微流控芯片的材料与加工方法研究进展

综述了微流控芯片的制作材料及其加工方法的研究进展.在介绍了传统硅质材料,如硅、玻璃、石英等的基础上,着重描述了高分子聚合物材料在微流控芯片的应用趋势.针对不同材料,详叙了其材料特性、应用范围及加工方法.特别介绍了一些新的加工方法,如激光刻蚀法、软光刻、LIGA方法在该领域的应用.针对微流控芯片的材料与加工做了一个简要而...     

电泳微芯片进样口与微沟道形状的优化设计

基于电渗流场的理论,建立电泳芯片的不同结构模型,以计算流体力学(CFD)方法来模拟不同设计参数和电压组合下的电泳微芯片微沟道中流体流动现象.最终优化基本型毛细管微沟道交叉口形状为矩形,微沟道宽度为20 μm,进样与分离场强为200～250V/cm.为在有限芯片面积下增加有效分离距离,设计螺旋形沟道电泳芯片模式.     

电泳芯片上非接触电导检测器的研究

非接触电导检测器克服了接触电导检测器的缺点,避免了电极污染,结构简单,易于集成化、微型化,适合芯片毛细管电泳检测.介绍了芯片上非接触电导检测器发展现状,检测原理以及检测池等效电路,并对信号处理电路做初步探讨.     

基于虚拟仪器技术的毛细管电泳仪的设计

针对毛细管电泳芯片的特点,毛细管电泳仪的设计,以S3C2410微处理器作为硬件核心,运用主从式虚拟仪器技术、模块化设计思路和面向对象的设计思想,提供了一个良好的用户平台,实现了对毛细管电泳芯片信号的实时采集、处理和分析。     

双单片机数据采集系统中TCP/IP网络模块的实现

介绍了一种使用双单片机的多通道的毛细管电泳芯片检测系统,详述了从单片机如何通过网卡芯片RTL8019AS,通过以太网实现与上位机的网络连接,阐述了在双单片机数据采集系统中TCP/IP网络模块的实现方法。对于仪器的网络化及其意义进行了讨论。     

毛细管区带电泳的紫外可见光吸收检测

利用紫外可见光吸收方法完成毛细管区带电泳的检测工作，本文就实验装置，实验结果进行了讨论。     

一种基于DSP和CCD的ICE芯片扫描分析系统

集成毛细管电泳(ICE)芯片扫描分析系统是ICE芯片能否得到广泛应用的关键仪器.针对传统的ICE芯片扫描分析系统结构复杂、处理速度慢、体积庞大等弱点,设计了以DSP TMS320DM642为核心处理器,基于CCD(电荷耦合器件)的实时扫描分析系统.该系统完成扫描控制和全自动数据分析处理,解决了传统ICE芯片扫描分析系统的上述弱点,使得开发高性能、廉价的ICE嵌入式系统成为可能.     

CO2激光直写结合湿法刻蚀加工玻璃基微流控芯片

玻璃是制作微流控芯片的重要材料,其加工工艺主要基于光刻后湿法腐蚀,对设备和实验室要求较高.本文提出以普通指甲油和指甲油/金/铬为牺牲层,利用CO2激光烧蚀开窗口,辅以湿法腐蚀加工玻璃基微流控芯片的方法,并考察了激光加工参数,腐蚀液组成,牺牲层等因素对芯片质量的影响.该方法简便易行,不需要光刻的昂贵设备和繁杂步骤.     

低成本聚合物微流控芯片加工技术综述

针对传统微流控芯片加工方法成本高昂、耗时长的问题,近年来出现了多种低成本的微流控芯片加工方法,在聚合物、纸等材料上加工、完成了能够满足其应用需求的微流控芯片。对当前各类基于聚合材料的低成本微流控芯片加工技术进行了梳理和总结,并对未来低成本微流控芯片的发展进行了展望。     

集成毛细管电泳芯片的设计

利用ANSYS软件对集成毛细管电泳芯片微沟道内样品流动情况进行模拟,获得了不同进样模式下微沟道的结构与流体流速之间的关系,并以此为依据对芯片整体结构参数进行设计:毛细管沟道最终尺寸为宽度16μm,深度10μm,有效分离长度为3.5cm的圆角转弯形沟道,从而确定整个芯片设计。     

Fabrication of fluidic chips with 1-D nanochannels on PMMA substrates by photoresist-free UV-lithography and UV-assisted low-temperature bonding

A novel method for fabricating nano- or submicro-fluidic PMMA chips using photoresist-free UV-lithography and UV-assisted low-temperature bonding was developed. The nano- or submicro-channels were fabricated by exposing the PMMA substrate to the UV-light through a mask for a certain time. The PMMA substrate with channels and another flat PMMA cover sheet were pretreated with the UV-light for 2 h before they were brought together in running water. The bonding was carried out under a pressure of (1.19 ± 0.12) × 10⁵ Pa and at a temperature of 45°C for 35 min. The chips bonded in this way could bear a tensile of 6.71 ± 2.50 MPa, and the deformation of the bonded channel was about 13%. A hybrid micro- and nano-fluidic PMMA chip fabricated with the developed method was demonstrated for the test of the electrokinetically driven ion enrichment and ion depletion.     

