Name: a cost-effective and reliable method to predict mechanical stress in single-use and standard pumps
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笔者想感谢委员会科技与创新（CTI，瑞士）的财政支持（第13236.1 PFFLI-LS）。

调查用一管道泵设置（Figu重新2），使机械应力实验在流速为将60μL分钟-1和压力下降到将要执行2巴进行。 如图ü重新2中，实验装置包括储存容器，泵电路和设备的内联内窥镜技术。储存容器的叶轮只用于混合表面活性剂。外围元件被整合到闭环监测的流速V和压降p在不同泵的设置。该调查是通过使用手轮阀变化。 1.实验装置<ol><li>确保生物反应器（D = 0.15 M，H / D = 2.2）装有一个叶轮，用于将surfacta的溶解核苷酸，并确保该入口管骤降到流体，以避免气体进入。 </li><li>装备在泵循环用注射器端口，所调查的泵，一个夹式流量计，单次使用的压力传感器和一个手轮阀。泵循环到贮存容器的连接后，将泵头部连接到马达，并准备内窥镜探针。 </li><li>装入可变反射面，在这种情况下，铑镜，在探头尖端和调整反射镜和透镜之间的距离为150μm。调整螺钉100微米聚焦物镜的清晰度。 </li><li>经由光纤电缆和内窥镜到计算机通过以太网电缆将相机将探头连接到所述频闪仪。然后，通过一个触发方框线连接相机和频闪仪一起。 </li><li>启动计算机并打开制造商提供的软件，其包括图像采集和识别软件，以及结果分析软件。 </li><li>选择主菜单图像获取软件。 </li><li>按一下按钮在屏幕来检测照相机的左上角"检测装置"。 </li><li>在"目录设置"选择计算机上的位置保存图像并激活命令"创建触发器子文件夹"。 </li><li>在输入部分工艺参数"触发模式:准备好"。 帧速率:7.5赫兹 每次触发帧:50 触发器数:60 触发间隔:60秒</li><li>的所有准备工作完成后，倒入5升去离子水，储存容器和泵切换到填充泵和泵回路。 </li><li>关闭水泵，并添加表面活性剂0.9毫升（C = 表面活性剂 0.18毫升L -1，ρ 表面活性剂，20°C =1070公斤米-3，临界胶束浓度（CMC）:CMCω0;≈0.018毫升L-1，ω 表面≈10·ωCMC）用10毫升吸管下搅拌。 10分钟后的表面活性剂完全溶解。 </li><li>关掉叶​​轮并打开泵。定位的内窥镜探头，使透镜入口管下方直接位于。 </li><li>设定为3.4 L分钟流速-1和0.03，0.3或0.61巴，通过改变叶轮的速度和手轮阀的压降。 </li><li>重6.3克的油直接在注射器（β 油 = 1.26Hz克L- -1，ρ 油，20℃=989.5千克米-3）。 </li><li>启动图像采集软件，并经由注射器端口加入油中。运行泵分配乳液滴。 </li><li> 1小时后，完成该剪切应力调查并清洁直列型内窥镜以及生物反应器具有集成的泵循环。随后，准备实验装置为下泵送过程。 </li></ol> 2.测量与图像分析<ol><li>打开在主菜单中的自动图像识别软件。 </li><li>在"批量根目录"选择计算机上的位置来保存文件（所有* .csv的）。 </li><li>在屏幕的左下角选择列"图片系列路径"，然后点击按钮"添加图片系列子文件夹"来加载图像序列。 </li><li>加载其由制造商提供的工艺参数。选择列"搜索设置（* .pss或定做_ *。MAT）"，然后单击在中等偏下的屏幕按钮"设置搜索设置"加载以指定的下降识别过程的参数。 </li><li>选择列"搜索模式（* .psp或F _ *。MAT），点击按钮"设置搜索模式"在屏幕的右下角加载以指定降分析的处理参数。 </li><li>通过点击按钮"开始批量"启动图像识别。 </li><li>图像识别结束后，表示所检测的液滴尺寸由Sauter平均径（d 32），或任何其他代表平均值或选择的分布，通过使用结果分析器软件。 </li><li>打开在主菜单中的结果分析软件。 </li><li>激活指令"的所有* .csv的1文件夹"，然后点击按钮"加载文件夹（S）"在屏幕的左上角加载以前保存的所有* .csv文件。 </li><li>在下拉列表在屏幕的上部中间选择相关值（ 例如，沙得平均粒径）以可视化的结果。对于直径的计算输入的0.6591微米像素-1缩放在右边，这是由制造商提供的。 </li></ol><img alt="图2" src="/files/ftp_upload/53052/53052fig2.jpg" /> 图2.实验装置的泵源电路用于使用内联内窥镜作为测量技术管道泵设置:（1）储存容器;（2）注射口，（3）泵，（4）压力传感器，（5）流量传感器，（ 6）频闪仪，（7）电脑制造商提供的软件，和（8）内窥镜探头。 <a href="https://www.jove.com/files/ftp_upload/53052/53052fig2highres.jpg" target="_blank">请点击此处查看该图的放大版本。</a>

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沃尔夫冈Dornfeld和雷托Schöb是Levitronix有限公司，磁悬浮离心式泵的制造商的员工。

