想伊利诺伊大学Urbana-Champaign分校感谢约瑟夫Muskin的马修拉古萨提供的横截面图像的三维结构如图1D。

1。预聚物溶液的制备<ol><li>混合的聚（乙二醇）二丙烯酸酯（PEG-DA）（平均分子量〜575，Sigma-Aldrich公司），聚（乙二醇）（PEG）（平均分子量约200，Sigma-Aldrich公司）以1:2的重量比。 </li><li>添加0.67％（重量）。光引发剂（苯基双（2,4,6 - 三甲基苯甲酰基）氧化膦，Sigma-Aldrich公司）。该解决方案应该保持在黑暗的环境，从这个角度上。 </li><li>添加0.05％（重量）。照片吸收剂（苏丹I，Sigma-Aldrich公司）。 </li><li>溶液混合24小时，在室温下用磁力搅拌器。 </li></ol> 2。建立一个桌面3D打印机使用数字数据投影机<ol><li>将数字数据投影机在一个平整，稳固的位置，并把它连接到的计算机上安装Microsoft PowerPoint。 </li><li>放置的凸透镜的光束输出的数字投影机镜头的前面权利。选择凸透镜，使焦平面的距离约10厘米的亲投影机。 （光学分辨率变小的镜头焦距越短，但是需要预留一些空间光学元件。） </li><li>放置一个反射镜后的凸透镜的光束路径上，在45°角的指示光束垂直向下。 </li><li>样本保持器放置在焦平面的投影光束。样本保持器应连接到样本保持器的垂直位置控制的线性阶段。 </li><li>将下方的样本保持器的树脂浴。 </li></ol> 3。凝胶管的设计与制作<ol><li>确定以被制造的凝胶管的直径，壁厚，和高度。 </li><li>绘制的横截面图像的凝胶管。应该是白色与黑色背景的图像。在Microsoft PowerPoint幻灯片中插入这些图像。 </li><li>开始幻灯片显示在Microsoft PowerPoint中的任何图像投影。通过调整垂直位置使用ATT样本保持器放置在焦平面疼痛难忍的阶段。 </li><li>切换到一个“虚拟”的黑色图象，以便有没有不需要的聚合反应的同时，将预聚物溶液。 </li><li>倒入树脂槽的预聚物溶液。填充浴直至溶液稍微覆盖样本保持器。现在，它已准备好打印三维物体。 </li><li>切换到滑动含有第一凝胶管的横截面的图像，以聚合所述第一层。投影图像，持续8秒，并切换到“停电”的幻灯片。 </li><li> ¼圈，旋转旋钮上的线性阶段（〜160微米），以降低样品架。现在，新的树脂流，以支付第一层聚合。 </li><li>投影的横截面的图像，再聚合的进行1的顶部上的第二层。重复步骤3.6-3.8来制造所需的高度，直到凝胶管。 </li><li>所有层都完成后，抬起样品架的预聚物溶液，并检索所制作的样品小心用剃刀BLADE。 </li><li>冲洗样品中丙酮〜3小时，然后允许它干〜1小时。 </li></ol> 4。膨胀弹性失稳通过规定模式形成试验<ol><li>准备水油双层液体在透明的玻璃盘。 </li><li>将干燥的样品在样品架上，使用超级胶水。 </li><li>翻转，使样品的样品架是上下颠倒。样品浸入液体浴中的水 - 油。接近样品从油层中的水 - 油界面。样品开始膨胀时，样品接触的水的表面，同时留在基底基板的一部分，在其上的凝胶管固定顶部油层。以这种方式，水可以扩散到管壁，使样品溶胀约束基底前放松通过润湿。监视使用数码相机作为凝胶管膨胀的模式变化。 </li></ol>

