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 border="0" cellpadding="0" cellspacing="0" style="width:572px;" width="573">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="37">
			<td height="37" style="height:37px;width:216px;">Silicon wafer</td>
			<td style="width:71px;">Huashi Co., Ltd</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="37">
			<td height="37" style="height:37px;width:216px;">SU-8 2025, 2100</td>
			<td style="width:71px;">Microchem Co.</td>
			<td style="width:119px;">Y111069</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="37">
			<td height="37" style="height:37px;width:216px;">SU-8 developer</td>
			<td style="width:71px;">Microchem Co.</td>
			<td style="width:119px;">Y020100</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="91">
			<td height="91" style="height:91px;width:216px;">Chromium mask</td>
			<td style="width:71px;">Qingyi Precision Mask Making Co., Ltd</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="37">
			<td height="37" style="height:37px;width:216px;">polydimethylsiloxane(PDMS)</td>
			<td style="width:71px;">Dow Corning</td>
			<td style="width:119px;">Sylgard 184</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="37">
			<td height="37" style="height:37px;width:216px;">poly(ethylene glycol) diacrylate (PEGDA)</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">26570-48-9</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="37">
			<td height="37" style="height:37px;width:216px;">2-hydroxy-40-(2-hydroxyethoxy)-2-methylpropiophenone</td>
			<td style="width:71px;">TCI</td>
			<td style="width:119px;">H1361-5G</td>
			<td style="width:167px;">photoinitiator</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Hexadecane</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">544-76- 3</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">ABIL EM 90</td>
			<td style="width:71px;">CHT</td>
			<td style="width:119px;">144243-53-8</td>
			<td style="width:167px;">surfactants</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Rhodamine B</td>
			<td style="width:71px;">Aladdin</td>
			<td style="width:119px;">81-88-9</td>
			<td style="width:167px;">fluorescent dye</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Spin Coater</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Lithography machine</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Automatic ointment agitator</td>
			<td style="width:71px;">Thinky</td>
			<td style="width:119px;">ARV-310</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Oven</td>
			<td style="width:71px;">BluePard</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Optical microscope</td>
			<td style="width:71px;">OLYMPUS</td>
			<td style="width:119px;">IX71</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="37">
			<td height="37" style="height:37px;width:216px;">High-speed camera</td>
			<td style="width:71px;">Hamamatsu, Japan</td>
			<td style="width:119px;">ORCA-flash</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="37">
			<td height="37" style="height:37px;width:216px;">MAESFLO Microfluidic Fluid Control System</td>
			<td style="width:71px;">FLUIGENT</td>
			<td style="width:119px;">MFCS-EZ</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:216px;">UV lamp</td>
			<td style="width:71px;">FUTANSI</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">365 nm UV light, 8000 MW/CM2</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

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

Determining 3D Flow Fields via Multi-camera Light Field Imaging

In the field of fluid mechanics, the resolution of computational schemes has outpaced experimental methods and widened the gap between predicted and observed phenomena in fluid flows. Thus, a need exists for an accessible method capable of resolving three-dimensional (3D) data sets for a range of problems. We present a novel technique for performing quantitative 3D imaging of many types of flow fields. The 3D technique enables investigation of complicated velocity fields and bubbly flows. Measurements of these types present a variety of challenges to the instrument. For instance, optically dense bubbly multiphase flows cannot be readily imaged by traditional, non-invasive flow measurement techniques due to the bubbles occluding optical access to the interior regions of the volume of interest. By using Light Field Imaging we are able to reparameterize images captured by an array of cameras to reconstruct a 3D volumetric map for every time instance, despite partial occlusions in the volume. The technique makes use of an algorithm known as synthetic aperture (SA) refocusing, whereby a 3D focal stack is generated by combining images from several cameras post-capture 1. Light Field Imaging allows for the capture of angular as well as spatial information about the light rays, and hence enables 3D scene reconstruction. Quantitative information can then be extracted from the 3D reconstructions using a variety of processing algorithms. In particular, we have developed measurement methods based on Light Field Imaging for performing 3D particle image velocimetry (PIV), extracting bubbles in a 3D field and tracking the boundary of a flickering flame. We present the fundamentals of the Light Field Imaging methodology in the context of our setup for performing 3DPIV of the airflow passing over a set of synthetic vocal folds, and show representative results from application of the technique to a bubble-entraining plunging jet.

A technique for performing quantitative three-dimensional (3D) imaging for a range of fluid flows is presented. Using concepts from the area of Light Field Imaging, we reconstruct 3D volumes from arrays of images. Our 3D results span a broad range including velocity fields and multi-phase bubble size distributions.

通过多摄像头的光场成像的三维流场测定

In the field of fluid mechanics, the resolution of computational schemes has outpaced experimental methods and widened the gap between predicted and ...

