作者没有得到任何外部资助。

1. LSI仪器与3D打印机的设置和对齐
<ol><li>将3D打印机放在稳定的表面上，以最大程度地减少振动。将LSI仪器放在旁边，以便相机可以清楚地看到打印区域。将LSI仪器放置在略高于3D打印机的构建板的位置，并将其向下稍微倾斜，以免遮挡视线。</li>
	<li>打开激光和明场照明，并验证它们是否与成像区域对齐。将激光功率设置为 20 mW，确保激光器离开设置盒，在大面积（几平方厘米）上扩展，并确保功率密度足够低（比激光指示器低几倍），无需激光护目镜或黑色外壳等额外安全措施即可 原位 使用。 注意:不要直视激光。</li>
	<li>从测试打印开始（例如， 补充编码文件 1 或 补充编码文件 2），以使对齐和实验设置更方便（步骤 1.3-1.6）。确保LSI相机聚焦在打印区域。</li>
	<li>在第一次测试打印期间，以最佳方式对齐照明和数码相机。调整激光方向，使整个成像区域均匀照明，并调整光圈，使斑点尺寸略大于像素尺寸。</li>
	<li>优化帧速率和曝光时间，使曝光不足和曝光过度的像素数量最小化，以实现最大动态范围。</li>
	<li>为实时LSI数据分析选择正确的参数;最重要的是，选择在熔融塑料和固化塑料之间产生最佳成像对比度的频率。调整感兴趣区域 （ROI） 和颜色图缩放。在这种情况下，选择16的傅里叶级数长度，并可视化第二频率的幅度。由于散斑图像采集速率为每秒 50 帧，因此可视化频率为 6.25 Hz。</li>
	<li>准备LSI仪器以捕获图像以进行一次3D打印实验。选择图像的保存频率和时长。在这种情况下，图像每0.25秒保存一次，以便每次通过打印机头保存多个图像。对于每个实验，图像保存15分钟，因为每个打印作业最多需要12分钟。</li>
</ol>2. 准备3D打印设计和G代码
<ol><li>使用所选的 3D 绘图软件绘制对象，并将对象导出为 .stl 文件。在这种情况下，使用了带有脊和孔的墙，如图 1 所示，可以从 补充编码文件 1 下载。</li>
	<li>将 .stl 文件导入切片软件，然后选择打印设置。这些设置将取决于材料的选择和3D打印机型号;对于本研究中使用的情况，请使用 表 1 中所示的设置。使用最好是白色或任何散射激光而不会明显吸收的颜色的灯丝。</li>
	<li>按下切片软件中的 切片 按钮，获取打印头的层数和行进路径。切片软件配置文件可以在 补充编码文件 3 中找到。</li>
	<li>保存生成的G代码（补充编码文件2），并将其发送到3D打印机。</li>
</ol><img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/65415/65415fig01.jpg"> 图 1:对象设计。 对象设计的侧面、正面和顶部的 3D 视图（左）和 2D 视图（右）。网格表示 1.0 毫米 x 1.0 毫米，粗体显示 1.0 厘米 x 1.0 厘米。墙体为25毫米×12毫米×1.2毫米（宽x高x深），脊宽1.0毫米，深0.4毫米，相隔1.0毫米。窗户的宽度为1.0毫米，高度为2.0毫米。3D 设计可以在 补充编码文件 1 中找到。 <a href="https://www.jove.com/files/ftp_upload/65415/65415fig01large.jpg" target="_blank">请点击此处查看此图的大图。</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always"><tbody><tr><td>属性/设置</td>
			<td>价值</td>
		</tr><tr><td>灯丝</td>
			<td>聚乳酸， 白色</td>
		</tr><tr><td>喷嘴直径</td>
			<td>0.4 毫米</td>
		</tr><tr><td>层厚</td>
			<td>0.2 毫米</td>
		</tr><tr><td>喷嘴温度</td>
			<td>210 °C</td>
		</tr><tr><td>冷却风扇速度</td>
			<td>100%</td>
		</tr><tr><td>打印速度</td>
			<td>10 毫米/秒</td>
		</tr><tr><td>行驶速度</td>
			<td>10 毫米/秒</td>
		</tr><tr><td>床温</td>
			<td>60 °C</td>
		</tr></tbody></table>表 1:3D 打印设置。 用于切片对象设计的设置和打印机属性。对于第二个实验，手动将风扇速度更改为 0%。
3. 进行实验
<ol><li>启动3D打印机，等待预热期结束。</li>
	<li>LSI测量可以随时开始，但为防止不必要的数据节省，请在塑料开始挤出时开始LSI测量。</li>
	<li>等待3D打印机完成，然后停止LSI测量。</li>
	<li>将结果数据加载到图像查看软件中，并目视检查打印对象。将打印过程中测量的塑料聚合物运动与最终的结构完整性和表面质量进行比较。</li>
</ol>

