本文报告了由丹麦创新基金资助的 "植入式医疗设备先进表面处理" 项目所开展的工作。撰文人感谢欧洲创新培训网 MICROMAN "零缺陷网络形状 MICROMANufacturing 过程指纹" 的支持, 由2020欧洲研究和创新框架方案资助联盟。

1. 通过添加剂制造 (AM) 进行插入加工
<ol><li>通过计算机辅助设计软件设计所需的孔洞 (请参阅本工作中使用的文件的补充材料)。 注: 在不支持的情况下, 直接在建筑台上制造刀片, 避免在固化过程中翘曲刀片。公差为0.05 毫米。</li>
	<li>选择一个树脂为照片聚合, 特别是一个可以承受压力和热在注塑成型。 注: 我们选择的树脂 (见材料表) 的抗拉强度为56兆帕, 断裂伸长率为 3.5%, 弯曲强度为115兆帕, 弯曲模量为3350兆帕, 热偏转温度为140摄氏度18。</li>
	<li>混合光敏混合 (专有甲基丙烯酸甲酯和丙烯酰胺混合, 与2基的照片启动器) 彻底至少30分钟, 通过运行的材料罐在湿实验室瓶辊, 烧瓶振动筛或类似的混合装置。</li>
	<li>准备照片聚合机 (体素大小为16µm):<ol>
<li>对于自下而上的 AM 机器, 检查增值税涂层是否未损坏并彻底清洗。</li>
		<li>对于自上而下的机器, 检查擦拭系统是否有任何缺陷。</li>
		<li>检查生成阶段, 并使用100µm 规格箔调整生成板, 以正确地将生成板偏移到增值税。</li>
		<li>如果可能的话, 预先点燃机床的光源, 以达到稳态温度, 然后再进行。这温度应该是65°c 在轻的引擎和30°c 在增值税之内。</li>
	</ol>
</li>
	<li>将几何图形导入作业准备软件。遵循从机器制造商19的指导方针。<ol>
<li>分配适当的机器参数以匹配所选的光敏 (使用的机器的光强度和层厚度)。</li>
		<li>以最高的垂直机器分辨率 (本研究中的25µm) 运行生成。</li>
	</ol>
</li>
	<li>清洗打印的插入件。<ol>
<li>将其冲洗在异丙醇暴露于超声波浴中3分钟, 彻底冲洗三次, 并确保打印的刀片表面不留光敏残留物。</li>
		<li>允许溶剂在室温下完全蒸发, 并将干燥中的插入物放在室温下过夜。</li>
	</ol>
</li>
	<li>后处理的干燥插入使用 UV 光闪烁两次, 每次2000年闪烁每秒10闪烁频率 (见材料表)。</li>
</ol>2. 注塑成型 (IM)
<ol><li>在常规注塑机上安装微注塑模块 (见材料表)。 注: 在我们的情况下, 注射模块有一个螺钉安装在45°的角度, 螺钉直径为8毫米, 夹紧力为 100 kN。</li>
	<li>将刀片装入模具板上。</li>
</ol><img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/57335/57335fig1.jpg"> 图 1: 注塑机与模具.(a) 注射方与板材装配。插入由红色圆圈突出显示。(b) 可移动侧与带有弹射销的板材装配。插入由红色圆圈突出显示。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/57335/57335fig1large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<ol start="3"><li>为了适应打印过程中的变化, 手动对所需的插入件进行任何细微的修改以适合模具。</li>
	<li>拧紧机器上的模具板。</li>
	<li>将 PE 颗粒装入料斗。</li>
	<li>将机床参数 T 模设置为摄氏60摄氏度, t桶为175摄氏度, V型注塑为65毫米/秒. 允许部件的冷却时间足够 demolded。</li>
	<li>加热螺丝在31°c, 155 °c, 165 °c, 170 °c, 和175°c 从第一到第五届会议。当熔体温度为175摄氏度时, 开始精确的注塑成型。一旦腔被填满, 保持300巴的包装压力5秒, 以弥补 PE 收缩。</li>
	<li>打开模具并允许弹射销将 PE 部件从插入件的可移动侧推出。如果 PE 部件夹在插入件上, 请手动取出零件。</li>
	<li>在100次注塑过程中停止机器 (循环是从模具关闭直到部件被弹出时定义的)。</li>
</ol>3. 质量评估
<ol><li>用激光扫描数字显微镜20测量注塑成型前孔的直径和深度。两个刀片的测量;在每个插入, 测量四孔在两个区域以不同的距离对门 "在门附近" 和 "远离门"。</li>
</ol><img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/57335/57335fig2.jpg"> 图 2: 在插入件的 CAD 图像上突出显示的测量区域.(a) 可移动侧插入对应于复制副本的屁股;(b) 注入端对应于复制副本的顶端。注射门位于中心。在研究中比较了两个区域, 分别与门的距离、"远离门" 和 "靠近门"。(这个数字已经从张等201722) 修改过了。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/57335/57335fig2large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<ol start="2"><li>测量直径和柱子的高度从注射成型获得的履带尖尖。 注: 将所获得的 PE 零件分组成批次10件;即1-10 是第一批, 11-20 是第二批;直到最后一块。在每个批次中使用一个随机样本, 并在顶部和后侧进行测量;在两边, 测量四根柱子在两个区域以不同的距离对门 ("在门附近" 和 "远离门")。</li>
	<li>通过图像处理软件21的辅助分析数据, 以获得尺寸。</li>
</ol>

