这项工作得到了深圳基础研究经费的支持 (批准号:JCYJ 20150630170146829, JCYJ20160531195439665 和 JCYJ20160317152359560)。作者要感谢中国科学院深圳先进技术研究院的教授, 为支持。

1. 模具制造
<ol><li>使用绘图软件设计两个光掩膜。描述微通道结构的轮廓, 并在同一绘图文件中使用两个单独的掩码1和2层, 以确保不同通道之间的所有连接。打印不同的层独立于玻璃上的铬板由供应商与1µm 分辨率。确保光掩膜是黑暗的, 透明设计的结构, 作为一个负极性。 注:掩模1包含分散的相进通道和孔。掩码2包含连续相进通道、过滤器和插座。</li>
	<li>在指定的光刻实验室, 清洁一个3英寸直径的硅片。将晶片放在旋转涂布机上, 打开真空, 将晶片贴在旋转卡盘上。自旋涂层2-3 毫升的 SU-8 2025 负光刻胶到硅片上十年代在 1000 rpm, 然后三十年代在 3000 rpm, 提供第一层厚度的20µm。</li>
	<li>软烘烤95°c 热板6分钟。涂层后的晶片冷却到室温 (RT), 暴露它通过面具1下的准直15兆瓦/cm2, 365 nm 紫外线十八年代. 曝光后, 烘烤95摄氏度热板6分钟, 然后让晶片冷却到 RT。</li>
	<li>重复自旋涂层过程。将2-3 毫升的 SU-8 2100 负光刻胶在硅片上, 十年代在 1000 rpm, 然后三十年代在 2000 rpm, 提供第二层厚度130µm。在软的烘烤在95°c 热板为35分钟之后, 安置面具2在第二层光刻胶揭露三十年代, 与分散的相位渠道层数是一致的由紫外光刻。曝光后, 烘烤95摄氏度热板7分钟。</li>
	<li>通过浸泡在50毫升丙二醇甲醚醋酸盐的搅拌浴中, 开发该晶片, 直到晶圆上的特征变得清晰, 然后用乙醇清洗。最后, 将晶片放在恒温平台上, 进行2小时的硬烘烤。</li>
</ol>2. Semi-3D 流聚焦微流控芯片制造
<ol><li>将该单体及其固化剂与顶部和底层的重量比略有不同, 通常为顶层 10:1, 8:1 为底层, 使用自动软膏搅拌器4分钟。 注:顶部和底部的基板是以略微不同的比例 (分别为10:1 和 8:1), 以固化剂为基础, 增强了粘结强度。当选择底部层的5:1 比时, 较硬的底板, 使对准困难, 并降低粘结强度由于缺乏灵活性。此外, 在适应显微镜工作距离的情况下, 底板的厚度约为1毫米。当选择15:1 比时, 芯片容易在高压下变形。</li>
	<li>将混合物倒入90毫米培养皿中完成的硅模具中, 并提供 2 ~ 3 毫米的厚度. 把它放在真空室里, 加德德, 直到所有气泡消失。在烤箱中治疗1小时80摄氏度。</li>
	<li>让它冷却到 RT. 使用手术刀切割设备至少3毫米以外的特点, 并慢慢剥离从硅片上的基片。使用0.75 毫米直径冲床, 在上一层中的分散相入口、连续相入口和出口处打孔。</li>
	<li>用胶带清洗该硅烷, 去除灰尘微粒。在 300 W 等离子清洗机中, 等离子同时对顶部和底部的两层都进行2分钟的处理。将顶层放在底层表面, 相对滑动曲面, 直到特征通过立体声显微镜对齐查看。</li>
	<li>在120摄氏度的烤箱中固化一天, 以提高强度和完整的粘合。</li>
</ol>3. 试剂制备
<ol><li>通过溶解18体积% 硅基非离子表面活性剂, 制备连续相的溶液: 烷。</li>
	<li>准备分散阶段的解决方案: 亲水性聚乙二醇二丙烯酸酯 (PEGDA, 兆瓦 255,) 含有 2-羟基 4 '-(2-hydroxyethoxy)-2-methylpropiophenone (98%, 兆瓦 224) 在浓度为5毫克/毫升作为照片引发剂, 和罗丹明 B (95%, 兆瓦 479.01), 浓度为1毫摩尔/升为荧光染料。</li>
	<li>用连续相填充气动压力控制器的1毫升储层。填充200µL 凝胶加载尖端与分散的阶段。</li>
</ol>4. 系统准备
<ol><li>将 semi-3D 微流控装置放在倒置光学显微镜的舞台上, 用高速相机观看。</li>
	<li>将氟化乙烯 (FEP) 管连接到连续相的冲孔孔上, 附加一个短的不锈钢管, 然后将凝胶加载尖端的末端插入到分散相的冲孔孔中。将20厘米长的 FEP 管插入设备的插座中, 并将末端放置在15毫升离心管中。 注:系统的配置如图 1所示。</li>
</ol>5. 液滴形成
<ol><li>将设备放在倒置显微镜工作台上, 确保不同通道的接合处大致位于显微镜光源的位置。将倒置显微镜聚焦于包含两相相交、孔区和下游通道的区域。</li>
	<li>设定两个阶段的压力, 使用气压控制器将流体缓慢地输送到相交的区域, 15 毫巴为离散相和30毫巴连续相。等待3分钟的稳定和平衡, 直到稳定的流体流动没有气泡和硅烷残渣。</li>
	<li>在控制软件的用户界面上输入参数。将分散相的压力设置为系统的基级压力, 例如, 将其保持在45毫巴。增加连续相的压力, 直到乳液破裂模式从射流转变为尖端流模式, 然后等待5分钟的稳定。</li>
	<li>将 FEP 管端连接出水孔和离心管以收集水滴。</li>
</ol>6. PEGDA 粒子的收集和表征
<ol><li>固定在夹具中的离心管斜。当液相流向管时, 通过紫外暴露快速凝固获得 PEGDA 颗粒。</li>
	<li>完成采集过程后, 分别通过20X 或60X 对象的荧光显微镜对 PEGDA 粒子进行取样和观察。 注意.通过定制的软件程序, 对摄像机捕获的数字荧光图像进行了分析。该图像是基于 R L 算法17的第一卷积, 消除聚焦光的模糊效应, 并基于精明边缘检测方法提取图像中的球面对象;最后, 用霍夫变换18计算出各球面对象的直径。因此, 可以估计每个图像中球面物体直径的平均值和标准偏差。</li>
</ol>