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	<li>Timoshenko, S. P., Gere, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Theory of Elastic Stability. , (1961).</li><li>Sharon, E., Marder, M., Swinney, H. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Leaves+Flowers+and+Garbage+Bags:+Making+Waves.">Leaves Flowers and Garbage Bags: Making Waves.</a> American Scientist. 92, 254-261 (2004).</li><li>K&#252;cken, M., Newell, A. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fingerprint+formation.">Fingerprint formation.</a> Journal of Theoretical Biology. 235, 71-83 (2005).</li><li>Liang, H., Mahadevan, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+shape+of+a+long+leaf.">The shape of a long leaf.</a> Proceedings of the National Academy of Sciences. 106, 22049-22054 (2009).</li><li>Bayer, S. A., Altman, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The human brain during the second trimester. , (2005).</li><li>Trujillo, V., Kim, J., Hayward, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Creasing+instability+of+surface-attached+hydrogels.">Creasing instability of surface-attached hydrogels.</a> Soft Matter. 4, 564 (2008).</li><li>Breid, D., Crosby, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+stress+state+on+wrinkle+morphology.">Effect of stress state on wrinkle morphology.</a> Soft Matter. 7, 4490 (2011).</li><li>Mora, T., Boudaoud, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Buckling+of+swelling+gels.">Buckling of swelling gels.</a> The European Physical Journal E. 20, 119-124 (2006).</li><li>DuPont, S. J., Cates, R. S., Stroot, P. G., Toomey, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Swelling-induced+instabilities+in+microscale,+surface-confined+poly(N-isopropylacryamide)+hydrogels.">Swelling-induced instabilities in microscale, surface-confined poly(N-isopropylacryamide) hydrogels.</a> Soft Matter. 6, 3876-3882 (2010).</li><li>Dervaux, J., Couder, Y., Guedeau-Boudeville, M. -. A., Ben Amar, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shape+Transition+in+Artificial+Tumors:+From+Smooth+Buckles+to+Singular+Creases.">Shape Transition in Artificial Tumors: From Smooth Buckles to Singular Creases.</a> Physical Review Letters. 107, 018103 (2011).</li><li>Jang, J. -. H., Koh, C. Y., Bertoldi, K., Boyce, M. C., Thomas, E. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Combining+Pattern+Instability+and+Shape-Memory+Hysteresis+for+Phononic+Switching.">Combining Pattern Instability and Shape-Memory Hysteresis for Phononic Switching.</a> Nano Letters. 9, 2113-2119 (2009).</li><li>Lee, H., Zhang, J., Jiang, H., Fang, N. X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prescribed+Pattern+Transformation+in+Swelling+Gel+Tubes+by+Elastic+Instability.">Prescribed Pattern Transformation in Swelling Gel Tubes by Elastic Instability.</a> Physical Review Letters. 108, 214304 (2012).</li><li>Sun, C., Fang, N., Wu, D. M., Zhang, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Projection+micro-stereolithography+using+digital+micro-mirror+dynamic+mask.">Projection micro-stereolithography using digital micro-mirror dynamic mask.</a> Sensors and Actuators A: Physical. 121, 113-120 (2005).</li><li>Muskin, J., Ragusa, M., Gelsthorpe, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-Dimensional+Printing+Using+a+Photoinitiated+Polymer.">Three-Dimensional Printing Using a Photoinitiated Polymer.</a> Journal of Chemical Education. 87, 512-514 (2010).</li></ol>

没有利益冲突的声明。

在肿胀的管状水凝胶在所述基板上的制约，稳定性只依赖于吨/小时和屈曲模式仅取决于在 h / D 12。四组样品的制作有不同程度的归一化厚度T / H（I-IV），I组厚和IV组更加修长。每个组由四个样品不同程度的归一化高度 h / D（I-IV），与样品 i短，样品四高。制备的样品的尺寸示于表1。 I 组和II的目的是在溶胀过程中保持稳定，而III和IV组的设计扣，改造后肿胀。屈曲样品，巴克林g模式应减少样品高度。 图3A显示了实验结果。理论预测，I 组和II的样品是稳定的，保持圆形肿胀，而III和IV组的样品中都经历了弹性不稳定，沉着应战。此外，样品具有相同的H / D显示类似的屈曲模态。 图3B实验观察到的屈曲模态的样品进行比较，III和IV组与理论预测。我们可以看到，样品具有相同的H / D构成相同的后屈曲模式的厚度无关，而与理论，实验结果吻合得很好。 我们提出了如何建立一个简单的桌面3D打印系统，使用市售的数字数据投影机。本文提出的方法依赖于光固化聚合物浓度结构的三维结构，因此，任何光固化的聚合物也可以使用一般，作为光引发剂在可见光波长范围内具有适当的吸光度。注意，许多市售的光聚合引发剂被设计用于超紫外线（UV）的波长，但这里所用的光引发剂在波长长于400nm的具有相对较高的吸光度。提供一个简单而快速的方式制作的3D对象，这个方法就可以找到许多应用在各个领域，包括软质材料力学，这里展示的。