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作者没有什么可透露的。

该方法适用于复杂形状高分子零件的插入件的制作。它用一组由聚合物制成的软刀片代替注塑机中的刀具钢模腔。与传统的金属加工相比, 缩短了加工时间和成本;因此, 生产周期缩短。该工艺链适用于中等规模的产品 (从 1000年-1万周期注塑或类似) 生产, 但在设计上的变化很大。此外, 对于3D 印刷刀片, 不需要特殊的模具板。标准的商用注塑板被购买和加工, 以适应插入。
在当前的技术状态下, 软模具由不同的机制17失败。该失效机理已被确定为连接软模具插入件的热偏转温度, 而分解则被确定为由于出气。因此, 最关键的一步是选择合适的树脂为插入物生产的添加剂制造。热力学性能决定了插入件的寿命,即在注塑过程中能承受多少循环。它还决定了模塑聚合物的范围;模塑聚合物的模具温度不应高于插入材料的挠度温度。
协议中的第二个关键步骤是插入的设计。应遵循模具设计的一般规则, 在3D 印制聚合物插入件时应避免机械薄弱部件;否则, 刀具寿命会因裂纹等故障而受到影响。
所获得的注塑件表面质量受外加添加剂制造工艺的限制。后处理, 如化学蚀刻是一个可能的解决方案, 以提高表面质量。表面特性的精度是由于添加剂制造过程而引起的另一个问题。
该方法在满足工业需求的新生产平台上创造了在真实自由曲面上创建微特征的可能性。因此, 这种方法有可能被应用和研究的应用与下一代医疗设备, 需要微功能的复杂形状, 例如与医疗器械或植入设备14.该方法通过大幅度降低中小批量生产系列产品的成本来促进价值创造, 并对 1-10 个单独设备与实际批量生产之间的差距产生积极影响。它将开辟新的高附加值产品和设计方案。