<ol>
	<li>Teh, S. Y., Lin, R., Hung, L. H., Lee, A. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Droplet+microfluidics.">Droplet microfluidics.</a> Lab on a chip. 8, 198-220 (2008).</li><li>Xiao, Q., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+multifunctional+NaYF4:Er3+,Yb3+/PEGDA+hybrid+microspheres:+NIR-light-activated+photopolymerization+and+drug+delivery.">Novel multifunctional NaYF4:Er3+,Yb3+/PEGDA hybrid microspheres: NIR-light-activated photopolymerization and drug delivery.</a> Chemical communications. 49, 1527-1529 (2013).</li><li>Pan, M., Kim, M., Blauch, L., Tang, S. K. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface-functionalizable+amphiphilic+nanoparticles+for+pickering+emulsions+with+designer+fluid-fluid+interfaces.">Surface-functionalizable amphiphilic nanoparticles for pickering emulsions with designer fluid-fluid interfaces.</a> RSC Adv. 6, 39926-39932 (2016).</li><li>Zhang, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfluidic+synthesis+of+rigid+nanovesicles+for+hydrophilic+reagents+delivery.">Microfluidic synthesis of rigid nanovesicles for hydrophilic reagents delivery.</a> Angewandte Chemie. 54, 3952-3956 (2015).</li><li>Shembekar, N., Chaipan, C., Utharala, R., Merten, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Droplet-based+microfluidics+in+drug+discovery,+transcriptomics+and+high-throughput+molecular+genetics.">Droplet-based microfluidics in drug discovery, transcriptomics and high-throughput molecular genetics.</a> Lab on a chip. 16, 1314-1331 (2016).</li><li>Soh, G. Y., Yeoh, G. H., Timchenko, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Numerical+investigation+on+the+velocity+fields+during+droplet+formation+in+a+microfluidic+T-junction.">Numerical investigation on the velocity fields during droplet formation in a microfluidic T-junction.</a> Chemical Engineering Science. 139, 99-108 (2016).</li><li>Chiarello, E., Derzsi, L., Pierno, M., Mistura, G., Piccin, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Generation+of+Oil+Droplets+in+a+Non-Newtonian+Liquid+Using+a+Microfluidic+T-Junction.">Generation of Oil Droplets in a Non-Newtonian Liquid Using a Microfluidic T-Junction.</a> Micromachines. 6, 1825-1835 (2015).</li><li>Moyle, T. M., Walker, L. M., Anna, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlling+thread+formation+during+tipstreaming+through+an+active+feedback+control+loop.">Controlling thread formation during tipstreaming through an active feedback control loop.</a> Lab on a chip. 13, 4534-4541 (2013).</li><li>Moon, B. U., Abbasi, N., Jones, S. G., Hwang, D. K., Tsai, S. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Water-in-Water+Droplets+by+Passive+Microfluidic+Flow+Focusing.">Water-in-Water Droplets by Passive Microfluidic Flow Focusing.</a> Analytical chemistry. 88, 3982-3989 (2016).</li><li>Zhu, P., Tang, X., Wang, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Droplet+generation+in+co-flow+microfluidic+channels+with+vibration.">Droplet generation in co-flow microfluidic channels with vibration.</a> Microfluidics and Nanofluidics. , 20 (2016).</li><li>Kim, S. H., Kim, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlled+formation+of+double-emulsion+drops+in+sudden+expansion+channels.">Controlled formation of double-emulsion drops in sudden expansion channels.</a> Journal of colloid and interface science. 415, 26-31 (2014).</li><li>Jeong, W. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlled+generation+of+submicron+emulsion+droplets+via+highly+stable+tip-streaming+mode+in+microfluidic+devices.">Controlled generation of submicron emulsion droplets via highly stable tip-streaming mode in microfluidic devices.