作者感谢台湾国家卫生研究院 (IRG) (EX106-10523EI)、台湾省科技部 (最 104-2218-032-004、104-2221) 在台湾提供的支持。E-001-015-MY3, 105-2221-001-002-MY2, 105-2221-032-006, 106-2221-032-018-MY2), 和研究院职业发展奖。作者感谢恒华许校对稿件。

1. 单层通道布局微流控装置的制作
注: 本文采用3软光刻法制作了微流控器件, 以演示如何制作不同断面的通道。
<ol><li>
用设计的拓扑特征创建一层聚硅烷的主模
	<ol>
<li>为单个蚀刻工艺或按顺序进行蚀刻, 设计了一个在该层上的通道布局。</li>
		<li>利用计算机辅助绘图程序, 勾勒出所设计的聚硅烷层的反向拓扑特征。</li>
		<li>将草绘文件传送到光刻设备, 以获得在透明24上打印的通道布局的高精度反向拓扑特征的图案化光掩模。</li>
		<li>使用异丙醇 (2-丙醇 (IPA), ≥ 99.9%), 丙酮 (Propan-2-one, ≥ 99.5%), 和缓冲氧化物蚀刻 (教委, NH4F: HF (v/v) = 6:1) 在一个4英寸的硅片表面, 以消除任何灰尘或残余物, 并避免污染物。</li>
		<li>用大约500毫升的去离子水清洗硅片进行最后的抛光, 然后用氮气干燥冲洗过的晶片。</li>
		<li>在晶片上放置一个20克左右的负色调光刻胶。然后旋转涂层的硅片在十五年代和2000转每分钟 500 rpm 三十年代生产的光刻胶层约75µm 在厚度。 注: 根据用户手册25,26, 不同的产品编号和不同的自旋涂层、烘烤和开发条件, 可以实现各种光刻胶厚度的光刻胶。</li>
		<li>软烤晶圆片加热在热板上65°c 3 分钟, 然后在95°c 9 分钟。</li>
		<li>将晶片放入光掩模光刻机中, 并将步骤1.1.3 中的图案透明度作为掩码。</li>
		<li>在光刻机中, 应用紫外线 (UV) 光在300兆焦耳/厘米2 , 以暴露晶片覆盖的透明度。</li>
		<li>紫外线照射后, 将硅片放在65摄氏度的热板上, 2 分钟, 然后在95摄氏度为7分钟后曝光烘烤 (PEB)。</li>
		<li>继 PEB 后, 强烈鼓动晶片浸入负色调的光刻胶显影液中, 或将浸入式晶片置于超声波浴中 (37 赫, 有效功率为 180 W) 为7分钟。</li>
		<li>再次用异丙醇清洗整个晶片, 以消除任何残留在晶片表面的显影液。</li>
		<li>为了防止不期望的粘合, silanize 硅片的表面, 将硅片与100µL 硅烷 (1h, 1H, 2h, 2hperfluorooctyl 烷) 一起放在干燥的6厘米培养皿中。</li>
		<li>将干燥连接到真空泵, 并将真空压力设置为 760 mmHg。</li>
		<li>接着, 把泵打开15分钟, 关掉它, 然后把晶片放在干燥的真空中休息30分钟。 注意: 蒸发的硅烷对人类极其有害;因此, 整个晶片表面钝化必须在通风罩中进行。</li>
		<li>提取硅烷化晶圆片, 该晶片正在进行表面钝化。将晶片固定在15厘米培养皿中以供进一步使用。 注: 该图案晶圆片已准备好用作模具, 可将设计的通道布局与该材料反向复制。</li>
	</ol>
</li>
	<li>
在模具上复制反向拓扑, 制作出了基于该电路的通道布局
	<ol>
<li>将基体 (单体) 与相应的催化剂 (固化剂) 放在10:1 的体积比上, 变成一个干净的单用塑料杯。</li>
		<li>使用动力搅拌器均匀地混合1.2.1 预聚体混合物 (从步进法)。</li>
		<li>把杯子放在与真空泵相连的干燥上60分钟, 以除去该混合物中的任何陷泡气泡。</li>
		<li>将20克 (2 节) 或8克 (3 节) 倒入主模具 (步骤 1.1) 的顶部, 与设计的通道布局的反向拓扑特征混合, 然后通过使用 t 来消除任何可能的气泡嵌入到该材料中。他干燥 (60 分钟)。</li>
		<li>将以60°c 为4小时的混合材料放入烤箱, 以固化硅基液体预聚物。</li>
		<li>在将晶片冷却到室温约20分钟后, 用手术刀和镊子将固化后的硅烷从模具中分离出来。</li>
		<li>用手术刀将分离后的一层 (2 或 2 x 7.5 厘米2 ) 的区域 (约为 6 x 6 厘米2 ) 定制为部分。</li>
		<li>使用直径为1.5 毫米的活检打孔创建通道访问端口 (入口和插座)。 注: 入口和插座的数量和位置是根据蚀刻工艺设计的, 用于制造特定的微流控通道。</li>
		<li>将30克的硅烷预聚物倒入培养皿中, 然后通过使用干燥 (60 分钟) 消除在该材料中嵌入的任何可能的气泡。</li>
		<li>将培养皿携带在60摄氏度的烤箱中, 以4多小时的温度来治疗液体预聚体材料。</li>
		<li>在将培养皿冷却到室温约20分钟后, 用手术刀和镊子将已固化的。</li>
		<li>使用手术刀, 在不带任何特征的情况下, 将独立的......... 6 x 6 厘米2 2 或 2 x 7.5 厘米2条的尺寸。</li>
		<li>在四十年代 90 W 的表面处理机上, 用设计的通道布局和不带任何特征的 1.2.7, 激活两层的表面。</li>