本发明的目的是通过软加工工艺制造具有微特征的复杂表面,即利用高分子添加剂制造生产聚合物注塑成型的刀片。换言之, 具有功能表面的聚合物部件是由聚合物插入模塑而成。
表面功能可通过微特征实现;例如, 杜安等。1和 Luchetta等。2展示细胞生物学领域的功能表面, 以及胡等。3显示了一个光学元件的例子,等等.一种表面特征, 微柱, 已被深入研究, 以促进细胞增殖。如果微柱以一定的方式4,5, 它们能够增强增生组织与表面的结合。
对微特征的聚合物复制进行了深入研究, 并通过6多个工艺实现了精密成型。例如, Metwally等人报告了模塑零件和模具之间的高保真度, 以复制微和亚微特征在平坦表面7。
有许多制造微柱或特征的协议;然而, 它们大多只能应用在平坦的表面或具有恒定曲率的曲面上。例如, 年等。8表明, 在曲面上的热压花可以实现微特征。这些协议不适用于具有三维曲面的复杂形状, 这是大多数实际设备所必需的。显然, 表面具有微特征的三维腔的制造挑战了当前的协议;同时, 如果在复杂表面上的高纵横比柱子不垂直于脱模方向, 则部件的弹射可能会失败。Bissacco等。9 ) 采用3D 模刀片, 通过注塑成型获得亚微米特征;在研究中, 采用铝阳极氧化工艺, 在复杂组分上成功地复制了具有低长宽比的特异性亚微米特征。
研究人员试图在聚合物复制的过程链中加入添加剂制造, 以达到设计的表面纹理。Lantada等人描述了从 AM 原型开始的工艺链, 然后采用涂装技术获取注塑成型10的金属模刀片。由 AM 生产的高分子零件已被证明是直接适用于模具插入11,12, 这是软模具过程中提出的协议。
在我们以前的工作中, 我们证明了Ø4µm PEEK 柱 (2 µm 高) 成功 demolded 在垂直墙上注塑成型13。在本协议中, 所研究的产品是一个四尖的环, 每一个都有一个角度的一角。本产品已由张等研究。14、采用预制备的镍板进行微特征提取, 在齿尖上采用硅橡胶注射成型法, 得到了µm 的微柱 (Ø4), 其长宽比为0.5。
在所提出的方法中, 可以在软模具加工链所创建的复杂曲面上获得微特征。钢模腔被一组由还原光聚合为基础的镶件所取代。与金属相比, 基于光敏的 am 技术能够达到更高的精度15。而且, 与传统的数控加工工艺相比, 加工时间和成本大大降低。根据最近的案例研究16, 通过使用软模具进行热成型, 成本降低了 91%, 而消耗的时间减少了93%。该协议适用于要求高设计灵活性和中间生产量的产品。经证明, 碳纤维增强 photopolymers 制造的刀片在明显的模具变质17前可承受2500的聚乙烯注塑周期。注射成型材料的选择受所选光敏的热性能的限制。高熔融温度的聚合物在光敏腔中可能不适用。本研究选用聚乙烯 (PE) 进行注射成型试验。

<table border="0" cellpadding="0" cellspacing="0" width="623">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Photopolymer resin&#160;</td>
			<td style="width:121px;">EnvisionTec</td>
			<td style="width:119px;">HTM140 V2</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Resin mixing device</td>
			<td style="width:121px;">IKA</td>
			<td>Vortex Genius 3</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">3d printer</td>
			<td>Envisiontec</td>
			<td>Perfactory 3&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">UV light flash unit</td>
			<td style="width:121px;">EnvisionTec</td>
			<td style="width:119px;">Otoflash unit</td>
			<td></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:24px;width:216px;">Polyethylene&#160;</td>
			<td style="width:121px;">lyondellbasell</td>
			<td style="width:119px;">PE Purell 1840</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Injection moulding machine</td>
			<td>Arburg</td>
			<td>Allrounder 370A&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Image processing</td>
			<td style="width:121px;">SPIP</td>
			<td style="width:119px;">6.2.8</td>
			<td></td>
		</tr>
	</tbody>
</table>

a soft tooling process chain for injection molding of a 3d component with micro pillars

本文的目的是介绍一种采用添加剂制造 (AM) 的软模具工艺链制造具有微表面特征的注塑刀片的方法。软工具插入是由数字光处理 (vat 照片聚合) 制造的, 使用的光敏可以承受相对较高的 temperaturea。这里制造的部件有四尖角的角度。微柱 (Ø200µm, 长宽比 1) 由两排排列在表面上。聚乙烯 (PE) 注塑与软模具插入是用来制造最后的零件。该方法表明, 采用外加剂制造的刀片, 在复杂几何上获得具有显微结构的注塑件是可行的。与基于计算机数控 (CNC) 加工的传统模具相比, 加工时间和成本显著降低。微特征的尺寸受外加添加剂制造过程的影响。插入的寿命决定了此过程更适合于先导生产。刀片生产的精度也受到添加剂制造过程的限制。