<table border="1"><tbody><tr><td> 的试剂的名称 </td><td> 公司 </td><td> 目录编号 </td><td> 评论（可选） </td></tr><tr><td>聚（乙二醇）二丙烯酸酯</td><td> Sigma-Aldrich公司</td><td> 437441 </td><td> MW〜575 </td></tr><tr><td>聚（乙二醇） </td><td> Sigma-Aldrich公司</td><td> P3015 </td><td> MW〜200 </td></tr><tr><td>苯基双（2,4,6 - 三甲基苯甲酰基）氧化膦</td><td> Sigma-Aldrich公司</td><td> 511447 </td><td>光引发剂</td></tr><tr><td>苏丹红I </td><td> Sigma-Aldrich公司</td><td> 103624 </td><td>光吸收</td></tr><tr><td>数字数据投影机</td><td>优派</td><td> PJD6221 </td><td></td></tr><tr><td>凸透镜</td><td> Thorlabs公司</td><td> LA1145 </td><td> F =75.0毫米的</td></tr><tr><td> MIRR或</td><td></td><td></td><td> 4“硅片</td></tr><tr><td>手动阶段</td><td> Velmex </td><td> A2506DE-S2.5 </td><td></td></tr></tbody></table>

micro 3d printing using a digital projector and its application in the study of soft materials mechanics

屈曲力学中是一个经典的话题。虽然屈曲长期以来一直研究的主要结构故障模式之一，它最近引起了新的关注，作为一个独特的机制，模式转型。自然是充满了这样的例子，在那里形成了丰富的异国情调的图案通过机械性不稳定2-5。这家典雅的机制的启发，许多研究表明，建立和改造的模式，使用软质材料，如弹性体和凝胶6-11。溶胀凝胶是特别感兴趣的，因为它们可以自发地触发机械不稳定性来创建各种图案，而不需要外力6-10。最近，我们曾报道了示范屈曲模式的规模微管凝胶使用投影微立体光刻（PμSL）的，三维（3D）的制造技术，能够迅速将计算机生成的三维模型我的完全控制权置身于物理对象在高分辨率12,13。在这里，我们提出了一个简单的方法来建立一个的简化PμSL系统，使用市售的数字数据投影机肿胀引起的屈曲失稳的控制方式转变的研究。 一个简单的桌面3D打印机使用的现成的数字数据投影机和简单的光学元件，如凸透镜和镜子14。从三维实体模型提取的横截面的图像被投影在感光性树脂表面顺序，液体树脂聚合成所需的三维固体结构中的层由层的方式。即使这个简单的配置和简单的过程，可以很容易制作任意三维物体低于100微米的分辨率。 桌面3D打印机具有潜在的软材料力学的研究提供了很好的机会，探索各种3D几何。我们使用这个系统来法布里卡特筒状水凝胶具有不同尺寸的结构。固定在基板的底部，管状凝胶开发期间肿胀，这就会引起屈曲失稳不均匀应力。出现各种波状图案沿着所述管的外周时，凝胶的结构进行屈曲。实验结果表明，周屈曲所需的模式，可以以受控的方式创建。模式转型的三维结构管状凝胶具有显着的含义不仅在力学和材料科学，而且在许多等新兴领域，如可调matamaterials。