		<li>通过在氧等离子体表面活化后, 在处理过的表面之间进行接触, 来粘合2层。然后, 在烤箱中将粘合的60摄氏度保持在30分钟以上。 注: 在烤箱中, 不存在将粘合的聚硅烷层留在上面的时间限制。</li>
		<li>在2个粘合后的单层冷却后, 将多余的材料从预制装置中修剪出来, 供以后的实验设备用。</li>
	</ol>
</li>
</ol>2. 用一步法制备不同断面的微流控流体通道
注: 为了表征其湿蚀刻速率, 建议利用单层和直通道矩形形状的微流控装置来识别与某些实验设置相对应的特定蚀刻速率。
<ol><li>
硅烷湿法蚀刻的实验表征
	<ol>
<li>用 1-甲基-2-咯烷酮 (NMP) 混合四氟铵氟化物 (TBAF, 1 M 溶液), 用 v: v = 1:10, 制备蚀刻溶液。 注: NMP 能有效溶解腐蚀剂诱导的化学残留。一般情况下, NMP 材料的肿胀略有上升, 而该微流控芯片仍能保持其形状、体积和密封条件。</li>
		<li>将混合 TBAF/NMP 腐蚀剂与不锈钢钝针 (16 克) 连接在一起的10毫升注射器中。</li>
		<li>在通道中设置注射器泵作为压力驱动流体的控制器。</li>
		<li>将用蚀刻溶液填充的注射器的钝针连接到上述简单设备的通道端口, 并将各自的端口从出口油管引导到废物容器, 如图 1所示。</li>
		<li>运行注射器泵携带注射器含有混合 TBAF/NMP 蚀刻解决方案, 以150µL/分钟的流量率, 以表征该法的湿蚀刻。</li>
		<li>使用光亮场显微观察, 确保沿流方向的蚀刻通道宽度一致, 从而确认腐蚀剂的体积混合比和蚀刻流速是足够的。</li>
		<li>捕获在反相显微镜下的通道剖面的时间序列图像, 并在其蚀刻过程中使用4X 放大倍数。</li>
		<li>通过在图像处理程序的2D 分析中应用基本测量函数对存储图像进行分析, 收集了在材料湿法蚀刻过程中通道宽度的时间序列。</li>
		<li>通过图 2所示的等式评估时间序列蚀刻速率, 该公式在50% 的通道宽度变化 (ΔW /2) 的持续时间内进行.</li>
		<li>对所收集的数据点进行线性回归, 估计混合 TBAF/NMP 腐蚀剂的总蚀刻率, 并以1:10 的具体体积混合比为原料, 如图 2所示。</li>
	</ol>
</li>
	<li>
用于制造不同几何剖面微流控通道的连续湿法蚀刻
	<ol>
<li>设计了单层蚀刻通道布局的排列方式, 为相应的蚀刻过程依次提供服务, 使图 3中所示的不同横截面形状的特定通道类型能够被制造出来。</li>
		<li>按照步骤 2.1.1 2.1.7 中描述的过程, 对其湿蚀刻方法进行操作。 注: 流量设置为 50 ul/分钟。</li>
		<li>当 TBAF/NMP 腐蚀剂在流动时, 检查显微镜下的蚀刻通道, 看看是否存在重大问题, 如明显的气泡量, 残余的几个化学残留的腐蚀剂诱导, 泄漏的腐蚀剂,或腐蚀剂在倾斜的平面上的流动。</li>
		<li>通过倒置显微镜观察微流控通道壁厚变化, 并对湿法蚀刻过程进行时间测量, 以确保正确的通道几何形状。</li>
	</ol>
</li>
</ol>3. 微流控搅拌机的设计
注: 介绍了一种能有效混合2种不同流体的微流控混合器的设计, 展示了微流控通道与各断面的优势应用。
<ol><li>
不同通道段微流控混频器的研制
	<ol>
<li>用软光刻复制器成型技术 (2 节) 制作图 4所示的单层微流控芯片。</li>
		<li>在单层微流控通道布局中, 介绍了 TBAF/NMP 蚀刻解决方案, 按照步骤2.1.1 中描述的过程, 从标记为 "插座" 的端口在图 4中的20µL/分钟流速。</li>
		<li>在显微镜下观察微流控通道壁厚变化, 并对湿法蚀刻过程进行时间测量, 以确保图 5所示的正确的通道几何。</li>
	</ol>
</li>
	<li>
微流控混合机的实验表征
	<ol>
<li>在一个交替模式中实现了不同形状截面的微流控通道后, 泵浦2种不同的流体, 其中有50µg/毫升浓度的荧光素钠盐溶液, 在20µL/分钟内将蒸馏水分成2个不同的通道。流量。</li>
		<li>在上图中以 A、B、C 和 D 为标记的位置, 在2混合器 (在蚀刻前) 和不同的几何截面 (舒瑞普2小时后) 下, 将该通道的荧光显微镜图像分别 (图 6)。 注: 采用荧光显微镜图像, 当稳定流发生时, 在5分钟的时间点, 计数从混合通过混合器通道的开始时刻。</li>
		<li>利用图像处理程序对捕获的荧光图像进行分析, 以估计在以下等式27中由混合残余 (MR, 0.5 = 纯, 0 = 完全混合) 定义的相应混合效率数.28: <img alt="Equation" src="/files/ftp_upload/57868/57868eq1v2.jpg"> 这里 t是蚀刻时间, L是通道宽度在某一位置的兴趣, S是在该位置的通道上的线段, 并 我是荧光强度分布在S t。</li>
		<li>将荧光强度分布在通道上, 在标记为 A、B、C 和 D 的位置上, 分别为2混合器 (在蚀刻前) 和不同的几何截面 (舒瑞普2小时后)。估计图 6所示的相应 MR。</li>
	</ol>
</li>
</ol>

