This work is supported by the NSF-EPSCoR (grant #0814194) and the Department of Bioengineering.

<html> 1.设备安装<ol><li>组装的分配系统和阀控制器和注射器筒连接到气动源，通过一个压力调节器，用来设置所述压力为15磅，以分配从针尖的聚合物溶液以2.45微升/分钟的流速。 </li><li>插入的3轴的机器人和分送系统入热敏外壳以确保一个稳定的工作环境（ 图2）。 </li><li>安装联合机器人控制点（JR-C点）软件系统制造商提供，并通过串行通讯端口3轴机器人连接到计算机。 </li><li>安装分配阀，以3轴的机器人和安装针尖到阀。 </li><li>根据制造商的指导，以确保平整度相对于所述阀头15的高度水平，机器人阶段压板。 </li><li>组装反馈控制加热器的外壳增加环境控制。 </li></ol>内容“FO：保持together.within页=”总是“&gt; <img alt="图2" src="/files/ftp_upload/52834/52834fig2.jpg" /> 图2.（A）3轴点胶机器人放置在机柜内所需的配件;和（B）关闭了连接的USB显微镜可视化分配阀的形象。 <a href="https://www.jove.com/files/ftp_upload/52834/52834fig2large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> 2.实验材料和控制因素<ol><li>控制因素及其组合。 <ol><li>而不同进料速度为1％的速度（5毫米/秒）到100％（500毫米/秒），由JR C-点软件。 对于这种应用，使用2％的速度（10毫米/秒）来制造纤维结构提出了这项工作。 </li><li>变化的聚合物溶液的浓度，以达到特定的粘度，表面张力和波动参数所需对于所需的应用程序。 对于这种应用，使用24％聚甲基丙烯酸甲酯（PMMA）在氯苯溶液来制造在这项工作中提出的纤维结构。 </li><li>为了喷射经由气动空气解决方案有所不同控制阀分配时间为0.02秒至1秒。 对于这种应用，使用0.02秒，制作在这项工作中提出的纤维结构。 </li><li>选择精度高的针尖的计示大小来分配聚合物溶液。 对于这种应用，使用一个30 G（内径（ID）= 152.4微米）尖端制造在这项工作中提出的纤维结构。 </li><li>在隔热箱以维持聚合物样品的恒定蒸发速度之间70°F设定的工作温度范围为100°F。 对于这种应用，使用70°F的温度以制造在这项工作中提出的纤维结构。 </li></ol></li><li>制备聚合物溶液的。 <ol><li>混合聚甲基丙烯酸甲酯的聚合物的树脂（聚甲基丙烯酸甲酯0.72克）与溶剂氯苯（2.28克）的化学流罩。 </li><li>计算聚合物（PMMA）和其溶剂（氯苯），以实现聚合物在溶液中的所需浓度的重量。 对于这种应用，使用24％聚甲基丙烯酸甲酯（PMMA）在氯苯溶液来制造在这项工作中提出的纤维结构。 </li><li>放置聚合物粉末/树脂在玻璃小瓶中的所需量。 对于这种应用，使用0.72克PMMA树脂的获得的PMMA的24％的浓度。 </li><li>通过移液管，直到3克的总重量达到内小瓶转移溶剂到聚合物。 </li><li>混合瓶内，用涡旋振荡器1分钟，并用超声波处理它们5小时，以完全溶解聚合物粉末/树脂。 </li><li>检查解决方案的透明度，如果有任何混浊或不透明来样继续下超声直至澄清。 </li></ol></li><li>聚合物溶液的粘度测量。 <ol><li>经由锥和板式粘度计测量溶液的粘度（ 例如，LVDV-II +和RVDV-II +）16。 </li><li>负载0.5毫升提供的粘度计制造商校准粘度计，以尽量减少在粘度测量中的误差已知粘度的标准样品（基于甘油和水的混合物）的。制造商提供的各种标准样品的校准粘度计。使用甘油为基础的标准样品与100,000厘泊的粘度。 </li><li>连接水套到粘度计，以保持测试流体在恒定的工作温度。 </li><li>通过移动On / Off开关到ON位置以启动主轴旋转开始测试流体测量。一旦在显示面板上的转矩的值稳定后，记录的转矩，并计算使用扭矩主轴1，主轴乘数常数与速度之间的关系的最后粘度6 <img alt="式（1）" src="/files/ftp_upload/52834/52834eq1.jpg" /> 其中，是粘度，转速为固定到锥形主轴的速度，TK是转矩（0.09373为LVDV-II + 1 RVDV-II +），SMC是主轴乘数常数依赖于特定锭子粘度期间使用测量。在这项研究中，将CP-52锭子被使用，其具有9.83的主轴乘数常数。 </li></ol></li><li>聚合物溶液的表面张力的测量。 <ol><li>测量方法是指威廉米技术。14 </li><li>放置在玻璃小瓶1毫升试验溶液到高分辨率平衡（尺度分辨率= 0.001克）。浸已知直径的玻璃棒成测试溶液。 </li><li>控制杆通过一个伺服或步进控制的线性致动器的位置，以触摸表面和部分地浸入试验溶液与零接触。 </li><li>监测和天平上的记录时，在质量测量的变化从溶液表面去除杆。 </li><li>通过计算力的变化，流体杆上杆和接触角的周界表面张力。 <img alt="公式（2）" src="/files/ftp_upload/52834/52834eq2.jpg" /> 其中，被棒的浸润周界（ 升=10.05毫米直径 = 3.2 毫米 ），θ是流体的接触角在杆上，F是力变化由于表面测试流体的张力杆的尖端。 </li></ol></li><li>解决方案的传质系数的测量。 <ol><li>测量聚合物溶液通过热重分析的传质系数。14 </li><li>负载30微升24％（重量）聚甲基丙烯酸甲酯的聚合物溶液上的铂板的去皮的平衡之前。 </li><li>泄腔室，程序设备在所需的操作温度（70°F）2小时，以监测目标的解决方案的质量。 </li><li>通过改变溶液的质量计算的传质系数，面积溶液/空气界面和密度。 <img alt="公式3" src="/files/ftp_upload/52834/52834eq3.jpg" /> 其中m（t）是聚甲基丙烯酸甲酯溶液的质量，A是溶液/空气界面的面积（等于78.5毫米2为标板），mPOLYMER是在溶液中的聚合物的质量，是该溶液的密度。 </li></ol></li></ol> 3.直写实验过程<ol><li>分配系统样品装载协议。 <ol><li>负载3毫升聚合物溶液到注射器筒，将活塞推入注射器筒，以消除不一致气动压力分布。 </li><li>拧上的注射器管的入口管线的转接器，其连接到源极线的空气管。 </li><li>选择的精度针尖所需尺寸大小来执行实验。 </li><li>在分配控制面板，切换到清除状态，然后单击“循环”按钮，以填补分配阀与聚合物等等lution直到从针尖排出。 </li><li>擦拭从尖端在制备编程纤维写入过程的残留聚合物溶液。 </li></ol></li><li>直写聚合物纤维具有3轴机器人和分送系统。 <ol><li>确定机器人阶段偏移来重新定位从默认位置到规定的微/亚微米纤维结构体的引发点的分配针的尖端，以进行绘制。挂载USB显微镜（放大倍数= 200X）到分配系统阀支架，其沿Z轴平移。手动聚焦于分配器触头通过调整上的USB显微镜，其有助于精确地定位在阀头至所需位置，预制基底或设备的调焦旋钮。 </li><li>创建/设计所需的纤维结构图案（ 图3A，4A和5A）使用CAD软件程序包。输入在ROBO的空间坐标（x，Y，Z）吨JR-C的控制用于 ​​在顺序所有起始和终止点的软件相对于所述CAD程序（ 图3B，4B和5B）内产生所需的图案。15 </li><li>通过点击“发送C＆T的数据”下的JR-C软件15内的机器人菜单从计算机传送完成的纤维结构设计方案的机器人。 </li><li>负载3毫升已知浓度（24％）到注射器筒，净化阀和针的聚甲基丙烯酸甲酯溶液的样品，将所有的阀门控制器和机器人控制软件分配的参数。 </li><li>放置预制基底上的机器人阶段压板，关闭热机柜门，以防止周围空气的流动，其可以诱导聚合物溶液的不稳定蒸发。 </li><li>首先单击菜单机器人从JR-C软件，并选择写纤维在基板上“试运行”15。 </li><li>直流溅射涂层的导电性金金属层2分钟，直到2纳米厚的金层沉积在被拉伸的纤维，以允许在扫描电子显微镜将纤维的可视化。 </li><li>测量纤维的通过扫描型电子显微镜17的直径和结构。显微镜参数：高电压等级：2.00千伏;目的：InLens，工作距离（9.0毫米）。 </li></ol></li><li>根据化学流罩进行分配系统清洗程序。 <ol><li>放置在分配系统中的化学流罩来执行清洁过程。 </li><li>根据制造商的协议拆卸针阀。 </li><li>将所有的金属部件放入烧杯中，倒入丙酮放入烧杯中，直到所有部分都沉浸。 </li><li>放置烧杯在超声浴中30分钟以除去所有的聚合物残余。 </li><li>下冲洗流动DI水各个部位，然后用气枪吹他们干。 </li></ol></<html> LI&gt; </ol><img alt="图3" src="/files/ftp_upload/52834/52834fig3.jpg" /> 在一个10毫米×10毫米框架设计的“四”的网络结构图3.（A）为例，（B）连续点至点空间指令被输入到JR-C点的软件。 <a href="https://www.jove.com/files/ftp_upload/52834/52834fig3large.jpg" target="_blank">请点击此处查看更大的版本这个数字。</a> <img alt="图4" src="/files/ftp_upload/52834/52834fig4.jpg" /> 图设计的“对称的”网络结构上有10毫米×10毫米框架4（A）的实施例，（B）的顺序点对点的空间的指示将其输入到JR-C的点的软件。空白“&gt;点击此处查看该图的放大版本。 <img alt="图5" src="/files/ftp_upload/52834/52834fig5.jpg" /> 设计的“双V形”网状结构上有10毫米×10毫米框架，（B）连续点至点的空间说明图5（A）例被输入到JR-C点的软件。 <a href="https://www.jove.com/files/ftp_upload/52834/52834fig5large.jpg" target="_blank">请点击这里查看一个更大的版本这个数字。</a>