甲的简单PμSL系统使用一种现成的，现成的数字数据投影机是在图1中所示。甲凸透镜的焦距75毫米到2厘米×2厘米的小照明区域的光束集中。从而导致在平面光学分辨率是约45微米。垂直分辨率被确定的线性阶段的精度级别。本研究提出的结构的层的厚度为160微米。每一层聚合为8秒光照明。一位代表由系统制造的三维结构， 如图1D所示。此对象由58层PEGDA。 我们制备光固化性PEGDA水凝胶。低交联，因此大的肿胀，PEGDA水凝胶是通过添加非交联PEG预聚物溶液。长度方向所得PEGDA水凝胶的溶胀比是1.5，其对应于大于300％的体积膨胀。 &gt; A组PEGDA水凝胶管的设计与制作的基础上我们的理论12。我们放置了一个样品翻转过来并把与油层覆盖在上面，如在图2A中示出的水的浴中。根据不同的尺寸的参数，圆形管保持稳定或转化成波状图案，如在图2B中所示的。由数字相机捕捉的各种各样的溶胀不同的样品的模式，并在图3A中。 <img alt="图1" src="/files/ftp_upload/4457/4457fig1.jpg" /> 图1：桌面投影微立体光刻系统（A）示意图（b）实际系统（C）特写视图组件（d）代表的三维结构。 <a href="http://www.jove.com/files/ftp_upload/4457/4457fig1large.jpg" target="_blank">点击此处查看大图</a> 。 帐篷“FO：保持together.within”页面=“总是”&gt; <img alt="图2" src="/files/ftp_upload/4457/4457fig2.jpg" /> 图2（a）实验设置水凝胶管，肿胀（二）约束水凝胶管变换成不同的图案。比例尺表示5毫米。 <img alt="图3" src="/files/ftp_upload/4457/4457fig3.jpg" /> 图3（一）形成在溶胀实验的模式。垂直轴表示吨/小时 （因此稳定性），并且水平轴表示小时/ D（从而屈曲模式）。比例尺表示5毫米。 （二）屈曲模式只依赖于H / D。实验结果与理论预测一致。 <a href="http://www.jove.com/files/ftp_upload/4457/4457fig3large.jpg" target="_blank">点击此处查看大图</a> 。 <table border="1"><tbody><tr><td colspan="2"> 样品&lt;/ STRONG&gt; </td><td> D（微米） </td><td> T（微米） </td><td> H（微米） </td></tr><tr><td rowspan="4"> 我 </td><td> 我 </td><td> 9300±420 </td><td> 760±40 </td><td> 840±40 </td></tr><tr><td> 二 </td><td> 9700±420 </td><td> 1040±40 </td><td> 1060±40 </td></tr><tr><td> 三 </td><td> 9700±420 </td><td> 1210±40 </td><td> 1340±40 </td></tr><tr><td> 四 </td><td> 9700±420 </td><td> 1660±40 </td><td> 1680±40 </td></tr><tr><td rowspan="4"> II </td><td> 我 </td><td> 9000±420 </td><td> 480±40 </td><td> 880±40 </td></tr><tr><td> 二 </td><td> 9000±420 </td><tD&gt; 660±40 </td><td> 1060±40 </td></tr><tr><td> 三 </td><td> 9500±420 </td><td> 740±40 </td><td> 1350±40 </td></tr><tr><td> 四 </td><td> 9200±420 </td><td> 970±40 </td><td> 1650±40 </td></tr><tr><td rowspan="4"> III </td><td> 我 </td><td> 8900±420 </td><td> 160±40 </td><td> 790±40 </td></tr><tr><td> 二 </td><td> 8900±420 </td><td> 300±40 </td><td> 1020±40 </td></tr><tr><td> 三 </td><td> 9100±420 </td><td> 380±40 </td><td> 1330±40 </td></tr><tr><td> 四 </td><td> 9000±420 </td><td> 490±40 </td><td> 1630±40 </td></tr><tr><td rowspan="4"> IV </td><td> 我 </td><td> 8900±420 </td><td> 140±40 </td><td> 780±40 </td></tr><tr><td> 二 </td><td> 8800±420 </td><td> 190±40 </td><td> 1010±40 </td></tr><tr><td> 三 </td><td> 9300±420 </td><td> 230±40 </td><td> 1340±40 </td></tr><tr><td> 四 </td><td> 8900±420 </td><td> 290±40 </td><td> 1650±40 </td></tr></tbody></table> 表1。尺寸测量通过光学显微镜。错误指示的测量不确定度。

