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://jove.unicartagenaproxy.elogim.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

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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><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://jove.unicartagenaproxy.elogim.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://jove.unicartagenaproxy.elogim.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://jove.unicartagenaproxy.elogim.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://jove.unicartagenaproxy.elogim.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://jove.unicartagenaproxy.elogim.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://jove.unicartagenaproxy.elogim.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://jove.unicartagenaproxy.elogim.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://jove.unicartagenaproxy.elogim.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://jove.unicartagenaproxy.elogim.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://jove.unicartagenaproxy.elogim.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://jove.unicartagenaproxy.elogim.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://jove.unicartagenaproxy.elogim.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://jove.unicartagenaproxy.elogim.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://jove.unicartagenaproxy.elogim.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://jove.unicartagenaproxy.elogim.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://jove.unicartagenaproxy.elogim.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://jove.unicartagenaproxy.elogim.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://jove.unicartagenaproxy.elogim.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://jove.unicartagenaproxy.elogim.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://jove.unicartagenaproxy.elogim.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://jove.unicartagenaproxy.elogim.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://jove.unicartagenaproxy.elogim.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://jove.unicartagenaproxy.elogim.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://jove.unicartagenaproxy.elogim.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

Universidad de Cartagena UDEC

Research

JoVE Journal

Engineering

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

3.1K 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  

Planar and Three-Dimensional Printing of Conductive Inks

Printed electronics rely on low-cost, large-area fabrication routes to create flexible or multidimensional electronic, optoelectronic, and biomedical devices1-3. In this paper, we focus on one- (1D), two- (2D), and three-dimensional (3D) printing of conductive metallic inks in the form of flexible, stretchable, and spanning microelectrodes.
Direct-write assembly4,5 is a 1-to-3D printing technique that enables the fabrication of features ranging from simple lines to complex structures by the deposition of concentrated inks through fine nozzles (~0.1 - 250 &mu;m). This printing method consists of a computer-controlled 3-axis translation stage, an ink reservoir and nozzle, and 10x telescopic lens for visualization. Unlike inkjet printing, a droplet-based process, direct-write assembly involves the extrusion of ink filaments either in- or out-of-plane. The printed filaments typically conform to the nozzle size. Hence, microscale features (&lt; 1 &mu;m) can be patterned and assembled into larger arrays and multidimensional architectures.
In this paper, we first synthesize a highly concentrated silver nanoparticle ink for planar and 3D printing via direct-write assembly. Next, a standard protocol for printing microelectrodes in multidimensional motifs is demonstrated. Finally, applications of printed microelectrodes for electrically small antennas, solar cells, and light-emitting diodes are highlighted.

Planar and three-dimensional printing of conductive metallic inks is described. Our approach provides new avenues for fabricating printed electronic, optoelectronic, and biomedical devices in unusual layouts at the microscale.

平面和立体印刷的导电油墨

Printed electronics rely on low-cost, large-area fabrication routes to create flexible or multidimensional electronic, optoelectronic, and biomedical ...

科研

生物工程

Correlative Microscopy for 3D Structural Analysis of Dynamic Interactions

Cryo-electron tomography (cryoET) allows 3D visualization of cellular structures at molecular resolution in a close-to-physiological state1. However, direct visualization of individual viral complexes in their host cellular environment with cryoET is challenging2, due to the infrequent and dynamic nature of viral entry, particularly in the case of HIV-1. While time-lapse live-cell imaging has yielded a great deal of information about many aspects of the life cycle of HIV-13-7, the resolution afforded by live-cell microscopy is limited (~ 200 nm). Our work was aimed at developing a correlation method that permits direct visualization of early events of HIV-1 infection by combining live-cell fluorescent light microscopy, cryo-fluorescent microscopy, and cryoET. In this manner, live-cell and cryo-fluorescent signals can be used to accurately guide the sampling in cryoET. Furthermore, structural information obtained from cryoET can be complemented with the dynamic functional data gained through live-cell imaging of fluorescent labeled target.
In this video article, we provide detailed methods and protocols for structural investigation of HIV-1 and host-cell interactions using 3D correlative high-speed live-cell imaging and high-resolution cryoET structural analysis. HeLa cells infected with HIV-1 particles were characterized first by confocal live-cell microscopy, and the region containing the same viral particle was then analyzed by cryo-electron tomography for 3D structural details. The correlation between two sets of imaging data, optical imaging and electron imaging, was achieved using a home-built cryo-fluorescence light microscopy stage. The approach detailed here will be valuable, not only for study of virus-host cell interactions, but also for broader applications in cell biology, such as cell signaling, membrane receptor trafficking, and many other dynamic cellular processes.

