基于石蜡打印的PDMS微流控芯片制备及实验应用

介绍了一种基于数字化石蜡液滴微喷射技术制作微流控芯片的方法及其应用,制作的聚二甲基硅氧烷(PDMS)微流控芯片可用于微液滴的生成和两相流的微混合。实验所需玻璃微喷嘴制备简单、成本低廉。石蜡阳模的形状可自主设计,通过调节驱动电压、驱动频率和加热温度可控制石蜡液滴尺寸及石蜡线宽。利用此方法在石英玻璃基底上打印出石蜡阳模,通过PDMS溶液浇注、固化、倒模、清洗再与石英玻璃基板键合等一系列工艺,最终可实现不同内径、不同流道形状的PDMS芯片,制作过程方便快捷,成品质量较好,设计自由度较高。最终通过调整系统各项参量制作出流道内径约为235μm的PDMS微流控芯片,并利用所制作的十字型流道PDMS微流控芯片生成了微液滴,用螺旋形流道的PDMS微流控芯片完成了亮蓝、柠檬黄两种颜色水溶液的微混合。     

利用PDMS纳米结构薄膜增强玻璃基板出光

以纳米压印技术为基础制备了具有纳米结构的聚二甲基硅氧烷(PDMS)薄膜.将纳米结构中间聚合物模板(IPS)薄膜覆盖在有PDMS溶液的玻璃基板上,真空加热后在玻璃基板上得到PDMS网格结构薄膜.这种方式得到的网格结构形状保持较好且厚度均匀无气泡,IPS薄膜不仅可以反复使用以减少Si母版的材料损耗,还可以缩短网格结构的制备...     

微流控芯片的键合技术

微流控芯片实验室的成品率普遍较低,其中密封技术是微流控芯片制造过程的关键步骤,也是难点之一。玻璃等硬质材料常通过热键合和阳极键合技术实现密封,而节能省时的低温玻璃键合技术更受科研人员的青睐。此外,胶黏剂键合和表面改性键合以其便捷性和实用性的优势成为玻璃和聚合物芯片键合领域重要的部分。常用的聚二甲基硅氧烷(PDMS)和聚甲基丙烯酸甲基(PMMA)高聚物材料则依据其不同的适用场合而采用不同的键合方式。介绍和分析了微流控芯片领域常用的玻璃、PDMS和PMMA材质键合方式,为微流控芯片制备方法提供了技术指向,对提高微流控芯片制作的成品率产生积极的影响。     

多用途全玻璃微流控芯片流通检测池（英文）

以玻璃为基材的微流控芯片具有光学透明、亲水性好和强度高的特点。介绍了一种具有可更换丝状电极的全玻璃微流控芯片流通检测池。该芯片通过玻璃光刻、湿法刻蚀和热封合制备。一对Pt丝电极通过平行的脊突精确定位在检测通道的两侧,之间相距190μm,流通检测池功能区的总体积仅约为300 nL。包括电化学(EC)、电化学发光(ECL)及化学发光(CL)的多模式检测均在此池体上进行了成功展示。利用微通道中的层流效应实现了电极之间的有效隔离。该芯片流通检测池具有耐用、透明、死体积小和与微型化在线流动检测相匹配的特点,可在高灵敏流动生物传感检测中得到应用。     

一种高效低成本制作三维聚焦微流沟道的方法

为了使用微流体细胞仪实现对细胞的精确计数,设计和制作了能够真正实现三维聚焦功能的微流沟道。首先用Ansys软件对微流沟道的结构进行了优化设计,利用斜曝光工艺制作了SU-8微流沟道模具;然后利用聚二甲基硅氧烷(PDMS)对SU-8模具进行倒模,得到其负模结构,对负模结构进行表面处理后,进行二次倒模,得到与原SU-8微流沟道结构一致的PDMS复制品;最后用荧光检测方法对封装好的PDMS微流沟道的封装和聚焦效果进行了测试。结果表明:该芯片结构可靠,可以满足进一步的流体聚焦检测要求,采用该方法生产的微流沟道具有生产周期短、成本低、效率高和结构可靠的特点。     