此协议的目的是显示在抽水过程中降三围尺寸内嵌内镜技术的适用性。为了这个目的，滴的油包水乳液体系的测定尺寸和一个测量索特平均直径计算为表征磁浮离心的机械应力泵以及对口，蠕动和4活塞隔膜泵。结果表明所测量索特的低变化的意思的直径，这是通过在15％以下的标准偏差量化，这表明液滴尺寸已可靠和准确地测量。其结果是，所测量索特平均直径可以成功地用作比较标准来评价调查了泵的机械应力。磁悬浮离心泵透露较大的测量索特平均直径，表明在乳液滴较低的机械应力的蠕动和4活塞隔膜泵相比。在螺柱独立实体迄今，直列内窥镜已被证明是一个强大的和简单的技术可靠滴尺寸测量1,6,12-14,20-21，这也证实了这项研究。相比于替代的测量技术，如光纤FBR传感器中，FBRM和2D-ORM技术，内窥镜技术可被用作用于获得精确的数据在液体/液体应用12,14的标准方法。 易于处理内嵌内窥镜和简单的生产的非生物油包水乳液体系的使得能够按照协议文本一个简单的程序，液滴尺寸检测（见上文）。然而，应该指出的是，在内窥镜探头的位置取决于在存储容器中的流体流动。进一步的调查（数据未显示）揭示，探针的透镜应直接流入管下方设于低流率高达5升分钟-1为了避免多重检测的一滴19。超过5升分钟-1的清晰图像，在流率时，建议定位探针至少10厘米的距离的入口管。独立的工艺参数，内联内窥镜的持有者应以避免变速探针，这可能会导致模糊的图像是稳定的。 此外，应该特别注意的是，检测到的液滴尺寸是接近所施加光的光学系统，其中，最小可检测水滴直径为6.5微米的检测下限。作为制造商提供的软件进行了改进，直列内窥镜技术可以可靠地检测的1微米的最小液滴尺寸。此外，图像处理将进一步发展，以使工业应用的实时监测。 虽然目前的研究重点是高达3.4 L相对低流量<html> 60;分-1，今后的研究应考虑更宽范围的运转条件。第一调查已经进行了在流率高达20升分钟-1（数据未显示）。然而，1:油-水乳液体系2稀释（三表面活性剂 =0.09毫升L-1，C 油 =0.64毫升L-1），建议在流速超过10升分钟-1 19，如增加滴解体致更高的机械应力，否则会影响下降检测和减少检测滴数。试验，进行了以1:2稀释并用未稀释的油包水乳液体系的结果进行比较。对于这两种方法，Sauter平均直径已可靠计量的（低于5％的标准偏差）。因此，减小的体积分数（1:2稀释）并不影响测量Sauter平均直径，并因此落滴解体是微不足道的。 NT"&gt;这些功能强大的实验方法为内镜技术的改进以及相关的图像采集，识别和分析结果软件的良好基础。此外，内镜技术是否适合类型的泵和系列分类，根据他们的机械应力被成功地证明，所获得的结果是对泵的设计开发和泵的优化来​​减少细胞损伤是至关重要的。

泵被用来传送细胞培养在制药和生物技术工业。在泵送过程中，机械应力可导致不可逆的细胞损伤，这可能会损害产品1-4的数量和质量。机械应力的水平取决于泵的类型和泵的设置，这表现在以前的研究5-6。通常，蠕动，注射器和隔膜泵被用于单次使用（SU）技术为基础的应用程序。这些泵导致引起的泵管的压缩和脉动流7高的局部剪切力。 为了克服这些缺点，磁悬浮离心泵（磁悬浮离心泵）构成一个有前途的替代方案。在电动机磁驱动，以避免在叶轮和泵壳（ 图1）之间狭窄的间隙。先前的研究调查了磁悬浮离心式泵和在中国仓鼠卵巢 （CHO）细胞中显示出较低的机械应力与蠕动和4活塞隔膜泵5比较。另外，溶血分析显示无显著血液创伤和血栓形成的范围上使用这些泵8-11操作条件。研究结果表明，利用这些专门设计的泵与蠕动和隔膜泵相比对生物系统应用较少的机械应力。调查了机械应力具有有限的实验费用，油包水乳液模型系统，由于其成本（ 约 99.8％）和时间减少（ 约 99.5％）的应用与生物细胞培养系统相比，推荐使用。 作为油包水乳液体系的滴解体是机械应力的函数，滴大小必须在剪切应力调查的实验时间进行计数。有很多技术选型提供滴，WHICH可分为声音，激光器和光电基础的技术12。具体地，使用光的光探测器直列内窥镜的显示几乎相同的液滴尺寸用于手动和自动检测（低于10％的标准偏差），使检测的250滴每分钟13。其准确性和可靠性，因为，将内窥镜技术已被证明是用于在液体/液体分散体的液滴大小分布的有效标准的测量技术，与其它常用的探头（ 例如，光纤前后比（FBR）传感器相比，聚焦光束反射法（FBRM）和二维光学反射率测量技术（2D-ORM））12,14。此外，内联内窥镜的适宜用于测量液滴大小在一个搅拌容器已经证明多次以前的调查15-18。 基于之前的研究6，本协议描述利用内嵌内窥镜来确定墨滴尺寸（索特平均直径）的油包水乳液体系在泵。 Sauter平均直径被用作比较标准，以便估计多用（MU）磁悬浮离心泵，蠕动和单次使用的（SU）4活塞隔膜泵的机械应力。 <img alt="图1" src="/files/ftp_upload/53052/53052fig1.jpg" /> 图1.磁悬浮离心式泵系统。（A）无轴承电机和（B）的PuraLev 200亩的原理，作为一个例子。 <a href="https://www.jove.com/files/ftp_upload/53052/53052fig1highres.jpg" target="_blank">请点击此处查看该图的放大版本。</a>