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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=Fabrication+of+suspended+electrokinetic+microchannels+from+directly-written+sacrificial+polymer+fibers.">Fabrication of suspended electrokinetic microchannels from directly-written sacrificial polymer fibers.</a> Microfluid. Nanofluid. 13, 451-459 (2012).</li></ol>

The authors have nothing to disclose.

在尝试每个试验中，该聚合物溶液的粘度，传质系数和表面张力测试准确地测量，以便确定机器人和分送系统是否能够处理所需的聚合物的这一点至关重要。正如我们小组先前所描述的，聚合物溶液必须保持足够的：1）表面张力，使液体细丝的形成为微米/亚微米结构; 2）粘度承受毛细血管分手;和，3）的蒸发速率，以提高纤维凝固18。这些参数之间的协同作用是关键成功地生产纤维超过直径的特定范围。与此同时，不稳定性，在任何这些参数可防止微米/亚微米级纤维的形成。维持期间纤维制造这些参数之间的协同作用，以保证针和针阀后一个直写S被彻底清洁是非常重要的分裂国家，以防止：1）污染溶液; 2）在通过针将聚合物溶液流率的降低;和，3）过度增长在针的尖端的聚合物珠。此外，在加热器的温度控制器必须设置为所需的温度，以保持聚合物溶液的恒定蒸发速度。 分叉支路纤维为59％，41％和24％的直径大于该支撑结构在图6-8中，分别使用了24％的PMMA溶液。这主要是由于在该纤维被拉伸的距离。具体地，支撑结构跨过衬底的整个宽度绘制（10.0毫米X和Y方向;14.4毫米对角线）。其结果是，这些是整体悬挂结构的最长纤维。分叉的分支结构显著短，从7毫米最大长度下降到2.5毫米。这种短纤维拉丝长度确实没吨有效地诱导在纤维减薄过程所需的光纤应变以产生小直径的纤维。另一方面，大直径的电线被要求作为支撑纤维，以便有效地维持在分叉支路拉拔处理引起的拖拽和变形。作为分岔分支横跨支承纤维拉伸，支撑纤维几何形状的重塑可能是由于该图的力以及聚甲基丙烯酸甲酯聚合物在所述载体之间的界面的本地化溶解和支纤维从溶剂中存在的聚合物溶液。因此，在一些情况下，载体纤维可能需要被选自聚合物的较高浓度的，以产生更大的直径和机械强纤维的聚合物溶液制成。 有主要3种有效的方法，用于修改现有的协议，以产生一个更广泛的支持和支纤维直径：1）最初分配从较大针尖的聚合物（ 例如，25 G组; n = 254微米），以产生载体纤维，然后交换为一个较小的针尖（ 例如，32 G组; n = 101.6微米），以制造较小的分支纤维; 2）如上所述，使用多个聚合物浓度;和/或，3）调整进给速率， 即，在该阶段遍历，其中，增加进料速率产生较小直径的纤维和降低进给速率的速度产生较大的直径的纤维。到目前为止，我们已经能够成功地制造纤维小到90纳米;然而，纤维产量在这方面是低，由于毛细血管破裂。 自动直写方法的一个限制是，只有一个浓度的聚合物溶液可以同时被分配。这个限制也可以，而不必开发悬浮结构的复杂性的级别：1）添加第二分配阀的机器人;或者，2）删除现有的阀门和分配第二聚合物溶液，这需要更多的时间之前进行清理协议（第3.4节）。第二个限制是进料速率（或打印速度），其中，最大进料速率，该系统能够实现的为500毫米/秒。然而，有进料速率和纤维形成之间的折衷。具体地说，如果惯性力（由于进料速率的力）大于表面张力和将聚合物溶液的蒸发速率，纤维形成不会发生。另一方面，如果进料速率太低，纤维将断裂，由于之前和期间的伸长过程过度蒸发。第三，纤维和结构的尺寸被限制为在x，y和z方向上的工作范围内的机器人的阶段， 即200毫米，200毫米和25毫米（用10微米的位置精度），分别。然而，这一工艺的确使高纵横比的形成（纤维升ength：直径）纤维。战略上改变分配尖端尺寸和聚合物溶液浓度将允许更广泛的纤维直径范围，创建，以产生更高的复杂性自由悬挂结构的能力。 按照上述的协议，微米和亚微米直径的聚合物纤维可以具有空间控制高水平通过利用聚合物溶液的表面张力驱动流体力学，不能与任何其他湿，干的或静电纺丝的过程控制而生成的。从以前的工作8,19，我们知道，这种技术可用于制造复杂的微/亚微米流体装置19和生物工程支架8。这种廉价和简单的技术都有自己的优势在许多方面传统的刨床加工方法。

在过去的几十年中，各种的制造技术，如湿纺，干纺和静电，已经被用来产生新的聚合物的纤维结构具有不同和健壮的生物，化学，电和机械性能1-12。虽然这些纺丝技术是能够产生悬浮三维纤维，他们在他们的精确控制纤维取向在三维空间中，因为通过这些过程纤维沉积是随机的能力是有限的。此外，这些技术被限制在其尺寸范围为纤维制造;具体地，通过湿纺和干纺生产的纤维变化的直径从几十到几百微米，而电纺丝收率纤维直径从数十纳米到单个微米13。 提供的纤维取向更精确地控制在3-D空间，我们小组开发出了自-assemble或“直写”光纤制造工艺直接弹出一个聚合材料出一个中空毛细管，然后绘制其薄且固化成可预测的纤维直径通过利用表面张力驱动的流体力学14根单丝。我们的用于提高光纤位置和直径的控制水平初始直接写入系统包括附连到由超高精度微细铣削机（ 图1）的自定义的头部的定制制造的弹簧加载的注射器分配系统。所述UHPMM有阶段与在X和Y方向1.25纳米和在被编程控制，以创建微米和亚微米尺度线和结构在Z方向20纳米的定位分辨率。这个特定的直写系统中的一个限制是缺乏通过针尖的聚合物溶液的流控制。虽然弹簧加载分配系统成功产生恒定的FLO瓦特通过末端，聚合物溶液连续扩张的球形珠在注射器尖端，在尺寸和容积变化取决于环境条件的出口被创建。 <img alt="图1" src="/files/ftp_upload/52834/52834fig1.jpg" /> 图超高精度微细铣削机1.图像：在制作微米/亚微米尺度结构采用的首次直接写入系统 <a href="https://www.jove.com/files/ftp_upload/52834/52834fig1large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> 这个源珠的不一致影响了系统的重复制造一个规定直径的线的能力。虽然，用这种直接写入处理成功产生的结构，增强了过程通过增加聚合物溶液的流动的控制将允许更多PRECI本身，通过珠尺寸的调节在注射器尖端规定的纤维直径。因此，该工作描述了一个3轴自动分配系统与气动分配器阀来精确控制来创建规定的聚合物溶液流速和尖珠尺寸，微米/亚微米悬浮结构的实施。