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Micro 3D Printing Using a Digital Projector and its Application in the Study of Soft Materials Mechanics

我们证明肿胀凝胶管控制模式转型的弹性不稳定。一个简单的投影微立体光刻设置的是使用的现成的数字数据投影机制造三维聚合物结构层一个层的方式。溶胀水凝胶管机械约束下显示不同的圆周屈曲模式，根据尺寸。

微三维打印使用数字投影机和软材料力学的研究及其应用

Buckling is a classical topic in mechanics. While buckling has long been studied as one of the major structural failure modes1, it has recently drawn new ...

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25.1K 次观看.  Massachusetts Institute of Technology. 我们证明肿胀凝胶管控制模式转型的弹性不稳定。一个简单的投影微立体光刻设置的是使用的现成的数字数据投影机制造三维聚合物结构层一个层的方式。溶胀水凝胶管机械约束下显示不同的圆周屈曲模式，根据尺寸。

视频: Micro 3D Printing Using a Digital Projector and its Application in the Study of Soft Materials Mechanics

Quantification of Hydrogen Concentrations in Surface and Interface Layers and Bulk Materials through Depth Profiling with Nuclear Reaction Analysis

Nuclear reaction analysis (NRA) via the resonant 1H(15N,&#945;&#947;)12C reaction is a highly effective method of depth profiling that quantitatively and non-destructively reveals the hydrogen density distribution at surfaces, at interfaces, and in the volume of solid materials with high depth resolution. The technique applies a 15N ion beam of 6.385 MeV provided by an electrostatic accelerator and specifically detects the 1H isotope in depths up to about 2 &#956;m from the target surface. Surface H coverages are measured with a sensitivity in the order of ~1013 cm-2 (~1% of a typical atomic monolayer density) and H volume concentrations with a detection limit of ~1018 cm-3 (~100 at. ppm). The near-surface depth resolution is 2-5 nm for surface-normal 15N ion incidence onto the target and can be enhanced to values below 1 nm for very flat targets by adopting a surface-grazing incidence geometry. The method is versatile and readily applied to any high vacuum compatible homogeneous material with a smooth surface (no pores). Electrically conductive targets usually tolerate the ion beam irradiation with negligible degradation. Hydrogen quantitation and correct depth analysis require knowledge of the elementary composition (besides hydrogen) and mass density of the target material. Especially in combination with ultra-high vacuum methods for in-situ target preparation and characterization, 1H(15N,&#945;&#947;)12C NRA is ideally suited for hydrogen analysis at atomically controlled surfaces and nanostructured interfaces. We exemplarily demonstrate here the application of 15N NRA at the MALT Tandem accelerator facility of the University of Tokyo to (1) quantitatively measure the surface coverage and the bulk concentration of hydrogen in the near-surface region of a H2 exposed Pd(110) single crystal, and (2) to determine the depth location and layer density of hydrogen near the interfaces of thin SiO2 films on Si(100).

We illustrate the application of 1H(15N,&#945;&#947;)12C resonant nuclear reaction analysis (NRA) to quantitatively evaluate the density of hydrogen atoms on the surface, in the volume, and at an interfacial layer of solid materials. The near-surface hydrogen depth profiling of a Pd(110) single crystal and of SiO2/Si(100) stacks is described.

通过与核反应分析深度剖面的表面和界面层和颗粒材料氢含量的定量

Nuclear reaction analysis (NRA) via the resonant 1H(15N,&#945;&#947;)12C reaction is a highly effective method of depth profiling that quantitatively and ...