</a> Lab on a chip. 12, 1446-1453 (2012).</li><li>Peng, L., Yang, M., Guo, S. S., Liu, W., Zhao, X. Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+interfacial+tension+on+droplet+formation+in+flow-focusing+microfluidic+device.">The effect of interfacial tension on droplet formation in flow-focusing microfluidic device.</a> Biomedical microdevices. 13, 559-564 (2011).</li><li>Nunes, J. K., Tsai, S. S., Wan, J., Stone, H. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dripping+and+jetting+in+microfluidic+multiphase+flows+applied+to+particle+and+fiber+synthesis.">Dripping and jetting in microfluidic multiphase flows applied to particle and fiber synthesis.</a> J Phys D Appl Phys. , 46 (2013).</li><li>Anna, S. L., Mayer, H. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microscale+tipstreaming+in+a+microfluidic+flow+focusing+device.">Microscale tipstreaming in a microfluidic flow focusing device.</a> Physics of Fluids. 18, 121512 (2006).</li><li>Liu, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfluidic+synthesis+of+QD-encoded+PEGDA+microspheres+for+suspension+assay.">Microfluidic synthesis of QD-encoded PEGDA microspheres for suspension assay.</a> J. Mater. Chem. B. 4, 482-488 (2016).</li><li>Richardson, W. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bayesian-based+iterative+method+of+image+restoration.">Bayesian-based iterative method of image restoration.</a> Journal of the Optical Society of America. 62, 55-59 (1972).</li><li>Mukhopadhyay, P., Chaudhuri, B. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+survey+of+Hough+Transform.">A survey of Hough Transform.</a> Pattern Recognition. 48, 993-1010 (2015).</li><li>Ward, T., Faivre, M., Stone, H. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Drop+production+and+tip-streaming+phenomenon+in+a+microfluidic+flow-focusing+device+via+an+interfacial+chemical+reaction.">Drop production and tip-streaming phenomenon in a microfluidic flow-focusing device via an interfacial chemical reaction.</a> Langmuir: the ACS journal of surfaces and colloids. 26, 9233-9239 (2010).</li><li>Anna, S. L., Bontoux, N., Stone, H. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Formation+of+dispersions+using+"flow+focusing"+in+microchannels.">Formation of dispersions using "flow focusing" in microchannels.</a> Applied Physics Letters. 82, 364 (2003).</li><li>Kim, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlled+production+of+emulsion+drops+using+an+electric+field+in+a+flow-focusing+microfluidic+device.">Controlled production of emulsion drops using an electric field in a flow-focusing microfluidic device.</a> Applied Physics Letters. 91, 133106 (2007).</li><li>Dangla, R., Gallaire, F., Baroud, C. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microchannel+deformations+due+to+solvent-induced+PDMS+swelling.">Microchannel deformations due to solvent-induced PDMS swelling.</a> Lab on a chip. 10, 2972-2978 (2010).</li><li>Chiu, Y. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Universally+applicable+three-dimensional+hydrodynamic+microfluidic+flow+focusing.">Universally applicable three-dimensional hydrodynamic microfluidic flow focusing.</a> Lab on a chip. 13, 1803-1809 (2013).</li><li>Oh, K. W., Lee, K., Ahn, B., Furlani, E. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Design+of+pressure-driven+microfluidic+networks+using+electric+circuit+analogy.">Design of pressure-driven microfluidic networks using electric circuit analogy.</a> Lab on a chip. 12, 515-545 (2012).</li></ol>