科研

工程学

Thermal Measurement Techniques in Analytical Microfluidic Devices

Thermal measurement techniques have been used for many applications such as thermal characterization of materials and chemical reaction detection. Micromachining techniques allow reduction of the thermal mass of fabricated structures and introduce the possibility to perform high sensitivity thermal measurements in the micro-scale and nano-scale devices. Combining thermal measurement techniques with microfluidic devices allows performing different analytical measurements with low sample consumption and reduced measurement time by integrating the miniaturized system on a single chip. The procedures of thermal measurement techniques for particle detection, material characterization, and chemical detection are introduced in this paper.

Here, we present three protocols for thermal measurements in microfluidic devices.

在分析微流体装置的热测量技术

Thermal measurement techniques have been used for many applications such as thermal characterization of materials and chemical reaction detection. ...

Fabrication and Operation of Acoustofluidic Devices Supporting Bulk Acoustic Standing Waves for Sheathless Focusing of Particles

Acoustophoresis refers to the displacement of suspended objects in response to directional forces from sound energy. Given that the suspended objects must be smaller than the incident wavelength of sound and the width of the fluidic channels are typically tens to hundreds of micrometers across, acoustofluidic devices typically use ultrasonic waves generated from a piezoelectric transducer pulsating at high frequencies (in the megahertz range). At characteristic frequencies that depend on the geometry of the device, it is possible to induce the formation of standing waves that can focus particles along desired fluidic streamlines within a bulk flow. Here, we describe a method for the fabrication of acoustophoretic devices from common materials and clean room equipment. We show representative results for the focusing of particles with positive or negative acoustic contrast factors, which move towards the pressure nodes or antinodes of the standing waves, respectively. These devices offer enormous practical utility for precisely positioning large numbers of microscopic entities (e.g., cells) in stationary or flowing fluids for applications ranging from cytometry to assembly.

Acoustofluidic devices use ultrasonic waves within microfluidic channels to manipulate, concentrate and isolate suspended micro and nanoscopic entities. This protocol describes the fabrication and operation of such a device supporting bulk acoustic standing waves to focus particles in a central streamline without the aid of sheath fluids.

制造和Acoustofluidic设备的运营支撑体声波驻波的聚焦鞘颗粒

Acoustophoresis refers to the displacement of suspended objects in response to directional forces from sound energy. Given that the suspended objects must ...

Creating Sub-50 Nm Nanofluidic Junctions in PDMS Microfluidic Chip via Self-Assembly Process of Colloidal Particles

Polydimethylsiloxane (PDMS) is the prevailing building material to make microfluidic devices due to its ease of molding and bonding as well as its transparency. Due to the softness of the PDMS material, however, it is challenging to use PDMS for building nanochannels. The channels tend to collapse easily during plasma bonding. In this paper, we present an evaporation-driven self-assembly method of silica colloidal nanoparticles to create nanofluidic junctions with sub-50 nm pores between two microchannels. The pore size as well as the surface charge of the nanofluidic junction is tunable simply by changing the colloidal silica bead size and surface functionalization outside of the assembled microfluidic device in a vial before the self-assembly process. Using the self-assembly of nanoparticles with a bead size of 300 nm, 500 nm, and 900 nm, it was possible to fabricate a porous membrane with a pore size of ~45 nm, ~75 nm and ~135 nm, respectively. Under electrical potential, this nanoporous membrane initiated ion concentration polarization (ICP) acting as a cation-selective membrane to concentrate DNA by ~1,700 times within 15 min. This non-lithographic nanofabrication process opens up a new opportunity to build a tunable nanofluidic junction for the study of nanoscale transport processes of ions and molecules inside a PDMS microfluidic chip.

We propose a simple self-assembly technique of silica colloidal nanoparticles to create a nanofluidic junction between two microchannels in polydimethylsiloxane (PDMS). Using this technique, a nanoporous bead membrane with a pore size down to ~45 nm was built inside a microchannel and applied to electrokinetic preconcentration of DNA samples.

通过胶体粒子自组装过程创建在PDMS微流控芯片分50纳米的纳米流体结

Polydimethylsiloxane (PDMS) is the prevailing building material to make microfluidic devices due to its ease of molding and bonding as well as its ...