科研

工程学

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

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

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

吸湿排汗试验单向织物：毛细管参数的标准评价在液体复合成型工艺毛细管压力

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

Challenges in Rheological Characterization of Highly Concentrated Suspensions &#8212; A Case Study for Screen-printing Silver Pastes

A comprehensive rheological characterization of highly concentrated suspensions or pastes is mandatory for a targeted product development meeting the manifold requirements during processing and application of such complex fluids. In this investigation, measuring protocols for a conclusive assessment of different process relevant rheological parameters have been evaluated. This includes the determination of yield stress, viscosity, wall slip velocity, structural recovery after large deformation and elongation at break as well as tensile force during filament stretching.
The importance of concomitant video recordings during parallel-plate rotational rheometry for a significant determination of rheological quantities is demonstrated. The deformation profile and flow field at the sample edge can be determined using appropriate markers. Thus, measurement parameter settings and plate roughness values can be identified for which yield stress and viscosity measurements are possible. Slip velocity can be measured directly and measuring conditions at which plug flow, shear banding or sample spillover occur can be identified clearly. 
Video recordings further confirm that the change in shear moduli observed during three stage oscillatory shear tests with small deformation amplitude in stage I and III but large oscillation amplitude in stage II can be directly attributed to structural break down and recovery. For the pastes investigated here, the degree of irreversible, shear-induced structural change increases with increasing deformation amplitude in stage II until a saturation is reached at deformations corresponding to the crossover of G' and G'', but the irreversible damage is independent of the duration of large amplitude shear. 
A capillary breakup elongational rheometer and a tensile tester have been used to characterize deformation and breakup behavior of highly filled pastes in uniaxial elongation. Significant differences were observed in all experiments described above for two commercial screen-printing silver pastes used for front side metallization of Si-solar cells.

Challenges in Rheological Characterization of Highly Concentrated Suspensions &amp;#8212; A Case Study for Screen-printing Silver Pastes

A protocol for a robust and application relevant rheological characterization of highly concentrated suspensions is presented. Silver pastes used for screen-printing application in solar cell production are employed as model systems.

挑战流变特性高度集中悬架 - 为例进行丝网印刷银浆

A comprehensive rheological characterization of highly concentrated suspensions or pastes is mandatory for a targeted product development meeting the ...

A Soft Tooling Process Chain for Injection Molding of a 3D Component with Micro Pillars

The purpose of this paper is to present the method of a soft tooling process chain employing Additive Manufacturing (AM) for fabrication of injection molding inserts with micro surface features. The Soft Tooling inserts are manufactured by Digital Light Processing (vat photo polymerization) using a photopolymer that can withstand relatively high temperaturea. The part manufactured here has four tines with an angle of 60&#176;. Micro pillars (&#216;200 &#181;m, aspect ratio of 1) are arranged on the surfaces by two rows. Polyethylene (PE) injection molding with the soft tooling inserts is used to fabricate the final parts. This method demonstrates that it is feasible to obtain injection-molded parts with microstructures on complex geometry by additive manufactured inserts. The machining time and cost is reduced significantly compared to conventional tooling processes based on computer numerical control (CNC) machining. The dimensions of the micro features are influenced by the applied additive manufacturing process. The lifetime of the inserts determines that this process is more suitable for pilot production. The precision of the inserts production is limited by the additive manufacturing process as well.

A protocol for fabricating injection molding inserts for complex geometry with micro features on surfaces employing Additive Manufacturing (AM) is presented.

微柱3D 构件注塑成型的软加工工艺链

The purpose of this paper is to present the method of a soft tooling process chain employing Additive Manufacturing (AM) for fabrication of injection ...

Studying Large Amplitude Oscillatory Shear Response of Soft Materials

We investigate the sequence of physical processes exhibited during large amplitude oscillatory shearing (LAOS) of polyethylene oxide (PEO) in dimethyl sulfoxide (DMSO) and xanthan gum in water &#8212; two concentrated polymer solutions used as viscosifiers in foods, enhanced oil recovery, and soil remediation. Understanding the nonlinear rheological behavior of soft materials is important in the design and controlled manufacturing of many consumer products. It is shown how the response to LAOS of these polymer solutions can be interpreted in terms of a clear transition from linear viscoelasticity to viscoplastic deformation and back again during a period. The LAOS results are analyzed via the fully quantitative Sequence of Physical Processes (SPP) technique, using free MATLAB-based software. A detailed protocol of performing a LAOS measurement with a commercial rheometer, analyzing nonlinear stress responses with the freeware, and interpreting physical processes under LAOS is presented. It is further shown that, within the SPP framework, a LAOS response contains information regarding the linear viscoelasticity, the transient flow curves, and the critical strain responsible for the onset of nonlinearity.