可视化聚合物动力学以优化 3D 打印质量

<ol>
	<li>Daminabo, S. C., Goel, S., Grammatikos, S. A., Nezhad, H. Y., Thakur, V. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fused+deposition+modeling-based+additive+manufacturing+(3D+printing):+Techniques+for+polymer+material+systems.">Fused deposition modeling-based additive manufacturing (3D printing): Techniques for polymer material systems.</a> Materials Today Chemistry. 16, 100248 (2020).</li><li>Lee, C. Y., Liu, C. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+influence+of+forced-air+cooling+on+a+3D+printed+PLA+part+manufactured+by+fused+filament+fabrication.">The influence of forced-air cooling on a 3D printed PLA part manufactured by fused filament fabrication.</a> Additive Manufacturing. 25, 196-203 (2019).</li><li>Seppala, J. E., Migler, K. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Infrared+thermography+of+welding+zones+produced+by+polymer+extrusion+additive+manufacturing.">Infrared thermography of welding zones produced by polymer extrusion additive manufacturing.</a> Additive Manufacturing. 12, 71-76 (2016).</li><li>Shmueli, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simultaneous+in+situ+X-ray+scattering+and+infrared+imaging+of+polymer+extrusion+in+additive+manufacturing.">Simultaneous in situ X-ray scattering and infrared imaging of polymer extrusion in additive manufacturing.</a> ACS Applied Polymer Materials. 1 (6), 1559-1567 (2019).</li><li>Dinwiddie, R. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Infrared+imaging+of+the+polymer+3D-printing+process.">Infrared imaging of the polymer 3D-printing process.</a> Thermosense: Thermal Infrared Applications XXXVI. 9105, 910502 (2014).</li><li>Yousefpour, A., Hojjati, M., Immarigeon, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fusion+bonding/welding+of+thermoplastic+composites.">Fusion bonding/welding of thermoplastic composites.</a> Journal of Thermoplastic Composite Materials. 17 (4), 303-341 (2004).</li><li>Peterson, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Review+of+acrylonitrile+butadiene+styrene+in+fused+filament+fabrication:+A+plastics+engineering-focused+perspective.">Review of acrylonitrile butadiene styrene in fused filament fabrication: A plastics engineering-focused perspective.</a> Additive Manufacturing. 27, 363-371 (2019).</li><li>Menaka, M., Vasudevan, M., Venkatraman, B., Raj, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Estimating+bead+width+and+depth+of+penetration+during+welding+by+infrared+thermal+imaging.">Estimating bead width and depth of penetration during welding by infrared thermal imaging.</a> Insight-Non-Destructive Testing and Condition Monitoring. 47 (9), 564-568 (2005).</li><li>M&#246;llmann, K. P., Vollmer, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Infrared+thermal+imaging+as+a+tool+in+university+physics+education.">Infrared thermal imaging as a tool in university physics education.</a> European Journal of Physics. 28 (3), 37 (2007).</li><li>Dela Torre, I. M., Montes, M. D. S. H., Flores-Moreno, J. M., Santoyo, F. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser+speckle+based+digital+optical+methods+in+structural+mechanics:+A+review.">Laser speckle based digital optical methods in structural mechanics: A review.</a> Optics and Lasers in Engineering. 87, 32-58 (2016).</li><li>Senarathna, J., Rege, A., Li, N., Thakor, N. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser+speckle+contrast+imaging:+Theory,+instrumentation+and+applications.">Laser speckle contrast imaging: Theory, instrumentation and applications.</a> IEEE Reviews in Biomedical Engineering. 6, 99-110 (2013).</li><li>Bu&#307;s, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simpler,+faster,+and+softer:+Towards+broad+application+of+laser+speckle+imaging+in+art+conservation+and+soft+matter.">Simpler, faster, and softer: Towards broad application of laser speckle imaging in art conservation and soft matter.</a> Wageningen University and Research. , (2022).</li><li>van der Kooij, H. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Morphing+of+liquid+crystal+surfaces+by+emergent+collectivity.">Morphing of liquid crystal surfaces by emergent collectivity.</a> Nature Communications. 10 (1), 3501 (2019).</li><li>van Der Kooij, H. M., Broer, D. J., Liu, D., Sprakel, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electroplasticization+of+liquid+crystal+polymer+networks.">Electroplasticization of liquid crystal polymer networks.</a> ACS Applied Materials &amp; Interfaces. 12 (17), 19927-19937 (2020).</li><li>van der Kooij, H. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser+speckle+strain+imaging+reveals+the+origin+of+delayed+fracture+in+a+soft+solid.">Laser speckle strain imaging reveals the origin of delayed fracture in a soft solid.</a> Science Advances. 4 (5), (2018).</li><li>vander Kooij, H. M., Susa, A., Garc&#237;a, S. J., vander Zwaag, S., Sprakel, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imaging+the+molecular+motions+of+autonomous+repair+in+a+self-healing+polymer.">Imaging the molecular motions of autonomous repair in a self-healing polymer.</a> Advanced Materials. 29 (26), 1701017 (2017).</li><li>Buijs, J., Gucht, J. V. D., Sprakel, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fourier+transforms+for+fast+and+quantitative+laser+speckle+imaging.">Fourier transforms for fast and quantitative laser speckle imaging.</a> Scientific Reports. 9 (1), 13279 (2019).</li><li>Ehrmann, G., Ehrmann, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Investigation+of+the+shape-memory+properties+of+3D+printed+PLA+structures+with+different+infills.">Investigation of the shape-memory properties of 3D printed PLA structures with different infills.</a> Polymers. 13 (1), 164 (2021).</li><li>Richards, L. M., Kazmi, S. S., Davis, J. L., Olin, K. E., Dunn, A. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Low-cost+laser+speckle+contrast+imaging+of+blood+flow+using+a+webcam.">Low-cost laser speckle contrast imaging of blood flow using a webcam.</a> Biomedical Optics Express. 4 (10), 2269-2283 (2013).</li><li>Chen, H. L., Lai, C. L., Hsu, K. Y., Liu, W. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Implementation+of+laser+speckle+imaging+system+with+low+cost+consumer+graded+instrumentation+for+skin+perfusion.">Implementation of laser speckle imaging system with low cost consumer graded instrumentation for skin perfusion.</a> 2016 IEEE International Conference on Consumer Electronics-Taiwan (ICCE-TW). , 1-2 (2016).</li></ol>

