达里尔·博伊德和迈克尔·丹尼尔是国家研究委员会博士后研究员。这项工作得到了国家住房和住房和住房部/NRL工作单位4286和9899的支持。这些观点是作者的观点，并不代表美国海军或国防部的意见或政策。

此协议描述了使用光启动硫化物单击化学制造空心纤维。微通道有雪佛龙槽或"条纹"作为塑造功能在通道的底部和顶部（图1）。引入三种流体，并定向同心流：从内流到外流流，这些流被称为核心流、包层流和护套流体。只有包层流被聚合形成空心纤维。所选材料如下：
<ol type="a"><li>核心流体：PEG （M.W. = 400），+100毫帕。秒（20°C）</li>
	<li>包层流体：硫化物聚合物（PETMP + ODY），启动器（DMPA）</li>
	<li>护套流体：PEG （M.W. = 400），+100毫帕。秒（20°C）</li>
</ol>微通道装置由数控铣削和 PDMS 铸造制造的铝和塑料部件组装而成。流经微通道由三个注射器泵控制。
1. 微通道的设计和模拟
在微通道内计算流体速度和对流/扩散时，为每个传入流体分配适当的粘度至关重要。
<ol><li>创建要导入计算流体动力学软件 （COMSOL） 所需的微通道的计算机模型。 图1 中的示例是用欧特克发明家CAD软件生成的。下列步骤是指使用 COMSOL 多物理来计算微通道内的流体流动。</li>
	<li>将设计微通道导入 COMSOL 后，可将迭流流速率引入纳维尔-斯托克斯溶剂中。<ol>
<li>初始化程序设置并选择 3D 层流+对流/扩散方程。微通道中生成的低雷诺兹数字允许设备内完全层压流。</li>
		<li>设计一个有限元素的网格，在上面进行数字计算。网格应在属性变化迅速的区域更精细（有小的部门）。建议将成形特征和出口的网格细化为<1 μm侧长。这为核心护套流体接口提供了"清晰"的可视化。</li>
		<li>流体流动的输入材料特性， 即 粘度、扩散常数和浓度。此时，还设置了出口流的边界条件。我们建议零粘性应力来模拟一个开放的插座。</li>
		<li>通过一系列输入流速反复循环计算流体流速研究。例如，核心流体 = 7.5 μl/min，护套流体 = 30μl/分钟。</li>
		<li>导入速度场解决方案作为解决微通道流对流/扩散特性的初始值。对流/扩散问题的解决方案将说明核心-护套流体接口，并有助于预测最终流体流和产生的纤维的形状。</li>
	</ol>
</li>
</ol>从计算结果中，可以预测所需的成型特征数量和类型，以达到所需的光纤形状。流体流速输入也将与生成纤维所需的流速相关。通过这些预测，可以制造出用于挤出聚合物纤维的微通道设备。
2. 护套流器件的制造
可将直接微磨、热浮雕和/或聚合物铸造相结合，以创建护套流装置的组件。根据资源，相应地选择策略。举例是使用计算机数字代码 （CNC） 的直接铣削过程。有五层（从上到下），这是在 图2：1中描绘的。入口夹头（铝），2。紧固板（铝），3.微通道顶层（环烯烃共聚物、COC 或 PDMS），4.微通道底层（COC或聚醚醚酮，PEEK），5.紧固板（铝）。（直接铣削的示例文件可在支持信息中以*.stl 格式提供）
<ol><li>使用与 COMSOL 模拟兼容的设计，通过计算机辅助绘图 （CAD） 开发系统的 3D 模型。为设备的每一层创建一个单独的 CAD 文件。</li>
	<li>当要通过直接微铣制造一层时，将 CAD 模型导入计算机辅助加工应用程序，以生成数字代码 （NC），由计算机数控 （CNC） 磨坊解释该数字代码以生产设备。</li>
	<li>获得5张30.5厘米×30.5厘米的牺牲层材料，最小厚度为3.2毫米。</li>
	<li>获得 1 张 COC、PEEK、铝和聚（甲基甲基酸酯）30.5 厘米× 30.5 厘米和 3.2 毫米厚。</li>
	<li>获得1片30.5厘米×30.5厘米厚和9.5毫米厚的铝板。</li>
	<li>将每张床单在步骤 2.4-2.5 中贴在一张从步骤 2.3 到双面胶粘剂的牺牲品表上。确保最多存在 2.5 厘米的外部未绑带边框。胶带用于在磨削时将工作材料保持到位，并在磨削部分在磨削周期结束时从库存材料中切开后保护它。</li>
	<li>将 COC + 牺牲库存固定到 CNC 磨坊的表中，加载数字代码 （NC） 中引用的工具，并将工具和库存（工作）材料校准为 x、y 和 z。</li>
	<li>加载NC代码并碾磨COC层。</li>