<table border="0" cellpadding="0" cellspacing="0">
	<colgroup>
		<col span="2" />
	</colgroup>
	<tbody>
		<tr>
			<td>ROBOT DR2203N 3 AXES 200MM X 200MM</td>
			<td>Nordson EFD</td>
			<td>7023145</td>
			<td>3-Axis Robot</td>
		</tr>
		<tr>
			<td>CONTROLLER 7100, DISPENSE VALVE</td>
			<td>Nordson EFD</td>
			<td>7015340</td>
			<td>Valve Controller</td>
		</tr>
		<tr>
			<td>MICRODOT VALVE</td>
			<td>Nordson EFD</td>
			<td>7021233</td>
			<td>Microdot Valve</td>
		</tr>
		<tr>
			<td>ROBOT ACC FIXTURE PLATE 200MM</td>
			<td>Nordson EFD</td>
			<td>7028276</td>
			<td>Fixture Platen</td>
		</tr>
		<tr>
			<td>ROBOT ACC DRN / DSRN POINTS SOFTWAR</td>
			<td>Nordson EFD</td>
			<td>7023144</td>
			<td>JR-C Software</td>
		</tr>
		<tr>
			<td>ROBOT MOUNT VALVE UNIVERSAL</td>
			<td>Nordson EFD</td>
			<td>7028273</td>
			<td>Microdot Valve Mount</td>
		</tr>
		<tr>
			<td>15 PSI BARREL PRESS. REGULATOR</td>
			<td>Nordson EFD</td>
			<td>7020585</td>
			<td>Barrel Regulator</td>
		</tr>
		<tr>
			<td>KIT O BRL/PIST 5CC CL/WH 40</td>
			<td>Nordson EFD</td>
			<td>7012096</td>
			<td>5CC Barrels with Pistons</td>
		</tr>
		<tr>
			<td>ADAPTER ASM O 5CC BL</td>
			<td>Nordson EFD</td>
			<td>7012054</td>
			<td>Pneumatic Barrel Adapter</td>
		</tr>
		<tr>
			<td>TIP 30GA .006X.25 LAVNDR 50PC</td>
			<td>Nordson EFD</td>
			<td>7018424</td>
			<td>30 GA Needle Tip (0.250&#34; length)</td>
		</tr>
		<tr>
			<td>Electric Baseboard Heater (500W, 30&#34; length)</td>
			<td>Cadet</td>
			<td>2F500</td>
			<td>Heater</td>
		</tr>
		<tr>
			<td>Temperature Controller with Timer</td>
			<td>Control Company</td>
			<td>130726596</td>
			<td>Temperature Controller</td>
		</tr>
		<tr>
			<td>eScope USB Microscope</td>
			<td>OiTez</td>
			<td>DP-M02</td>
			<td>200X USB Microscope</td>
		</tr>
		<tr>
			<td>Poly(methyl methacrylate)</td>
			<td>Aldrich</td>
			<td>182265-500G</td>
			<td>PMMA Powder</td>
		</tr>
		<tr>
			<td>Chlorobenzene</td>
			<td>Sigma Aldrich</td>
			<td>284513</td>
			<td>Solvent to dissolve PMMA</td>
		</tr>
	</tbody>
</table>

prescribed 3-d direct writing of suspended micron/sub-micron scale fiber structures via a robotic dispensing system

A 3-axis dispensing system is utilized to control the initiating and terminating fiber positions and trajectory via the dispensing software. The polymer fiber length and orientation is defined by the spatial positioning of the dispensing system 3-axis stages. The fiber diameter is defined by the prescribed dispense time of the dispensing system valve, the feed rate (the speed at which the stage traverses from an initiating to a terminating position), the gauge diameter of the dispensing tip, the viscosity and surface tension of the polymer solution, and the programmed drawing length. The stage feed rate affects the polymer solution&#8217;s evaporation rate and capillary breakup of the filaments. The dispensing system consists of a pneumatic valve controller, a droplet-dispensing valve and a dispensing tip. Characterization of the direct write process to determine the optimum combination of factors leads to repeatedly acquiring the desired range of fiber diameters. The advantage of this robotic dispensing system is the ease of obtaining a precise range of micron/sub-micron fibers onto a desired, programmed location via automated process control. Here, the discussed self-assembled micron/sub-micron scale 3D structures have been employed to fabricate suspended structures to create micron/sub-micron fluidic devices and bioengineered scaffolds.