Jesse Buijs正在创办一家初创公司，销售本文中使用的LSI仪器和软件。其他作者声明不存在利益冲突。

本研究中描述的实验和结果表明，LSI是一种易于应用的工具，可以更深入地了解增材制造过程中的层粘合。LSI允许直接测量聚合物运动，必须通过聚合物链的相互渗透和随后的缠绕对其进行微调以形成相干材料。原位测量层粘合的最常见替代方案是红外成像3，4，5。这种成熟的方法对塑料8，9的局部表面温度进行成像，这是对材料内部聚合物运动的间接测量。使用更热的塑料，运动速度更快，粘合力更强。然而，温度和运动之间的关系不是线性的，因为印刷温度穿过熔化和玻璃化转变温度6，7。这种非平凡的关系可以在LSI图像中直接观察到;具体来说，液体状顶部和固体底部区域之间存在急剧过渡，而温度梯度预计会更加缓慢。红外成像的另一个缺点是它只测量表面温度，而LSI测量材料内部通常几毫米深的聚合物运动。
就像红外成像一样，LSI的这种实现本质上是一种傻瓜式方法;如果相机可以指向感兴趣的区域，则可以 就地 使用。多功能三脚架和0.7米的长工作距离使您可以自由使用任何可用的3D打印机。至关重要的是，LSI对纳米运动很敏感，因此必须尽量减少来自周围环境和印刷过程本身的振动17。例如，在同一张桌子上执行另一项任务或关上门会造成干扰。因此，应该仔细走动设置;但是，室内灯光或气流通常不会干扰该过程。
LSI提供了对层粘合过程的详细见解，并且可以像红外成像一样轻松应用。我们设想LSI在帮助开发和理解先进的3D打印方法方面具有巨大的潜力。冷却风扇速度扫描展示了将LSI与3D打印相结合的可能性。如引言中所讨论的，最佳冷却速度是保持塑料熔融足够长的时间以改善层粘合与冷却足够快以防止流动之间的平衡。40%-100%冷却风扇速度的结果非常相似;事实上，这些风扇速度没有显示出任何流量，并产生了良好的表面质量。在0%冷却风扇速度下，材料开始从打印位置流出，但在LSI测量中观察到大量的层粘合。根据我们的结果，20%的冷却风扇速度可能是在不影响表面质量的情况下实现略微改善的层粘合的最佳选择。但是，为了得出可以应用于实践的结论，必须评估0%至40%之间的更多冷却风扇速度。还需要建立表面质量和材料强度的定量测量，以获得聚合物运动对所需性能的影响的客观和完整的视图。通过这一补充，该方法可以更强大地评估创造性的3D打印进展。
只要能够清楚地区分类液体塑料相和类固体塑性相，为LSI分析选择的确切设置就不容易出现严重误差。当跨越熔化和玻璃化转变温度时，聚合物运动会发生巨大变化，因此广泛的LSI设置可以很好地捕捉对比度。这可以通过材料供应商推荐的3D打印机设置对简单物体（例如直壁）的测试打印轻松进行测试。对于更高级的LSI用户，深入研究频率范围可以获得额外的信息，因为可以定量区分不同类型的聚合物运动。例如，高频聚合物运动与最高温度相关，最高温度仅存在于打印机头附近。较低频率的聚合物运动与中等温度有关，中等温度存在于打印机头周围的更大区域，并且持续时间也更长17。必须检查累积低频聚合物运动的粘合程度是否与短时高频运动（例如，动态机械分析）的粘合程度相同。大多数其他设置（如颜色图缩放、ROI、保存间隔和实验长度）仅选择以提供视觉上清晰且吸引人的结果。关于3D打印设置，也有很大的自由度，因为LSI允许用户客观地评估更改任何设置的结果。值得注意的是，大幅改变打印速度会改变LSI数据的解释。在这项工作中，使用了10 mm / s的慢速打印和行进速度，以便在打印机头的一次通过期间捕获多个LSI图像。如果使用更常见的 PLA 打印速度 60 mm/s，则每个 LSI 图像将打印大约一个完整层，因此，将在一层内发生平均。如果尝试300 mm/s或更快的高端速度，则会在多层上进行平均。然而，这完全取决于确切的打印几何形状和LSI设置，有经验的LSI用户可以通过先进的机器设计、调整视场大小或使用更快的相机轻松缓解。这两种方法都需要更强大的激光器，与反射式打印机头结合使用，需要额外的激光安全预防措施。相对较慢的印刷速度对层粘合也有积极影响，因为之前已经证明，塑料的热传递随着印刷速度的降低而增加5。
这种方法的一个可能的新方向是测试新材料;例如，LSI可用于可视化相关过渡，并客观地量化推荐的打印机设置，这些设置在应用顶层时提供五层焊接区域。另一个应用可能是在打印质量不太好的特定情况下研究焊接区域，例如桥梁、悬垂或尖角。如果可以更好地理解困难情况下的焊接区域，则应该可以在G代码中进行补偿。通常的做法是打印第一层比其余层更热、更慢，以实现对构建板18 的良好附着力。我们设想使用类似的动态G代码切片，例如，可以调整风扇冷却以产生拐角或桥梁。还应该可以打印具有更光滑光洁度的外壁材料，而其余材料和填充更粗糙但更坚固，以最大限度地提高材料强度和视觉外观。
本文讨论了LSI在研究塑料挤出后层粘合工艺中的应用。该技术非常适合这项任务，因为它可以在3D打印过程中实时可视化潜在的聚合物运动，而无需先验假设。但是，它没有提供有关材料内聚力的任何信息，因此需要进行额外的测试。讨论的其他缺点是情境性的;每秒四张LSI图像的有限成像速度可以通过更大的激光器和额外的激光安全措施来提高，并且振动灵敏度需要预防措施或减振硬件。LSI可以使用廉价的小型数码相机和激光器19，20执行，这允许集成到几乎每台3D打印机中，以进行实时质量控制和打印参数的动态调整。然而，使用LSI来全面了解3D打印过程中的层粘合更有意义。如果将这种理解用于开发更先进的切片软件，那么每台消费者3D打印机都可以从获得的知识中受益。