作者没有什么可透露的。

使用2D 和 semi-3D 微流控装置的流聚焦模式产生的水滴, 以前已经在各种报告8,9,15,19,20, 21。在这些系统中, 不凝固的水溶液被选择为分散的相, 如去离子水8,15,20,<sup class="xre...

液滴基微流控系统具有从纳米到微米直径范围1的高单分散液滴的能力, 在高通量药物发现2中具有很大的潜力, 生物大分子的合成3 、4和诊断测试5。由于小水滴的独特优势, 如表面积大、体积比大、应用少, 微升的样品多, 这项技术在广泛的领域引起了广泛的关注。两种不相容液体的乳化是产生水滴的最典型方法之一。在以前的报告中, 研究人员开发了各种不同的水滴形成几何学, 包括 T 连接, 流动聚焦和共同流动的几何图形。在 T 形连接几何中, 分散相通过垂直通道传递到主通道中, 连续相流6,7。在典型的二维 (2D) 流聚焦8、9几何中, 分散相流从侧面剪切;而对于共流几何10,11, 另一方面, 一毛细管引入分散相流被放置在一个较大的毛细管内的共同流动的几何, 使分散的相流被剪切从所有方向。
液滴尺寸通过调整通道尺寸和流速比来控制, 而由共流或 T 结产生的最小尺寸仅限于数微米。对于流动聚焦液滴形成系统, 通过调整两相和表面活性剂浓度的压力比, 包括滴水状态、喷射机制和尖端流15, 形成三种液滴破裂形式。提示流模式也称为螺纹形成, 并观察从分散相流锥尖端绘制出的细线的外观。先前的研究表明, 在2D 或 semi-3D 流聚焦装置8,12中, 可以产生小于几微米的水滴。然而, 作为一个含有极低浓度 PEGDA 的水溶液作为分散相, PEGDA 颗粒的收缩率大约是光聚合后直径的原水滴的 60%, 而 PEGDA 不稀释作为分散相位导致不稳定的尖端流模式12。界面张力是乳化过程的重要参数, 由于表面活性剂加入到连续相液中会降低, 从而降低液滴尺寸、高频率13、高弯曲尖端, 并防止不稳定14。此外, 当大块表面活性剂浓度比临界胶束浓度高得多时, 在饱和态13中界面张力近似不变, 尖端流态可发生15。
在此基础上, 本文利用多层软光刻技术制备了一种 semi-3D 流聚焦微流控器 PEGDA 液滴生成方法。与典型的2D 流聚焦装置不同, semi-3D 流聚焦装置具有浅分散相通道和深部连续相通道, 使分散相可以在侧边上下剪切。这为流聚焦模式提供了更大的调整范围, 减少了液滴破碎所需的能量和压力。与上一次报告12不同, 分散相是纯 PEGDAcontaining 的光引发剂, 确保 PEGDA 颗粒的收缩率低于 10%16;连续相是烷溶于硅基非离子表面活性剂的高体积浓度的混合物。通过调整两个相的压力比, 产生尺寸可控和均匀的水滴。水滴的直径从80µm 到1µm, 因为液滴分解过程从射流模式到尖端流模式的变化。此外, 在紫外曝光的光聚合过程中合成了 PEGDA 颗粒。易于制造的液滴生成微流控系统将为生物应用提供更多的可能性。

<table><tbody><tr><td>Silicon wafer</td><td>Huashi Co., Ltd</td><td></td><td></td></tr><tr><td>SU-8 2025, 2100</td><td>Microchem Co.</td><td>Y111069</td><td></td></tr><tr><td>SU-8 developer</td><td>Microchem Co.</td><td>Y020100</td><td></td></tr><tr><td>Chromium mask</td><td>Qingyi Precision Mask Making Co., Ltd</td><td></td><td></td></tr><tr><td>polydimethylsiloxane(PDMS)</td><td>Dow Corning</td><td>Sylgard 184</td><td></td></tr><tr><td>poly(ethylene glycol) diacrylate (PEGDA)</td><td>Sigma</td><td>26570-48-9</td><td></td></tr><tr><td>2-hydroxy-40-(2-hydroxyethoxy)-2-methylpropiophenone</td><td>TCI</td><td>H1361-5G</td><td>photoinitiator</td></tr><tr><td>Hexadecane</td><td>Sigma</td><td>544-76- 3</td><td></td></tr><tr><td>ABIL EM 90</td><td>CHT</td><td>144243-53-8</td><td>surfactants</td></tr><tr><td>Rhodamine B</td><td>Aladdin</td><td>81-88-9</td><td>fluorescent dye</td></tr><tr><td>Spin Coater</td><td></td><td></td><td></td></tr><tr><td>Lithography machine</td><td></td><td></td><td></td></tr><tr><td>Automatic ointment agitator</td><td>Thinky</td><td>ARV-310</td><td></td></tr><tr><td>Oven</td><td>BluePard</td><td></td><td></td></tr><tr><td>Optical microscope</td><td>OLYMPUS</td><td>IX71</td><td></td></tr><tr><td>High-speed camera</td><td>Hamamatsu, Japan</td><td>ORCA-flash</td><td></td></tr><tr><td>MAESFLO Microfluidic Fluid Control System</td><td>FLUIGENT</td><td>MFCS-EZ</td><td></td></tr><tr><td>UV lamp</td><td>FUTANSI</td><td></td><td>365 nm UV light, 8000 MW/CM&lt;sup&gt;2&lt;/sup&gt;</td></tr></tbody></table>

generation of size-controlled poly (ethylene glycol) diacrylate droplets via semi-3-dimensional flow focusing microfluidic devices