通过为每个在图3-5A＆B如上所定义的相应的设计和JR的C-点算法的3轴的机器人和直写方法产生的实际结构的图像分别示于图6A，7A和8A所示 。如可在所产生的图像中可以看出，三维的，自由悬挂纤维已通过精确操纵分配器触头到规定的空间位置包括所述发起/终止点以及交叉点成功“写入”一直到基片上。这些数字的插图放大交点悬浮的纤维，这表明该系统的精确控制纤维取向（ 图6B，7B和8B）在3-D空间的能力的点。 <img alt="图6" src="/files/ftp_upload/52834/52834fig6.jpg" /> 图6（A）欧普<html> （;比例尺=1毫米15X光学倍率），单光纤分叉（289X放大倍率（二）SEM图像;捏造“四”有2支纤维（对角线）和12支岔PMMA纤维悬浮网结构蒂卡尔图像比例酒吧= 100微米）。 <a href="https://www.jove.com/files/ftp_upload/52834/52834fig6large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图7" src="/files/ftp_upload/52834/52834fig7.jpg" /> 图7（A）制造的“对称”暂停网，它具有1支持光纤（水平）和11支岔PMMA纤维结构的光学图像;单一分叉（15X光学放大倍率比例尺= 1毫米），（B）SEM图像纤维（107X放大;比例尺= 100微米）。52834fig7large.jpg“目标=”_空白“&gt;点击此处查看该图的放大版本。 <img alt="图8" src="/files/ftp_upload/52834/52834fig8.jpg" /> 图8（A）的制备“双V形”光学影像悬浮有1支持光纤（水平）和22支岔PMMA纤维网状结构（15X光学放大倍数;比例尺= 1毫米），（B）单的SEM图像分叉纤维（80X放大;比例尺= 100微米） <a href="https://www.jove.com/files/ftp_upload/52834/52834fig8large.jpg" target="_blank">请点击这里查看这个数字的放大版本。</a> 图9显示特写视图纤维制造的连续点至点顺序在该3轴机器人和分送系统可以生成自由悬浮幅状结构。在P<html>用数字显示olymer接触点对应于编程发起和终止点在图3B中引用上述JR-C软件。箭头代表机器人的运动轨迹。 图10显示了微米和亚微米级聚合物纤维，这表明直接写入系统的制作不同大小的导线能力。 <img alt="图9" src="/files/ftp_upload/52834/52834fig9.jpg" /> 图9. SEM图像说明用于绘制微米和亚微米级的聚合物纤维（29X放大倍数;比例尺= 200微米）的连续点至点的制造订单。 <a href="https://www.jove.com/files/ftp_upload/52834/52834fig9large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> 2834 / 52834fig10.jpg“/&gt; 图10. SEM微米（6.5微米）和亚微米（555纳米）用20％浓度的PMMA聚合物溶液拉伸纤维的形象。（2,270X放大;比例尺= 2微米）， <a href="https://www.jove.com/files/ftp_upload/52834/52834fig10large.jpg" target="_blank">请点击此处查看大图这个数字。</a> 聚合物纤维长度和直径分别使用扫描电子显微镜测定。 表1示出的平均金属丝直径为每个独特的结构之上对应于分叉支路纤维和支撑纤维示于图6-8。表2显示测定该聚合物的参数从被用于制造如上所述的结构，其中24％的PMMA的解决方案。 <table border="0" cellpadding="0" cellspacing="0"><tbody><tr><td></td><td>结构的直径在图6中</td><td>结构的直径在图7中</td><td>结构的直径在图8中</td></tr><tr><td> 支撑纤维 </td><td> 8.65±1.43微米</td><td> 9.39±1.23微米</td><td> 9.31±1.65微米</td></tr><tr><td> 分支光纤 </td><td> 20.96±3.35微米</td><td> 15.92±1.44微米</td><td> 12.24±5.42微米</td></tr></tbody></table> 暂停支持和分支光纤的表1的平均直径在图6-8为24％PMMA解决方案如图所示。 <table border="0" cellpadding="0" cellspacing="0"><tbody><tr><td></td><td> 24％的PMMA </td></tr><tr><td> 粘度（帕·秒） </td><td> 35.19 </td></tr><tr><td> 表面张力（达因/厘米） </td><td> 262.01 </td></tr><tr><tD&gt; 传质系数（米/秒） </td><td> 8.59×10 -8 </td></tr></tbody></table> 被用于制造在这项工作中提出的纤维结构，其在24％的PMMA溶液表2聚合物的参数。

Watch this Scientific Journal Video about Prescribed 3-D Direct Writing of Suspended Micron/Sub-micron Scale Fiber Structures via a Robotic Dispensing System at JoVE.com

Prescribed 3-D Direct Writing of Suspended Micron/Sub-micron Scale Fiber Structures via a Robotic Dispensing System

在这里，我们提出了一个协议，以制造自由悬浮，微米/亚微米尺度的聚合物通过自动化的直接写入过程由一个3轴分配系统的装置产生的纤维和“网状”结构。

暂停规定微米/亚微米尺度的纤维结构的3-D直写经全自动点胶系统

A 3-axis dispensing system is utilized to control the initiating and terminating fiber positions and trajectory via the dispensing software. The polymer ...

prescribed-3-d-direct-writing-suspended-micronsub-micron-scale-fiber

Research

JoVE Journal

Engineering

7.9K 次观看.  University of Louisville. 在这里，我们提出了一个协议，以制造自由悬浮，微米/亚微米尺度的聚合物通过自动化的直接写入过程由一个3轴分配系统的装置产生的纤维和“网状”结构。 