3D打印方法是一种增材制造技术，其中物体被逐层制造以形成所需的形状。由于其多功能性、可负担性和易用性，这种方法具有庞大而多样化的用户群。熔融沉积建模的特点是移动挤出机（直径从数百微米到几毫米），将熔融塑料沉积成所需的形状1。挤出的塑料应在一定时间内以液体状方式表现，以实现与先前印刷的塑料的良好融合并形成强粘合材料。但是，塑料应在印刷后迅速冷却并固化，以防止塑料从印刷位置流出并降低印刷质量。加热和冷却之间的这种微妙相互作用已被证明直接巩固了最终3D打印物体2的机械强度和几何精度之间的平衡。为了达到最佳的加热-冷却平衡，塑料在刚高于其熔化温度的温度下挤出，并使用连接到打印机的风扇头快速冷却塑料。深入了解打印温度和冷却速度的影响可以提供开发高级切片和打印协议所需的见解，从而在最重要的领域最大限度地提高机械或几何结果。更深入地了解这些过程的努力通常依赖于红外（IR）成像，它只能看到表面温度3，4，5，而不指示塑料的内部温度。熔融转变以外的局部加热大大增加了聚合物的迁移率，从而允许新旧材料之间的聚合物纠缠。这种时间增强的聚合物运动是形成最终内聚材料6，7的要求，但红外成像只能通过表面温度8，9间接测量聚合物运动。因此，将表面温度转换为层键合需要精确了解核-表面温度梯度以及相关复杂聚合物动力学在一系列时间和长度尺度上。直接测量层粘合（即聚合物缠结过程）将允许可视化散装材料内聚力的机制，而无需先验信息或假设。
为了了解层键合的空间和时间分布，这项工作采用了一种直接量化构成塑料长丝的聚合物动力学的成像技术。这种技术，激光散斑成像（LSI），依靠干涉光散射来可视化纳米运动，与化学成分无关。根据样品的光学特性，它可以精确测量非透明材料10，11，12的几毫米到厘米，这与仅报告表面温度8，9的红外成像不同。这些属性最近使基于斑点的方法在理解大量材料的动态过程方面很受欢迎，尽管它们最初是为医疗应用而开发的10，11，12。最近，LSI已被用于深入了解先进聚合物材料的行为，例如自清洁液晶聚合物网络13，14，以及预测橡胶中的断裂15和研究自修复材料16。
将LSI应用于3D打印的可行性在之前的文章17中得到了展示，其中介绍了具有实时分析功能的便携式LSI设置，并表明熔融塑料的沉积导致聚合物运动增加在当前层以下的多层。本文对冷却风扇转速对多层粘合程度的影响进行了系统研究。使用便携式仪器的改进即插即用版本，无需光学或编程专业知识的用户即可操作。使用傅里叶变换17实时分析散斑图像，该变换可视化散斑强度波动的幅度。该仪器有一个额外的明场相机，该相机与散斑相机对齐，因此LSI运动图可以与明场图像叠加，以便于解释，而明场光不会影响运动图。本文介绍的实验方法可用于更深入地了解在具有挑战性的几何形状和材料进行 3D 打印过程中挤出塑料的熔化、层粘合和凝固。

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>3D-drawing sofware</td>
			<td>Autodesk</td>
			<td>TinkerCad</td>
			<td>tinkercad.com</td>
		</tr>
		<tr>
			<td>3D-Printer</td>
			<td>Prusa3D</td>
			<td>Original Prusa i3 MK3S</td>
			<td></td>
		</tr>
		<tr>
			<td>Advanced data analysis software</td>
			<td>MathWorks</td>
			<td>MATLAB R2018b</td>
			<td></td>
		</tr>
		<tr>
			<td>Image viewing sofware</td>
			<td>National Institutes of Health</td>
			<td>ImageJ 1.47v</td>
			<td></td>
		</tr>
		<tr>
			<td>LSI instrument</td>
			<td>NanoMoI</td>
			<td>NanoMoi allround</td>
			<td>company to be founded 2023</td>
		</tr>
		<tr>
			<td>Polylactic acid (PLA) filament</td>
			<td>REAL</td>
			<td>filament white 1,75 mm PLA 1 kg</td>
			<td></td>
		</tr>
		<tr>
			<td>Slicing software</td>
			<td>Prusa3D</td>
			<td>PrusaSlicer-2.5.0</td>
			<td></td>
		</tr>
	</tbody>
</table>

real-time imaging of bonding in 3d-printed layers

最近，3D打印技术彻底改变了我们设计和生产产品的能力，但优化打印质量可能具有挑战性。挤出3D打印的过程涉及通过薄喷嘴对熔融材料施加压力并将其沉积到先前挤出的材料上。这种方法依赖于连续层之间的粘合，以创建坚固且具有视觉吸引力的最终产品。这并非易事，因为必须对喷嘴温度、层厚和打印速度等许多参数进行微调才能获得最佳效果。在这项研究中，提出了一种可视化挤出过程中聚合物动力学的方法，从而深入了解层粘合过程。使用激光散斑成像，塑料流动和融合可以通过非侵入性、内部和高时空分辨率进行解析。这种测量易于执行，可以深入了解影响最终打印质量的基本机制。该方法在一系列冷却风扇速度下进行了测试，结果显示，随着风扇速度的降低，聚合物运动增加，因此解释了关闭冷却风扇时打印质量差的原因。这些发现表明，这种方法可以优化打印设置并了解材料行为。这些信息可用于新型印刷材料的开发和测试或先进的切片程序。通过这种方法，可以更深入地了解挤出，将3D打印提升到一个新的水平。