	<li>从磨坊中取出材料板，并小心地从基板上取下加工过的部分。在此过程中，磨坊冷却剂将饱和部分和库存。在轻轻取出部分之前彻底冲洗。用温和的洗涤剂清洗，然后用70%的异丙醇清洗。温和的洗涤剂会去除油性残留物，酒精会去除残留的粘合剂。如果毛刺被困在微观结构中，则可能需要声波化来驱赶它们。</li>
	<li>对于用于创建护套流设备的其他每个图层重复步骤 2.7 和 2.9。</li>
	<li>除 PMMA 层外，已为此准备到此点的每个图层将直接用于设备。PMMA 将用于准备 PDMS 层，将 10 个部件 Sylgard 184 碱基与 1 个零件固化剂相结合，并通过搅拌彻底混合。如果人们宁愿用类似垫片的 PDMS 材料替换其中一个 COC 层，则提供此信息。</li>
	<li>将 Sylgard 184 倒入之前准备的 PMMA 模具腔中，确保消除气泡。如有必要，气泡可以在真空中去除。PDMS 可在室温下固化 48 小时，45 分钟在 100 °C，20 分钟在 125 °C，或 10 分钟在 150 °C。</li>
</ol>3. 护套流设备总成
<ol><li>通过在底部放置一个紧固板，然后将 COC 层放在另一个 COC 层，以及剩余的紧固板（图 2），从下到上组装护套流装置。确保成形槽沿通道边缘相互对齐，并确保 COC 层中流体成形几何形状完全重叠。解剖显微镜可用于辅助对齐。</li>
	<li>在设备中心插入螺栓，并手紧固螺母和螺栓，将设备夹在一起。</li>
	<li>从左到右交替，从中心向外重复步骤 3.2 以锁定对齐并防止泄漏。到达安装孔时加入进液夹头，并以交替方式继续安装螺钉。</li>
	<li>使用标准 HPLC 配件将护套流装置与包含护套流体和预聚合物溶液的管子和注射器接口。手紧固足以满足所有连接。</li>
	<li>使用环形支架和夹子垂直安装设备。确保设备使用最上面部分的水平是垂直的。如果护套流动装置不是垂直的，纤维可能会接触微通道壁并导致堵塞。</li>
	<li>将紫外线源垂直定位在护套流装置的 COC 表面约 1 厘米处，以便对微通道的最后 3-5 厘米进行辐照。紫外线源应校准，以提供 ±200 mW/cm2。</li>
</ol>4. 解决方案准备
如前所述，许多材料可用于使用类似的协议和护套流系统创建微纤维，但硫化物化学在这里使用。在开始纤维挤出过程之前立即准备前聚合物溶液，以避免在存储中随着时间的推移可能出现的粘度增加。
<ol><li>准备聚乙二醇400（PEG 400）的亚力克作为护套流体。</li>
	<li>用PEG 400填充1ml Luer-尖注射器，作为不可填充的核心液体，并填充一个30毫升的Luer尖注射器与PEG 400作为护套流体。</li>
	<li>准备一个前聚合物溶液，其中包含 0.01 熔醇五角星四重奏 3 甲基苯丙酸酯 （PETMP） 和 0.01 醇 1，7-八角星 （ODY）。确保这两个组件在整个实验中混合良好，最大限度地减少所有聚合物试剂暴露在紫外光源中，包括环境光（例如 用铝箔包装注射器）。</li>
	<li>用 4 x 10-4 熔胶 2，2-二甲基二甲基丙酮 （DMPA） 光启动器补充 PETMP/ODY 解决方案。继续确保解决方案混合良好，并且通过用铝箔覆盖容器，不会暴露在紫外线下。</li>
	<li>用前聚合物溶液装载 5 毫升铝箔包装的 Luer 尖注射器。</li>
</ol>5. 微纤维生产（视频焦点）
<ol><li>确保微流体通道的出口与收集浴缸中的溶液接触（图 3）。对于复杂的结构，收集浴中的溶液应与核心和护套流体粘度匹配，但对于简单的空心纤维，水就足够了。</li>
	<li>将芯、包层和护套液体注射器泵分别注入 1、30 和 120 μl/min。确保各自的注射器直径已正确输入注射器泵。</li>
	<li>将注射器安装到相应的注射器泵中，并将其连接到护套流量装置，并配有紫外线保护 Tygon 管。</li>
	<li>启动护套流体，为护套流动装置提供素数，并消除系统中的空气。目视检查微通道，确保在进入下一步之前，微通道中不会存在气泡。特别注意条纹。解剖显微镜可用于辅助微通道检查。如果存在气泡，请通过旋转和 / 或在时轻轻敲击来搅拌设备，以冲洗设备中的气泡。</li>
	<li>启动包层流体，也使流量稳定下来。在进入下一步之前，确保微通道中不会存在气泡。特别注意塑造槽。如果存在气泡，在流动时搅拌设备，将气泡冲出设备。</li>
	<li>最后，启动核心流体：再次，确保系统中不存在气泡。</li>
	<li>打开紫外线源，观察收集浴，以持续生产空心微纤维（图4A），因为它与护套流体一起喷射。使用改良的铲子或接种环从收集浴缸中检索纤维，并允许在电动滑阀上收集连续纤维（图 3）。</li>
</ol>