We describe a correlative microscopy method that combines high-speed 3D live-cell fluorescent light microscopy and high-resolution cryo-electron tomography. We demonstrate the capability of the correlative method by imaging dynamic, small HIV-1 particles interacting with host HeLa cells.

Cryo-electron tomography (cryoET) allows 3D visualization of cellular structures at molecular resolution in a close-to-physiological state1. However, ...

Automated 3D Optical Coherence Tomography to Elucidate Biofilm Morphogenesis Over Large Spatial Scales

Biofilms are a most successful microbial lifestyle and prevail in a multitude of environmental and engineered settings. Understanding biofilm morphogenesis, that is the structural diversification of biofilms during community assembly, represents a remarkable challenge across spatial and temporal scales. Here, we present an automated biofilm imaging system based on optical coherence tomography (OCT). OCT is an emerging imaging technique in biofilm research. However, the amount of data that currently can be acquired and processed hampers the statistical inference of large scale patterns in biofilm morphology. The automated OCT imaging system allows covering large spatial and extended temporal scales of biofilm growth. It combines a commercially available OCT system with a robotic positioning platform and a suite of software solutions to control the positioning of the OCT scanning probe, as well as the acquisition and processing of 3D biofilm imaging datasets. This setup allows the in situ and non-invasive automated&#160;monitoring of biofilm development and may be further developed to couple OCT imaging with macrophotography and microsensor profiling.

Microbial biofilms form complex architectures at interphases and develop into highly scale-dependent spatial patterns. Here, we introduce an experimental system (hard- and software) for the automated acquisition of 3D optical coherence tomography (OCT) datasets. This toolset allows the non-invasive and multi-scale characterization of biofilm morphogenesis in space and time.

自动 3D 光学相干断层扫描，以在大型空间尺度上阐明生物膜变形

Biofilms are a most successful microbial lifestyle and prevail in a multitude of environmental and engineered settings. Understanding biofilm ...

环境科学

Stereolithographic 3D Printing with Renewable Acrylates

The accessibility of cost-competitive renewable materials and their application in additive manufacturing is essential for an efficient biobased economy. We demonstrate the rapid prototyping of sustainable resins using a stereolithographic 3D printer. Resin formulation takes place by straightforward mixing of biobased acrylate monomers and oligomers with a photoinitiatior and optical absorber. Resin viscosity is controlled by the monomer to oligomer ratio and is determined as a function of shear rate by a rheometer with parallel plate geometry. A stereolithographic apparatus charged with the biobased resins is employed to produce complex shaped prototypes with high accuracy. The products require a post-treatment, including alcohol rinsing and UV irradiation, to ensure complete curing. The high feature resolution and excellent surface finishing of the prototypes is revealed by scanning electron microscopy.

A protocol for additive manufacturing with renewable photopolymer resins on a stereolithography apparatus is presented.

Stereolithographic 3D 印刷用可再生丙烯酸酯

The accessibility of cost-competitive renewable materials and their application in additive manufacturing is essential for an efficient biobased economy. ...