绘制一个简单的物体作为实验的测试目标:背面有脊的墙，两个窗户和一个大孔（图1）。使用 表 1 中列出的打印机设置和属性对对象进行切片。
将LSI仪器与3D打印机对齐，并进行实验。用户友好的设置具有一个额外的明场摄像头，有助于在对准过程中，并允许在塑料挤出和测量的聚合物运动之间轻松比较。散斑和明场相机都配备了滤光片，可防止来自其他通道的干扰。有关设置的更多技术细节可以在 补充文件 1 中找到，分析例程的说明在 补充文件 2 中提供。该实验结果的亮点如图 2所示，完整的视频可以在 补充视频1中找到。如前所述，该实验也可以使用自制仪器17进行。
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/65415/65415fig02.jpg"> 图 2:以 100% 冷却风扇速度打印的延时。 左:明场，打印机几乎完成时对象的前视图图像。检查时打印质量看起来不错;虽然表面显示了层线，但已经生成了整体设计的几何图形。右:打印过程中白色划定区域的四个LSI快照;蓝色箭头表示快照时的打印头位置，因为LSI图像与明场图像的时间不对应。每个快照中较浅的颜色表示聚合物运动增加，这在最近打印的层中观察到。请注意，具有增强运动的区域（焊接区域）是多层厚的。实验的完整详细影片可在 补充影片 1 中找到。 <a href="https://www.jove.com/files/ftp_upload/65415/65415fig02large.jpg" target="_blank">请点击此处查看此图的大图。</a>
与这些结果相辅相成的是，对印刷品进行了目视检查;正如预期的那样，对于这些常用的聚合物长丝和打印设置，质量很好。设计的几何形状确实被复制了，表面是均匀的，每层上都可以看到一条小线。使用LSI数据，可以深入了解打印过程。新挤出的塑料具有高度流动性，并且随着冷却而逐渐降低流动性。在整个打印过程中，高流动性区域（即焊接区域）的高度为四到五层厚，表明层融合的持续时间明确。
重复实验，将冷却风扇速度手动调整至0%。使用此设置，塑料冷却速度不够快，从而影响了打印质量。结果的亮点如图 3所示，完整的详细视频可以在 补充视频2中找到。
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/65415/65415fig03.jpg"> 图 3:冷却风扇速度为 0% 时的打印延时。 左:明场，打印机几乎完成时对象的前视图图像。印刷品的视觉质量看起来很差;表面显示不规则的层线和大斑点。此外，整体设计的几何形状被不完美地再现;值得注意的是，窗户和孔是变形的。右:打印过程中白色划定区域的四个LSI快照;蓝色箭头表示快照时的打印头位置，因为LSI图像与明场图像的时间不对应。每个快照中较浅的颜色表示聚合物运动增加，这可以在整个物体中观察到。实验的完整详细影片可在 补充影片 2 中找到。 <a href="https://www.jove.com/files/ftp_upload/65415/65415fig03large.jpg" target="_blank">请点击此处查看此图的大图。</a>
符合预期，对3D打印结构的目视检查确实显示出较差的打印质量。层分布不均匀，设计的几何形状通过变形再现。图2和图3中的明场图像比较显示了冷却风扇对打印结果的表面质量和形状的主要影响。通过比较图2和图3中的LSI结果来确定这种效应的来源。在100%的冷却风扇速度下，在挤出塑料下方仅几层的区域观察到增强的聚合物运动。因此，每层适度液化几次，以实现无塑性流动的层粘合。在0%冷却风扇速度下，在整个物体中观察到增强的聚合物运动。因此，每一层都经过多次液化，并且非常接近新挤出的塑料，导致塑料流动导致几何精度下降。
为了更定量地了解在更温和的情况下冷却风扇效果，系统地改变了冷却风扇速度。物体设计被简化为25 mm x 12 mm x 0.8 mm（宽x高x深）的墙，没有孔或脊。使用了与表1中相同的打印设置。实验进行了12次，冷却风扇速度为0%，20%，40%，60%，80%和100%，每个一式两份。生成的电影可以在补充影片 3、补充影片 4、补充影片 5、补充影片 6、补充影片 7 和补充影片 8 以及补充编码文件 6、补充编码文件 7、补充编码文件 8、补充编码文件 9、补充编码文件 10 和补充编码文件 11 中找到。
为了定量比较不同风扇速度下的焊接区域，对LSI结果进行了高级数据分析。该数据分析的目的是获得焊接区域中聚合物运动程度的高度剖面。相关的完全注释的 MATLAB 脚本可以在 补充编码文件 4 中找到，并进行了简要描述。对于电影中的每个LSI图像，高度剖面图是通过沿水平方向取平均值来计算的。打印头在ROI中的图像轮廓在焊接区域周围显示出明显的峰值。要专门选择这些配置文件，仅考虑峰值高于8 dB的配置文件。此峰值太接近ROI边缘的配置文件也会被丢弃。随后对齐所有轮廓的峰位置，以得出相对于聚合物最易移动的高度的平均轮廓。 图 4 绘制了六种不同冷却风扇速度的结果曲线。
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/65415/65415fig04.jpg"> 图 4:冷却风扇速度系统变化的高度曲线。左:冷却风扇速度为 100%（黑色）、80%（蓝色）、60%（紫色）、40%（红色）、20%（橙色）和 0%（黄色）的焊接区域剖面图，从补充编码文件 4 中的高级数据分析脚本获得。阴影区域是重复实验之间的标准偏差。右图解释了获得典型LSI图像轮廓的取平均值过程。通过对齐所有获得的轮廓的峰值的最大值，获得焊接区域。焊接区域的最大值（相对高度 = 0）是聚合物最具流动性的高度。每个实验的完整详细LSI和明场动画可在补充视频3，补充视频4，补充视频5，补充视频6，补充视频7和 补充视频8中找到。 为该图打印的对象可以在补充编码文件 5 中找到，相应的 G 代码文件在补充编码文件 6 中找到。<a href="https://www.jove.com/files/ftp_upload/65415/65415fig04large.jpg" target="_blank">请点击此处查看此图的大图。</a>
40%-100%冷却的焊接区域轮廓几乎相同。用于 20% 冷却的焊接区域的肩部延伸到几个更深的层。0%冷却的焊接区域延伸到整个测量区域。聚合物最易移动的高度位于或略低于最近打印的层。这种现象解释了在正相对高度存在LSI信号的原因，因为迁移率峰值上方有印刷材料。在所有情况下，焊接区域都比0.2 mm的层厚深得多。
补充文件 1:LSI 设置.xls。 此处使用的 LSI 仪器的硬件参数。 <a href="https://www.jove.com/files/ftp_upload/65415/LSI%20analysis_RE.docx" target="_blank">请点击此处下载此文件。</a>
补充文件2:LSI分析.docx。 将原始散斑图像转换为LSI图像的说明。 <a href="https://www.jove.com/files/ftp_upload/65415/Lsi%20setup_RE.xls" target="_blank">请点击此处下载此文件。</a>
补充视频1: LSI和明场动画的实验描述如图2所示。 电影以 12.5 倍的实时速度播放。上半部分是LSI结果，下半部分是指示LSI ROI的同步明场视图。 <a href="https://www.jove.com/files/ftp_upload/65415/Movie%201.zip" target="_blank">请点击这里下载此影片。</a>
补充视频2: LSI和明场视频的实验如图3所示。 电影以 12.5 倍的实时速度播放。上半部分是LSI结果，下半部分是指示LSI ROI的同步明场视图。 <a href="https://www.jove.com/files/ftp_upload/65415/Movie%202.zip" target="_blank">请点击这里下载此影片。</a>
补充视频3: 图4中描述的100%冷却风扇速度实验。 电影以 12.5 倍的实时速度播放。上半部分是LSI结果，下半部分是指示LSI ROI的同步明场视图。 <a href="https://www.jove.com/files/ftp_upload/65415/Movie%203.zip" target="_blank">请点击这里下载此影片。</a>
补充视频4: 图4中描述的80%冷却风扇速度实验。 电影以 12.5 倍的实时速度播放。上半部分是LSI结果，下半部分是指示LSI ROI的同步明场视图。 <a href="https://www.jove.com/files/ftp_upload/65415/Movie%204.zip" target="_blank">请点击这里下载此影片。</a>
补充视频5: 图4中描述的60%冷却风扇速度实验。 电影以 12.5 倍的实时速度播放。上半部分是LSI结果，下半部分是指示LSI ROI的同步明场视图。 <a href="https://www.jove.com/files/ftp_upload/65415/Movie%205.zip" target="_blank">请点击这里下载此影片。</a>
补充视频6: 图4中描述的40%冷却风扇速度实验。 电影以 12.5 倍的实时速度播放。上半部分是LSI结果，下半部分是指示LSI ROI的同步明场视图。 <a href="https://www.jove.com/files/ftp_upload/65415/Movie%206.zip" target="_blank">请点击这里下载此影片。</a>
补充视频7: 图4中描述的20%冷却风扇速度实验。 电影以 12.5 倍的实时速度播放。上半部分是LSI结果，下半部分是指示LSI ROI的同步明场视图。 <a href="https://www.jove.com/files/ftp_upload/65415/Movie%207.zip" target="_blank">请点击这里下载此影片。</a>
补充视频8: 图4中描述的0%冷却风扇速度实验。 电影以 12.5 倍的实时速度播放。上半部分是LSI结果，下半部分是指示LSI ROI的同步明场视图。 <a href="https://www.jove.com/files/ftp_upload/65415/Movie%208.zip" target="_blank">请点击这里下载此影片。</a>
补充编码文件 1:wall_with_holes.stl。 图 1 中描述的对象的 3D 设计。<a href="https://www.jove.com/files/ftp_upload/65415/wall_with_holes.zip" target="_blank">请点击此处下载此文件。</a>
补充编码文件 2:wall_with_holes.gcode。 切片对象 wall_with_holes .stl ，具有 表 1 中的设置。 <a href="https://www.jove.com/files/ftp_upload/65415/wall_with_holes_gcode.zip" target="_blank">请点击此处下载此文件。</a>
补充编码文件 3:配置.ini。 切片软件的配置文件。 <a href="https://www.jove.com/files/ftp_upload/65415/config.ini" rel="nofollow" target="_blank">请点击此处下载此文件。</a>
补充编码文件 4:AdvancedDataAnalysis_FanSpeed.m. 该脚本对散热风扇扫描数据进行高级数据分析并绘制 图4。脚本已完全注释。 <a href="https://www.jove.com/files/ftp_upload/65415/AdvancedDataAnalysis_FanSpeed.zip" target="_blank">请点击此处下载此文件。</a>
补充编码文件 5:wall.stl. 用于收集 图 4 中的数据的对象的 3D 设计。 <a href="https://www.jove.com/files/ftp_upload/65415/wall.zip" target="_blank">请点击此处下载此文件。</a>
补充编码文件 6:wall_100%fan.gcode。 切片对象 wall.stl ，冷却风扇速度为 100%。 <a href="https://www.jove.com/files/ftp_upload/65415/wall_100FAn.zip" target="_blank">请点击此处下载此文件。</a>
补充编码文件 7:wall_80%fan.gcode。 切片对象 wall.stl ，冷却风扇速度为 80%。 <a href="https://www.jove.com/files/ftp_upload/65415/wall_80FAn.zip" target="_blank">请点击此处下载此文件。</a>
补充编码文件 8:wall_60%fan.gcode。 切片对象 wall.stl ，冷却风扇速度为 60%。 <a href="https://www.jove.com/files/ftp_upload/65415/wall_60FAn.zip" target="_blank">请点击此处下载此文件。</a>
补充编码文件 9:wall_40%fan.gcode。 切片对象 wall.stl ，冷却风扇速度为 40%。 <a href="https://www.jove.com/files/ftp_upload/65415/wall_40FAn.zip" target="_blank">请点击此处下载此文件。</a>
补充编码文件 10:wall_20%fan.gcode。 切片对象 wall.stl ，冷却风扇速度为 20%。 <a href="https://www.jove.com/files/ftp_upload/65415/wall_20FAn.zip" target="_blank">请点击此处下载此文件。</a>
补充编码文件 11:wall_0%fan.gcode。 切片对象 wall.stl ，冷却风扇速度为 0%。 <a href="https://www.jove.com/files/ftp_upload/65415/wall_0FAn.zip" target="_blank">请点击此处下载此文件。</a>