通过微流控装置中的流动聚焦过程, 可以产生均匀和大小可控的聚乙二醇二丙烯酸酯 (PEGDA) 液滴。本文提出了一种用于雾滴形成的三维 (semi-3D) 流聚焦微流控芯片。采用多层软光刻法制作了烷芯片。烷含有表面活性剂作为连续相, PEGDA 与紫外光引发剂是分散相。表面活性剂允许局部表面张力下降, 形成了一个更 cusped 的尖端, 促进破碎成微小的微滴。当分散相的压力恒定时, 液滴的大小随着连续相压力的增大而逐渐减小, 从而使分散相流中断。因此, 通过改变两个进气道的压力比, 可选择性地实现直径从1µm 到80µm 的水滴, 平均变化系数估计在7% 以下。此外, 在光聚合中, 液滴可以通过紫外线照射变成微珠。这种微珠表面的共轭生物分子在生物学和化学领域有许多潜在的应用。

semi-3D 流聚焦微流控芯片采用多层软光刻技术制作而成。protocolare 中主模的制作过程和结果如图 2所示。第一层提供65µm 宽通道, 用于引入分散相和50µm 宽孔 (图 2a), 厚度为20µm。另外130µm 厚度层用于提供连续相通道和出口通道 (图 2b)。图 2c显示?...

Watch this Scientific Journal Video about Generation of Size-controlled Poly ethylene Glycol Diacrylate Droplets via Semi-3-Dimensional Flow Focusing Microfluidic Devices at JoVE.com

Generation of Size-controlled Poly ethylene Glycol Diacrylate Droplets via Semi-3-Dimensional Flow Focusing Microfluidic Devices

在这里, 我们提出了一个协议来说明一个半三维 (semi-3D) 流聚焦微流控芯片的形成过程和验证实验。

Semi-3-Dimensional 流聚焦微流控装置产生尺寸控制的聚乙二醇二丙烯酸酯液滴

Uniform and size-controllable poly (ethylene glycol) diacrylate (PEGDA) droplets could be produced via the flow focusing process in a microfluidic device. ...

generation-size-controlled-poly-ethylene-glycol-diacrylate-droplets

Universidad de Cartagena UDEC

Research

JoVE Journal

Engineering

Generation of Size-controlled Poly (ethylene Glycol) Diacrylate Droplets via Semi-3-Dimensional Flow Focusing Microfluidic Devices

7.7K 次观看.  Tsinghua University. 在这里, 我们提出了一个协议来说明一个半三维 (semi-3D) 流聚焦微流控芯片的形成过程和验证实验。

视频: Generation of Size-controlled Poly ethylene Glycol Diacrylate Droplets via Semi-3-Dimensional Flow Focusing Microfluidic Devices

Fluorescence detection methods for microfluidic droplet platforms

The development of microfluidic platforms for performing chemistry and biology has in large part been driven by a range of potential benefits that accompany system miniaturisation. Advantages include the ability to efficiently process nano- to femoto- liter volumes of sample, facile integration of functional components, an intrinsic predisposition towards large-scale multiplexing, enhanced analytical throughput, improved control and reduced instrumental footprints.1
In recent years much interest has focussed on the development of droplet-based (or segmented flow) microfluidic systems and their potential as platforms in high-throughput experimentation.2-4 Here water-in-oil emulsions are made to spontaneously form in microfluidic channels as a result of capillary instabilities between the two immiscible phases. Importantly, microdroplets of precisely defined volumes and compositions can be generated at frequencies of several kHz. Furthermore, by encapsulating reagents of interest within isolated compartments separated by a continuous immiscible phase, both sample cross-talk and dispersion (diffusion- and Taylor-based) can be eliminated, which leads to minimal cross-contamination and the ability to time analytical processes with great accuracy. Additionally, since there is no contact between the contents of the droplets and the channel walls (which are wetted by the continuous phase) absorption and loss of reagents on the channel walls is prevented.
Once droplets of this kind have been generated and processed, it is necessary to extract the required analytical information. In this respect the detection method of choice should be rapid, provide high-sensitivity and low limits of detection, be applicable to a range of molecular species, be non-destructive and be able to be integrated with microfluidic devices in a facile manner. To address this need we have developed a suite of experimental tools and protocols that enable the extraction of large amounts of photophysical information from small-volume environments, and are applicable to the analysis of a wide range of physical, chemical and biological parameters. Herein two examples of these methods are presented and applied to the detection of single cells and the mapping of mixing processes inside picoliter-volume droplets. We report the entire experimental process including microfluidic chip fabrication, the optical setup and the process of droplet generation and detection.

Droplet-based microfluidic platforms are promising candidates for high throughput experimentation since they are able to generate picoliter, self-compartmentalized vessels inexpensively at kHz rates. Through integration with fast, sensitive and high resolution fluorescence spectroscopic methods, the large amounts of information generated within these systems can be efficiently extracted, harnessed and utilized.

荧光检测方法，为微流体液滴平台

The development of microfluidic platforms for performing chemistry and biology has in large part been driven by a range of potential benefits that ...