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NANO SU-8 2000 Negative Tone Photoresist formulations 2002-2025 Available from: <a target="_blank" href="https://www.seas.upenn.edu/~nanosop/documents/SU8_2002-2025.pdf">https://www.seas.upenn.edu/~nanosop/documents/SU8_2002-2025.pdf</a> (2000)</li><li>. NANO SU-8 2000 Negative Tone Photoresist formulations 2035-2100 Available from: <a target="_blank" href="https://www.seas.upenn.edu/~nanosop/documents/SU8_2035-2100.pdf">https://www.seas.upenn.edu/~nanosop/documents/SU8_2035-2100.pdf</a> (2000)</li><li>Hardt, S., Sch&#246;nfeld, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laminar+Mixing+in+Different+Interdigital+Micromixers:+II.+Numerical+Simulations.">Laminar Mixing in Different Interdigital Micromixers: II. 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作者没有什么要申报的。

在过去的几十年中, 微流体为化学和生物医学研究的实验平台提供了有希望的手段, 可以系统地构建1、2、3、4、 5。这些平台还展示了他们的能力, 通过体外细胞研究6,7,在生理微环境条件下研究体内的几种细胞功能,8,9. 在实验研究和相关应用中, 微流控器件的大部分通道截面都是均匀的, 呈矩形状。在微流控器件中, 通道结构在微环境条件下起着重要的作用。例如, 在使用微流体作为药物传递设备时, 对这种化学运输的被动控制是通过调整标准截面几何29的矩形通道中的流速来调制的。对于沿流向通道的物质输送所需的通量分布, 可能需要在整体容积流速下设置不同几何截面的微流控通道。相当多的研究已经采取了一些重要的步骤, 以制造这样的芯片与理想的渠道, 不同的部分, 包括建造主模具的特殊表面模式的各种高度或非矩形交叉13、14、15和对几何特征曲面的蚀刻技术 (17、18、19、20 ),21,22. 然而, 这些努力不仅涉及复杂的制造过程, 而且还限于渠道16、23的具体横断面形状。
本文以一种简单、一致的方式, 将蚀刻引入到单层方案中, 以一种直接的、连贯的方法, 将多节段中的双通道的设计方法导入到特定渠道中。利用迭代数值计算30, 验证了不同截面形状形成通道的各向同性连续湿蚀刻过程。显然, 由于在连续的湿蚀刻过程中, 对该材料的各向同性去除, 很难制造出具有尖锐角度的通道截面几何。在实际应用中, 对微流控通道的预制截面几何的精确控制要求对其湿蚀刻速率进行精确的描述, 并对相关油管系统的安装进行仔细的安排。与现有的不同几何形状的微流控流体通道的制造方法相比, 所开发的一步法可以显著简化非矩形截面或不同高度的通道加工过程。因此, 所开发的技术为复杂的微流控通道的构建提供了一种途径, 可为各种应用开发新型微流控系统。