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S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Design+and+fabrication+of+uniquely+shaped+thiol-ene+microfibers+using+a+two-stage+hydrodynamic+focusing+design.">Design and fabrication of uniquely shaped thiol-ene microfibers using a two-stage hydrodynamic focusing design.</a> Lab Chip. 13, 3105-3110 (2013).</li></ol>

参考文献中列出的专利可获得海军部<a href="http://www.nrl.navy.mil/doing-business/tech-transfer/">（http://www.nrl.navy.mil/doing-business/tech-transfer/）</a>的许可。

与其他纤维制造技术相比，采用护套流法制造聚合物纤维具有多重优点。其中一个优点是能够使用各种试剂组合制造纤维。虽然这里提出了一个特定的硫醇-yne组合，但其他几个硫醇咔嗒声（包括硫醇-ene）化学组合同样有效。只要护套溶液与要聚合的核心材料混杂在一起，就可以使用多种其他组合来生产纤维。只要将这些添加剂对前聚合物溶液粘度的贡献考虑在内，纳米纤维、颗粒和细胞等内含物也是可能的。
Thiol 点击化学是点击化学家族的子集，其中具有硫醇组的复合物可以通过紫外光光聚合与烷基（双键）或烷基（三键）功能组共用地连接到复合体中。涉及藻类的反应称为硫利安反应，涉及阿尔基内斯的反应称为硫化物反应。紫外线照射时，一个 pi 键（来自烷基或烷基尼）将附着在一个硫醇组上。该过程非常适合响应的点击系列，并已有效地用于我们的微流体通道，从众多的硫醇点击启动组件中产生各种形状的纤维（如 圆形、带状、双锚）。
与大多数其他类似工艺相比，此处概述的方法的一个具体优势是能够控制所生产的纤维的形状和大小（图 4A-H）。通过设计一个有条纹、切夫龙或鱼骨的通道，产生的纤维将具有不同的横截面形状。一般来说，条纹可用于产生圆形或引入额外的护套流，以完全包围以前形状的溪流，并在聚合之前将它们从通道壁上移开。雪佛龙减少了形状流中心的垂直维度，保持了水平对称性。鱼骨减少了形状流一侧的垂直尺寸，产生不对称。这些成型工具可以混合成无数的组合。等效功能的数量（即 7个切夫龙与10个切夫龙）也可用于生产具有不同横截面特征的纤维。
除了控制纤维形状的能力外，所呈现的纤维制造方法还能够控制所制造的纤维的大小，即使使用单个护套流总成（如图 1）。调整护套：核心流速比是制造不同横截面区域的纤维的一种手段。还可以通过调整通道设计来控制光纤的大小，从而具有额外的护套阶段。无论成型是在一个阶段还是多个阶段进行，都可以使用简单的最后阶段来减少核心的大小而不更改形状。
使用这种微流体通道设计，多种试剂组合可用于生产各种形状和尺寸的纤维，这种易用性将在从组织工程到光通信到智能纺织品等广泛应用中被证明是有用的。

组织脚手架1、复合材料2、光通信3、导导混合材料4是利用专用聚合物纤维进行研究的领域。传统的纤维制造方法包括熔体挤出、纺纱、绘图、铸造和电纺。这些方法产生的大多数聚合物纤维都表现出聚合物和空气在制造过程中表面张力引起的圆形横截面。然而，非横截面的纤维可以增强复合材料5，6的机械特性，增加表面面积与体积的比例，控制湿润或芯7，并用作波导8或极化9。
利用一条流（护套流）来包围和塑造另一个流（核心流）的微流系统生产专用聚合物纤维很有吸引力，因为这种条件温和，而且能够持续生产高可重复性纤维。初步实验产生的圆形纤维的大小取决于前聚合物和护套流体10-12的相对流速。发现微流道顶部和底部的凹槽会偏转护套，为核心流13，14 生成预定形状，从而产生更复杂的纤维形状10-12，15-17的技术。
NRL 调查人员已经演示了以下关键技术特征13-21：
<ol><li>各种塑造功能可用于引导护套流体塑造核心流：凹槽或脊可以配置为条纹、切夫龙或鱼骨。</li>
	<li>这些功能的工具箱可以映射到所需的流结果。</li>
	<li>微通道可以使用光刻、成型、铣削或印刷技术创建。基板材料不得在预聚合物或护套溶液中溶解或侵蚀，对于光启动聚合物，外部层必须透明于紫外线。</li>
	<li>单组成型功能创建的形状可以通过更改流道的流速来更改。COMSOL 多物理模拟微通道中的流体流能够预测由此产生的流体和纤维形状。</li>
	<li>匹配护套和核心流体的粘度和相位（亲水性）对于避免因流体界面剪切应变而引起的屈曲型不稳定至关重要。如果发生大粘度或相错配粘性屈曲，可能会变形最终纤维形状，甚至堵塞微通道。</li>
	<li>纤维可以通过铸造或聚合形成，但聚合提供了对形状的更多控制。</li>
	<li>聚合（核心流体的凝固）必须在退出微通道之前发生。但是，通道内的聚合速度较慢可能导致粘度增加，影响纤维形状，甚至堵塞通道。必须严格控制聚合事件的时间和地点。</li>
	<li>由于其快速反应动力学，照片诱导的自由基聚合物，特别是硫醇基点击化学，特别适合纤维生产。</li>
	<li>在制造过程中可以更改相对流速率，以创建非单位纤维直径。</li>
	<li>由于以下原因，可将多个成型功能组集成到单个通道中：<ol type="a">
<li>将成型和大小功能分开</li>
		<li>创建多层或空心纤维</li>
		<li>从单个微流体通道生产多种纤维</li>
	</ol>
</li>
	<li>在极化光下，聚合物中加入的液晶中生代在极化光下表现出双裂，这表明聚合物分子可以沿着纤维轴对齐。</li>
	<li>细胞可以融入生物相容水凝胶预聚物中，并在高生存能力22的制造过程中存活下来。</li>
</ol>当使用护套流的水动力学聚焦来制造聚合物纤维以形成前聚合物流时，选择聚合物材料是实际的第一步。应在以下指南中确定适当的聚合物、相应的启动器化学和护套液：
<ol><li>聚合物和护套液是可混杂的，粘度相似。例如，水性单体溶液可以将水用作可行的护套流体，但不能将六烷用作护套液。</li>
	<li>聚合机制必须具有足够快的速度动力学，在形成后和纤维退出通道之前立即凝固核心流体。</li>
</ol>选定材料后，必须设计微通道以生成所需的纤维形状和尺寸。为了确定所需的成形特征（条纹、刺骨、切夫龙），可以使用计算流体动力学软件来预测流体流动模式。成形功能将护套流体输送到核心流体周围。一般来说，条纹将护套流体从一侧移动到另一侧，而鱼骨和雪佛龙则将液体从两侧移向通道的顶部和/或底部，然后直接回到通道的中心。通道顶部和底部的重复槽数影响护套流体的定向程度。核心流体和护套流体的流量比率也调解了影响。使用 COMSOL 多物理软件进行模拟已证明在评估塑造特征和流速比的相互作用以预测横截面形状方面是可靠的。这些模拟还提供了有用的见解，了解溶解物在核心和护套之间的扩散与通道的大小，粘度和流速建议。
如果需要复杂的形状，例如博伊德等人描述的"双锚 "。23，区分成型和尺寸的功能是有用的。复杂的形状可以创建一组功能，然后战略性地放置在第二个护套流入口处的单槽结构可用于减少聚合流的横截面区域，而不会显著改变其形状。
复杂微通道设计的另一个例子可以生成多层纤维。在此设计中，引入了连续的成型功能和额外的包层流体。这些同心流可以凝固成固体核心包层纤维或空心管。下方将介绍此设备的示例。
一旦选择了微流体装置的设计，就可以开始微通道制造过程。可使用的制造工具包括软平版印刷、数控铣削、热浮雕和 3D 打印。无论使用的工具如何，重要的是要认识到，意外引入微流体通道壁的特征也会引导护套流，并可能导致使用该设备制造的所有纤维的横截面形状发生高度可重复的偏差。还应仔细选择微通道基材，以物理坚固、化学惰性和抗紫外线损伤。例如，聚二甲基硅氧烷（PDMS）可以很容易地铸造，提供类似垫片的密封，并且紫外线透明：PDMS 对通道的透明顶部有用，但对通道的两侧和底部没有用处，后者需要更刚性。
最终，通过以流体动力学模拟预测的流速引入正确选择的核心和护套流体，成形功能将生成适当的流体轮廓，下游紫外线固化灯将凝固设计聚合物纤维。从通道中连续挤出聚合纤维只能受流体储层体积的限制，提供可重复的纤维长度。