集成阵列叉指电极介电泳芯片粒子分离北大核心

制备了用于粒子分离的集成阵列叉指电极介电泳微流控芯片,该芯片由以玻璃为基底的氧化铟锡(ITO)电极以及聚二甲基硅氧烷(PDMS)微流通道构成。采用该芯片测定了聚苯乙烯微球在电导率为1μS/cm的悬浮溶液中在不同频率下的介电泳响应。聚苯乙烯微球产生正负介电泳响应的临界频率为20 kHz。当交流电压和频率分别为8Vp-p(峰峰值)和2 MHz时获得最优的粒子分离条件,在此条件下对聚苯乙烯微球和酵母菌细胞进行分离实验。实验结果表明,酵母菌细胞受到正介电泳力的作用,被富集到电极的边缘,而聚苯乙烯微球受到负介电泳力的作用被排斥而远离电极,其分离效率能够达到90%。     

基于液滴打印的纸质微流控芯片制备

介绍了一种基于液滴打印技术制作纸质微流控芯片的简单方法。蜡以液滴的形式喷射到滤纸上,加热蜡图案形成疏水屏障,用于生物试剂测定。制作的玻璃微喷嘴无需复杂的制造技术,成本低廉,简单且容易制作。喷射蜡滴稳定均匀。通过改变驱动电压、频率和加热温度及时间来实验研究蜡线的宽度,最终在纸质芯片上制备出宽度为2 600μm、长度为10 mm的蜡质疏水流道。用所制的纸质微流控芯片装置实现蛋白质、葡萄糖和pH值的多重测试。采用以液滴打印技术为基础的蜡滴生成系统制作纸质微流控芯片,成本低,简单,易于使用且制作快速。     

一种低成本高效率气动式微流控混合器

液体混合是微流控芯片的重要功能之一,微流控液体混合方式可分为主动式和被动式两种。针对目前微流控混合器存在的被动式混合效率不高和主动式混合器制作工艺复杂等问题,研究设计了一种基于雕刻机加工的低成本、高效率气动式微流控混合器。该微流控芯片采用数控雕刻机快速加工微模具,经PDMS固化、翻模、打孔和键合等工艺,实现了微流控混合器的制作。同时研究设计了多气室脉冲气体驱动模式,有效实现了微量试剂和样品的快速混合。实验结果表明,所研究的主动式微流控混合器可以产生对流混沌作用,显著提高微尺度下的混合效率,为实现低成本的微流控芯片制作和高效试剂混合的MEMS生化检测系统提供了一种有效的技术途径。     

基于微流控技术的数字PCR的发展及其应用

作为一种新兴的扩增检测技术,基于微流控的数字聚合酶链式反应(PCR)有着高通量、高灵敏度及高耐受性等优势,因而得到了研究者的广泛关注,其相关技术也在不断的发展中。综述了基于微流控的数字PCR的研究进展,重点讨论了基于微流控的数字PCR的液滴打印技术、多层微流控芯片技术、微珠技术、聚二甲基硅氧烷(PDMS)技术等的不同实现方式。介绍了基于微流控的数字PCR在定量检测、精准分子诊断、肿瘤个性化诊断以及食品安全检测中的应用。最后,对基于微流控的数字PCR技术目前存在的不足和问题进行了阐述,并对其未来的研究方向和发展趋势进行了展望。     

基于PDMS模具热模压制备微流控通道结构的方法

介绍了一种利用聚二甲基硅氧烷(PDMS)的快速成型来制备模具,再进行热模压制造微流控通道结构的方法。通过在硅片上旋涂SU-8胶进行光刻显影,得到结构模版,在此模版上浇注PDMS,脱模即得到PDMS模具。将PDMS模具进行热压,成功地在聚甲基丙烯酸甲酯(PMMA)基片上复制了特定的微流控通道结构。相对于常规的硅微加工和UV-LIGA工艺制造热模压模具,本方法具有加工周期短、工艺简单、成本低等优点。另外,还对温度、压力、时间等热模压的主要工艺参数进行了初步的优化研究。     

光敏微晶玻璃-PDMS微流控芯片制备及电渗性能研究

以光敏微晶玻璃和PDMs为材料,通过光化学加工和等离子体改性,制备了光敏微晶玻璃-PDMs微流控芯片,并对该芯片的电渗性能进行了初步的研究.结果表明,该芯片的制作工艺简单,且电渗性能稳定.芯片的电渗速度随缓冲液浓度的增大而增加,表面活性剂的加入可以改善电渗速度,电压在1.8 kV内与电渗速度具有线性关系.     