化学

3D Printing and In Situ Surface Modification via Type I Photoinitiated Reversible Addition-Fragmentation Chain Transfer Polymerization

3D printing provides facile access to geometrically complex materials. However, these materials have intrinsically linked bulk and interfacial properties dependent on the chemical composition of the resin. In the current work, 3D printed materials are post-functionalized using the 3D printer hardware via a secondary surface-initiated polymerization process, thus providing independent control over the bulk and interfacial material properties. This process begins with preparing liquid resins, which contain a monofunctional monomer, a crosslinking multifunctional monomer, a photochemically labile species that enables initiation of polymerization, and critically, a thiocarbonylthio compound which facilitates reversible addition-fragmentation chain transfer (RAFT) polymerization. The thiocarbonylthio compound, known commonly as a RAFT agent, mediates the chain growth polymerization process and provides polymeric materials with more homogeneous network structures. The liquid resin is cured in a layer-by-layer fashion using a commercially available digital light processing 3D printer to give three-dimensional materials having spatially controlled geometries. The initial resin is removed and replaced with a new mixture containing functional monomers and photoinitiating species. The 3D printed material is then exposed to light from the 3D printer in the presence of the new functional monomer mixture. This allows photoinduced surface-initiated polymerization to occur from the latent RAFT agent groups on the surface of the 3D printed material. Given the chemical flexibility of both resins, this process allows a wide range of 3D printed materials to be produced with tailorable bulk and interfacial properties.

3D Printing and In Situ Surface Modification via Type I Photoinitiated Reversible Addition-Fragmentation Chain Transfer Polymerization

The present protocol describes the digital light processing-based 3D printing of polymeric materials using type I photoinitiated reversible addition-fragmentation chain transfer polymerization and the subsequent in situ material post-functionalization via surface-mediated polymerization. Photoinduced 3D printing provides materials with independently tailored and spatially controlled bulk and interfacial properties.

通过I型光引发可逆加成-碎片链转移聚合进行3D打印和原位表面改性

3D printing provides facile access to geometrically complex materials. However, these materials have intrinsically linked bulk and interfacial properties ...

Frugal Imaging Technique of Capillary Flow Through Three-Dimensional Polymeric Printing Powders

The development of novel imaging techniques of molecular and colloidal transport, including nanoparticles, is an area of active investigation in microfluidic and millifluidic studies. With the advent of three-dimensional (3D) printing, a new domain of materials has emerged, thereby increasing the demand for novel polymers. Specifically, polymeric powders, with average particle sizes on the order of a micron, are experiencing a growing interest from academic and industrial communities. Controlling material tunability at the mesoscopic to microscopic length scales creates opportunities to develop innovative materials, such as gradient materials. Recently, a need for micron-sized polymeric powders has been growing, as clear applications for the material are developing. Three-dimensional printing provides a high-throughput process with a direct link to new applications, driving investigations into the physio-chemical and transport interactions on a mesoscale. The protocol that is discussed in this article provides a non-invasive technique to image fluid flow in packed powder beds, providing high temporal and spatial resolution while leveraging mobile technology that is readily available from mobile devices, such as smartphones. By utilizing a common mobile device, the imaging costs that would normally be associated with an optical microscope are eliminated, resulting in a frugal-science approach. The proposed protocol has successfully characterized a variety of combinations of fluids and powders, creating a diagnostic platform for quickly imaging and identifying an optimal combination of fluid and powder.

The proposed technique will provide a novel, efficient, frugal, and non-invasive approach for imaging fluidic flow through a packed powder bed, yielding high spatial and temporal resolution.

毛细管流通过三维聚合物印刷粉末的节俭成像技术

The development of novel imaging techniques of molecular and colloidal transport, including nanoparticles, is an area of active investigation in ...