高聚物微流控芯片上集成化气动微阀的研制

报道了一种新型的聚甲基丙烯酸甲酯(PMMA)/聚二甲基硅氧烷(PDMS)复合芯片。该芯片采用PMMA-PDMS…PDMS-PMMA的四层构型,以在芯片上集成气动微阀。具有液路和控制通道网路的PMMA基片与PDMS弹性膜间采用不可逆封接,分别形成液路半芯片和控制半芯片,而2个半芯片则依靠PDMS膜间的粘性实现可逆封接,组成带有微阀的全芯片。这种制备方法解决了制备PMMA-PDMS-PMMA三层结构芯片的封接难题,封接过程简单可靠。其控制部分和液路部分可以单独更换,可进一步降低使用成本,尤其适合一次性应用场合。初步实验表明:该微阀具有良好的开关性能和耐用性。     

Fabrication and characterization of a polymethyl methacrylate continuous-flow PCR microfluidic chip using CO2 laser ablation

An improved microfabrication method was used to fabricate a continuous-flow PCR (polymerase chain reaction) microfluidic chip on the PMMA substrate using the low-power CO₂ laser ablation technique. The use of the low-power CO₂ laser and the PMMA material could reduce the cost and the time of the fabrication process, especially at the step of laboratory research because of the high flexibility of the laser fabrication technique and the low cost of PMMA. A CO₂ laser output power of 4.5 W and a laser scanning velocity of 76.2 mm/s were chosen to fabricate the chip in this work. The micromachining quality could satisfy the microfluidic requirement of the PCR mixture within the microchannel. Good temperature distribution and gradient were obtained on the PMMA chip with a home-built integrated heating system. An amplification of DNA template with a 990 base pair fragment of Pseudomonas was successfully performed with this chip to characterize its availability and performance with various flow rates.     

A new technology for microfluidic structures preparation based on a photoimageable ceramic

A new method for fabrication of hybrid ceramic-polymer structures with diversified geometry of microchannel was elaborated. This method is universal, non-complicated, and utilises commercially available materials and basic equipment for thick film technology and photolithography. A microchip for capillary electrophoresis was prepared as an example of microfluidic structure fabrication. The chip was prepared by using a photosensitive paste (dielectric FODEL 6050) which was screen printed onto a ceramic substrate, exposed through an appropriate mask, developed, fired and then glazed. In this way, we obtained the structure which can be bonded with poly(dimethylsiloxane) PDMS after oxygen plasma treatment. The application of transparent PDMS as a seal of the microchannel enabled the optical detection.     

A microvalve for hybrid microfluidic systems

A hybrid valve for lab on chip applications is presented. The valve is assembled by bonding poly (methyl methacrylate), PMMA, and silicon-based elastomers. The process used to promote the hybrid bonding includes the deposition of an organosilane (TMSPM) on the thermoplastic polymer, PMMA to interface PMMA and elastomers. For this study, a membrane in ELASTOSIL^? is bonded in correspondence of the end of two microfluidic channels of a fabricated PMMA microfluidic chip. Prior the bonding, a plasma etching process has been used to remove the TMSPM in a confined circular area. This process made possible to bond selectively the edge of a membrane leaving free to move its central part. Actuating the membrane with an external positive pressure or vacuum is possible, respectively, to obstruct or to connect the microfluidic channels. The microvalve may be simply integrated in microfluidic devices and permits the control of microvolumes of fluid in processes such as transport, separation, and mixing. The deposition of the TMSPM, the bonding of the valve and its actuation has been characterized and tested. The flow rate control of liquids through the valve has been characterized. The results have been discussed and commented. The valve can stand up to 14 psi without showing leakages.     