Fabrication of Stable Metallic Patterns Embedded in Poly(dimethylsiloxane) and Model Applications in Non‐Planar Electronic and Lab‐on‐a‐Chip Device Patterning

This article describes the fabrication of durable metallic patterns that are embedded in poly(dimethylsiloxane) (PDMS) and demonstrates their use in several representative applications. The method involves the transfer and subsequent embedding of micrometer‐scale gold (and other thin‐film material) patterns into PDMS via adhesion chemistries mediated by silane coupling agents. We demonstrate the process as a suitable method for patterning stable functional metallization structures on PDMS, ones with limiting feature sizes less than 5 μm, and their subsequent utilization as structures suitable for use in applications ranging from soft‐lithographic patterning, non‐planar electronics, and microfluidic (lab‐on‐a‐chip, LOC) analytical systems. We demonstrate specifically that metal patterns embedded in both planar and spherically curved PDMS substrates can be used as compliant contact photomasks for conventional photolithographic processes. The non‐planar photomask fabricated with this technique has the same surface shape as the substrate, and thus facilitates the registration of structures in multilevel devices. This quality was specifically tested in a model demonstration in which an array of one hundred metal oxide semiconductor field‐effect transistor (MOSFET) devices was fabricated on a spherically curved Si single‐crystalline lens. The most significant opportunities for the processes reported here, however, appear to reside in applications in analytical chemistry that exploit devices fabricated using the methods of soft lithography. Toward this end, we demonstrate durably bonded metal patterns on PDMS that are appropriate for use in microfluidic, microanalytical, and microelectromechanical systems. We describe a multilayer metal‐electrode fabrication scheme (multilaminate metal–insulator–metal (MIM) structures that substantially enhance performance and stability) and use it to enable the construction of PDMS LOC devices using electrochemical detection. A polymer‐based microelectrochemical analytical system, one incorporating an electrode array for cyclic voltammetry and a microfluidic system for the electrophoretic separation of dopamine and catechol with amperometric detection, is demonstrated.     

PDMS微流控光纤芯片的研制

用集成在芯片上的光纤作为激发光源,可使激发光斑的大小与微流控沟道的深度尺寸相接近,提高了检测灵敏度,省去了光学聚焦系统.利用二次曝光的方法制作了PDMS光纤芯片,实现了光纤与沟道的对准.对PDMS光纤芯片的加工工艺、封装方法和结构特征进行了探讨.用所制作的芯片对FITC（异硫氰酸荧光素）和以FITC标记的氨基酸进行了检测,结果证明了该芯片的可行性.     

Cover Picture: Fabrication of Stable Metallic Patterns Embedded in Poly(dimethylsiloxane) and Model Applications in Non‐Planar Electronic and Lab‐on‐a‐Chip Device Patterning (Adv. Funct. Mater. 4/2005)

A composite image is shown that highlights examples of device architectures that either incorporate or exploit polymer‐embedded metallic microstructures. In work reported by Nuzzo and co‐workers on p. 557, new applications of soft lithography, in conjunction with advanced forms of multilayer metallization, are used to construct these exceptionally durable structures. They are suitable for use in non‐planar lithographic patterning, and as device components finding applications ranging from microelectronics to Lab‐on‐a‐Chip analytical systems. This article describes the fabrication of durable metallic patterns that are embedded in poly(dimethylsiloxane) (PDMS) and demonstrates their use in several representative applications. The method involves the transfer and subsequent embedding of micrometer‐scale gold (and other thin‐film material) patterns into PDMS via adhesion chemistries mediated by silane coupling agents. We demonstrate the process as a suitable method for patterning stable functional metallization structures on PDMS, ones with limiting feature sizes less than 5 μm, and their subsequent utilization as structures suitable for use in applications ranging from soft‐lithographic patterning, non‐planar electronics, and microfluidic (lab‐on‐a‐chip, LOC) analytical systems. We demonstrate specifically that metal patterns embedded in both planar and spherically curved PDMS substrates can be used as compliant contact photomasks for conventional photolithographic processes. The non‐planar photomask fabricated with this technique has the same surface shape as the substrate, and thus facilitates the registration of structures in multilevel devices. This quality was specifically tested in a model demonstration in which an array of one hundred metal oxide semiconductor field‐effect transistor (MOSFET) devices was fabricated on a spherically curved Si single‐crystalline lens. The most significant opportunities for the processes reported here, however, appear to reside in applications in analytical chemistry that exploit devices fabricated using the methods of soft lithography. Toward this end, we demonstrate durably bonded metal patterns on PDMS that are appropriate for use in microfluidic, microanalytical, and microelectromechanical systems. We describe a multilayer metal‐electrode fabrication scheme (multilaminate metal–insulator–metal (MIM) structures that substantially enhance performance and stability) and use it to enable the construction of PDMS LOC devices using electrochemical detection. A polymer‐based microelectrochemical analytical system, one incorporating an electrode array for cyclic voltammetry and a microfluidic system for the electrophoretic separation of dopamine and catechol with amperometric detection, is demonstrated.     