工程学

Three-dimensional Patterning of Engineered Biofilms with a Do-it-yourself Bioprinter

Biofilms are aggregates of bacteria embedded in a self-produced spatially-patterned extracellular matrix. Bacteria within a biofilm develop enhanced antibiotic resistance, which poses potential health dangers, but can also be beneficial for environmental applications such as purification of drinking water. The further development of anti-bacterial therapeutics and biofilm-inspired applications will require the development of reproducible, engineerable methods for biofilm creation. Recently, a novel method of biofilm preparation using a modified three-dimensional (3D) printer with a bacterial ink has been developed. This article describes the steps necessary to build this efficient, low-cost 3D bioprinter that offers multiple applications in bacterially-induced materials processing. The protocol begins with an adapted commercial 3D printer in which the extruder has been replaced with a bio-ink dispenser connected to a syringe pump system enabling a controllable, continuous flow of bio-ink. To develop a bio-ink suitable for biofilm printing, engineered Escherichia coli bacteria were suspended in a solution of alginate, so that they solidify in contact with a surface containing calcium. The inclusion of an inducer chemical within the printing substrate drives expression of biofilm proteins within the printed bio-ink. This method enables 3D printing of various spatial patterns composed of discrete layers of printed biofilms. Such spatially-controlled biofilms can serve as model systems and can find applications in multiple fields that have a wide-ranging impact on society, including antibiotic resistance prevention or drinking water purification, among others.

This article describes a method of transforming a low-cost commercial 3D printer into a bacterial 3D printer that can facilitate printing of patterned biofilms. All necessary aspects of preparing the bioprinter and bio-ink are described, as well as verification methods to assess the formation of biofilms.

工程生物膜的三维造型

Biofilms are aggregates of bacteria embedded in a self-produced spatially-patterned extracellular matrix. Bacteria within a biofilm develop enhanced ...

Controlled Strain of 3D Hydrogels under Live Microscopy Imaging

External forces are an important factor in tissue formation, development, and maintenance. The effects of these forces are often studied using specialized in vitro stretching methods. Various available systems use 2D substrate-based stretchers, while the accessibility of 3D techniques to strain soft hydrogels, is more restricted. Here, we describe a method that allows external stretching of soft hydrogels from their circumference, using an elastic silicone strip as the sample carrier. The stretching system utilized in this protocol is constructed from 3D-printed parts and low-cost electronics, making it simple and easy to replicate in other labs. The experimental process begins with polymerizing thick (&#62;100 &#956;m) soft fibrin hydrogels (Elastic Modulus of ~100 Pa) in a cut-out at the center of a silicone strip. Silicone-gel constructs are then attached to the printed-stretching device and placed on the confocal microscope stage. Under live microscopy the stretching device is activated, and the gels are imaged at various stretch magnitudes. Image processing is then used to quantify the resulting gel deformations, demonstrating relatively homogenous strains and fiber alignment throughout the gel&#8217;s 3D thickness (Z-axis). Advantages of this method include the ability to strain extremely soft hydrogels in 3D while executing in situ microscopy, and the freedom to manipulate the geometry and size of the sample according to the user&#8217;s needs. Additionally, with proper adaptation, this method can be used to stretch other types of hydrogels (e.g., collagen, polyacrylamide or polyethylene glycol) and can allow for analysis of cells and tissue response to external forces under more biomimetic 3D conditions.

The presented method involves uniaxial stretching of 3D soft hydrogels embedded in silicone rubber while allowing live confocal microscopy. Characterization of the external and internal hydrogel strains as well as fiber alignment are demonstrated. The device and protocol developed can assess the response of cells to various strain regimes.

实时显微镜成像下的 3D 水凝胶控制应变

External forces are an important factor in tissue formation, development, and maintenance. The effects of these forces are often studied using specialized ...