科研

生物工程

Capillary-based Centrifugal Microfluidic Device for Size-controllable Formation of Monodisperse Microdroplets

Here, we demonstrate a simple method for the rapid production of size-controllable, monodisperse, W/O microdroplets using a capillary-based centrifugal microfluidic device. W/O microdroplets have recently been used in powerful methods that enable miniaturized chemical experiments. Therefore, developing a versatile method to yield monodisperse W/O microdroplets is needed. We have developed a method for generating monodisperse W/O microdroplets based on a capillary-based centrifugal axisymmetric co-flowing microfluidic device. We succeeded in controlling the size of microdroplets by adjusting the capillary orifice. Our method requires equipment that is easier-to-use than with other microfluidic techniques, requires only a small volume (0.1-1 &#181;l) of sample solution for encapsulation, and enables the production of hundreds of thousands number of W/O microdroplets per second. We expect this method will assist biological studies that require precious biological samples by conserving the volume of the samples for rapid quantitative analysis biochemical and biological studies.

Here, we demonstrate a simple production method for size-controllable, monodisperse, water-in-oil (W/O) microdroplets using a capillary-based centrifugal microfluidic device. This method requires only a small sample volume and enables high-yield production. We expect this method will be useful for rapid biochemical and cellular analyses.

基于毛细管的离心微流体装置单分散微滴的大小可控的形成

Here, we demonstrate a simple method for the rapid production of size-controllable, monodisperse, W/O microdroplets using a capillary-based centrifugal ...

工程学

Double Emulsion Generation Using a Polydimethylsiloxane (PDMS) Co-axial Flow Focus Device

Double emulsions are useful in a number of biological and industrial applications in which it is important to have an aqueous carrier fluid. This paper presents a polydimethylsiloxane (PDMS) microfluidic device capable of generating water/oil/water double emulsions using a coaxial flow focusing geometry that can be fabricated entirely using soft lithography. Similar to emulsion devices using glass capillaries, double emulsions can be formed in channels with uniform wettability and with dimensions much smaller than the channel sizes. Three dimensional flow focusing geometry is achieved by casting a pair of PDMS slabs using two layer soft lithography, then mating the slabs together in a clamshell configuration. Complementary locking features molded into the PDMS slabs enable the accurate registration of features on each of the slab surfaces. Device testing demonstrates formation of double emulsions from 14 &#181;m to 50 &#181;m in diameter while using large channels that are robust against fouling and clogging.

Double Emulsion Generation Using a Polydimethylsiloxane PDMS Co-axial Flow Focus Device

Microfluidic double emulsions generation typically involves devices with patterned wettability or custom-fabricated glass components. Here we describe the fabrication and testing of an all polydimethylsiloxane (PDMS) double emulsion generator that does not require surface treatment or complicated fabrication processes, and is capable of producing double emulsions down to 14 &#181;m.

复乳代使用聚二甲基硅氧烷（PDMS）同轴流量聚焦设备

Double emulsions are useful in a number of biological and industrial applications in which it is important to have an aqueous carrier fluid. This paper ...

A Femtoliter Droplet Array for Massively Parallel Protein Synthesis from Single DNA Molecules

Advances in spatial resolution and detection sensitivity of scientific instrumentation make it possible to apply small reactors for biological and chemical research. To meet the demand for high-performance microreactors, we developed a femtoliter droplet array (FemDA) device and exemplified its application in massively parallel cell-free protein synthesis (CFPS) reactions. Over one million uniform droplets were readily generated within a finger-sized area using a two-step oil-sealing protocol. Every droplet was anchored in a femtoliter microchamber composed of a hydrophilic bottom and a hydrophobic sidewall. The hybrid hydrophilic-in-hydrophobic structure and the dedicated sealing oils and surfactants are crucial for stably retaining the femtoliter aqueous solution in the femtoliter space without evaporation loss. The femtoliter configuration and the simple structure of the FemDA device allowed minimal reagent consumption. The uniform dimension of the droplet reactors made large-scale quantitative and time-course measurements convincing and reliable. The FemDA technology correlated the protein yield of the CFPS reaction with the number of DNA molecules in each droplet. We streamlined the procedures about the microfabrication of the device, the formation of the femtoliter droplets, and the acquisition and analysis of the microscopic image data. The detailed protocol with the optimized low running cost makes the FemDA technology accessible to everyone who has standard cleanroom facilities and a conventional fluorescence microscope in their own place.

The overall goal of the protocol is to prepare over one million ordered, uniform, stable, and biocompatible femtoliter droplets on a 1 cm2 planar substrate that can be used for cell-free protein synthesis.

用于从单一DNA分子大规模平行蛋白质合成的Femtoliter滴体阵列

Advances in spatial resolution and detection sensitivity of scientific instrumentation make it possible to apply small reactors for biological and ...