Miniaturized continuous-flow polymerase chain reaction microfluidic chip system

A miniaturized continuous-flow polymerase chain reaction (PCR) microfluidic chip system was developed to perform DNA amplification. This system consists of a 20-cycle continuous-flow PCR microfluidic chip, an electrical heating system and a miniature air pressure-vacuum pump. The chip was ablated with excimer laser direct-writing micromachining technique on a polymethyl methacrylate (PMMA) sheet. The ablated microchannel was inverse trapezoidal with a depth of 70 μm, top width of 200 μm and bottom width of 120 μm. Its surface roughness Ra was 1.42 μm after being treated with excimer laser polishing. The substrate sheet ablated with the microchannel was bonded with other cover sheets using hot-press bonding method to form a closed structure. The electrical heating system consisted of three groups of heating membranes, Pt100 sensors, copper blocks and PID temperature digital controllers. It could provide three distinct maintained temperature zones and a uniform temperature distribution in each zone. PCR amplification of a 170 base pair (bp) DNA fragment was carried out to validate the system's feasibility. The PCR temperatures were set as 94℃ for denaturation, 55℃ for primer annealing and 72℃ for extension. The flow rate in the microchannel was 40 nL/s and the total time for the completion of a 20-cycle amplification of 20 μL reagent was 15 min.     

基于MEMS技术的PDMS电泳微芯片的研制

介绍了一种基于MEMS技术的PDM25电泳微芯片，该芯片主要由三部分组成：集成了高压电极的玻璃基底、PDMS薄膜以及刻有微流路的PDMS板。利用lift—off工艺，在玻璃基底上制作了为电泳分离提供高压的Pt电极。为了提高PDMS微芯片的密封效率，同时也为了保持微流路材料的一致性，通过挤压法首先在玻璃基底上形成了一层PDMS薄膜。电泳分离实验表明：在该微芯片上能够实现DNA片段的有效分离。     

基于液态金属的柔性频率可重构CPW天线设计

针对固态金属天线在受力弯曲后易产生裂纹导致功能失效的问题,本文提出一种频率可重构的柔性液态金属共面波导馈电天线.该天线由四个不同半径的开口谐振环（Split-Ring Resonators,SRR）构成,利用紫外光刻技术（ultraviolet lithography）制备天线的SU-8负模结构,其次浇注聚二甲基硅氧烷进行倒模并键合,最后将液态金属合金注入至微流沟道,完成天线的制作.通过机械施压方式改变不同谐振环间的通断状态,可在1GHz~6GHz范围内实现频率可重构,满足WLAN、WiMAX和部分C波段的通信要求.弹性体和液态金属的特性使天线具有更好的灵活性和耐久度,可应用于集成电子设备的弯曲表面.     

微流控分析芯片制作中的低温键合技术

微流控分析芯片制作方法的研究是微流控分析的基础。制作性能良好的微流控分析芯片时,基片与盖片的键合技术十分重要。本文针对近年来发展迅速的低温键合技术,对各种方法进行了评价,并对其发展前景进行了展望。     

Stable Stretchable Silver Electrode Directly Deposited on Wavy Elastomeric Substrate

We demonstrated a stable operation of stretchable silver (Ag) electrodes under fast cycling strain stress conditions. Relatively thick Ag electrodes (700 nm) were directly deposited on an elastomeric polydimethylsiloxane (PDMS) substrate with vertical wavy patterns that were formed by using an aluminum mold. The large surface roughness of PDMS substrate that was transferred from an intentionally roughened mold surface enhanced the adhesion between thick electrode and PDMS layer. Top PDMS layer was coated on the Ag electrode for encasement. During a slow stretching test (16.7 $muhbox{m/s}$), the resistance of the Ag electrode on the wavy substrate was increased only by three times for 50% tensile strain. The change in Ag electrode resistance was monitored during 10 000 times of fast (1 mm/s) cycling of 10% tensile strain. The maximum resistance was increased by less than five times during the stress test and returned to its initial value after the stress was removed.