Watch this Scientific Journal Video about Real-Time Imaging of Bonding in 3D-Printed Layers at JoVE.com

作者聚焦:3D 打印层中粘合的实时成像  

通过非侵入性和实时技术，在3D打印过程中对聚合物长丝内的纳米级聚合物运动进行成像。微调此运动对于生产具有最佳性能和外观的结构至关重要。这种方法达到了塑料层熔合的核心，从而提供了对最佳印刷条件和材料设计标准的见解。

3D 打印层中粘合的实时成像

In recent times, 3D printing technology has revolutionized our ability to design and produce products, but optimizing the print quality can be ...

我们的研究旨在改善3D打印过程中的层粘合。我们使用一种称为激光散斑成像的方法来实时可视化粘合过程。这些见解将指导打印条件的优化，有望增强材料设计和性能。目前，使用红外成像技术研究层粘合，该技术可可视化该塑料*表面温度。为了用红外成像研究层粘合，假设内部温度和表面温度相等。此外，还必须知道温度与塑性流动性之间的复杂关系。我们已经将激光散斑成像应用于3D打印，并展示了如何轻松获得对层粘合的更深入理解。我们的LSI方法测量塑料内部的聚合物运动，可视化层粘合，无需任何假设。该技术也是非侵入性的，易于使用，并且具有出色的灵敏度。本研究中显示的方法可用于研究具有挑战性的3D打印或图案。结果可用于了解如何更改设置以提高打印质量。

real-time-imaging-of-bonding-in-3d-printed-layers

Research

JoVE Journal

Engineering

Real-Time Imaging of Bonding in 3D-Printed Layers

3.0K 次观看.  Wageningen University & Research. 我们的研究旨在改善3D打印过程中的层粘合。我们使用一种称为激光散斑成像的方法来实时可视化粘合过程。这些见解将指导打印条件的优化，有望增强材料设计和性能。目前，使用红外成像技术研究层粘合，该技术可可视化该塑料*表面温度。为了用红外成像研究层粘合，假设内部温度和表面温度相等。此外，还必须知道温度与塑性流动性之间的复杂关系。我们已...