视频: Prescribed 3-D Direct Writing of Suspended Micron/Sub-micron Scale Fiber Structures via a Robotic Dispensing System

Fabrication of Uniform Nanoscale Cavities via Silicon Direct Wafer Bonding

Measurements of the heat capacity and superfluid fraction of confined 4He have been performed near the lambda transition using lithographically patterned and bonded silicon wafers. Unlike confinements in porous materials often used for these types of experiments3, bonded wafers provide predesigned uniform spaces for confinement. The geometry of each cell is well known, which removes a large source of ambiguity in the interpretation of data.
Exceptionally flat, 5 cm diameter, 375 &#181;m thick Si wafers with about 1 &#181;m variation over the entire wafer can be obtained commercially (from Semiconductor Processing Company, for example). Thermal oxide is grown on the wafers to define the confinement dimension in the z-direction. A pattern is then etched in the oxide using lithographic techniques so as to create a desired enclosure upon bonding. A hole is drilled in one of the wafers (the top) to allow for the introduction of the liquid to be measured. The wafers are cleaned2 in RCA solutions and then put in a microclean chamber where they are rinsed with deionized water4. The wafers are bonded at RT and then annealed at ~1,100 &#176;C. This forms a strong and permanent bond. This process can be used to make uniform enclosures for measuring thermal and hydrodynamic properties of confined liquids from the nanometer to the micrometer scale.

A method for permanently bonding two silicon wafers so as to realize a uniform enclosure is described. This includes wafer preparation, cleaning, RT bonding, and annealing processes. The resulting bonded wafers (cells) have uniformity of enclosure ~1%1,2. The resulting geometry allows for measurements of confined liquids and gasses.

通过硅直接晶圆粘接制造均匀纳米级腔

Measurements of the heat capacity and superfluid fraction of confined 4He have been performed near the lambda transition using lithographically patterned ...

科研

工程学

Writing and Low-Temperature Characterization of Oxide Nanostructures

Oxide nanoelectronics is a rapidly growing field which seeks to develop novel materials with multifunctional behavior at nanoscale dimensions. Oxide interfaces exhibit a wide range of properties that can be controlled include conduction, piezoelectric behavior, ferromagnetism, superconductivity and nonlinear optical properties. Recently, methods for controlling these properties at extreme nanoscale dimensions have been discovered and developed. Here are described explicit step-by-step procedures for creating LaAlO3/SrTiO3 nanostructures using a reversible conductive atomic force microscopy technique. The processing steps for creating electrical contacts to the LaAlO3/SrTiO3 interface are first described. Conductive nanostructures are created by applying voltages to a conductive atomic force microscope tip and locally switching the LaAlO3/SrTiO3 interface to a conductive state. A versatile nanolithography toolkit has been developed expressly for the purpose of controlling the atomic force microscope (AFM) tip path and voltage. Then, these nanostructures are placed in a cryostat and transport measurements are performed. The procedures described here should be useful to others wishing to conduct research in oxide nanoelectronics.

Oxide nanostructures provide new opportunities for science and technology. The interfacial conductivity between LaAlO3 and SrTiO3 can be controlled with near-atomic precision using a conductive atomic force microscopy technique. The protocol for creating and measuring conductive nanostructures at LaAlO3/SrTiO3 interfaces is demonstrated.

写作和氧化物纳米结构的低温特性

Oxide nanoelectronics is a rapidly growing field which seeks to develop novel materials with multifunctional behavior at nanoscale dimensions.  Oxide ...

Writing Bragg Gratings in Multicore Fibers

Fiber Bragg gratings in multicore fibers can be used as compact and robust filters in astronomical and other research and commercial applications. Strong suppression at a single wavelength requires that all cores have matching transmission profiles. These gratings cannot be inscribed using the same method as for single-core fibers because the curved surface of the cladding acts as a lens, focusing the incoming UV laser beam and causing variations in exposure between cores. Therefore we use an additional optical element to ensure that the beam shape does not change while passing through the cross-section of the multicore fiber. This consists of a glass capillary tube which has been polished flat on one side, which is then placed over the section of the fiber to be inscribed. The laser beam enters the fiber through the flat surface of the capillary tube and hence maintains its original dimensions. This paper demonstrates the improvements in core-to-core uniformity for a 7-core fiber using this method. The technique can be generalized to larger multicore fibers.

We describe a technique for inscribing identical fiber Bragg gratings into each core of a multicore fiber. This is achieved by introducing an additional surface into the optical path to mitigate lensing by the curved surface of the fiber cladding.

写布拉格光栅在多核纤维

Fiber Bragg gratings in multicore fibers can be used as compact and robust filters in astronomical and other research and commercial applications. Strong ...

A Robotic Platform to Study the Foreflipper of the California Sea Lion

The California sea lion (Zalophus californianus), is an agile and powerful swimmer. Unlike many successful swimmers (dolphins, tuna), they generate most of their thrust with their large foreflippers. This protocol describes a robotic platform designed to study the hydrodynamic performance of the swimming California sea lion (Zalophus californianus). The robot is a model of the animal&#39;s foreflipper that is actuated by motors to replicate the motion of its propulsive stroke (the &#39;clap&#39;). The kinematics of the sea lion&#39;s propulsive stroke are extracted from video data of unmarked, non-research sea lions at the Smithsonian Zoological Park (SNZ). Those data form the basis of the actuation motion of the robotic flipper presented here. The geometry of the robotic flipper is based a on high-resolution laser scan of a foreflipper of an adult female sea lion, scaled to about 60% of the full-scale flipper. The articulated model has three joints, mimicking the elbow, wrist and knuckle joint of the sea lion foreflipper. The robotic platform matches dynamics properties&#8212;Reynolds number and tip speed&#8212;of the animal when accelerating from rest. The robotic flipper can be used to determine the performance (forces and torques) and resulting flowfields.