<table><tbody><tr><td>CCD camera</td><td>Allied Vision Technologies GmbH</td><td>GX2750</td><td>Equipment for inline endoscopy</td></tr><tr><td>C-Flex Biopharmaceutical Tubing</td><td>Saint-Gobain Performance Plastics</td><td>374-375-4</td><td>Tube&lt;br/&gt; Select a tubing length of about 45&amp;nbsp;cm before the pump.</td></tr><tr><td>C-Flex Biopharmaceutical Tubing</td><td>Saint-Gobain Performance Plastics</td><td>374-375-3</td><td>Tube&lt;br/&gt; Select a tubing length of about 45&amp;nbsp;cm after the pump and clamp on the flow sensor to this tubing.</td></tr><tr><td>CLAVE Connector</td><td>Victus</td><td>011-C2000</td><td>Sampling port</td></tr><tr><td>Controller LPC-200.1-02</td><td>Levitronix GmbH</td><td>100-30030</td><td>PuraLev 200MU controller</td></tr><tr><td>Controller LPC-600.1-02</td><td>Levitronix GmbH</td><td>100-30033</td><td>PuraLev 600MU controller</td></tr><tr><td>LeviFlow Clamp-On Sensor LFSC-12</td><td>Levitronix GmbH</td><td>100-30329</td><td>Flow sensor for flow rates below 5&amp;nbsp;L&amp;nbsp;min&lt;sup&gt;-1&lt;/sup&gt;</td></tr><tr><td>LeviFlow Converter LFC-1C-CS</td><td>Levitronix GmbH</td><td>100-30328</td><td>Flow sensor output device&amp;nbsp;</td></tr><tr><td>Masterflex I/P Easy Load</td><td>Fisher Scientific AG</td><td>EW-77963-10</td><td>Peristaltic pump</td></tr><tr><td>Mitos free flow valve</td><td>Parker Hannifin Europe S&amp;agrave;rl</td><td>FFLQR16S6S6AM</td><td>Valve</td></tr><tr><td>Mobil Eal Arctic</td><td>Exxon Mobil Corporation</td><td>Mobil EAL Arctic 22</td><td>Oil&lt;br/&gt; Prepare the emulsion directly before the experiment.</td></tr><tr><td>Motor</td><td>Elektromotorenwerk Brienz AG</td><td>7WAC72N4THTF</td><td>Motor for agitator shaft</td></tr><tr><td>Motor BSM-1.4</td><td>Levitronix GmbH</td><td>100-10005</td><td>PuraLev 200MU motor</td></tr><tr><td>Motor LPM-600.4</td><td>Levitronix GmbH</td><td>100-10038</td><td>PuraLev 600MU motor</td></tr><tr><td>Norm-Ject 10 ml Luer Lock</td><td>Restek Corporation</td><td>22775</td><td>Syringe</td></tr><tr><td>Pump Head LPP-200.5</td><td>Levitronix GmbH</td><td>100-90525</td><td>PuraLev 200MU pump head</td></tr><tr><td>Pump Head LPP-600.18</td><td>Levitronix GmbH</td><td>100-90548</td><td>PuraLev 600MU pump head</td></tr><tr><td>Quattroflow 1200-SU</td><td>Almatechnik AG</td><td>QF 1200</td><td>4-piston diaphragm pump</td></tr><tr><td>SciPres Sensor</td><td>SciLog</td><td>080-695PSX</td><td>Pressure sensor</td></tr><tr><td>SciPres Sensor Monitor</td><td>SciLog</td><td>080-690</td><td>Pressure sensor output device&amp;nbsp;</td></tr><tr><td>SOPAT-VF Inline Endoscopic Probe</td><td>SOPAT GmbH</td><td></td><td>Inline endoscopy</td></tr><tr><td>Stroboscope</td><td>Drello GmbH &amp;amp; Co KG</td><td>Drelloscop 255-01</td><td>Equipment for inline endoscopy</td></tr><tr><td>Triton X-100</td><td>Sigma-Aldrich</td><td>X100</td><td>Surfactant&lt;br/&gt;Handle with gloves and goggles.&lt;br/&gt; (acute toxicity, eye irritation)</td></tr></tbody></table>

a cost-effective and reliable method to predict mechanical stress in single-use and standard pumps

在生物制药和生物技术生产过程转移无菌培养肉汤时，泵主要使用。然而，在泵送过程中的剪切力发生可导致定性和/或定量的产品损失。来计算机械应力具有有限的实验费用，油包水乳液体系中使用时，其适用性被证明为在生物反应器1滴大小检测。作为油包水乳液体系的滴解体是机械应力的函数，滴大小需要过度的剪切应力调查的实验时间进行计数。在以前的研究中，内联内窥镜已被证明是在液体/液体分散体的液滴大小检测的精确和可靠的测量技术。此协议的目的是显示在抽水过程中降三围尺寸内嵌内镜技术的适用性。为了表示的液滴尺寸，沙得平均粒径ð32被用作在油包水乳液液滴的代 ​​表性直径。结果表明低变化的索特平均直径，这是通过在15％以下的标准偏差量化，表示测量技术的可靠性。