微流控技术在过去的几十年中引起了人们的注意, 因为它们在各种生物医学和化学研究和应用中具有内在的优势。目前有几种用于构造微流控芯片的材料使用方法, 如聚合物、陶瓷和硅材料。根据我们的知识, 在微流控材料中, 由于其对各种微流体的研究和应用, 包括其光学和生物兼容性与粒子, 因此, 它是最常见的一种材料。液体和非常小活有机体1,2,3,4,5。此外, 通过应用这种聚合物基微流控器件 10, 可调整其表面化学和结构力学性能, 以促进 microelectromechanical 和 mechanobiological 研究, 11,12。对于采用设计的通道模式制造微流控器件, 通常采用软光刻复制模塑方法, 利用其相应的主模具来创建微流控通道, 其组成为光刻图案光刻胶层和硅片基板12。由于采用了带有图案光刻胶层的硅片的成型方法的性质, 微流控通道通常具有相同高度的矩形形状的正截面。
最近, 研究人员在生物医学研究方面取得了重大进展, 例如, 利用 hydrophoresis、分离血浆和丰富白细胞的途径对微粒和细胞进行分类, 并将微流控芯片应用于不同的高度或几何部分6,7,8,9。通过自定义不同几何剖面的通道, 实现了生物医学应用中微流体的分类和分离功能。通过制作具有不同高度或非矩形截面的特殊表面模式的主模具, 对具有各几何特征截面的微流控通道进行了若干研究。这些关于模具制造的研究包括多步光刻、光刻胶回流和灰阶光刻13、14、15等技术。不可避免的是, 现有的技术包括精心制作的光掩膜或在多步制造过程中的精确对准, 这可能大大提高了相应制造微流控通道的复杂性水平。到目前为止, 对不同断面微流控通道的单步法制造工艺进行了几次尝试, 但各自的技术高度限制在16通道的特定横断面形状上。
在过去的两年中, 除了用不同的截面制造新的微流控流体通道的成型方法外, 采用几何特征的模式的蚀刻技术已成为各种选择的制造方式。微流控应用程序。例如, 微流体的湿法蚀刻是利用多层的聚硅烷键合来构建一种具有重组器官级肺功能的气动驱动细胞培养装置的17。采用 microwells 的湿法蚀刻技术, 利用计算机辅助控制系统加工制造3D 敷微针阵列18的外圆管, 对其进行了制备。在微机电致动器19、20中, 采用了聚硅烷干法蚀刻, 使其作为微观结构的组成部分。通过21的干法蚀刻工艺, 设计出孔隙布局的多孔型聚合物膜。湿式和干法蚀刻技术都可以集成到图案为22的几何形状。
然而, 由于其在微流控加工中的固有局限性, 形成复杂断面形状的聚硅烷通道结构的蚀刻技术还没有得到普遍应用。首先, 在建立不同断面微流控流体通道的化学物质层流法的基础上, 对其湿蚀刻技术进行了研究, 但由于其基本特征, 后续通道段的形成仍受到限制。各向同性化学蚀刻工艺23。此外, 虽然似乎有合理的空间, 以控制通道剖面几何在微流体制造使用了20, 所需的蚀刻时间通常是太长 (在小时)生产微流控芯片的实用。此外, 该材料与相应的屏蔽光刻胶层之间的蚀刻选择性一般都很低, 因此, 这些通道的蚀刻深度是不可接受的20。
本文提出了一种单步法制备不同几何横截面微流控通道的方法 (以下简称舒瑞普)。舒瑞普从单层通道的微流控芯片开始。通过对各种通道的布局设计, 通过顺序蚀刻工艺, 制作出不同几何截面的微流控通道。顺序蚀刻只需要一个蚀刻, 被引入到计划的单层布局的具体渠道嵌入在该材料。与传统的舒瑞普制造工艺相比, 该方法只需要一个进一步的步骤来制造非矩形截面或不同高度的微流控通道。所提出的舒瑞普提供了一个简单而简便的方法, 制造微流控通道的各个部分沿流动方向, 这可以大大简化上述方法的过程。

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</table>

one-step approach to fabricating polydimethylsiloxane microfluidic channels of different geometric sections by sequential wet etching processes

烷的材料被大量利用来制造微流控器件, 采用软光刻复制的成型技术。在许多生物医学和化学应用 (如细胞培养、生物传感、化学合成和液体处理) 中, 对微流控器件的特定功能和综合性能而言, 定制的渠道布局设计是必要的。由于采用了以光刻为主模的光刻胶层的硅晶片的成型方法的性质, 微流控通道通常具有相同高度的矩形形状的正截面。通常, 具有多个高度或不同几何截面的通道设计为具有特定功能, 并可在各种微流控应用程序中执行 (例如, hydrophoresis 用于对粒子进行排序, 并在连续流中用于分离血细胞6,7,8,9)。因此, 通过多步骤的方法, 如光刻, 采用不同的光刻胶层和组合, 在各断面的施工渠道进行了大量的努力。然而, 这种多步骤方法通常涉及繁琐的程序和广泛的工具。此外, 捏造的设备可能不会持续执行, 结果实验数据可能是不可预知的。在这里, 为直接制造不同几何横截面的微流控通道提供了一步法, 该方法将蚀刻引入计划的单层布局通道中。嵌入式材料。与现有的不同几何形状的微流控流体通道制造方法相比, 所研制的一步法可显著简化非矩形截面或不同高度的通道制作过程。因此, 该技术是构造复杂微流控通道的一种方法, 为创新微流控系统的发展提供了一种制造方案。