<table border="0" cellpadding="0" cellspacing="0" width="685">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="43">
			<td height="43" style="height:43px;width:197px;">Pentaerythritol tetrakis 3-mercaptopropionate</td>
			<td style="width:99px;">Sigma-Aldrich</td>
			<td style="width:139px;">381462</td>
			<td style="width:251px;">See references</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:197px;">1.7-Octadiyne</td>
			<td style="width:99px;">Sigma-Aldrich</td>
			<td style="width:139px;">161292</td>
			<td style="width:251px;">See references</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:197px;">2,2-Dimethoxy-2-phenylacetophenone</td>
			<td style="width:99px;">Sigma-Aldrich</td>
			<td style="width:139px;">196118</td>
			<td style="width:251px;">See references</td>
		</tr>
		<tr height="64">
			<td height="64" style="height:64px;width:197px;">Polyethylene glycol 400</td>
			<td style="width:99px;">Sigma-Aldrich</td>
			<td style="width:139px;">202398</td>
			<td style="width:251px;">Polyethylene glycol 200 or 600, dextrose, or glycerol may be substituted</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:197px;">Sylgard 184&#160;</td>
			<td style="width:99px;">Sigma-Aldrich</td>
			<td style="width:139px;">761036</td>
			<td style="width:251px;">QSIL 216, OptiTec 7020, or GS RTV 615 may be substituted</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;"></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="22">
			<td colspan="2" height="22" style="height:22px;">Table of Specific Equipment</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:197px;">Equipment</td>
			<td style="width:99px;">Company</td>
			<td style="width:139px;">Catalogue number</td>
			<td style="width:251px;">Comments</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:197px;">MiniMill</td>
			<td style="width:99px;">Haas</td>
			<td style="width:139px;">MINIMILL</td>
			<td style="width:251px;">Any NC code interpreting 2.5 axis (or higher) mill may be substituted</td>
		</tr>
		<tr height="85">
			<td height="85" style="height:85px;width:197px;">Syringe pumps (3)</td>
			<td style="width:99px;">Harvard Apparatus</td>
			<td style="width:139px;">702212</td>
			<td style="width:251px;">Syringe pumps that can be programmed to deliver the desired volume flow rates may be substituted</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:197px;">Tygon tubing (3 m)</td>
			<td style="width:99px;">Fisher Scientific</td>
			<td style="width:139px;">14-169-13A</td>
			<td style="width:251px;">NA</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:197px;">PEEK tubing</td>
			<td style="width:99px;">Upchurch Scientific</td>
			<td style="width:139px;">1435</td>
			<td style="width:251px;">NA</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:197px;">HPLC fittings</td>
			<td style="width:99px;">Upchurch Scientific</td>
			<td style="width:139px;">1457</td>
			<td style="width:251px;">NA</td>
		</tr>
		<tr height="67">
			<td height="67" style="height:67px;width:197px;">BlueWave 200 UV lamp with stand and light guides</td>
			<td style="width:99px;">Dymax</td>
			<td style="width:139px;">38905; 38477; 39700</td>
			<td style="width:251px;">Any guided UV source that delivers 300-450 nm, &#62;200 mW/cm2 may be substituted</td>
		</tr>
		<tr height="64">
			<td height="64" style="height:64px;width:197px;">500 ml beaker</td>
			<td style="width:99px;">Fisher Scientific</td>
			<td style="width:139px;">FB-100-600</td>
			<td style="width:251px;">Any vessel of approximately the same size and shape may be substituted</td>
		</tr>
		<tr height="85">
			<td height="85" style="height:85px;width:197px;">Ring stand</td>
			<td style="width:99px;">Fisher Scientific</td>
			<td style="width:139px;">S47807</td>
			<td style="width:251px;">Any ring stand capable of mounting a clamped sheath flow apparatus above the level of the syringe pumps may be substituted</td>
		</tr>
		<tr height="64">
			<td height="64" style="height:64px;width:197px;">Ring stand clamp holder (2)</td>
			<td style="width:99px;">Fisher Scientific</td>
			<td style="width:139px;">S02625</td>
			<td style="width:251px;">Any ring stand clamp holder capable of holding the clamps may be substituted</td>
		</tr>
		<tr height="85">
			<td height="85" style="height:85px;width:197px;">Ring stand clamps (2)</td>
			<td style="width:99px;">Fisher Scientific</td>
			<td style="width:139px;">02-216-352</td>
			<td style="width:251px;">Any ring stand clamp capable of holding the clamped sheath flow apparatus and light guides may be substituted</td>
		</tr>
		<tr height="64">
			<td height="64" style="height:64px;width:197px;">1, 5, and 60 ml Syringes</td>
			<td style="width:99px;">Fisher Scientific</td>
			<td style="width:139px;">14-823-16H; 14-823-16D; 14-820-11</td>
			<td style="width:251px;">Any syringe with known inner diameter and sufficient volume may be substituted</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:197px;">Poly(methylmethacrylate) (3.2 mm)</td>
			<td style="width:99px;">McMaster-Carr</td>
			<td style="width:139px;">8560K239</td>
			<td style="width:251px;">Polycarbonate and cyclic olefin copolymer may be substituted</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:197px;">Polyether ether ketone (3.2 mm)</td>
			<td style="width:99px;">McMaster-Carr</td>
			<td style="width:139px;">8504K25</td>
			<td style="width:251px;">Solvent resistant machinable materials may be substituted</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:197px;">Aluminum (3.2, 9.5 mm)</td>
			<td style="width:99px;">McMaster-Carr</td>
			<td style="width:139px;">1651T41; 9246K23</td>
			<td style="width:251px;">Substitute other materials as needed</td>
		</tr>
	</tbody>
</table>