光学评估 图û重新3示出后1小时的泵送时间的粒子识别图像。上部四个图像显示识别之前的液滴而其低四位图像显示标记的识别软件的液滴。检测到的液滴突出了一个绿色的边。比较所述上部和下部的图像显示，降边缘分别由图像识别软件精确地检测。左侧的照片显示了磁悬浮离心滴分配泵PuraLev 200亩和PuraLev 600亩，以及那些在右侧示出了4活塞隔膜和蠕动泵。光学评估所允许的机械应力的初始分类模型中的乳液体系。这表明，较大的液滴尺寸和较低的降计数由磁悬浮离心泵生成与4活塞diaphr相比股东周年大会及蠕动泵。因此，磁悬浮离心泵，尤其是PuraLev 200亩，显示减少破损下降，表明较低的机械应力。 <img alt="图3" src="/files/ftp_upload/53052/53052fig3.jpg" /> 内嵌内镜图3.图像后（A，B，C，D）后（E，F，G，H）的粒子识别1小时用（A，E）的PuraLev 200亩抽乳液之前滴，（ B，F）的PuraLev 600亩，（C，G）的​​4活塞隔膜泵，和（D，H），在相同的工作条件蠕动泵（3.4 L -1分钟和0.03条）。 <a href="https://www.jove.com/files/ftp_upload/53052/53052fig3highres.jpg" target="_blank">请点击此处查看更大的版本这个数字。</a> 索泰我一个直径进一步调查发现下面ð32±0.4微米的标准偏差，并保证可重复的结果使用内联内镜19时。因此，并不需要这种方式，其还降低了实验费用多的调查。 为了表示的液滴尺寸，沙得平均直径d 32（见公式1）作为在油-水乳液，用于这种方法液滴的代 ​​表直径。在一般情况下，在沙得平均粒径随时间而减少的所有类型的泵和泵设置，直至达到稳态12。在这项研究中调查证实Sauter平均直径的进展（ 图û重新4A至D），的PuraLev 200亩（ 图曲线Ü重新＆＃160; 4A）和蠕动泵（ 图Ú重新4D）在这个协议中被示例性地讨论。 与此相反的PuraLev 200亩，沙得平均直径为高达40％，为蠕动泵较小在相同的操作条件下（流速= 3.4 L分钟-1;压降= 0.03巴）。其结果是，更高的机械应力产生了一个增加的滴解体，因此，更小的液滴尺寸。此外，在沙得平均粒径与在PuraLev 200亩增加压降（ 图Ú重新4A），这表明液滴尺寸的依赖压降减小。与此相反，蠕动泵呈沙得平均的D- 32,60min = 10微米直径在实验的所有工艺参数的端部（ 图ü重新4D）。因此，沙得平均粒径被认为是独立的压降。然而，调查结果反映了下降解体物理的理解:具有较高的机械应力，较小的索特平均直径测定（参见图也重新ü5）。 对于每个测量点，至少300下降，以保证统计确定性进行了测定。最大标准差降低为PuraLev 200亩从D 32,4min±42微米，为PuraLev 600亩从D 32,6min±21微米到大约ð32±0.5微米，在泵送过程结束。从增加的均匀的液滴尺寸分布的减小标准偏差导致直至达到稳定状态。在比较牛逼Ø磁悬浮离心式泵，蠕动和4活塞隔膜泵透露下面ð32±10微米的标准偏差。 <img alt="式（1）" src="/files/ftp_upload/53052/53052eq1.jpg" width="80" /> （1） <img alt="图4" src="/files/ftp_upload/53052/53052fig4.jpg" /> 索泰图4.典型剖面直径平均32ð随着时间的推移和测量索特平均直径的D判断32，男 。的沙得平均直径比较ð32（A）中为PuraLev 200亩，（B）为PuraLev 600亩，（C）为4-活塞隔膜泵，和（D）为蠕动泵。的沙得平均直径ð32分别以3.4 L分钟-1的流速来确定和压力下降，从0.03至0.61巴。所测量索特平均直径d 32，米 ，计算在过去的10分钟（边界）。 Sauter平均直径的标准产生的偏差D 32（N≥300）显示。 <a href="https://www.jove.com/files/ftp_upload/53052/53052fig4highres.jpg" target="_blank">请点击此处查看该图的放大版本。</a> 测量索特平均直径作为比较系统 如上所述，沙得平均粒径随时间降低直至液滴尺寸达到稳定状态。在实验时间过去10分钟时，沙得的平均值平均直径计算为确定所测量的沙得平均直径，这是作为一个比较标准（ 见图边界ü重新4A-D）。所测量索特平均直径ð32，米示为3.4升的流率＃160;分-1和压降范围从0.03至0.61巴图ü重新5。较大的测量索特平均直径测定为磁悬浮离心泵（200亩和600亩）和4活塞隔膜泵在较低的压降和叶轮速度。蠕动泵透露测量Sauter平均直径ð32，M = 10微米的所有工艺参数。如前所述，剪切力是独立的蠕动泵的压力降。 最大测量索特平均直径ð32米 = 36微米，为PuraLev 200亩以及d 32，M = 34微米的PuraLev 600亩分别以0.03巴的压降得到。在与他们的同行相比，磁悬浮离心泵系列获得了较大的59％测量Sauter平均直径。这些结果S所示滴解体的较低的速率和从使用离心泵所得从而降低机械应力。 测量索特的标准偏差是指直径在稳定状态低于15％，从而证实了液滴尺寸可靠和准确的值。 <img alt="图5" src="/files/ftp_upload/53052/53052fig5.jpg" /> 测量索特平均直径的图5的比较ð32微米 。测量Sauter平均直径为磁悬浮离心泵和他们的同行在3.4 L -1分钟和压降为0.03，0.30和0.61条。所测量索特平均直径的所得标准偏差ð32，在稳定状态下米被示出。 缩写 <a href="https://www.jove.com/files/ftp_upload/53052/53052fig5highres.jpg" target="_blank">PLE</a>ASE点击此处查看该图的放大版本。 <table border="0" cellpadding="0" cellspacing="0"><tbody><tr><td> 2D-ORM </td><td>二维光反射测量</td></tr><tr><td> CCD </td><td>电荷耦合器件</td></tr><tr><td> CHO </td><td>中国仓鼠卵巢</td></tr><tr><td> CMC </td><td>临界胶束浓度</td></tr><tr><td> FBR </td><td>前后比</td></tr><tr><td> FBRM </td><td>聚焦光束反射法</td></tr><tr><td> MU </td><td>多用</td></tr><tr><td> SU </td><td>单次使用的</td></tr></tbody></table> 命名法 <table border="0" cellpadding="0" cellspacing="0"><tbody><tr><td><img alt="V" fo:content-="" src="/files/ftp_upload/53052/V.jpg" width="8
" /></td><td> [米3秒-1] </td><td>流量</td></tr><tr><td> C </td><td> [米3米-3] </td><td>浓度</td></tr><tr><td> ð32 </td><td> [M] </td><td>索特平均直径</td></tr><tr><td> ð32，男 </td><td> [M] </td><td>测量索特平均直径</td></tr><tr><td> ðs </td><td> [M] </td><td>面直径</td></tr><tr><td> D V </td><td> [M] </td><td>卷径</td></tr><tr><td> F </td><td> [赫兹] </td><td>频率</td></tr><tr><td> ñ </td><td> [秒-1] </td><td>叶轮转速</td></tr><tr><td> ñ </td><td> [ - ] </td><td>滴的数目</td></tr><tr><td> p </td><td>霸</td><td>压力下降</td></tr><tr><td> Ť </td><td>秒</td><td>时间</td></tr><tr><td> β </td><td> [公斤米-3] </td><td>质量浓度</td></tr><tr><td> ρ </td><td> [公斤米-3] </td><td>密度</td></tr><tr><td>69; </td><td> [米3米-3] </td><td>质量分数</td></tr></tbody></table> 见表1。表缩写和命名。