近年来, 大量研究了通过光刻复制13、14、15和聚硅烷蚀刻技术, 对不同断面通道的微流控装置进行制作;17,18,19,20,21,22. 然而, 在制造作业16、23中, 图案形状和困难仍然存在相当大的限制。本文提出了用舒瑞普对不同几何剖面的微流控流体通道进行一步法制备的方法。
图 1示意性地显示了微流控单层通道布局, 用于通过舒瑞普创建不同剖面的异型材通道, 并显示相关油管系统的实验设置。NMP 是用于舒瑞普实验的缓冲区, 如图 1a和1b所示。在舒瑞普实验中, 选择合适的溶剂来消除腐蚀过程中所利用的层流流中的蚀刻产品是很重要的。因此, 选择 NMP 缓冲器作为溶剂, 有效地溶解舒瑞普22、23的产物。
蚀刻的渠道也充满了蓝色的食品染料, 以证明在微流控装置内的通道部分的演变。通过对设计的单层通道模式的蚀刻入口进行排列, 可以通过图 3所示的舒瑞普, 得到各种不同几何特征的微流控通道剖面。
为了表征其湿蚀刻的特点, 利用单层和直槽的微流控装置, 确定了混合 TBAF/NMP 腐蚀剂的总蚀刻率, 并给出了特定的掺量比。材料。通过对某些蚀刻时间的通道宽度变化的收集数据点的线性回归, 实验估计蚀刻溶液的总蚀刻速率为2.714 µm/分钟 (图 2)。
在具有均匀剖面的微流控通道中, 流体主要沿通道壁流动, 抑制物质颗粒间的随机接触;因此, 扩散驱动的流体混合通常通过特别长的通道来实现。因此, 预计不同几何剖面的微流体通道可以促进流体在通道剖面上的横向流体运动。在本研究中, 本文展示了两种不同流体有效混合的微流控混频器 (图 4) 的设计, 介绍了微流控通道的一个有利应用。图 5展示了舒瑞普在0小时、0.25 小时、0.40 小时、0.55 h、0.70 h、1.00 h 和 2.00 h 的刻蚀阶段, 用在顶部视图制造的微流控混频器通道的时间序列图像。
在一个交替模式中实现了不同形状截面的微流控通道后, 两种不同的流体, 包括荧光素钠盐和蒸馏水的溶液, 随后被泵入两个独立的通道, 荧光在上图中标记为 A、B、C 和 D 位置的通道的显微镜图像被捕获在一个倒置显微镜下, 用于两个混合器 (在蚀刻前) 和不同的几何部分 (舒瑞普2小时后), 分别 (图 6)。这些图像是采取的, 而稳定的流动发生, 在5分钟的时间点, 从混合通过混合通道的开始时刻计数。然后, 将这些荧光显微镜图像传送到本研究开发的自动化程序中, 提取相应的 MR 数字, 表示混合效率。
在蚀刻过程之前, 带有蛇形通道布局的混频器的通道具有矩形形状的相同截面。由于扩散机制所需的足够的通道长度, 微流控混合器在 A、B、C 和 D 位置分别以0.4607、0.3403、0.2450 和0.1940 的 MR 数字来表示基本的混合效率。在 2 h 的舒瑞普, 与原来一个相同的总通道长度, 微流控混频器有不同形状的通道部分在一个交替的模式。重要的是, 混合器与不同的通道部分提供显著上升的混合效率, 代表明显减少 0.3875, 0.1915, 0.1336 和0.0680 在 a, B, C 和 D 位置, 分别是由于横向流体除扩散机制外, 导致平流的运动。此外, 从位置 B D, 这种平流机制发生在通道部分导致了明显的和一致的增加混合效率的舒瑞普制造的搅拌机。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/57868/57868fig1.jpg"> 图 1: 微流控单层通道布局上的油管设置, 用于通过连续的湿刻蚀过程 (舒瑞普) 来创建不同几何剖面的异型材.(a) 该示意图显示了单层通道的微流控装置。顶层是由多通道设计的蚀刻的湿式进口安排。底层是用一个空白模式的。(顶部: 一个蚀刻入口; 中间: 两个蚀刻入口.)底部是顶层制造的模具。(b) 这些面板显示了组装装置, 用于制作不同断面的通道。通道宽度和壁厚分别为50µm 和100µm。(c) 这些面板显示了舒瑞普微流控单层通道布局上油管设置的实验照片。(顶行: 一个蚀刻入口; 底部行: 两个蚀刻入口。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/57868/57868fig1large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/57868/57868fig2.jpg"> 图 2: 对其进行湿法蚀刻的表征.该图显示了所收集的半通道宽度变化的线性回归, 用于估计混合 TBAF/NMP 腐蚀剂的总蚀刻速率, 并对该材料的特定体积混合比进行估算。[该嵌入是一个简单和直通道模式的横断面几何示意图, 用于表征其湿蚀刻速率的材料。TBAF/NMP 的总蚀刻率 (v: v = 1:10) 是2.714 µm/分钟, 相应的 R2 (确定系数) 为0.9913。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/57868/57868fig2large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/57868/57868fig3.jpg"> 图 3: 按顺序对异型材进行湿法蚀刻, 制备出不同几何剖面的微流体通道.这些面板显示了蚀刻入口的各种安排, 用于为相应的蚀刻工艺服务的单层的, 用于制造不同断面形状的特定通道类型, 如 (a)十字形, (b) 哑铃形, (c) 钟形横断面几何图形。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/57868/57868fig3large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/57868/57868fig4.jpg"> 图 4: 利用不同截面的通道制作的微流控混合器.(a) 本小组是一幅设计图, 是单层通道布局, 用于制作微流式混合器, 利用不同断面的通道。底部显示了单层通道制造的模具。(b) 这些面板显示了在1和2小时内, 在对其进行湿法蚀刻之前和之后整个混频器通道的瓷砖扫描显微镜图像。(c) 这些面板显示了混合通道部分的实验性明亮场图像, 这是由1和 2 h 在顶部视图 (顶部), 在垂直于沿x轴的流向方向的切割视图 (第二次从顶部), 并在一个截面视图在 a-a 切口 (第三个从顶部) 和 b b 切割 (底部行) 的位置。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/57868/57868fig4large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/57868/57868fig5.jpg"> 图 5: 用连续湿法蚀刻的微流体混合通道的时间序列图像.(a) 此面板显示单层通道布局示意图, 用于制作具有不同通道段的微流控混频器。(b) 这些面板在每个蚀刻阶段按顺序显示混合器通道的显微镜图像。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/57868/57868fig5large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 6" class="xfigimg" src="/files/ftp_upload/57868/57868fig6.jpg"> 图 6: 用连续的聚甲基化法进行湿蚀刻制备微流体混合器的特性.(a) 这些小组在介绍腐蚀剂和 2 h 湿法蚀刻材料前, 在标记为 a、B、C 和 D 的位置上显示混合器通道的荧光显微镜图像。(b) 这些面板显示在 a、b、C 和 D 位置的混合通道上, 在 (顶部) 和 2 h 的正离子湿蚀刻 (中间) 之前, 以规范化的坐标呈现的测量荧光强度场。分析表明, 在 2 h 的蚀刻 (底部) 的不同通道位置上, 混合效率 (0.5: 纯, 0: 完全混合) 的 MR 表示。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/57868/57868fig6large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>