microfluidic fabrication of polymeric and biohybrid fibers with predesigned size and shape

以低雷诺兹数通过微流体通道的"护套"流体可以围绕另一个"核心"流进行定向，并用于支配核心流的形状和直径。微流道顶部和底部的凹槽设计用于引导护套流体并塑造核心流体。通过匹配护套和核心流体的粘度和亲水性，最大限度地减少面间效应，形成复杂的流体形状。控制护套和核心流体的相对流速决定核心流体的横截面区域。纤维的尺寸从 300 nm 到 ~1 mm 不等，纤维横截面可以是圆形、平坦的、方形的或复杂的，就像双锚纤维一样。形成区域下游核心流体的聚合凝固了纤维。光启动咔嗒化学非常适合通过紫外光照射快速聚合核心流体。各种形状的纤维都是从包括液晶、聚（甲基甲基丙烯）、硫烯和硫醇-恩脂、聚乙二醇和水凝胶衍生物在内的聚合物清单中产生的。在成形过程中最小剪切和温和的聚合条件也使制造过程非常适合细胞和其他生物成分的封装。

简单的两级设计，使用成型槽和三个溶液输入，用于创建空心纤维（图1）。COMSOL 模拟用于确定适当的流速比率，以获得所需的横截面大小（图 1， ESI 视频）。铣削和成型的组合产生了护套流总成组件，以制造纤维（图2）。完整的装配包括护套流装置、光纤耦合紫外线激光器、三个注射器泵、一个收集浴池（烧嘴）和一个光纤收集线轴（图3）。
包层材料的聚合是由紫外光源启动的，空心纤维从微通道挤出到收集池中。纤维形成并不断收集，直到紫外线关闭。纤维的生产持续了几分钟，并产生了一个超过一米长的单个纤维。在这些条件下制造的纤维直径约为200微米。光纤结构采用光学和电子显微镜可视化。纤维有一个椭圆形的空心核心。毛细细金像用于将液体和气泡引入纤维内部，并确认空心结构在纤维长度（图4A）上是连续的。
<img alt="Figure 1" fo:content-width="5in" fo:src="/files/ftp_upload/50958/50958fig1highres.jpg" src="/files/ftp_upload/50958/50958fig1.jpg"> 图1。护套流设备设计和 COMSOL 数据。选择带直槽的两节制造装置以产生空心纤维（在 x 轴 45°旋转）。左侧的 COMSOL 模拟演示了核心：包层：护套流速比（低于每个模拟的数字）如何影响空心纤维的最终大小。微通道横截面为1毫米×0.75毫米，条纹宽0.38毫米，深250微米。条纹相对于通道的∠45°。
<img alt="Figure 2" fo:content-width="5in" src="/files/ftp_upload/50958/50958fig2highres.jpg" width="500"> 图2。护套流装配的爆炸视图。从上到下，（A）入口夹头、（B）紧固板、（C）微通道盖、（D）微通道底座、（E）紧固板。这些部件分别由铝、铝、COC（或 PDMS）、COC（或 PEEK）和铝制成。定期间隔的孔可容纳装配螺丝。
<img alt="Figure 3" fo:content-width="5in" fo:src="/files/ftp_upload/50958/50958fig3highres.jpg" src="/files/ftp_upload/50958/50958fig3.jpg"> 图3。布局照片和示意图概述。设置包括垂直固定在含水浴的烧瓶上护套流总成、用于光聚合的光纤激光器、三个注射器泵和用于收集聚合物纤维的主轴。插图显示带有紫外线照明的制造装配。（A） 护套和核心入口 ， （B） 微流体通道 ， （C） 紫外线 ， （D） 收集储液层 ， （E） 聚合纤维被收集。
<img alt="Figure 4" fo:content-width="5in" fo:src="/files/ftp_upload/50958/50958fig4highres.jpg" src="/files/ftp_upload/50958/50958fig4.jpg"> 图4。使用流体动力聚焦制作的光纤和扫描电子显微图图像。纤维采用流体动力聚焦制成，形状如下：（A）空心管、（B）矩形带、（C）细弹性丝带、（D）三角形、（E）肾豆、（F）珍珠串、（G）带嵌入式碳纳米纤维的圆形纤维和（H）双锚形。纤维由各种材料制成，包括丙烯酸酯、甲基丙烯酸酯和硫烯。
 <a href="/files/ftp_upload/50958/ESI_Video.mp4" target="_blank">ESI 视频。</a> COMSOL 多物理中产生的切片图描绘了一半的微通道，其中核心、包层和护套流体进入设备并穿过两级换流对角线条纹槽。模拟的核心、包层和护套流量分别为 1、28 和 256 μl/min。该视频实时表示约 6 秒，出于说明目的减慢 6 倍。