图 3显示了由 AM 和注塑成型的 PE 零件制造的插入件。两行圆孔垂直于尖尖上的曲面 (图 3 (b))。插入孔的公称尺寸为Ø200µm, 深度为200µm, 中心到中心距离为400µm。由于 AM 过程的层结构清晰可见。在左下线有一个可看见的折叠的标记, 在准备期间无意中发生在 SEM。
脱模过程如图 4所示。柱子不平行于脱模方向。在所有研究样品中没有发现柱断裂 (图 5)。从这个意义上说, 脱模是成功的。由于压力下降, 远距门位置的柱子明显低于顶部, 这一点已经可见。关于直径, 区别从位置不一样突出象为高度。
图 6和图 7说明了复制在注塑成型的100个周期中的传播方式。复制的程度由柱子的尺寸和插入物的尺寸之间的比值来定义。沿100循环, 在每个位置上实现了垂直和横向复制的稳定过程。在注塑成型后, 插入孔的尺寸不变, 证实了这一结论。离闸门很远的柱子的高度低于浇口的位置, 因为聚合物流动增加了其粘度。
注射成型参数在材料数据表允许的范围内变化。在 "探索的过程" 窗口中, 大多数运行都达到了80个以上的周期, 确认在探索的过程窗口中, AM 插入的刀具寿命不受影响。但是, 在注射压力较高时, 在某些试验中, 注塑侧的插入件发生开裂。这是由于插入的中心部分更薄。
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/57335/57335fig3.jpg"> 图 3: 插入和复制副本.(a) 由模具腔体组成的添加剂制造工艺制成的刀片;展示了一种由注塑成型的聚乙烯 (PE) 复制品。参考标尺上的标记为毫米;数字标记厘米。(b) 扫描电子显微镜 (SEM) 图像显示插入的表面;(c) SEM 图像显示注塑成型 PE 零件的表面。((a) 及 (b) 已由张等人修改 201722)<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/57335/57335fig3large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/57335/57335fig4.jpg"> 图 4: 成功的脱模.尽管柱子与脱模方向不平行, 脱模还是成功的。(a) 模具关闭和 (b) 模具开放脱模。(这个数字已经从张等201722) 修改过了。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/57335/57335fig4large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/57335/57335fig5.jpg"> 图 5: 一个随机齿尖侧面的 SEM 图像.所调查的四个位置被标记在图像上。(这个数字已经从张等201722) 修改过了。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/57335/57335fig5large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 6" class="xfigimg" src="/files/ftp_upload/57335/57335fig6.jpg"> 图 6: 柱高复制度.柱高度的复制程度是由孔的柱/深的高度来定义的。每批中显示四个位置的复制程度的平均值。每个批次中都测量了一个随机选取的样本。四位置是 "后远" 的位置远离门在后面, "后面的位置靠近门的后面," 顶部 "的位置远离大门在上面, 和" 顶部附近 "的位置附近的大门在顶部。(这个数字已经从张等2017 22) 修改过了。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/57335/57335fig6large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 7" class="xfigimg" src="/files/ftp_upload/57335/57335fig7.jpg"> 图 7: 柱径复制度.柱直径的复制程度由孔的柱直径或直径确定。每批中显示四个位置的复制程度的平均值。每个批次中都测量了一个随机选取的样本。四位置是 "后远" 的位置远离门在后面, "后近" 的位置附近的大门在后面, "顶部" 的位置远离大门在上面, 和 "顶部附近" 的位置附近的大门在顶端一侧。(这个数字已从张等2017 22) 修改。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/57335/57335fig7large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>

Watch this Scientific Journal Video about A Soft Tooling Process Chain for Injection Molding of a 3D Component with Micro Pillars at JoVE.com

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

微柱3D 构件注塑成型的软加工工艺链

提出了一种采用添加剂制造 (AM) 的表面具有微特征的复杂几何形状的注塑件的制作方案。

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

a-soft-tooling-process-chain-for-injection-molding-3d-component-with

Nanyang Technological University

Research

JoVE Journal

Engineering

12.5K 次观看.  Technical University of Denmark. 提出了一种采用添加剂制造 (AM) 的表面具有微特征的复杂几何形状的注塑件的制作方案。

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

Fabrication, Densification, and Replica Molding of 3D Carbon Nanotube Microstructures