Rapid glucose concentration detection utilizing disposable integrated microfluidic chip

A novel three-dimensional (3D) disposable glucose concentration detection chip is presented. The chip comprises a four-layer polymethyl methacrylate (PMMA) structure and is fabricated using a commercial CO₂ laser and a hot-press bonding technique. In the proposed device, the glucose solution is injected into a double parallel connection micromixer (DPCM) and is mixed with DNS reagent by means of a self-rotation effect. An experimental platform has been created for multiple reaction process by integrating chip and micro-heater. The fluid streams exiting the two circular mixing chambers of the DPCM are then combined and mixed further at a T-type microchannel outlet before passing to a collection chamber. Numerical simulations are performed to analyze the vortex streamline distribution within the DPCM and to estimate the mixing performance. The numerical results show that a mixing efficiency as high as 92.5% can be obtained at low Reynolds numbers (Re = 12). It is found a good linear relation of R ² = 0.9953 from the chip detection method comparing to the traditional method of R ² = 0.9976 at DNS reagent and glucose solution volume ratio of 1:1. In addition, the experimental results show that the accuracy of the glucose concentration measurements obtained using the proposed microfluidic chip is comparable with that of the measurements obtained using a conventional large-scale detection method. Overall, the results presented in this study indicate that the DPCM chip provides a rapid and low-cost means of detecting the concentration of glucose solutions.     

Plasma assisted thermal bonding for PMMA microfluidic chips with integrated metal microelectrodes

Fracture of integrated metal microelectrodes likely happens during the thermal bonding process of PMMA [poly (methylmethacrylate)] microfluidic chips. In this paper, the fracture behaviors are studied. The fracture is mainly caused by the plastic deformation of the electrode plate (the PMMA plate with microelectrodes) and the thermal stress of microelectrodes, which is due to the high bonding temperature. To decrease the bonding temperature, a plasma assisted thermal bonding method is evaluated and first used to eliminate the fracture of microelectrodes. In this process, the surface of the cover plate (the PMMA plate with microchannels) is modified using oxygen plasma before the electrode plate is thermally bonded to the cover plate. The parameters of the oxygen plasma treatment are optimized, and the contact angle is decreased from 71.7° to 43.6°. The thermal bonding temperature is optimized, which decreases the temperature from 100 °C to 85 °C. Testing of bonding strength shows an average failure pressure of 1.75 MPa, which is comparable to the bonding strength of 1.46 MPa for chips bonded at 100 °C without plasma modification. In order to demonstrate this bonding method, a PMMA microfluidic chip with integrated copper interdigitated microelectrode arrays for AC electroosmotic pump is fabricated.     

PMMA to Polystyrene bonding for polymer based microfluidic systems

A thermal bonding technique for Poly (methylmethacrylate) (PMMA) to Polystyrene (PS) is presented in this paper. The PMMA to PS bonding was achieved using a thermocompression method, and the bonding strength was carefully characterized. The bonding temperature ranged from 110 to 125 °C with a varying compression force, from 700 to 1,000 N (0.36–0.51 MPa). After the bonding process, two kinds of adhesion quantification methods were used to measure the bonding strength: the double cantilever beam method and the tensile stress method. The results show that the bonding strength increases with a rising bonding temperature and bonding force. The results also indicate that the bonding strength is independent of bonding time. A deep-UV surface treatment method was also provided in this paper to lower the bonding temperature and compression force. Finally, a PMMA to PS bonded microfluidic device was fabricated successfully.     

PMMA microfluidic chip fabrication using laser ablation and low temperature bonding with OCA film and LOCA

A new PMMA microfluidic chip fabrication method by combining laser ablation technology with low-temperature bonding using optically clear adhesive (OCA) film and liquid optically clear adhesive (LOCA) was presented in this paper. The deformation and clogging issues of the microfluidic channel were well solved. The effective bonding area ratio of microfluidic chips could be greatly improved by adjusting bonding temperature and bonding time. The crevices around the microchannels were effectively eliminated by coating treatment of LOCA. The bonding strength and waterproof of PMMA microfluidic chips coating with/without LOCA were also evaluated in this paper.

     

Fabrication and testing of embedded microvalves within PMMA microfluidic devices

The integration of a PDMS membrane within orthogonally placed PMMA microfluidic channels enables the pneumatic actuation of valves within bonded PMMA–PDMS–PMMA multilayer devices. Here, surface functionalization of PMMA substrates via acid catalyzed hydrolysis and air plasma corona treatment were investigated as possible techniques to permanently bond PMMA microfluidic channels to PDMS surfaces. FTIR and water contact angle analysis of functionalized PMMA substrates showed that air plasma corona treatment was most effective in inducing PMMA hydrophilicity. Subsequent fluidic tests showed that air plasma modified and bonded PMMA multilayer devices could withstand fluid leakage at an operational flow rate of 9 μl/min. The pneumatic actuation of the embedded PDMS membrane was observed through optical microscopy and an electrical resistance based technique. PDMS membrane actuation occurred at pneumatic pressures of as low as 10 kPa and complete valving occurred at 14 kPa for ~100 μm by 100 μm channel cross-sections.