视频: 作者聚焦:3D 打印层中粘合的实时成像  

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

Real-Time DC-dynamic Biasing Method for Switching Time Improvement in Severely Underdamped Fringing-field Electrostatic MEMS Actuators

Mechanically underdamped electrostatic fringing-field MEMS actuators are well known for their fast switching operation in response to a unit step input bias voltage. However, the tradeoff for the improved switching performance is a relatively long settling time to reach each gap height in response to various applied voltages. Transient applied bias waveforms are employed to facilitate reduced switching times for electrostatic fringing-field MEMS actuators with high mechanical quality factors. Removing the underlying substrate of the fringing-field actuator creates the low mechanical damping environment necessary to effectively test the concept. The removal of the underlying substrate also a has substantial improvement on the reliability performance of the device in regards to failure due to stiction. Although DC-dynamic biasing is useful in improving settling time, the required slew rates for typical MEMS devices may place aggressive requirements on the charge pumps for fully-integrated on-chip designs. Additionally, there may be challenges integrating the substrate removal step into the back-end-of-line commercial CMOS processing steps. Experimental validation of fabricated actuators demonstrates an improvement of 50x in switching time when compared to conventional step biasing results. Compared to theoretical calculations, the experimental results are in good agreement.

The robust device design of fringing-field electrostatic MEMS actuators results in inherently low squeeze-film damping conditions and long settling times when performing switching operations using conventional step biasing. Real-time switching time improvement with DC-dynamic waveforms reduces the settling time of fringing-field MEMS actuators when transitioning between up-to-down and down-to-up states.

实时直流偏置的动态法切换时间改善严重欠阻尼边缘化场静电MEMS致动器

Mechanically underdamped electrostatic fringing-field MEMS actuators are well known for their fast switching operation in response to a unit step input ...

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 ...

Methods for Measuring the Orientation and Rotation Rate of 3D-printed Particles in Turbulence

Experimental methods are presented for measuring the rotational and translational motion of anisotropic particles in turbulent fluid flows. 3D printing technology is used to fabricate particles with slender arms connected at a common center. Shapes explored are crosses (two perpendicular rods), jacks (three perpendicular rods), triads (three rods in triangular planar symmetry), and tetrads (four arms in tetrahedral symmetry). Methods for producing on the order of 10,000 fluorescently dyed particles are described. Time-resolved measurements of their orientation and solid-body rotation rate are obtained from four synchronized videos of their motion in a turbulent flow between oscillating grids with R&#955; = 91. In this relatively low-Reynolds number flow, the advected particles are small enough that they approximate ellipsoidal tracer particles. We present results of time-resolved 3D trajectories of position and orientation of the particles as well as measurements of their rotation rates.

We use 3D printing to fabricate anisotropic particles in the shapes of jacks, crosses, tetrads, and triads, whose alignments and rotations in turbulent fluid flow can be measured from multiple simultaneous video images.

测量的方向和旋转速率方法3D打印在湍流颗粒

Experimental methods are presented for measuring the rotational and translational motion of anisotropic particles in turbulent fluid flows. 3D printing ...

Use of a Multi-compartment Dynamic Single Enzyme Phantom for Studies of Hyperpolarized Magnetic Resonance Agents

Imaging of hyperpolarized substrates by magnetic resonance shows great clinical promise for assessment of critical biochemical processes in real time. Due to fundamental constraints imposed by the hyperpolarized state, exotic imaging and reconstruction techniques are commonly used. A practical system for characterization of dynamic, multi-spectral imaging methods is critically needed. Such a system must reproducibly recapitulate the relevant chemical dynamics of normal and pathological tissues. The most widely utilized substrate to date is hyperpolarized [1-13C]-pyruvate for assessment of cancer metabolism. We describe an enzyme-based phantom system that mediates the conversion of pyruvate to lactate. The reaction is initiated by injection of the hyperpolarized agent into multiple chambers within the phantom, each of which contains varying concentrations of reagents that control the reaction rate. Multiple compartments are necessary to ensure that imaging sequences faithfully capture the spatial and metabolic heterogeneity of tissue. This system will aid the development and validation of advanced imaging strategies by providing chemical dynamics that are not available from conventional phantoms, as well as control and reproducibility that is not possible in vivo.

A multi-compartment dynamic phantom is used to simulate some biology of interest for metabolic studies using hyperpolarized magnet resonance agents.

一个多腔动态单一酶幻影超极化磁共振剂研究的用途

Imaging of hyperpolarized substrates by magnetic resonance shows great clinical promise for assessment of critical biochemical processes in real time. Due ...

Solvent Bonding for Fabrication of PMMA and COP Microfluidic Devices

Thermoplastic microfluidic devices offer many advantages over those made from silicone elastomers, but bonding procedures must be developed for each thermoplastic of interest. Solvent bonding is a simple and versatile method that can be used to fabricate devices from a variety of plastics. An appropriate solvent is added between two device layers to be bonded, and heat and pressure are applied to the device to facilitate the bonding. By using an appropriate combination of solvent, plastic, heat, and pressure, the device can be sealed with a high quality bond, characterized as having high bond coverage, bond strength, optical clarity, durability over time, and low deformation or damage to microfeature geometry. We describe the procedure for bonding devices made from two popular thermoplastics, poly(methyl-methacrylate) (PMMA), and cyclo-olefin polymer (COP), as well as a variety of methods to characterize the quality of the resulting bonds, and strategies to troubleshoot low quality bonds. These methods can be used to develop new solvent bonding protocols for other plastic-solvent systems.

Solvent bonding is a simple and versatile method for fabricating thermoplastic microfluidic devices with high quality bonds. We describe a protocol to achieve strong, optically clear bonds in PMMA and COP microfluidic devices that preserve microfeature details, by a judicious combination of pressure, temperature, an appropriate solvent, and device geometry.

溶剂粘接的PMMA的制备和COP微流体装置

Thermoplastic microfluidic devices offer many advantages over those made from silicone elastomers, but bonding procedures must be developed for each ...

A 3D-printed Chamber for Organic Optoelectronic Device Degradation Testing

In this manuscript, we outline the manufacture of a small, portable, easy-to-use atmospheric chamber for organic and perovskite optoelectronic devices, using 3D-printing. As these types of devices are sensitive to moisture and oxygen, such a chamber can aid researchers in characterizing the electronic and stability properties. The chamber is intended to be used as a temporary, reusable, and stable environment with controlled properties (including humidity, gas introduction, and temperature). It can be used to protect air-sensitive materials or to expose them to contaminants in a controlled way for degradation studies. To characterize the properties of the chamber, we outline a simple procedure to determine the water vapor transmission rate (WVTR) using relative humidity as measured by a standard humidity sensor. This standard operating procedure, using a 50% infill density of polylactic acid (PLA), results in a chamber that can be used for weeks without any significant loss of device properties. The versatility and ease of use of the chamber allows it to be adapted to any characterization condition that requires a compact-controlled atmosphere.