Watch this Scientific Journal Video about Microfluidic Fabrication of Polymeric and Biohybrid Fibers with Predesigned Size and Shape at JoVE.com

Microfluidic Fabrication of Polymeric and Biohybrid Fibers with Predesigned Size and Shape

两个相邻的流体通过凹槽的微流体通道，可以定向形成围绕前聚合物核心的护套：从而确定形状和横截面。光启动聚合，如硫醇点击化学，非常适合快速凝固核心流体成微纤维与预定的大小和形状。

预设计尺寸和形状的聚合物纤维和生物贿赂纤维的微流体制造

A &#8220;sheath&#8221; fluid passing through a microfluidic channel at low Reynolds number can be directed around another &#8220;core&#8221; stream and ...

microfluidic-fabrication-polymeric-biohybrid-fibers-with-predesigned

Research

JoVE Journal

Bioengineering

8.4K 次观看.  US Naval Research Laboratory. 两个相邻的流体通过凹槽的微流体通道，可以定向形成围绕前聚合物核心的护套：从而确定形状和横截面。光启动聚合，如硫醇点击化学，非常适合快速凝固核心流体成微纤维与预定的大小和形状。

视频: Microfluidic Fabrication of Polymeric and Biohybrid Fibers with Predesigned Size and Shape

Microfluidic Chip Fabrication and Method to Detect Influenza

Fast and effective diagnostics play an important role in controlling infectious disease by enabling effective patient management and treatment. Here, we present an integrated microfluidic thermoplastic chip with the ability to amplify influenza A virus in patient nasopharyngeal (NP) swabs and aspirates. Upon loading the patient sample, the microfluidic device sequentially carries out on-chip cell lysis, RNA purification and concentration steps within the solid phase extraction (SPE), reverse transcription (RT) and polymerase chain reaction (PCR) in RT-PCR chambers, respectively. End-point detection is performed using an off-chip Bioanalyzer (Agilent Technologies, Santa Clara, CA). For peripherals, we used a single syringe pump to drive reagent and samples, while two thin film heaters were used as the heat sources for the RT and PCR chambers. The chip is designed to be single layer and suitable for high throughput manufacturing to reduce the fabrication time and cost. The microfluidic chip provides a platform to analyze a wide variety of virus and bacteria, limited only by changes in reagent design needed to detect new pathogens of interest.

An integrated microfluidic thermoplastic chip has been developed for use as a molecular diagnostic. The chip performs nucleic acid extraction, reverse transcriptase, and PCR. Methods for fabricating and running the chip are described.

微流控芯片的制备及方法检测甲型流感

Fast  and effective diagnostics play an important role in controlling infectious  disease by enabling effective patient management and treatment. Here, we ...

科研

生物工程

Microfluidic Picoliter Bioreactor for Microbial Single-cell Analysis: Fabrication, System Setup, and Operation

In this protocol the fabrication, experimental setup and basic operation of the recently introduced microfluidic picoliter bioreactor (PLBR) is described in detail. The PLBR can be utilized for the analysis of single bacteria and microcolonies to investigate biotechnological and microbiological related questions concerning, e.g.&#160;cell growth, morphology, stress response, and metabolite or protein production on single-cell level. The device features continuous media flow enabling constant environmental conditions for perturbation studies, but in addition allows fast medium changes as well as oscillating conditions to mimic any desired environmental situation. To fabricate the single use devices, a silicon wafer containing sub micrometer sized SU-8 structures served as the replication mold for rapid polydimethylsiloxane casting. Chips were cut, assembled, connected, and set up onto a high resolution and fully automated microscope suited for time-lapse imaging, a powerful tool for spatio-temporal cell analysis. Here, the biotechnological platform organism Corynebacterium glutamicum&#160;was seeded into the PLBR and cell growth and intracellular fluorescence were followed over several hours unraveling time dependent population heterogeneity on single-cell level, not possible with conventional analysis methods such as flow cytometry. Besides insights into device fabrication, furthermore, the preparation of the preculture, loading, trapping of bacteria, and the PLBR cultivation of single cells and colonies is demonstrated. These devices will add a new dimension in microbiological research to analyze time dependent phenomena of single bacteria under tight environmental control. Due to the simple and relatively short fabrication process the technology can be easily adapted at any microfluidics lab and simply tailored towards specific needs.

In this protocol the fabrication, setup and basic operation of a microfluidic picoliter bioreactor (PLBR) for single-cell analysis of prokaryotic microorganisms is introduced. Industrially relevant microorganisms were analyzed as proof of principle allowing insights into growth rate, morphology, and phenotypic heterogeneity over certain time periods, hardly possible with conventional methods.

In this protocol the fabrication, experimental setup and basic operation of the recently introduced microfluidic picoliter bioreactor (PLBR) is described ...