A robotic platform is described that will be used to study the hydrodynamic performance&#8212;forces and flowfields&#8212;of the swimming California sea lion. The robot is a model of the animal&#39;s foreflipper that is actuated by motors to replicate the motion of its propulsive stroke (the &#39;clap&#39;).

机器人平台研究加州海狮的Foreflipper

The California sea lion (Zalophus californianus), is an agile and powerful swimmer. Unlike many successful swimmers (dolphins, tuna), they generate most ...

Three-Dimensional Ultrasonic Needle Tip Tracking with a Fiber-Optic Ultrasound Receiver

Ultrasound is frequently used for guiding minimally invasive procedures, but visualizing medical devices is often challenging with this imaging modality. When visualization is lost, the medical device can cause trauma to critical tissue structures. Here, a method to track the needle tip during ultrasound image-guided procedures is presented. This method involves the use of a fiber-optic ultrasound receiver that is affixed within the cannula of a medical needle to communicate ultrasonically with the external ultrasound probe. This custom probe comprises a central transducer element array and side element arrays. In addition to conventional two-dimensional (2D) B-mode ultrasound imaging provided by the central array, three-dimensional (3D) needle tip tracking is provided by the side arrays. For B-mode ultrasound imaging, a standard transmit-receive sequence with electronic beamforming is performed. For ultrasonic tracking, Golay-coded ultrasound transmissions from the 4 side arrays are received by the hydrophone sensor, and subsequently the received signals are decoded to identify the needle tip&#39;s spatial location with respect to the ultrasound imaging probe. As a preliminary validation of this method, insertions of the needle/hydrophone pair were performed in clinically realistic contexts. This novel ultrasound imaging/tracking method is compatible with current clinical workflow, and it provides reliable device tracking during in-plane and out-of-plane needle insertions.

Accurate and efficient visualization of invasive medical devices is extremely important in many ultrasound-guided minimally invasive procedures. Here, a method for localizing the spatial position of a needle tip relative to the ultrasound imaging probe is presented.

基于光纤超声接收机的三维超声针尖跟踪

Ultrasound is frequently used for guiding minimally invasive procedures, but visualizing medical devices is often challenging with this imaging modality. ...

Conducting Elevated Temperature Normal and Combined Pressure-Shear Plate Impact Experiments Via a Breech-end Sabot Heater System

A novel approach for conducting normal and/or combined pressure-shear plate impact experiments at test temperatures up to 1000 &#176;C is presented. The method enables elevated temperature plate-impact experiments aimed towards probing dynamic behavior of materials under thermomechanical extremes, while mitigating several special experimental challenges faced while performing similar experiments using the conventional plate impact approach. Custom adaptations are made to the breech-end of a single-stage gas-gun at Case Western Reserve University; these adaptations include a precision-machined extension piece made from SAE 4340 steel, which is strategically designed to mate the existing gun-barrel while providing a high tolerance match to the bore and keyway. The extension piece contains a vertical cylindrical heater-well, which houses a heater assembly. A resistive coil heater-head, capable of reaching temperatures of up 1200 &#176;C, is attached to a vertical stem with axial/rotational degrees of freedoms; this enables thin metal specimens held at the front-end of a heat-resistant sabot to be heated uniformly across the diameter to the desired test temperatures. By heating the flyer plate (in this case, the sample) at the breech-end of the gun-barrel instead of at the target-end, several critical experimental challenges can be averted. These include: 1) severe changes in the alignment of the target plate during heating due to the thermal expansion of the several constituents of the target holder assembly; 2) challenges that arise due to the diagnostics elements, (i.e., polymer holographic gratings, and optical probes) being too close to the heated target assembly; 3) challenges that arise for target plates with an optical window, where crucial tolerances between the sample, bond layer, and window become increasingly difficult to maintain at high temperatures; 4) in the case of combined compression-shear plate impact experiments, the need for high-temperature resistant diffraction gratings for the measurement of transverse particle velocity at the free surface of the target; and 5) limitations imposed on the impact velocity necessary for unambiguous interpretation of the measured free surface velocity versus time profile due to thermal softening and possibly yielding of the bounding target plates.By utilizing the adaptations mentioned above, we present results from a series of reverse geometry normal plate impact experiments on commercial purity aluminum at a range of sample temperatures. These experiments show decreasing particle velocities in the impacted state, which are indicative of material softening (decrease in post-yield flow stress) with increasing sample temperatures.

Here, we present a detailed protocol of a new approach for conducting elevated temperature reverse normal plate impact, and combined pressure-and-shear plate impact. The approach involves the use of a breech-end resistive coil heater to heat a sample held at the front-end of a heat-resistant sabot to the desired temperature.

采用臀端穿甲弹加热系统进行高温常压联合压力-剪切板冲击试验

A novel approach for conducting normal and/or combined pressure-shear plate impact experiments at test temperatures up to 1000 &#176;C is presented. The ...