Watch this Scientific Journal Video about One-Step Approach to Fabricating Polydimethylsiloxane Microfluidic Channels of Different Geometric Sections by Sequential Wet Etching Processes at JoVE.com

One-Step Approach to Fabricating Polydimethylsiloxane Microfluidic Channels of Different Geometric Sections by Sequential Wet Etching Processes

连续湿法刻蚀法制作不同几何断面烷微流控通道的一步法

对烷微流控器件中嵌入的非矩形截面通道的制作, 有几种方法可供选择。其中大部分涉及多步骤制造和广泛的对准。本文介绍了用烷连续湿法刻蚀法制作不同几何剖面微流控通道的一步法。

Polydimethylsiloxane (PDMS) materials are substantially exploited to fabricate microfluidic devices by using soft lithography replica molding techniques. ...

one-step-approach-to-fabricating-polydimethylsiloxane-microfluidic

Nanyang Technological University

Research

JoVE Journal

Engineering

9.7K 次观看.  Academia Sinica. 对烷微流控器件中嵌入的非矩形截面通道的制作, 有几种方法可供选择。其中大部分涉及多步骤制造和广泛的对准。本文介绍了用烷连续湿法刻蚀法制作不同几何剖面微流控通道的一步法。

视频: One-Step Approach to Fabricating Polydimethylsiloxane Microfluidic Channels of Different Geometric Sections by Sequential Wet Etching Processes

Fabricating Metamaterials Using the Fiber Drawing Method

Metamaterials are man-made composite materials, fabricated by assembling components much smaller than the wavelength at which they operate 1. They owe their electromagnetic properties to the structure of their constituents, instead of the atoms that compose them. For example, sub-wavelength metal wires can be arranged to possess an effective electric permittivity that is either positive or negative at a given frequency, in contrast to the metals themselves 2. This unprecedented control over the behaviour of light can potentially lead to a number of novel devices, such as invisibility cloaks 3, negative refractive index materials 4, and lenses that resolve objects below the diffraction limit 5. However, metamaterials operating at optical, mid-infrared and terahertz frequencies are conventionally made using nano- and micro-fabrication techniques that are expensive and produce samples that are at most a few centimetres in size 6-7. Here we present a fabrication method to produce hundreds of meters of metal wire metamaterials in fiber form, which exhibit a terahertz plasmonic response 8. We combine the stack-and-draw technique used to produce microstructured polymer optical fiber 9 with the Taylor-wire process 10, using indium wires inside polymethylmethacrylate (PMMA) tubes. PMMA is chosen because it is an easy to handle, drawable dielectric with suitable optical properties in the terahertz region; indium because it has a melting temperature of 156.6 &deg;C which is appropriate for codrawing with PMMA. We include an indium wire of 1 mm diameter and 99.99% purity in a PMMA tube with 1 mm inner diameter (ID) and 12 mm outside diameter (OD) which is sealed at one end. The tube is evacuated and drawn down to an outer diameter of 1.2 mm. The resulting fiber is then cut into smaller pieces, and stacked into a larger PMMA tube. This stack is sealed at one end and fed into a furnace while being rapidly drawn, reducing the diameter of the structure by a factor of 10, and increasing the length by a factor of 100. Such fibers possess features on the micro- and nano- scale, are inherently flexible, mass-producible, and can be woven to exhibit electromagnetic properties that are not found in nature. They represent a promising platform for a number of novel devices from terahertz to optical frequencies, such as invisible fibers, woven negative refractive index cloths, and super-resolving lenses.

Metamaterials at terahertz frequencies offer unique opportunities, but are challenging to fabricate in bulk. We adapt the fabrication procedure for microstructured polymer optical fibers to inexpensively fabricate metamaterials potentially on an industrial scale. We produce polymethylmethacrylate fibers containing ~10 &mu;m diameter indium wires separated by ~100 &mu;m, which exhibit a terahertz plasmonic response.

制造超材料使用光纤拉丝法

Metamaterials are man-made composite materials, fabricated by assembling components much smaller than the wavelength at which they operate 1. They owe ...

科研

工程学

Simulation of the Planetary Interior Differentiation Processes in the Laboratory

A planetary interior is under high-pressure and high-temperature conditions and it has a layered structure. There are two important processes that led to that layered structure, (1) percolation of liquid metal in a solid silicate matrix by planet differentiation, and (2) inner core crystallization by subsequent planet cooling. We conduct high-pressure and high-temperature experiments to simulate both processes in the laboratory. Formation of percolative planetary core depends on the efficiency of melt percolation, which is controlled by the dihedral (wetting) angle. The percolation simulation includes heating the sample at high pressure to a target temperature at which iron-sulfur alloy is molten while the silicate remains solid, and then determining the true dihedral angle to evaluate the style of liquid migration in a crystalline matrix by 3D visualization. The 3D volume rendering is achieved by slicing the recovered sample with a focused ion beam (FIB) and taking SEM image of each slice with a FIB/SEM crossbeam instrument. The second set of experiments is designed to understand the inner core crystallization and element distribution between the liquid outer core and solid inner core by determining the melting temperature and element partitioning at high pressure. The melting experiments are conducted in the multi-anvil apparatus up to 27 GPa and extended to higher pressure in the diamond-anvil cell with laser-heating. We have developed techniques to recover small heated samples by precision FIB milling and obtain high-resolution images of the laser-heated spot that show melting texture at high pressure. By analyzing the chemical compositions of the coexisting liquid and solid phases, we precisely determine the liquidus curve, providing necessary data to understand the inner core crystallization process.