Polymeric Microneedle Array Fabrication by Photolithography

This manuscript describes the fabrication of polymeric microneedle (MN) arrays by photolithography. It involves a simple mold-free process by using a photomask consisting of embedded micro-lenses. Embedded micro-lenses were found to influence MN geometry (sharpness). Robust MN arrays with tip diameters ranging between 41.5 &#181;m &#177; 8.4 &#181;m and 71.6 &#181;m &#177; 13.7 &#181;m, with two different lengths (1,336 &#181;m &#177; 193 &#181;m and 957 &#181;m &#177; 171 &#181;m) were fabricated. These MN arrays may provide potential applications in delivery of low molecular and macromolecular therapeutic agents through skin.

Here, we present a protocol describing a mold-free fabrication process of the polymeric microneedles by photolithography.

聚合物微针阵列制造用光刻

This manuscript describes the fabrication of polymeric microneedle (MN) arrays by photolithography. It involves a simple mold-free process by using a ...

Fabrication of a Bioactive, PCL-based "Self-fitting" Shape Memory Polymer Scaffold

Tissue engineering has been explored as an alternative strategy for the treatment of critical-sized cranio-maxillofacial (CMF) bone defects. Essential to the success of this approach is a scaffold that is able to conformally fit within an irregular defect while also having the requisite biodegradability, pore interconnectivity and bioactivity. By nature of their shape recovery and fixity properties, shape memory polymer (SMP) scaffolds could achieve defect &#8220;self-fitting.&#8221; In this way, following exposure to warm saline (~60 &#186;C), the SMP scaffold would become malleable, permitting it to be hand-pressed into an irregular defect. Subsequent cooling (~37 &#186;C) would return the scaffold to its relatively rigid state within the defect. To meet these requirements, this protocol describes the preparation of SMP scaffolds prepared via the photochemical cure of biodegradable polycaprolactone diacrylate (PCL-DA) using a solvent-casting particulate-leaching (SCPL) method. A fused salt template is utilized to achieve pore interconnectivity. To realize bioactivity, a polydopamine coating is applied to the surface of the scaffold pore walls. Characterization of self-fitting and shape memory behaviors, pore interconnectivity and in vitro bioactivity are also described.

Fabrication of a Bioactive, PCL-based &quot;Self-fitting&quot; Shape Memory Polymer Scaffold

Scaffolds capable of fitting within cranio-maxillofacial (CMF) bone defects while exhibiting osteoconductivity and bioactivity are of interest. This protocol describes the preparation of a shape memory scaffold based on polycaprolactone diacrylate (PCL-DA) using a solvent-casting particulate-leaching (SCPL) method employing a fused salt template and application of a bioactive polydopamine coating.

生物活性，PCL为基础的“自我装配”形状记忆聚合物支架的制备

Tissue engineering has been explored as an alternative strategy for the treatment of critical-sized cranio-maxillofacial (CMF) bone defects. Essential to ...

A Microfluidic Platform for Precision Small-volume Sample Processing and Its Use to Size Separate Biological Particles with an Acoustic Microdevice

A major advantage of microfluidic devices is the ability to manipulate small sample volumes, thus reducing reagent waste and preserving precious sample. However, to achieve robust sample manipulation it is necessary to address device integration with the macroscale environment. To realize repeatable, sensitive particle separation with microfluidic devices, this protocol presents a complete automated and integrated microfluidic platform that enables precise processing of 0.15&#8211;1.5 ml samples using microfluidic devices. Important aspects of this system include modular device layout and robust fixtures resulting in reliable and flexible world to chip connections, and fully-automated fluid handling which accomplishes closed-loop sample collection, system cleaning and priming steps to ensure repeatable operation. Different microfluidic devices can be used interchangeably with this architecture. Here we incorporate an acoustofluidic device, detail its characterization, performance optimization, and demonstrate its use for size-separation of biological samples. By using real-time feedback during separation experiments, sample collection is optimized to conserve and concentrate sample. Although requiring the integration of multiple pieces of equipment, advantages of this architecture include the ability to process unknown samples with no additional system optimization, ease of device replacement, and precise, robust sample processing.

This protocol describes a system architecture for performing automated small volume (0.15&#8211;1.5 ml) particle separations using a microfluidic device, and discusses methods to optimize acoustofluidic device performance and operation.

微流体平台精密小批量来样加工及它的使用尺寸分离生物颗粒的声微型

A major advantage of microfluidic devices is the ability to manipulate small sample volumes, thus reducing reagent waste and preserving precious sample. ...

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 ...

Fabrication of Three-dimensional Paper-based Microfluidic Devices for Immunoassays

Paper wicks fluids autonomously due to capillary action. By patterning paper with hydrophobic barriers, the transport of fluids can be controlled and directed within a layer of paper. Moreover, stacking multiple layers of patterned paper creates sophisticated three-dimensional microfluidic networks that can support the development of analytical and bioanalytical assays. Paper-based microfluidic devices are inexpensive, portable, easy to use, and require no external equipment to operate. As a result, they hold great promise as a platform for point-of-care diagnostics. In order to properly evaluate the utility and analytical performance of paper-based devices, suitable methods must be developed to ensure their manufacture is reproducible and at a scale that is appropriate for laboratory settings. In this manuscript, a method to fabricate a general device architecture that can be used for paper-based immunoassays is described. We use a form of additive manufacturing (multi-layer lamination) to prepare devices that comprise multiple layers of patterned paper and patterned adhesive. In addition to demonstrating the proper use of these three-dimensional paper-based microfluidic devices with an immunoassay for human chorionic gonadotropin (hCG), errors in the manufacturing process that may result in device failures are discussed. We expect this approach to manufacturing paper-based devices will find broad utility in the development of analytical applications designed specifically for limited-resource settings.