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A Cost-effective and Reliable Method to Predict Mechanical Stress in Single-use and Standard Pumps

Shear stress investigations on an oil-water emulsion system result in drop breakup over the experimental time. To count drop sizes in pumping processes, the suitability of inline endoscopy was successfully demonstrated in this protocol.

高性价比和可靠的方法来预测机械应力一次性使用和标准泵

Pumps are mainly used when transferring sterile culture broths in biopharmaceutical and biotechnological production processes. However, during the pumping ...

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Concept of Stress

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9.4K 次观看.  Zurich University of Applied Sciences. Shear stress investigations on an oil-water emulsion system result in drop breakup over the experimental time. To count drop sizes in pumping processes, the suitability of inline endoscopy was successfully demonstrated in this protocol. 

视频: A Cost-effective and Reliable Method to Predict Mechanical Stress in Single-use and Standard Pumps

Protocol for Relative Hydrodynamic Assessment of Tri-leaflet Polymer Valves

Limitations of currently available prosthetic valves, xenografts, and homografts have prompted a recent resurgence of developments in the area of tri-leaflet polymer valve prostheses. However, identification of a protocol for initial assessment of polymer valve hydrodynamic functionality is paramount during the early stages of the design process. Traditional in vitro pulse duplicator systems are not configured to accommodate flexible tri-leaflet materials; in addition, assessment of polymer valve functionality needs to be made in a relative context to native and prosthetic heart valves under identical test conditions so that variability in measurements from different instruments can be avoided. Accordingly, we conducted hydrodynamic assessment of i) native (n = 4, mean diameter, D = 20 mm), ii) bi-leaflet mechanical (n= 2, D = 23 mm) and iii) polymer valves (n = 5, D = 22 mm) via the use of a commercially available pulse duplicator system (ViVitro Labs Inc, Victoria, BC) that was modified to accommodate tri-leaflet valve geometries. Tri-leaflet silicone valves developed at the University of Florida comprised the polymer valve group. A mixture in the ratio of 35:65 glycerin to water was used to mimic blood physical properties. Instantaneous flow rate was measured at the interface of the left ventricle and aortic units while pressure was recorded at the ventricular and aortic positions. Bi-leaflet and native valve data from the literature was used to validate flow and pressure readings. The following hydrodynamic metrics were reported: forward flow pressure drop, aortic root mean square forward flow rate, aortic closing, leakage&#160;and regurgitant volume, transaortic closing, leakage, and total energy losses. Representative results indicated that hydrodynamic metrics from the three valve groups could be successfully obtained by incorporating a custom-built assembly into a commercially available pulse duplicator system and subsequently, objectively compared to provide insights on functional aspects of polymer valve design.

There has been renewed interest in developing polymer valves. Here, the objectives are to demonstrate the feasibility of modifying a commercial pulse duplicator to accommodate tri-leaflet geometries and to define a protocol to present polymer valve hydrodynamic data in comparison to native and prosthetic valve data collected under near-identical conditions.

协议相对液力评估的三单张聚合物阀

Limitations of currently available prosthetic valves, xenografts, and homografts have prompted a recent resurgence of developments in the area of ...