We present a detailed protocol outlining how to perform nonlinear oscillatory shear rheology on soft materials, and how to run the SPP-LAOS analysis to understand the responses as a sequence of physical processes.

软材料大振幅振荡剪切响应的研究

We investigate the sequence of physical processes exhibited during large amplitude oscillatory shearing (LAOS) of polyethylene oxide (PEO) in dimethyl ...

Multimodal 3D Printing of Phantoms to Simulate Biological Tissue

Biomedical optical imaging is playing an important role in diagnosis and treatment of various diseases. However, the accuracy and the reproducibility of an optical imaging device are greatly affected by the performance characteristics of its components, the test environment, and the operations. Therefore, it is necessary to calibrate these devices by traceable phantom standards. However, most of the currently available phantoms are homogeneous phantoms that cannot simulate multimodal and dynamic characteristics of biological tissue. Here, we show the fabrication of heterogeneous tissue-simulating phantoms using a production line integrating a spin coating module, a polyjet module, a fused deposition modeling (FDM) module, and an automatic control framework. The structural information and the optical parameters of a &#34;digital optical phantom&#34; are defined in a prototype file, imported to the production line, and fabricated layer-by-layer with sequential switch between different printing modalities. Technical capability of such a production line is exemplified by the automatic printing of skin-simulating phantoms that comprise the epidermis, dermis, subcutaneous tissue, and an embedded tumor.

Spin coating, polyjet printing, and fused deposition modeling are integrated to produce multilayered heterogeneous phantoms that simulate structural and functional properties of biological tissue.

幻影的多模态3D打印模拟生物组织

Biomedical optical imaging is playing an important role in diagnosis and treatment of various diseases. However, the accuracy and the reproducibility of ...

In Situ Transmission Electron Microscopy with Biasing and Fabrication of Asymmetric Crossbars Based on Mixed-Phased a-VOx

Resistive switching crossbar architecture is highly desired in the field of digital memories due to low cost and high-density benefits. Different materials show variability in resistive switching properties due to the intrinsic nature of the material used, leading to discrepancies in the field because of underlying operation mechanisms. This highlights a need for a reliable technique to understand mechanisms using nanostructural observations. This protocol explains a detailed process and methodology of in&#160;situ nanostructural analysis as a result of electrical biasing using transmission electron microscopy (TEM). It provides visual and reliable evidence of underlying nanostructural changes in real time memory operations. Also included is the methodology of fabrication and electrical characterizations for asymmetric crossbar structures incorporating amorphous vanadium oxide. The protocol explained here for vanadium oxide films can be easily extended to any other materials in a metal-dielectric-metal sandwiched structure. Resistive switching crossbars are predicted to serve the programmable logic and neuromorphic circuits for next-generation memory devices, given the understanding of the operation mechanisms. This protocol reveals the switching mechanism in a reliable, timely, and cost-effective way in any type of resistive switching materials, and thereby predicts the device&#39;s applicability.

In Situ Transmission Electron Microscopy with Biasing and Fabrication of Asymmetric Crossbars Based on Mixed-Phased a-VOx

Presented here is a protocol for analyzing nanostructural changes during in&#160;situ biasing with transmission electron microscopy (TEM) for a stacked metal-insulator-metal structure. It has significant applications in resistive switching crossbars for the next generation of programmable logic circuits and neuromimicking hardware, to reveal their underlying operation mechanisms and practical applicability.

基于混合相位a-VOx的不对称横杆的偏置和制造现场传输电子显微镜

Resistive switching crossbar architecture is highly desired in the field of digital memories due to low cost and high-density benefits. Different ...