化学

Fabricating Degradable Thermoresponsive Hydrogels on Multiple Length Scales via Reactive Extrusion, Microfluidics, Self-assembly, and Electrospinning

While various smart materials have been explored for a variety of biomedical applications (e.g., drug delivery, tissue engineering, bioimaging, etc.), their ultimate clinical use has been hampered by the lack of biologically-relevant degradation observed for most smart materials. This is particularly true for temperature-responsive hydrogels, which are almost uniformly based on polymers that are functionally non-degradable (e.g., poly(N-isopropylacrylamide) (PNIPAM) or poly(oligoethylene glycol methacrylate) (POEGMA)). As such, to effectively translate the potential of thermoresponsive hydrogels to the challenges of remote-controlled or metabolism-regulated drug delivery, cell scaffolds with tunable cell-material interactions, theranostic materials with the potential for both imaging and drug delivery, and other such applications, a method is required to render the hydrogels (if not fully degradable) at least capable of renal clearance following the required lifetime of the material. To that end, this protocol describes the preparation of hydrolytically-degradable hydrazone-crosslinked hydrogels on multiple length scales based on the reaction between hydrazide and aldehyde-functionalized PNIPAM or POEGMA oligomers with molecular weights below the renal filtration limit. Specifically, methods to fabricate degradable thermoresponsive bulk hydrogels (using a double barrel syringe technique), hydrogel particles (on both the microscale through the use of a microfluidics platform facilitating simultaneous mixing and emulsification of the precursor polymers and the nanoscale through the use of a thermally-driven self-assembly and cross-linking method), and hydrogel nanofibers (using a reactive electrospinning strategy) are described. In each case, hydrogels with temperature-responsive properties similar to those achieved via conventional free radical cross-linking processes can be achieved, but the hydrazone cross-linked network can be degraded over time to re-form the oligomeric precursor polymers and enable clearance. As such, we anticipate these methods (which may be generically applied to any synthetic water-soluble polymer, not just smart materials) will enable easier translation of synthetic smart materials to clinical applications.

Protocols are described for the fabrication of degradable thermoresponsive hydrogels based on hydrazone cross-linking of polymeric oligomers on the bulk scale, microscale, and nanoscale, the latter for preparation of both gel nanoparticles and nanofibers.

通过反应挤出、微流体、自组装和电纺丝制备多长尺度可降解 Thermoresponsive 水凝胶

While various smart materials have been explored for a variety of biomedical applications (e.g., drug delivery, tissue engineering, bioimaging, etc.), ...

Image-guided, Laser-based Fabrication of Vascular-derived Microfluidic Networks

This detailed protocol outlines the implementation of image-guided, laser-based hydrogel degradation for the fabrication of vascular-derived microfluidic networks embedded in PEGDA hydrogels. Here, we describe the creation of virtual masks that allow for image-guided laser control; the photopolymerization of a micromolded PEGDA hydrogel, suitable for microfluidic network fabrication and pressure head-driven flow; the setup and use of a commercially available laser scanning confocal microscope paired with a femtosecond pulsed Ti:S laser to induce hydrogel degradation; and the imaging of fabricated microfluidic networks using fluorescent species and confocal microscopy. Much of the protocol is focused on the proper setup and implementation of the microscope software and microscope macro, as these are crucial steps in using a commercial microscope for microfluidic fabrication purposes that contain a number of intricacies. The image-guided component of this technique allows for the implementation of 3D image stacks or user-generated 3D models, thereby allowing for creative microfluidic design and for the fabrication of complex microfluidic systems of virtually any configuration. With an expected impact in tissue engineering, the methods outlined in this protocol could aid in the fabrication of advanced biomimetic microtissue constructs for organ- and human-on-a-chip devices. By mimicking the complex architecture, tortuosity, size, and density of in vivo vasculature, essential biological transport processes can be replicated in these constructs, leading to more accurate in vitro modeling of drug pharmacokinetics and disease.

This protocol outlines the implementation of image-guided, laser-based hydrogel degradation to fabricate vascular-derived, biomimetic microfluidic networks embedded in poly(ethylene glycol) diacrylate (PEGDA) hydrogels. These biomimetic microfluidic systems may be useful for tissue engineering applications, generation of in vitro disease models, and fabrication of advanced "on-a-chip" devices.

影像引导下，血管源性微流控网络的基于激光的研制

This detailed protocol outlines the implementation of image-guided, laser-based hydrogel degradation for the fabrication of vascular-derived microfluidic ...

Glass-Based Devices to Generate Drops and Emulsions

In this manuscript, three different step-by-step protocols to generate highly monodisperse emulsion drops using glass-based microfluidics are described. The first device is built for the generation of simple drops driven by gravity. The second device is designed to generate emulsion drops in a coflowing scheme. The third device is an extension of the coflowing device with the addition of a third liquid that acts as an electric ground, allowing the formation of electrified drops that subsequently discharge. In this setup, two of the three liquids have an appreciable electrical conductivity. The third liquid mediates between these two and is a dielectric. A&#160;voltage difference applied between the two conducting liquids creates an electric field that couples with hydrodynamic stresses of the coflowing liquids, affecting the jet and drop formation process. The addition of the electric field provides a path to generate smaller drops than in simple coflow devices and for generating particles and fibers with a wide range of sizes.

Here, a protocol to manufacture glass-based microfluidic devices used for generating highly monodisperse emulsions with controlled drop size is presented.

