves incorporated in the chip to enable fluid/vapor retention during the PCR and controlled fluid flow from the PCR chamber to the CE section for further analysis.     

基于SU-8的微流沟道的设计和制作

以SU—8作为结构材料,采用紫外光刻工艺,尤以斜曝光工艺为主,制造一种新型的、小型化的、低成本的、三维的、高深宽比的微流沟道,微流沟道的高度约为1100μm。初步确定出加工此微流沟道结构所需要的曝光计量、前烘时间、后烘时间和显影时间以及工艺方法,为加工其他尺寸的微流沟道提供参考。基于此方法加工的微流沟道可以应用在微型流式细胞仪上,来提供红细胞计数、血色素浓度、血小板计数和红细胞单元指数等参数。     

PCR 扩增芯片中微加热器结构优化分析

针对PCR扩增芯片中微加热器的传热问题进行有限元分析,用计算机模拟了不同形状微加热器的温度分布,通过对比分析,得出了提高温度分布均匀性的加热器结构和布置规律;根据分析结果,设计出双螺旋环形微加热器,这种结构能在一定范围内提供均匀的温度分布,为完成高质量的片上PCR扩增提供所需的温度环境;同时该结构还能有效减小微加热器本身的自感效应,提高加热效率.     

电泳芯片分离指标的模拟分析

对电泳芯片中影响区带展宽的相关因素进行了分析，给出了分离综合效率的表达式，建立了分离指标的数学模型。以此为基础，结合实验条件，利用计算机对影响分离指标的相关因素进行了模拟分析。结果表明，以分离综合效率为分离指标，可以反映分离条件对理论塔板数和分离时间的综合影响，而且，以分离指标的模拟分析为依据，可望实现电泳芯片的优化设计，在满足分离的前提下尽快地完成样品的分离分析过程。     

Simulation and experimental characterization of plug distortion in hybrid microchannels

The plug distortion for on-chip capillary zone electrophoresis systems with rectangular separation channels, manufactured in a hybrid layer system with different material properties of the vertical and the horizontal walls has been examined. Experimental data and simulation results indicate that plug widening caused by different values of the ζ-potential of the walls in contact with the fluid depends strongly on the aspect ratio of the channel cross section. If the height to width ratio is much greater or much smaller than 1, as is often the case for commonly used labchip architectures, plug widening may be negligible. The difference of the ζ-potentials between the vertical and the horizontal sidewalls has been determined from the shape of the plug edges. For an architecture using glass for the top and bottom walls, but SU-8 for the sidewalls, the difference of the ζ-potentials was measured to be on the order of only 2.4 mV for a pH of 9.2, suggesting that such device architectures may be used for on-chip electrophoresis analysis without uniform coating of the channel inside for less-demanding applications.     

PCR温度模糊PID控制器的设计及仿真

根据PCR对温度控制的要求设计出一种模糊PID控制器,采用误差和误差变化率作为模糊PID控制器的输入,PID参数作为模糊PID控制器的输出,并使用一组模糊规则实现对PID参数的在线优化调节.通过使用Simulink图形化工具平台对模糊PID控制器和传统的PID控制器进行建模和仿真.结果表明,与传统PID控制器相比,模糊PID控制器性能优良,使系统响应速度加快,超调减小.     

基于单片机的热水器温度智能控制设计

将现代智能控制中的模糊控制与传统控制中的PID控制相结合,使用单片机作为下位机控制器,PC机为上位机控制设备,实现对温度的智能、实时控制,现场与远程同时监控。