Here, we present a protocol for the design, manufacture, and use of a simple, versatile 3D-printed and controlled atmospheric chamber for the optical and electrical characterization of air-sensitive organic optoelectronic devices.

用于有机光电器件降解测试的3维印制腔

In this manuscript, we outline the manufacture of a small, portable, easy-to-use atmospheric chamber for organic and perovskite optoelectronic devices, ...

Theoretical Calculation and Experimental Verification for Dislocation Reduction in Germanium Epitaxial Layers with Semicylindrical Voids on Silicon

Reduction of threading dislocation density (TDD) in epitaxial germanium (Ge) on silicon (Si) has been one of the most important challenges for the realization of monolithically integrated photonics circuits. The present paper describes methods of theoretical calculation and experimental verification of a novel model for the reduction of TDD. The method of theoretical calculation describes the bending of threading dislocations (TDs) based on the interaction of TDs and non-planar growth surfaces of selective epitaxial growth (SEG) in terms of dislocation image force. The calculation reveals that the presence of voids on SiO2 masks help to reduce TDD. Experimental verification is described by germanium (Ge) SEG, using an ultra-high vacuum chemical vapor deposition method and TD observations of the grown Ge via etching and cross-sectional transmission electron microscope (TEM). It is strongly suggested that the TDD reduction would be due to the presence of semicylindrical voids over the SiO2 SEG masks and growth temperature. For experimental verification, epitaxial Ge layers with semicylindrical voids are formed as the result of SEG of Ge layers and their coalescence. The experimentally obtained TDDs reproduce the calculated TDDs based on the theoretical model. Cross-sectional TEM observations reveal that both the termination and generation of TDs occur at semicylindrical voids. Plan-view TEM observations reveal a unique behavior of TDs in Ge with semicylindrical voids (i.e., TDs are bent to be parallel to the SEG masks and the Si substrate).

Theoretical calculation and experimental verification are proposed for a reduction of threading dislocation (TD) density in germanium epitaxial layers with semicylindrical voids on silicon. Calculations based on the interaction of TDs and surface via image force, TD measurements, and transmission electron microscope observations of TDs are presented.

硅上半圆柱空隙锗外延层位错还原的理论计算和实验验证

Reduction of threading dislocation density (TDD) in epitaxial germanium (Ge) on silicon (Si) has been one of the most important challenges for the ...

Optimized Sealing Process and Real-Time Monitoring of Glass-to-Metal Seal Structures

Residual stress is an essential factor to keeping the hermeticity and robustness of a glass-to-metal seal structure. The purpose of this report is to demonstrate a novel protocol to characterize and measure residual stress in a glass-to-metal seal structure without destroying the insulation and hermeticity of sealing materials. In this research, a femto-laser inscribed fiber Bragg grating sensor is used. The glass-to-metal seal structure that is measured consists of a metal shell, sealing glass, and Kovar conductor. To make the measurements worthwhile, the specific heat treatment of metal-to-glass seal (MTGS) structure is explored to obtain the model with best hermeticity. Then, the FBG sensor is embedded into the path of sealing glass and becomes well-fused with the glass as the temperature cools to RT. The Bragg wavelength of FBG shifts with the residual stress generated in sealing the glass. To calculate the residual stress, the relationship between Bragg wavelength shift and strain is applied, and the finite element method is also used to make the results reliable. The online monitoring experiments of residual stress in sealing glass are carried out at different loads, such as high temperature and high pressure, to broaden functions of this protocol in harsh environments.

Key procedures to optimize the sealing process and achieve real-time monitoring of the metal-to-glass seal (MTGS) structure are described in detail. The embedded fiber Bragg grating (FBG) sensor is designed to achieve online monitoring of temperature and high-level residual stress in the MTGS with simultaneous environmental pressure monitoring.

玻璃到金属密封结构的优化密封工艺和实时监控

Residual stress is an essential factor to keeping the hermeticity and robustness of a glass-to-metal seal structure. The purpose of this report is to ...

In vitro Assessment of Aortic Regurgitation Using Four-Dimensional Flow Magnetic Resonance Imaging

Aortic regurgitation (AR) refers to backward blood flow from the aorta into the left ventricle (LV) during ventricular diastole. The regurgitant jet arising from the complex shape is characterized by the three-dimensional flow and high-velocity gradient, sometimes limiting an accurate measurement of the regurgitant volume using 2D echocardiography. Recently developed four-dimensional flow magnetic resonance imaging (4D flow MRI) enables three-dimensional volumetric flow measurements, which can be used to accurately quantify the amount of the regurgitation. This study focuses on (i) magnetic resonance compatible AR model fabrication (dilatation, perforation, and prolapse) and (ii) systematic analysis of the performance of 4D flow MRI in AR quantification. The results indicated that the formation of the forward and backward jets over time was highly dependent on the types of AR origin. The amount of regurgitation volume bias for the model types were -7.04%, -33.21%, 6.75%, and 37.04% compared to the ground truth (48 mL) volume measured from the pump stroke volume. The largest error of the regurgitation fraction was around 12%. These results indicate that careful selection of imaging parameters is required when absolute regurgitation volume is important. The suggested in vitro flow phantom can easily be modified to simulate other valvular diseases such as aortic stenosis or bicuspid aortic valve (BAV) and can be used as a standard platform to test different MRI sequences in the future.

In vitro Assessment of Aortic Regurgitation Using Four-Dimensional Flow Magnetic Resonance Imaging

Aortic regurgitation is an aortic valve heart disease. This manuscript demonstrates how four-dimensional flow magnetic resonance imaging can evaluate aortic regurgitation using in vitro heart valves mimicking aortic regurgitation.

体外 使用四维流动磁共振成像评估主动脉瓣反流

Aortic regurgitation (AR) refers to backward blood flow from the aorta into the left ventricle (LV) during ventricular diastole. The regurgitant jet ...