科研

生物工程

A Coupled Experiment-finite Element Modeling Methodology for Assessing High Strain Rate Mechanical Response of Soft Biomaterials

This study offers a combined experimental and finite element (FE) simulation approach for examining the mechanical behavior of soft biomaterials (e.g. brain, liver, tendon, fat, etc.) when exposed to high strain rates. This study utilized a Split-Hopkinson Pressure Bar (SHPB) to generate strain rates of 100-1,500 sec-1. The SHPB employed a striker bar consisting of a viscoelastic material (polycarbonate). A sample of the biomaterial was obtained shortly postmortem and prepared for SHPB testing. The specimen was interposed between the incident and transmitted bars, and the pneumatic components of the SHPB were activated to drive the striker bar toward the incident bar. The resulting impact generated a compressive stress wave (i.e. incident wave) that traveled through the incident bar. When the compressive stress wave reached the end of the incident bar, a portion continued forward through the sample and transmitted bar (i.e. transmitted wave) while another portion reversed through the incident bar as a tensile wave (i.e. reflected wave). These waves were measured using strain gages mounted on the incident and transmitted bars. The true stress-strain behavior of the sample was determined from equations based on wave propagation and dynamic force equilibrium. The experimental stress-strain response was three dimensional in nature because the specimen bulged. As such, the hydrostatic stress (first invariant) was used to generate the stress-strain response. In order to extract the uniaxial (one-dimensional) mechanical response of the tissue, an iterative coupled optimization was performed using experimental results and Finite Element Analysis (FEA), which contained an Internal State Variable (ISV) material model used for the tissue. The ISV material model used in the FE simulations of the experimental setup was iteratively calibrated (i.e. optimized) to the experimental data such that the experiment and FEA strain gage values and first invariant of stresses were in good agreement.

The current study prescribes a coupled experiment-finite element simulation methodology to obtain the uniaxial dynamic mechanical response of soft biomaterials (brain, liver, tendon, fat, etc.). The multiaxial experimental results that arose because of specimen bulging obtained from Split-Hopkinson Pressure Bar testing were rendered to a uniaxial true stress-strain behavior when simulated through iterative optimization of the finite element analysis of the biomaterial.

一个耦合试验，有限元建模方法以评估生物材料软的高应变率力学响应

This study offers a combined experimental and finite element (FE) simulation approach for examining the mechanical behavior of soft biomaterials (e.g. ...

In Vitro Model of Physiological and Pathological Blood Flow with Application to Investigations of Vascular Cell Remodeling

Vascular disease is a common cause of death within the United States. Herein, we present a method to examine the contribution of flow dynamics towards vascular disease pathologies. Unhealthy arteries often present with wall stiffening, scarring, or partial stenosis which may all affect fluid flow rates, and the magnitude of pulsatile flow, or pulsatility index. Replication of various flow conditions is the result of tuning a flow pressure damping chamber downstream of a blood pump. Introduction of air within a closed flow system allows for a compressible medium to absorb pulsatile pressure from the pump, and therefore vary the pulsatility index. The method described herein is simply reproduced, with highly controllable input, and easily measurable results. Some limitations are recreation of the complex physiological pulse waveform, which is only approximated by the system. Endothelial cells, smooth muscle cells, and fibroblasts are affected by the blood flow through the artery. The dynamic component of blood flow is determined by the cardiac output and arterial wall compliance. Vascular cell mechano-transduction of flow dynamics may trigger cytokine release and cross-talk between cell types within the artery. Co-culture of vascular cells is a more accurate picture reflecting cell-cell interaction on the blood vessel wall and vascular response to mechanical signaling. Contribution of flow dynamics, including the cell response to the dynamic and mean (or steady) components of flow, is therefore an important metric in determining disease pathology and treatment efficacy. Through introducing an in vitro co-culture model and pressure damping downstream of blood pump which produces simulated cardiac output, various arterial disease pathologies may be investigated.

In Vitro Model of Physiological and Pathological Blood Flow with Application to Investigations of Vascular Cell Remodeling

This protocol replicates physiological or pathological blood flow in vitro to aid in determining cell response in disease pathologies. By introducing a pressure damping chamber downstream of a blood pump, blood flow across the vasculature can be recapitulated and imposed on a monolayer of vascular endothelium or a mimetic co-culture.

在生理体外模型和病理血流应用的血管细胞重塑调查

Vascular disease is a common cause of death within the United States. Herein, we present a method to examine the contribution of flow dynamics towards ...

A Multi-Cue Bioreactor to Evaluate the Inflammatory and Regenerative Capacity of Biomaterials under Flow and Stretch

The use of resorbable biomaterials to induce regeneration directly in the body is an attractive strategy from a translational perspective. Such materials induce an inflammatory response upon implantation, which is the driver of subsequent resorption of the material and the regeneration of new tissue. This strategy, also known as in situ tissue engineering, is pursued to obtain cardiovascular replacements such as tissue-engineered vascular grafts. Both the inflammatory and the regenerative processes are determined by the local biomechanical cues on the scaffold (i.e., stretch and shear stress). Here, we describe in detail the use of a custom-developed bioreactor that uniquely enables the decoupling of stretch and shear stress on a tubular scaffold. This allows for the systematic and standardized evaluation of the inflammatory and regenerative capacity of tubular scaffolds under the influence of well-controlled mechanical loads, which we demonstrate on the basis of a dynamic co-culture experiment using human macrophages and myofibroblasts. The key practical steps in this approach&#8212;the construction and setting up of the bioreactor, preparation of the scaffolds and cell seeding, application and maintenance of stretch and shear flow, and sample harvesting for analysis&#8212;are discussed in detail.