Solvent Bonding for Fabrication of PMMA and COP Microfluidic Devices

Thermoplastic microfluidic devices offer many advantages over those made from silicone elastomers, but bonding procedures must be developed for each thermoplastic of interest. Solvent bonding is a simple and versatile method that can be used to fabricate devices from a variety of plastics. An appropriate solvent is added between two device layers to be bonded, and heat and pressure are applied to the device to facilitate the bonding. By using an appropriate combination of solvent, plastic, heat, and pressure, the device can be sealed with a high quality bond, characterized as having high bond coverage, bond strength, optical clarity, durability over time, and low deformation or damage to microfeature geometry. We describe the procedure for bonding devices made from two popular thermoplastics, poly(methyl-methacrylate) (PMMA), and cyclo-olefin polymer (COP), as well as a variety of methods to characterize the quality of the resulting bonds, and strategies to troubleshoot low quality bonds. These methods can be used to develop new solvent bonding protocols for other plastic-solvent systems.

Solvent bonding is a simple and versatile method for fabricating thermoplastic microfluidic devices with high quality bonds. We describe a protocol to achieve strong, optically clear bonds in PMMA and COP microfluidic devices that preserve microfeature details, by a judicious combination of pressure, temperature, an appropriate solvent, and device geometry.

溶剂粘接的PMMA的制备和COP微流体装置

Thermoplastic microfluidic devices offer many advantages over those made from silicone elastomers, but bonding procedures must be developed for each ...

Scanning Light Scattering Profiler (SLPS) Based Methodology to Quantitatively Evaluate Forward and Backward Light Scattering from Intraocular Lenses

The scanning light scattering profiler (SLSP) methodology has been developed for the full-angle quantitative evaluation of forward and backward light scattering from intraocular lenses (IOLs) using goniophotometer principles. This protocol describes the SLSP platform and how it employs a 360&#176; rotational photodetector sensor that is scanned around an IOL sample while recording the intensity and location of scattered light as it passes through the IOL medium. The SLSP platform can be used to predict, non-clinically, the propensity for current and novel IOL designs and materials to induce light scatter. Non-clinical evaluation of light scattering properties of IOLs can significantly reduce the number of patient complaints related to unwanted glare, glistening, optical defects, poor image quality, and other phenomena associated with the unintended light scattering. Future studies should be conducted to correlate SLSP data with clinical results to help identify which measured light scatter is most problematic for patients that have undergone cataract surgery subsequent to IOL implantation.

Scanning Light Scattering Profiler SLPS Based Methodology to Quantitatively Evaluate Forward and Backward Light Scattering from Intraocular Lenses

This protocol describes the scanning light scattering profiler (SLSP) that enables the full-angle quantitative evaluation of forward and backward scattering of light from intraocular lenses (IOLs) using goniophotometer principles.

基于扫描光散射分析器（SLPS）的方法来量化评估来自眼内镜的前向和后向光散射

The scanning light scattering profiler (SLSP) methodology has been developed for the full-angle quantitative evaluation of forward and backward light ...

Microfluidic Imaging Flow Cytometry by Asymmetric-detection Time-stretch Optical Microscopy (ATOM)

Scaling the number of measurable parameters, which allows for multidimensional data analysis and thus higher-confidence statistical results, has been the main trend in the advanced development of flow cytometry. Notably, adding high-resolution imaging capabilities allows for the complex morphological analysis of cellular/sub-cellular structures. This is not possible with standard flow cytometers. However, it is valuable for advancing our knowledge of cellular functions and can benefit life science research, clinical diagnostics, and environmental monitoring. Incorporating imaging capabilities into flow cytometry compromises the assay throughput, primarily due to the limitations on speed and sensitivity in the camera technologies. To overcome this speed or throughput challenge facing imaging flow cytometry while preserving the image quality, asymmetric-detection time-stretch optical microscopy (ATOM) has been demonstrated to enable high-contrast, single-cell imaging with sub-cellular resolution, at an imaging throughput as high as 100,000 cells/s. Based on the imaging concept of conventional time-stretch imaging, which relies on all-optical image encoding and retrieval through the use of ultrafast broadband laser pulses, ATOM further advances imaging performance by enhancing the image contrast of unlabeled/unstained cells. This is achieved by accessing the phase-gradient information of the cells, which is spectrally encoded into single-shot broadband pulses. Hence, ATOM is particularly advantageous in high-throughput measurements of single-cell morphology and texture &#8211; information indicative of cell types, states, and even functions. Ultimately, this could become a powerful imaging flow cytometry platform for the biophysical phenotyping of cells, complementing the current state-of-the-art biochemical-marker-based cellular assay. This work describes a protocol to establish the key modules of an ATOM system (from optical frontend to data processing and visualization backend), as well as the workflow of imaging flow cytometry based on ATOM, using human cells and micro-algae as the examples.

Microfluidic Imaging Flow Cytometry by Asymmetric-detection Time-stretch Optical Microscopy ATOM

This protocol describes the implementation of an asymmetric-detection time-stretch optical microscopy system for single-cell imaging in ultrafast microfluidic flow and its applications in imaging flow cytometry.