The high-pressure and high-temperature experiments described here mimic planet interior differentiation processes. The processes are visualized and better understood by high-resolution 3D imaging and quantitative chemical analysis.

模拟行星内部分化过程中的实验室

A planetary interior is under high-pressure and high-temperature conditions and it has a layered structure. There are two important processes that led to ...

Knowledge Based Cloud FE Simulation of Sheet Metal Forming Processes

The use of Finite Element (FE) simulation software to adequately predict the outcome of sheet metal forming processes is crucial to enhancing the efficiency and lowering the development time of such processes, whilst reducing costs involved in trial-and-error prototyping. Recent focus on the substitution of steel components with aluminum alloy alternatives in the automotive and aerospace sectors has increased the need to simulate the forming behavior of such alloys for ever more complex component geometries. However these alloys, and in particular their high strength variants, exhibit limited formability at room temperature, and high temperature manufacturing technologies have been developed to form them. Consequently, advanced constitutive models are required to reflect the associated temperature and strain rate effects. Simulating such behavior is computationally very expensive using conventional FE simulation techniques.
This paper presents a novel Knowledge Based Cloud FE (KBC-FE) simulation technique that combines advanced material and friction models with conventional FE simulations in an efficient manner thus enhancing the capability of commercial simulation software packages. The application of these methods is demonstrated through two example case studies, namely: the prediction of a material's forming limit under hot stamping conditions, and the tool life prediction under multi-cycle loading conditions.

The following paper presents a novel FE simulation technique (KBC-FE), which reduces computational cost by performing simulations on a cloud computing environment, through the application of individual modules. Moreover, it establishes a seamless collaborative network between world leading scientists, enabling the integration of cutting edge knowledge modules into FE simulations.

板料成形过程的知识基于云的有限元模拟

The use of Finite Element (FE) simulation software to adequately predict the outcome of sheet metal forming processes is crucial to enhancing the ...

Electrochemical Etching and Characterization of Sharp Field Emission Points for Electron Impact Ionization

A new variation of the drop-off method for fabricating field emission points by electrochemically etching tungsten rods in a NaOH solution is described. The results of studies in which the etching current and the molarity of the NaOH solution used in the etching process were varied are presented. The investigation of the geometry of the tips, by imaging them with a scanning electron microscope, and by operating them in field emission mode is also described. The field emission tips produced are intended to be used as an electron beam source for ion production via electron impact ionization of background gas or vapor in Penning trap mass spectrometry applications.

A method for electrochemically etching field emission tips is presented. Etching parameters are characterized and the operation of the tips in field emission mode is investigated.

电化学腐蚀和电子碰撞电离夏普场发射点的表征

A new variation of the drop-off method for fabricating field emission points by electrochemically etching tungsten rods in a NaOH solution is described. ...

Wicking Tests for Unidirectional Fabrics: Measurements of Capillary Parameters to Evaluate Capillary Pressure in Liquid Composite Molding Processes

During impregnation of a fibrous reinforcement in liquid composite molding (LCM) processes, capillary effects have to be understood in order to identify their influence on void formation in composite parts. Wicking in a fibrous medium described by the Washburn equation was considered equivalent to a flow under the effect of capillary pressure according to the Darcy law. Experimental tests for the characterization of wicking were conducted with both carbon and flax fiber reinforcement. Quasi-unidirectional fabrics were then tested by means of a tensiometer to determine the morphological and wetting parameters along the fiber direction. The procedure was shown to be promising when the morphology of the fabric is unchanged during capillary wicking. In the case of carbon fabrics, the capillary pressure can be calculated. Flax fibers are sensitive to moisture sorption and swell in water. This phenomenon has to be taken into account to assess the wetting parameters. In order to make fibers less sensitive to water sorption, a thermal treatment was carried out on flax reinforcements. This treatment enhances fiber morphological stability and prevents swelling in water. It was shown that treated fabrics have a linear wicking trend similar to those found in carbon fabrics, allowing for the determination of capillary pressure.

An experimental method to measure geometrical parameters and the apparent advancing contact angles describing capillary wicking in unidirectional synthetic and natural fabrics is proposed. These parameters are mandatory for the determination of the capillary pressures that must be taken into account for liquid composite molding (LCM) applications.

吸湿排汗试验单向织物:毛细管参数的标准评价在液体复合成型工艺毛细管压力

During impregnation of a fibrous reinforcement in liquid composite molding (LCM) processes, capillary effects have to be understood in order to identify ...

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 ...

Fabricating Reactive Surfaces with Brush-like and Crosslinked Films of Azlactone-Functionalized Block Co-Polymers

In this paper, fabrication methods that generate novel surfaces using the azlactone-based block co-polymer, poly (glycidyl methacrylate)-block-poly (vinyl dimethyl azlactone) (PGMA-b-PVDMA), are presented. Due to the high reactivity of azlactone groups towards amine, thiol, and hydroxyl groups, PGMA-b-PVDMA surfaces can be modified with secondary molecules to create chemically or biologically functionalized interfaces for a variety of applications. Previous reports of patterned PGMA-b-PVDMA interfaces have used traditional top-down patterning techniques that generate non-uniform films and poorly controlled background chemistries. Here, we describe customized patterning techniques that enable precise deposition of highly uniform PGMA-b-PVDMA films in backgrounds that are chemically inert or that have biomolecule-repellent properties. Importantly, these methods are designed to deposit PGMA-b-PVDMA films in a manner that completely preserves azlactone functionality through each processing step. Patterned films show well-controlled thicknesses that correspond to polymer brushes (~90 nm) or to highly crosslinked structures (~1-10 &#956;m). Brush patterns are generated using either the parylene lift-off or interface directed assembly methods described and are useful for precise modulation of overall chemical surface reactivity by adjusting either the PGMA-b-PVDMA pattern density or the length of the VDMA block. In contrast, the thick, crosslinked PGMA-b-PVDMA patterns are obtained using a customized micro-contact printing technique and offer the benefit of higher loading or capture of secondary material due to higher surface area to volume ratios. Detailed experimental steps, critical film characterizations, and trouble-shooting guides for each fabrication method are discussed.