3D Printing - Evaluating Particle Emissions of a 3D Printing Pen

Three-dimensional (3D) printing as a type of additive manufacturing shows continuing increase in application and consumer popularity. The fused filament fabrication (FFF) is an inexpensive method used most frequently by consumers. Studies with 3D printers have shown that during the printing process particulate and volatile substances are released. Handheld 3D printing pens also use the FFF method but the consumer&#8217;s proximity to the 3D pens gives reason to higher exposure compared to a 3D printer. At the same time, 3D printing pens are often marketed for children who could be more sensitive to the printing emission. The aim of this study was to implement a low cost method to analyze the emissions of 3D printing pens. Polylactide (PLA) and acrylonitrile butadiene styrene (ABS) filaments of different colors were tested. In addition, filaments containing metal and carbon nanotubes (CNTs) were analyzed. An 18.5 L chamber and sampling close to the emission source was used to characterize emissions and concentrations near the breathing zone of the user.
Particle emissions and particle size distributions were measured and the potential release of metal particles and CNTs investigated. Particle number concentrations were found in a range of 105 - 106 particles/cm3, which is comparable to previous reports from 3D printers. Transmission electron microscopy (TEM) analysis showed nanoparticles of the different thermoplastic materials as well as of metal particles and CNTs. High contents of metal were observed by inductively coupled plasma mass spectrometry (ICP-MS).
These results call for a cautious use of 3D pens due to potential risk to the consumers.

This protocol presents a method to analyze the emission of 3D printing pens. Particle concentration and particle size distribution of the released particle is measured. Released particles are further analyzed with transmission electron microscopy (TEM). Metal content in filaments is quantified by inductively coupled plasma mass spectrometry (ICP-MS).

3D 打印 - 评估 3D 打印笔的粒子排放

Three-dimensional (3D) printing as a type of additive manufacturing shows continuing increase in application and consumer popularity. The fused filament ...

Pneumatically Driven Microfluidic Platform for Micro-Particle Concentration

The present article introduces a method for fabricating and operating a pneumatic valve to control particle concentration using a microfluidic platform. This platform has a three-dimensional (3D) network with curved fluid channels and three pneumatic valves, which create networks, channels, and spaces through duplex replication with polydimethylsiloxane (PDMS). The device operates based on the transient response of a fluid flow rate controlled by a pneumatic valve in the following order: (1) sample loading, (2) sample blocking, (3) sample concentration, and (4) sample release. The particles are blocked by thin diaphragm layer deformation of the sieve valve (Vs) plate and accumulate in the curved microfluidic channel. The working fluid is discharged by the actuation of two on/off valves. As a result of the operation, all particles of various magnifications were successfully intercepted and disengaged. When this technology is applied, the operating pressure, the time required for concentration, and the concentration rate may vary depending on the device dimensions and particle size magnification.

The present protocol describes a pneumatic microfluidic platform that can be used for efficient microparticle concentration.

气动驱动的微流体平台，用于微颗粒浓缩

The present article introduces a method for fabricating and operating a pneumatic valve to control particle concentration using a microfluidic platform. ...

Microfluidic Acoustophoresis for Flowthrough Separation of Gram-Negative Bacteria using Aptamer Affinity Beads

This article describes the fabrication and operation of microfluidic acoustophoretic chips using a microfluidic acoustophoresis technique and aptamer-modified microbeads that can be used for the fast, efficient isolation of Gram-negative bacteria from a medium. This method enhances the separation efficiency using a mix of long, square microchannels. In this system, the sample and buffer are injected into the inlet port through a flow controller. For bead centering and sample separation, AC power is applied to the piezoelectric transducer via a function generator with a power amplifier to generate acoustic radiation force in the microchannel. There is a bifurcated channel at both the inlet and outlet, enabling simultaneous separation, purification, and concentration. The device has a recovery rate of &gt;98% and purity of 97.8% up to a 10x dose concentration. This study has demonstrated a recovery rate and purity higher than the existing methods for separating bacteria, suggesting that the device can separate bacteria efficiently.

This paper describesthe fabrication and operation of microfluidic acoustophoretic chips using the microfluidic acoustophoresis technique and aptamer-modified microbeads that can be used for fast, efficient isolation of Gram-negative bacteria from a medium.