微流控成像流式细胞仪通过不对称检测时间延伸光学显微镜（ATOM）

Scaling the number of measurable parameters, which allows for multidimensional data analysis and thus higher-confidence statistical results, has been the ...

Flow-assisted Dielectrophoresis: A Low Cost Method for the Fabrication of High Performance Solution-processable Nanowire Devices

Flow-assisted dielectrophoresis (DEP) is an efficient self-assembly method for the controllable and reproducible positioning, alignment, and selection of nanowires. DEP is used for nanowire analysis, characterization, and for solution-based fabrication of semiconducting devices. The method works by applying an alternating electric field between metallic electrodes. The nanowire formulation is then dropped onto the electrodes which are on an inclined surface to create a flow of the formulation using gravity. The nanowires then align along the gradient of the electric field and in the direction of the liquid flow. The frequency of the field can be adjusted to select nanowires with superior conductivity and lower trap density. 
In this work, flow-assisted DEP is used to create nanowire field effect transistors. Flow-assisted DEP has several advantages: it allows selection of nanowire electrical properties; control of nanowire length; placement of nanowires in specific areas; control of orientation of nanowires; and control of nanowire density in the device. 
The technique can be expanded to many other applications such as gas sensors and microwave switches. The technique is efficient, quick, reproducible, and it uses a minimal amount of dilute solution making it ideal for the testing of novel nanomaterials. Wafer scale assembly of nanowire devices can also be achieved using this technique, allowing large numbers of samples for testing and large-area electronic applications.

In this paper, flow assisted dielectrophoresis is demonstrated for the self-assembly of nanowire devices. The fabrication of a silicon nanowire field effect transistor is shown as an example.

流动辅助介: 一种低成本的制备高性能溶液可纳米线器件的方法

Flow-assisted dielectrophoresis (DEP) is an efficient self-assembly method for the controllable and reproducible positioning, alignment, and selection of ...

Experimental Investigation of the Flow Structure over a Delta Wing Via Flow Visualization Methods

It is well known that the flow field over a delta wing is dominated by a pair of counter rotating leading edge vortices (LEV). However, their mechanism is not well understood. The flow visualization technique is a promising non-intrusive method to illustrate the complex flow field spatially and temporally. A basic flow visualization setup consists of a high-powered laser and optic lenses to generate the laser sheet, a camera, a tracer particle generator, and a data processor. The wind tunnel setup, the specifications of devices involved, and the corresponding parameter settings are dependent on the flow features to be obtained.
Normal smoke wire flow visualization uses a smoke wire to demonstrate the flow streaklines. However, the performance of this method is limited by poor spatial resolution when it is conducted in a complex flow field. Therefore, an improved smoke flow visualization technique has been developed. This technique illustrates the large-scale global LEV flow field and the small-scale shear layer flow structure at the same time, providing a valuable reference for later detailed particle image velocimetry (PIV) measurement.
In this paper, the application of the improved smoke flow visualization and PIV measurement to study the unsteady flow phenomena over a delta wing is demonstrated. The procedure and cautions for conducting the experiment are listed, including wind tunnel setup, data acquisition, and data processing. The representative results show that these two flow visualization methods are effective techniques for investigating the three-dimensional flow field qualitatively and quantitatively.

Here, we present a protocol to observe unsteady vortical flows over a delta wing using a modified smoke flow visualization technique and investigate the mechanism responsible for the oscillations of the leading-edge vortex breakdown locations.

基于流动可视化方法的三角洲机翼流动结构实验研究

It is well known that the flow field over a delta wing is dominated by a pair of counter rotating leading edge vortices (LEV). However, their mechanism is ...

Safe Experimentation in Optical Levitation of Charged Droplets Using Remote Labs

The work presents an experiment that allows the study of many fundamental physical processes, such as photon pressure, diffraction of light or the motion of charged particles in electrical fields. In this experiment, a focused laser beam pointing upwards levitate liquid droplets. The droplets are levitated by the photon pressure of the focused laser beam which balances the gravitational force. The diffraction pattern created when illuminated with laser light can help measure the size of a trapped droplet. The charge of the trapped droplet can be determined by studying its motion when a vertically directed electrical field is applied. There are several reasons motivating this experiment to be remotely controlled. The investments required for the setup exceeds the amount normally available in undergraduate teaching laboratories. The experiment requires a laser of Class 4, which is harmful to both skin and eyes and the experiment uses voltages that are harmful.

Optical levitation is a method for levitating micrometer-sized dielectric objects using laser light. Utilizing computers and automation systems, an experiment on optical levitation can be controlled remotely. Here, we present a remotely controlled optical levitation system that is used both for educational and research purposes.

远程实验室对带电液滴光学悬浮的安全实验

The work presents an experiment that allows the study of many fundamental physical processes, such as photon pressure, diffraction of light or the motion ...