The goal of this protocol is to execute a dynamic co-culture of human macrophages and myofibroblasts in tubular electrospun scaffolds to investigate material-driven tissue regeneration, using a bioreactor which enables the decoupling of shear stress and cyclic stretch.

评估流和拉伸下生物材料的炎症和再生能力的多奎生物反应器

The use of resorbable biomaterials to induce regeneration directly in the body is an attractive strategy from a translational perspective. Such materials ...

工程学

Modeling and Experimental Analysis of the Single-Shaft Coaxial Motor-Pump Assembly in Electrohydrostatic Actuators

An electrohydrostatic actuator (EHA) can be the most promising alternative compared with the traditional hydraulic servo actuators for its high power density, ease of maintenance, and reliability. As the core power unit that determines the performance and service life of the EHA, the motor-pump assembly should simultaneously possess a wide speed/pressure range and a high dynamic response.
This paper presents a method to test the performance of the motor-pump assembly through simulation and experimentation. The flow output characteristics were defined through simulation and analysis of the assembly at the beginning of the experiment, leading to the conclusion of whether the pump could meet the requirements of the EHA. A series of performance tests were conducted on the motor-pump assembly via a pump test bench in the speed range of 1,450-9,000 rpm and the pressure range of 1-30 MPa.
We tested the overall efficiency of the motor-pump assembly under various working conditions after confirming the consistency between the test results of the flow output characteristics with the simulation results. The results showed that the assembly has higher overall efficiency when working at 4,500-7,000 rpm under the pressure of 10-25 MPa and at 2,000-2,500 rpm under 5-15 MPa. Overall, this method can be utilized for determining in advance whether the motor-pump assembly meets the requirements of EHA. Moreover, this paper proposes a rapid test method of the motor-pump assembly in various working conditions, which could assist in predicting EHA performance.

We built a simulation model to evaluate pump flow characteristics and performance of the single-shaft coaxial motor-pump assembly in electrohydrostatic actuators and investigate the overall efficiency in a wide set of working conditions of the motor-pump assembly experimentally.

静电静压执行器中单轴同轴电机泵组件的建模与实验分析

An electrohydrostatic actuator (EHA) can be the most promising alternative compared with the traditional hydraulic servo actuators for its high power ...

A Modeling and Simulation Method for Preliminary Design of an Electro-Variable Displacement Pump

Electro-hydrostatic actuators (EHAs) have been considerably researched in academia, and their applications in various industrial fields are expanding. The variable-speed EHA has now taken priority over the variable-displacement EHA, but its driving motor and associated electronics encounter issues when applied in high-power applications: low-dynamics, high thermal dissipation, high price, etc. Therefore, a variable-displacement EHA equipped with an electro-variable displacement pump (EVDP) has been considered. The EVDP itself is a mechatronic system that integrates a piston pump, a ball screw, a gearbox, and a permanent magnet synchronous motor (PMSM). Consequently, the EVDP needs to be investigated to ensure its system-level performance when applied in an EHA. In addition to the previous research on the technical parameters of the EVDP, a dedicated design method is necessary for further reducing the cost of using the EVDP and exploring its performance potential. Here, a simulation based EVDP preliminary design method is selected for designing a 37 kW EVDP. Firstly, a previously proposed multidisciplinary model of the EVDP is extended by improving the parameter generation, including the EVDP life, reliability, control models, etc. Secondly, the proposed model is partially verified using a downsized prototype. Thirdly, the EVDP is simulated at a system level, supported by the proposed model. The EVDP performance is evaluated according to the specified design requirements. The temperature, bandwidth and accuracy, reliability and lifetime, etc., are all predicted for the EVDP. The simulation results demonstrate the EVDP's applicability in variable-displacement EHA. The proposed modeling and simulation method can be used to evaluate diverse EVDP performance and respond to general design requirements. The method can also support the resolution of the preliminary design challenges in terms of limited information and robustness. Therefore, the proposed method is appropriate for the realization of the simulation-based EVDP preliminary design method.

A simulation model specifically supporting the preliminary design of an electro-variable displacement pump (EVDP) is developed and partially verified by experiments. The control performance, life, reliability, etc., can all be evaluated using the proposed model, which covers the main performance requirements under the EVDP preliminary design task.

一种电动变量泵初步设计的建模与仿真方法

Electro-hydrostatic actuators (EHAs) have been considerably researched in academia, and their applications in various industrial fields are expanding. The ...

A Performance-testing Platform for a Conduction Micropump with an FR-4 Copper-clad Electrode Plate

Here, a conduction micropump with symmetric planar electrode pairs prepared on flame-retardant glass-reinforced epoxy (FR-4) copper-clad laminate (CCL) is fabricated. It is used to investigate the influence of chamber dimensions on the performance of a conduction micropump and to determine the reliability of the conduction pump when acetone is used as the working fluid. A testing platform is set up to evaluate conduction micropump performance under different conditions. When the chamber height is 0.2 mm, the pump pressure reaches its peak value.

This paper presents a protocol for the fabrication of a conduction micropump using symmetric planar electrodes on flame-retardant glass-reinforced epoxy (FR-4) copper-clad laminate (CCL) to test the influence of chamber dimensions on the performance of a conduction micropump.

FR-4 铜包电极板导电微泵性能测试平台

Here, a conduction micropump with symmetric planar electrode pairs prepared on flame-retardant glass-reinforced epoxy (FR-4) copper-clad laminate (CCL) is ...