A Random-displacement Measurement by Combining a Magnetic Scale and Two Fiber Bragg Gratings

Long-distance displacement measurements using optical fibers have always been a challenge in both basic research and industrial production. We developed and characterized a temperature-independent fiber Bragg grating (FBG)-based random-displacement sensor that adopts a magnetic scale as a novel transferring mechanism. By detecting shifts of two FBG center wavelengths, a full-range measurement can be obtained with a magnetic scale. For identification of the clockwise and counterclockwise rotation direction of the motor (in fact, the direction of movement of the object to be tested), there is a sinusoidal relationship between the displacement and the center wavelength shift of the FBG; as the anticlockwise rotation alternates, the center wavelength shift of the second FBG detector shows a leading phase difference of around 90&#176; (+90&#176;). As the clockwise rotation alternates, the center wavelength shift of the second FBG displays a lagging phase difference of around 90&#176; (-90&#176;). At the same time, the two FBG-based sensors are temperature independent. If there is some need for a remote monitor without any electromagnetic interference, this striking approach makes them a useful tool for determining the random displacement. This methodology is appropriate for industrial production. As the structure of the whole system is relatively simple, this displacement sensor can be used in commercial production. In addition to it being a displacement sensor, it can be used to measure other parameters, such as velocity and acceleration.

A protocol to create a full-range linear displacement sensor, combining two packaged fiber Bragg grating detectors with a magnetic scale, is presented.

通过组合磁量表和两个光纤布拉格光栅进行随机位移测量

Long-distance displacement measurements using optical fibers have always been a challenge in both basic research and industrial production. We developed ...

Design and Implementation of a Bespoke Robotic Manipulator for Extra-corporeal Ultrasound

With the potential for high precision, dexterity, and repeatability, a self-tracked robotic system can be employed to assist the acquisition of real-time ultrasound. However, limited numbers of robots designed for extra-corporeal ultrasound have been successfully translated into clinical use. In this study, we aim to build a bespoke robotic manipulator for extra-corporeal ultrasound examination, which is lightweight and has a small footprint. The robot is formed by five specially shaped links and custom-made joint mechanisms for probe manipulation, to cover the necessary range of motion with redundant degrees of freedom to ensure the patient&#39;s safety. The mechanical safety is emphasized with a clutch mechanism, to limit the force applied to patients. As a result of the design, the total weight of the manipulator is less than 2 kg and the length of the manipulator is about 25 cm. The design has been implemented, and simulation, phantom, and volunteer studies have been performed, to validate the range of motion, the ability to make fine adjustments, mechanical reliability, and the safe operation of the clutch. This paper details the design and implementation of the bespoke robotic ultrasound manipulator, with the design and assembly methods illustrated. Testing results to demonstrate the design features and clinical experience of using the system are presented. It is concluded that the current proposed robotic manipulator meets the requirements as a bespoke system for extra-corporeal ultrasound examination and has great potential to be translated into clinical use.

This paper introduces the design and implementation of a bespoke robotic manipulator for extra-corporeal ultrasound examination. The system has five degrees of freedom with lightweight joints made by 3D printing and a mechanical clutch for safety management.

一种用于体外超声的自定义机器人机械手的设计与实现

With the potential for high precision, dexterity, and repeatability, a self-tracked robotic system can be employed to assist the acquisition of real-time ...

A Rapid Method for Modeling a Variable Cycle Engine

The variable cycle engines (VCE) that combine the advantages of turbofan and turbojet engines, are widely considered to be the next generation aircraft engines. However, developing VCE requires high costs. Thus, it is essential to build a mathematical model when developing an aircraft engine, which may avoid a large number of real tests and reduce the cost dramatically. Modeling is also crucial in control law development. In this article, based on a graphical simulation environment, a rapid method for modeling a double bypass variable cycle engine using object-oriented modeling technology and modular hierarchical architecture is described. Firstly, the mathematical model of each component is built based on the thermodynamic calculation. Then, a hierarchical engine model is built via the combination of each component mathematical model and the N-R solver module. Finally, the static and dynamic simulations are carried out in the model and the simulation results prove the effectiveness of the modeling method. The VCE model built through this method has the advantages of clear structure and real-time observation.

Here, we present a protocol to build a component-level mathematical model for a variable cycle engine.

可变循环引擎建模的快速方法

The variable cycle engines (VCE) that combine the advantages of turbofan and turbojet engines, are widely considered to be the next generation aircraft ...

Characterization of SiN Integrated Optical Phased Arrays on a Wafer-Scale Test Station

Optical phased arrays (OPAs) can produce low-divergence laser beams and can be used to control the emission angle electronically without the need for moving mechanical parts. This technology is particularly useful for beam steering applications. Here, we focus on OPAs integrated into SiN photonic circuits for a wavelength in the near infrared. A characterization method of such circuits is presented, which allows the output beam of integrated OPAs to be shaped and steered. Furthermore, using a wafer-scale characterization setup, several devices can easily be tested across multiple dies on a wafer. In this way, fabrication variations can be studied, and high-performance devices identified. Typical images of OPA beams are shown, including beams emitted from OPAs with and without a uniform waveguide length, and with varying numbers of channels. In addition, the evolution of output beams during the phase optimization process and beam steering in two dimensions is presented. Finally, a study of the variation in the beam divergence of identical devices is performed with respect to their position on the wafer.

Here, we describe the operation of a SiN integrated photonic circuit containing optical phased arrays. The circuits are used to emit low divergence laser beams in the near infrared and steer them in two dimensions.

晶圆级试验站上SiN集成光学相控阵列的特性

Optical phased arrays (OPAs) can produce low-divergence laser beams and can be used to control the emission angle electronically without the need for ...