3D Scanning Technology Bridging Microcircuits and Macroscale Brain Images in 3D Novel Embedding Overlapping Protocol

The human brain, being a multiscale system, has both macroscopic electrical signals, globally flowing along thick white-matter fiber bundles, and microscopic neuronal spikes, propagating along axons and dendrites. Both scales complement different aspects of human cognitive and behavioral functions. At the macroscopic level, MRI has been the current standard imaging technology, in which the smallest spatial resolution, voxel size, is 0.1&#8211;1 mm3. Also, at the microscopic level, previous physiological studies were aware of nonuniform neuronal architectures within such voxels. This study develops a powerful way to accurately embed microscopic data into a macroscopic map by interfacing biological scientific research with technological advancements in 3D scanning technology. Since 3D scanning technology has mostly been used for engineering and industrial design until now, it is repurposed for the first time to embed microconnectomes into the whole brain while preserving natural spiking in living brain cells. In order to achieve this purpose, first, we constructed a scanning protocol to obtain accurate 3D images from living bio-organisms inherently challenging to image due to moist and reflective surfaces. Second, we trained to keep speed to prevent the degradation of living brain tissue, which is a key factor in retaining better conditions and recording more natural neuronal spikes from active neurons in the brain tissue. Two cortical surface images, independently extracted from two different imaging modules, namely MRI and 3D scanner surface images, surprisingly show a distance error of only 50 &#956;m as mode value of the histogram. This accuracy is comparable in scale to the microscopic resolution of intercellular distances; also, it is stable among different individual mice. This new protocol, the 3D novel embedding overlapping (3D-NEO) protocol, bridges macroscopic and microscopic levels derived by this integrative protocol and accelerates new scientific findings to study comprehensive connectivity architectures (i.e., microconnectome).

This article introduces an experimental protocol using 3D scanning technology bridging two spatial scales: the macroscopic spatial scale of whole-brain anatomy imaged by MRI at &#62;100 &#956;m and the microscopic spatial scale of neuronal distributions using immunohistochemistry staining and a multielectrode array system and other methods (~10 &#956;m).

3D 扫描技术在 3D 新颖嵌入重叠协议中桥接微电路和宏观大脑图像

The human brain, being a multiscale system, has both macroscopic electrical signals, globally flowing along thick white-matter fiber bundles, and ...

神经科学

Agarose Fluid Gels Formed by Shear Processing During Gelation for Suspended 3D Bioprinting

The use of granular matrices to support parts during the bioprinting process was first reported by Bhattacharjee et al. in 2015, and since then, several approaches have been developed for the preparation and use of supporting gel beds in 3D bioprinting. This paper describes a process to manufacture microgel suspensions using agarose (known as fluid gels), wherein particle formation is governed by the application of shear during gelation. Such processing produces carefully defined microstructures, with subsequent material properties that impart distinct advantages as embedding print media, both chemically and mechanically. These include behaving as viscoelastic solid-like materials at zero shear, limiting long-range diffusion, and demonstrating the characteristic shear-thinning behavior of flocculated systems. 
On the removal of shear stress, however, fluid gels have the capacity to rapidly recover their elastic properties. This lack of hysteresis is directly linked to the defined microstructures previously alluded to; because of the processing, reactive, non-gelled polymer chains at the particle interface facilitate interparticle interactions-similar to a Velcro effect. This rapid recovery of elastic properties enables bioprinting high-resolution parts from low-viscosity biomaterials, as rapid reformation of the support bed traps the bioink in situ, maintaining its shape. Furthermore, an advantage of agarose fluid gels is the asymmetric gelling/melting transitions (gelation temperature of ~30 &#176;C and melting temperature of ~90 &#176;C). This thermal hysteresis of agarose makes it possible to print and culture the bioprinted part in situ without the supporting fluid gel melting. This protocol shows how to manufacture agarose fluid gels and demonstrates their use to support the production of a range of complex hydrogel parts within suspended-layer additive manufacture (SLAM).

Shear processing during hydrogel formation results in the production of microgel suspensions that shear-thin but rapidly restructure following the removal of shear forces. Such materials have been used as a supporting matrix for bioprinting complex, cell-laden structures. Here, methods used to manufacture the supporting bed and compatible bioinks are described.

琼脂糖流体凝胶在凝胶过程中通过剪切处理形成，用于悬浮3D生物打印

The use of granular matrices to support parts during the bioprinting process was first reported by Bhattacharjee et al. in 2015, and since then, several ...