The Quantification of Injectability by Mechanical Testing

Injectable biomaterials are becoming increasingly popular for the minimally invasive delivery of drugs and cells. These materials are typically more viscous than traditional aqueous injections and may be semi-solid, therefore, their injectability cannot be assumed. This protocol describes a method to objectively assess the injectability of these materials using a standard mechanical tester. The syringe plunger is compressed by the crosshead at a set rate, and the force is measured. The maximum or plateau force value can then be used for comparison between samples, or to an absolute force limit. This protocol can be used with any material, and any syringe and needle size or geometry. The results obtained may be used to make decisions about formulations, syringe and needle sizes early in the translational process. Further, the effects of altering formulations on injectability may be quantified, and the optimum time to inject temporally changing materials determined. This method is also suitable as a reproducible way to examine the effects of injection on a material, to study phenomena such as self-healing and filter pressing or study the effects of injection on cells. This protocol is faster and more directly applicable to injectability than rotational rheology, and requires minimal post processing to obtain key values for direct comparisons.

Presented here is a protocol for quantitatively evaluating the injectability of a material through a syringe-needle system using a standard mechanical testing rig.

机械测试的注入性量化

Injectable biomaterials are becoming increasingly popular for the minimally invasive delivery of drugs and cells. These materials are typically more ...

Pneumococcus Infection of Primary Human Endothelial Cells in Constant Flow

Interaction of Streptococcus pneumoniae with the surface of endothelial cells is mediated in blood flow via mechanosensitive proteins such as the Von Willebrand Factor (VWF). This glycoprotein changes its molecular conformation in response to shear stress, thereby exposing binding sites for a broad spectrum of host-ligand interactions. In general, culturing of primary endothelial cells under a defined shear flow is known to promote the specific cellular differentiation and the formation of a stable and tightly linked endothelial layer resembling the physiology of the inner lining of a blood vessel. Thus, the functional analysis of interactions between bacterial pathogens and the host vasculature involving mechanosensitive proteins requires the establishment of pump systems that can simulate the physiological flow forces known to affect the surface of vascular cells.
The microfluidic device used in this study enables a continuous and pulseless recirculation of fluids with a defined flow rate. The computer-controlled air-pressure pump system applies a defined shear stress on endothelial cell surfaces by generating a continuous, unidirectional, and controlled medium flow. Morphological changes of the cells and bacterial attachment can be microscopically monitored and quantified in the flow by using special channel slides that are designed for microscopic visualization. In contrast to static cell culture infection, which in general requires a sample fixation prior to immune labeling and microscopic analyses, the microfluidic slides enable both the fluorescence-based detection of proteins, bacteria, and cellular components after sample fixation; serial immunofluorescence staining; and direct fluorescence-based detection in real time. In combination with fluorescent bacteria and specific fluorescence-labeled antibodies, this infection procedure provides an efficient multiple component visualization system for a huge spectrum of scientific applications related to vascular processes.

This study describes the microscopic monitoring of pneumococcus adherence to von Willebrand factor strings produced on the surface of differentiated human primary endothelial cells under shear stress in defined flow conditions. This protocol can be extended to detailed visualization of specific cell structures and quantification of bacteria by applying differential immunostaining procedures.

恒流中原发性人类内皮细胞的肺炎球菌感染

Interaction of Streptococcus pneumoniae with the surface of endothelial cells is mediated in blood flow via mechanosensitive proteins such as the Von ...

免疫与感染

Construction of a Human Aorta Smooth Muscle Cell Organ-On-A-Chip Model for Recapitulating Biomechanical Strain in the Aortic Wall

Conventional two-dimensional cell culture techniques and animal models have been used in the study of human thoracic aortic aneurysm and dissection (TAAD). However, human TAAD sometimes cannot be characterized by animal models. There is an apparent species gap between clinical human studies and animal experiments that may hinder the discovery of therapeutic drugs. In contrast, the conventional cell culture model is unable to simulate in vivo biomechanical stimuli. To this end, microfabrication and microfluidic techniques have developed greatly in recent years, providing novel techniques for establishing organoids-on-a-chip models that replicate the biomechanical microenvironment. In this study, a human aorta smooth muscle cell organ-on-a-chip (HASMC-OOC) model was developed to simulate the pathophysiological parameters of aortic biomechanics, including the amplitude and frequency of cyclic strain experienced by human aortic smooth muscle cells (HASMCs) that play a vital role in TAAD. In this model, the morphology of HASMCs became elongated in shape, aligned perpendicularly to the strain direction, and presented a more contractile phenotype under strain conditions than under static conventional conditions. This was consistent with the cell orientation and phenotype in native human aortic walls. Additionally, using bicuspid aortic valve-related TAAD (BAV-TAAD) and tricuspid aortic valve-related TAAD (TAV-TAAD) patient-derived primary HASMCs, we established BAV-TAAD and TAV-TAAD disease models, which replicate HASMC characteristics in TAAD. The HASMC-OOC model provides a novel in vitro platform that is complementary to animal models for further exploring the pathogenesis of TAAD and discovering therapeutic targets.

Here, we developed a human aorta smooth muscle cell organ-on-a-chip model to replicate the in vivo biomechanical strain of smooth muscle cells in the human aortic wall.

构建人主动脉平滑肌细胞器官芯片模型，用于概括主动脉壁中的生物力学应变

Conventional two-dimensional cell culture techniques and animal models have been used in the study of human thoracic aortic aneurysm and dissection ...