Surface fabrication methods for patterned deposition of nanometer thick brushes or micron thick, crosslinked films of an azlactone block co-polymer are reported. Critical experimental steps, representative results, and limitations of each method are discussed. These methods are useful for creating functional interfaces with tailored physical features and tunable surface reactivity.

Azlactone 功能块共聚物的刷状和交联膜制备反应表面

In this paper, fabrication methods that generate novel surfaces using the azlactone-based block co-polymer, poly (glycidyl methacrylate)-block-poly (vinyl ...

Nerve Stem Cell Differentiation by a One-step Cold Atmospheric Plasma Treatment In Vitro

As the development of physical plasma technology, cold atmospheric plasmas (CAPs) have been widely investigated in decontamination, cancer treatment, wound healing, root canal treatment, etc., forming a new research field named plasma medicine. Being a mixture of electrical, chemical, and biological reactive species, CAPs have shown their abilities to enhance nerve stem cells differentiation both in vitro and in vivo and are becoming a promising way for neurological disease treatment in the future. The much more exciting news is that using CAPs may realize one-step, and safely directed, differentiation of neural stem cells (NSCs) for tissue transportation. We demonstrate here the detailed experimental protocol of using a self-made CAP jet device to enhance NSC differentiation in C17.2-NSCs and primary rat neural stem cells, as well as observing the cell fate by inverted and fluorescence microscopy. With the help of immunofluorescence staining technology, we found both the NSCs showed an accelerated differential rate than the untreated group, and ~75% of the NSCs selectively differentiated into neurons, which are mainly mature, cholinergic, and motor neurons.

Nerve Stem Cell Differentiation by a One-step Cold Atmospheric Plasma Treatment In Vitro

This protocol aims to provide detailed experimental steps of a cold atmospheric plasma treatment on neural stem cells and immunofluorescence detection for differentiation enhancement.

一步冷常压等离子体体外处理神经干细胞分化

As the development of physical plasma technology, cold atmospheric plasmas (CAPs) have been widely investigated in decontamination, cancer treatment, ...

Drawing and Hydrophobicity-patterning Long Polydimethylsiloxane Silicone Filaments

Polydimethylsiloxane (PDMS) silicone is a versatile polymer that cannot readily be formed into long filaments. Traditional spinning methods fail because PDMS does not exhibit long-range fluidity at melting. We introduce an improved method to produce filaments of PDMS by a stepped temperature profile of the polymer as it cross-links from a fluid to an elastomer. By monitoring its warm-temperature viscosity, we estimate a window of time when its material properties are amendable to drawing into long filaments. The filaments pass through a high-temperature tube oven, curing them sufficiently to be harvested. These filaments are on the order of hundreds of micrometers in diameter and tens of centimeters in length, and even longer and thinner filaments are possible. These filaments retain many of the material properties of bulk PDMS, including switchable hydrophobicity. We demonstrate this capability with an automated corona-discharge patterning method. These patternable PDMS silicone filaments have applications in silicone weavings, gas-permeable sensor components, and model microscale foldamers.

Here, we present a protocol to produce long filaments of polydimethylsiloxane (PDMS) silicone by gravity-drawing through a furnace. Filaments are on the order of hundreds of micrometers in diameter and tens of centimeters in length and are hydrophobically patternable via an Arduino-controlled corona discharge system.

拉伸和疏水图案长聚二甲基硅氧烷硅丝丝

Polydimethylsiloxane (PDMS) silicone is a versatile polymer that cannot readily be formed into long filaments. Traditional spinning methods fail because ...

Fabricating van der Waals Heterostructures with Precise Rotational Alignment

In this work we describe a technique for creating new crystals (van der Waals heterostructures) by stacking distinct ultrathin layered 2D materials. We demonstrate not only lateral control but, importantly, also control over the angular alignment of adjacent layers. The core of the technique is represented by a home-built transfer setup which allows the user to control the position of the individual crystals involved in the transfer. This is achieved with sub-micrometer (translational) and sub-degree (angular) precision. Prior to stacking them together, the isolated crystals are individually manipulated by custom-designed moving stages that are controlled by a programmed software interface. Moreover, since the entire transfer setup is computer controlled, the user can remotely create precise heterostructures without coming into direct contact with the transfer setup, labeling this technique as &#8220;hands-free&#8221;. In addition to presenting the transfer set-up, we also describe two techniques for preparing the crystals that are subsequently stacked.

In this work we describe a technique that is used to create new crystals (van der Waals heterostructures) by stacking ultrathin layered 2D materials with precise control over position and relative orientation.

使用精确旋转对齐来制造范德瓦尔斯异构结构

In this work we describe a technique for creating new crystals (van der Waals heterostructures) by stacking distinct ultrathin layered 2D materials. We ...