基于玻璃的设备，用于产生液滴和乳液

In this manuscript, three different step-by-step protocols to generate highly monodisperse emulsion drops using glass-based microfluidics are described. ...

Multi-step Variable Height Photolithography for Valved Multilayer Microfluidic Devices

Microfluidic systems have enabled powerful new approaches to high-throughput biochemical and biological analysis. However, there remains a barrier to entry for non-specialists who would benefit greatly from the ability to develop their own microfluidic devices to address research questions. Particularly lacking has been the open dissemination of protocols related to photolithography, a key step in the development of a replica mold for the manufacture of polydimethylsiloxane (PDMS) devices. While the fabrication of single height silicon masters has been explored extensively in literature, fabrication steps for more complicated photolithography features necessary for many interesting device functionalities (such as feature rounding to make valve structures, multi-height single-mold patterning, or high aspect ratio definition) are often not explicitly outlined. 
Here, we provide a complete protocol for making multilayer microfluidic devices with valves and complex multi-height geometries, tunable for any application. These fabrication procedures are presented in the context of a microfluidic hydrogel bead synthesizer and demonstrate the production of droplets containing polyethylene glycol (PEG diacrylate) and a photoinitiator that can be polymerized into solid beads. This protocol and accompanying discussion provide a foundation of design principles and fabrication methods that enables development of a wide variety of microfluidic devices. The details included here should allow non-specialists to design and fabricate novel devices, thereby bringing a host of recently developed technologies to their most exciting applications in biological laboratories.

Multilayer microfluidic devices often involve the fabrication of master molds with complex geometries for functionality. This article presents a complete protocol for multi-step photolithography with valves and variable height features tunable to any application. As a demonstration, we fabricate a microfluidic droplet generator capable of producing hydrogel beads.

多级可变高度的光刻多层带瓣微流体装置

Microfluidic systems have enabled powerful new approaches to high-throughput biochemical and biological analysis. However, there remains a barrier to ...

Generation of Dynamical Environmental Conditions using a High-Throughput Microfluidic Device

Mimicking in vivo environmental conditions is crucial for in vitro studies on complex life machinery. However, current techniques targeting live cells and organs are either highly expensive, like robotics, or lack nanoliter volume and millisecond time accuracy in liquid manipulation. We herein present the design and fabrication of a microfluidic system, which consists of 1,500 culture units, an array of enhanced peristaltic pumps and an on-site mixing modulus. To demonstrate the capacities of the microfluidic device, neural stem cell (NSC) spheres are maintained in the proposed system. We observed that when the NSC sphere is exposed to CXCL in day 1 and EGF in day 2, the round-shaped conformation is well maintained. Variation in the input order of 6 drugs causes morphological changes to the NSC sphere and the expression level representative marker for NSC stemness (i.e., Hes5 and Dcx). These results indicate that dynamic and complex environmental conditions have great effects on NSC differentiation and self-renewal, and the proposed microfluidic device is a suitable platform for high throughput studies on the complex life machinery.

We present a microfluidic system for high throughput studies on complex life machinery, which consists of 1500 culture units, an array of enhanced peristaltic pumps and an on-site mixing modulus. The microfluidic chip allows for the analysis of the highly complex and dynamic micro-environmental conditions in vivo.

使用高通量微流体设备生成动态环境条件

Mimicking in vivo environmental conditions is crucial for in vitro studies on complex life machinery. However, current techniques targeting live cells and ...

用于组合插头生产的微流体装置的设置

Bilayer Microfluidic Device for Combinatorial Plug Production

Droplet microfluidics is a versatile tool that allows the execution of a large number of reactions in chemically distinct nanoliter compartments. Such systems have been used to encapsulate a variety of biochemical reactions - from incubation of single cells to implementation of PCR reactions, from genomics to chemical synthesis. Coupling the microfluidic channels with regulatory valves allows control over their opening and closing, thereby enabling the rapid production of large-scale combinatorial libraries consisting of a population of droplets with unique compositions. In this paper, protocols for the fabrication and operation of a pressure-driven, PDMS-based bilayer microfluidic device that can be utilized to generate combinatorial libraries of water-in-oil emulsions called plugs are presented. By incorporating software programs and microfluidic hardware, the flow of desired fluids in the device can be controlled and manipulated to generate combinatorial plug libraries and to control the composition and quantity of constituent plug populations. These protocols will expedite the process of generating combinatorial screens, particularly to study drug response in cells from cancer patient biopsies.

作者聚焦：在精准肿瘤学中整合计算和实验方法

The fabrication of a polydimethylsiloxane (PDMS)-based bilayer device for the production of combinatorial libraries in water-in-oil emulsions (plugs) is presented here. The necessary hardware and software required to automate plug production are detailed in the protocol, and the production of a quantitative library of fluorescent plugs is also demonstrated.

用于组合塞生产的双层微流控装置

Droplet microfluidics is a versatile tool that allows the execution of a large number of reactions in chemically distinct nanoliter compartments. Such ...