We detail a method to fabricate three-dimensional paper-based microfluidic devices for use in the development of immunoassays. Our approach to device assembly is a type of multilayer, additive manufacturing. We demonstrate a sandwich immunoassay to provide representative results for these types of paper-based devices.

三维纸基微流体装置的制造用于免疫分析

Paper wicks fluids autonomously due to capillary action. By patterning paper with hydrophobic barriers, the transport of fluids can be controlled and ...

Dry Film Photoresist-based Electrochemical Microfluidic Biosensor Platform: Device Fabrication, On-chip Assay Preparation, and System Operation

In recent years, biomarker diagnostics became an indispensable tool for the diagnosis of human disease, especially for the point-of-care diagnostics. An easy-to-use and low-cost sensor platform is highly desired to measure various types of analytes (e.g., biomarkers, hormones, and drugs) quantitatively and specifically. For this reason, dry film photoresist technology - enabling cheap, facile, and high-throughput fabrication - was used to manufacture the microfluidic biosensor presented here. Depending on the bioassay used afterwards, the versatile platform is capable of detecting various types of biomolecules. For the fabrication of the device, platinum electrodes are structured on a flexible polyimide (PI) foil in the only clean-room process step. The PI foil serves as a substrate for the electrodes, which are insulated with an epoxy-based photoresist. The microfluidic channel is subsequently generated by the development and lamination of dry film photoresist (DFR) foils onto the PI wafer. By using a hydrophobic stopping barrier in the channel, the channel is separated into two specific areas: an immobilization section for the enzyme-linked assay and an electrochemical measurement cell for the amperometric signal readout.
The on-chip bioassay immobilization is performed by the adsorption of the biomolecules to the channel surface. The glucose oxidase enzyme is used as a transducer for electrochemical signal generation. In the presence of the substrate, glucose, hydrogen peroxide is produced, which is detected at the platinum working electrode. The stop-flow technique is applied to obtain signal amplification along with rapid detection. Different biomolecules can quantitatively be measured by means of the introduced microfluidic system, giving an indication of different types of diseases, or, in regard to therapeutic drug monitoring, facilitating a personalized therapy.

A microfluidic biosensor platform was designed and fabricated using low-cost dry film photoresist technology for the rapid and sensitive quantification of various analytes. This single-use system allows for the electrochemical readout of on-chip-immobilized enzyme-linked assays by means of the stop-flow technique.

干膜 Photoresist-based 电化学微流控生物传感器平台: 器件制备、片上检测制备及系统运行

In recent years, biomarker diagnostics became an indispensable tool for the diagnosis of human disease, especially for the point-of-care diagnostics. An ...

Scalable Fabrication of Stretchable, Dual Channel, Microfluidic Organ Chips

A significant number of lead compounds fail in the pharmaceutical pipeline because animal studies often fail to predict clinical responses in human patients. Human Organ-on-a-Chip (Organ Chip) microfluidic cell culture devices, which provide an experimental in vitro platform to assess efficacy, toxicity, and pharmacokinetic (PK) profiles in humans, may be better predictors of therapeutic efficacy and safety in the clinic compared to animal studies. These devices may be used to model the function of virtually any organ type and can be fluidically linked through common endothelium-lined microchannels to perform in vitro studies on human organ-level and whole body-level physiology without having to conduct experiments on people. These Organ Chips consist of two perfused microfluidic channels separated by a permeable elastomeric membrane with organ-specific parenchymal cells on one side and microvascular endothelium on the other, which can be cyclically stretched to provide organ-specific mechanical cues (e.g., breathing motions in lung). This protocol details the fabrication of flexible, dual channel, Organ Chips through casting of parts using 3D printed molds, enabling combination of multiple casting and post-processing steps. Porous poly (dimethyl siloxane) (PDMS) membranes are cast with micrometer sized through-holes using silicon pillar arrays under compression. Fabrication and assembly of Organ Chips involves equipment and steps that can be implemented outside of a traditional cleanroom. This protocol provides researchers with access to Organ Chip technology for in vitro organ- and body-level studies in drug discovery, safety and efficacy testing, as well as mechanistic studies of fundamental biological processes.

Here, we present a protocol that describes the fabrication of stretchable, dual channel, organ chip microfluidic cell culture devices for recapitulating organ-level functionality in vitro.

可伸缩、双通道、微流控芯片制造

A significant number of lead compounds fail in the pharmaceutical pipeline because animal studies often fail to predict clinical responses in human ...

A Microfluidic Platform for Stimulating Chondrocytes with Dynamic Compression

Mechanical stimuli are known to modulate biological functions of cells and tissues. Recent studies have suggested that compressive stress alters growth plate cartilage architecture and results in growth modulation of long bones of children. To determine the role of compressive stress in bone growth, we created a microfluidic device actuated by pneumatic pressure, to dynamically (or statically) compress growth plate chondrocytes embedded in alginate hydrogel cylinders. In this article, we describe detailed methods for fabricating and characterizing this device. The advantages of our protocol are: 1) Five different magnitudes of compressive stress can be generated on five technical replicates in a single platform, 2) It is easy to visualize cell morphology via a conventional light microscope, 3) Cells can be rapidly isolated from the device after compression to facilitate downstream assays, and 4) The platform can be applied to study mechanobiology of any cell type that can grow in hydrogels.

This article provides detailed methods for fabricating and characterizing a pneumatically actuating microfluidic device for chondrocyte compression.

微流体平台，用于用动态压缩刺激软骨细胞

Mechanical stimuli are known to modulate biological functions of cells and tissues. Recent studies have suggested that compressive stress alters growth ...