The introduction of new materials and processes to microfabrication has, in large part, enabled many important advances in microsystems, lab-on-a-chip devices, and their applications. In particular, capabilities for cost-effective fabrication of polymer microstructures were transformed by the advent of soft lithography and other micromolding techniques 1, 2, and this led a revolution in applications of microfabrication to biomedical engineering and biology. Nevertheless, it remains challenging to fabricate microstructures with well-defined nanoscale surface textures, and to fabricate arbitrary 3D shapes at the micro-scale. Robustness of master molds and maintenance of shape integrity is especially important to achieve high fidelity replication of complex structures and preserving their nanoscale surface texture. The combination of hierarchical textures, and heterogeneous shapes, is a profound challenge to existing microfabrication methods that largely rely upon top-down etching using fixed mask templates. On the other hand, the bottom-up synthesis of nanostructures such as nanotubes and nanowires can offer new capabilities to microfabrication, in particular by taking advantage of the collective self-organization of nanostructures, and local control of their growth behavior with respect to microfabricated patterns. 
Our goal is to introduce vertically aligned carbon nanotubes (CNTs), which we refer to as CNT "forests", as a new microfabrication material. We present details of a suite of related methods recently developed by our group: fabrication of CNT forest microstructures by thermal CVD from lithographically patterned catalyst thin films; self-directed elastocapillary densification of CNT microstructures; and replica molding of polymer microstructures using CNT composite master molds. In particular, our work shows that self-directed capillary densification ("capillary forming"), which is performed by condensation of a solvent onto the substrate with CNT microstructures, significantly increases the packing density of CNTs. This process enables directed transformation of vertical CNT microstructures into straight, inclined, and twisted shapes, which have robust mechanical properties exceeding those of typical microfabrication polymers. This in turn enables formation of nanocomposite CNT master molds by capillary-driven infiltration of polymers. The replica structures exhibit the anisotropic nanoscale texture of the aligned CNTs, and can have walls with sub-micron thickness and aspect ratios exceeding 50:1. Integration of CNT microstructures in fabrication offers further opportunity to exploit the electrical and thermal properties of CNTs, and diverse capabilities for chemical and biochemical functionalization 3.

We present methods for fabrication of patterned microstructures of vertically aligned carbon nanotubes (CNTs), and their use as master molds for production of polymer microstructures with organized nanoscale surface texture. The CNT forests are densified by condensation of solvent onto the substrate, which significantly increases their packing density and enables self-directed formation of 3D shapes.

制备，致密，副本三维碳纳米管微结构成型

The introduction of new materials and processes to microfabrication has, in large part, enabled many important advances in microsystems, lab-on-a-chip ...

科研

工程学

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

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 attention as a unique mechanism for pattern transformation. Nature is full of such examples where a wealth of exotic patterns are formed through mechanical instability2-5. Inspired by this elegant mechanism, many studies have demonstrated creation and transformation of patterns using soft materials such as elastomers and hydrogels6-11. Swelling gels are of particular interest because they can spontaneously trigger mechanical instability to create various patterns without the need of external force6-10. Recently, we have reported demonstration of full control over buckling pattern of micro-scaled tubular gels using projection micro-stereolithography (P&mu;SL), a three-dimensional (3D) manufacturing technology capable of rapidly converting computer generated 3D models into physical objects at high resolution12,13. Here we present a simple method to build up a simplified P&mu;SL system using a commercially available digital data projector to study swelling-induced buckling instability for controlled pattern transformation.
A simple desktop 3D printer is built using an off-the-shelf digital data projector and simple optical components such as a convex lens and a mirror14. Cross-sectional images extracted from a 3D solid model is projected on the photosensitive resin surface in sequence, polymerizing liquid resin into a desired 3D solid structure in a layer-by-layer fashion. Even with this simple configuration and easy process, arbitrary 3D objects can be readily fabricated with sub-100 &mu;m resolution.
This desktop 3D printer holds potential in the study of soft material mechanics by offering a great opportunity to explore various 3D geometries. We use this system to fabricate tubular shaped hydrogel structure with different dimensions. Fixed on the bottom to the substrate, the tubular gel develops inhomogeneous stress during swelling, which gives rise to buckling instability. Various wavy patterns appear along the circumference of the tube when the gel structures undergo buckling. Experiment shows that circumferential buckling of desired mode can be created in a controlled manner. Pattern transformation of three-dimensionally structured tubular gels has significant implication not only in mechanics and material science, but also in many other emerging fields such as tunable matamaterials.

We demonstrate controlled pattern transformation of swelling gel tubes by elastic instability. A simple projection micro stereo-lithography setup is built using an off-the-shelf digital data projector to fabricate three-dimensional polymeric structures in a layer-by-layer fashion. Swelling hydrogel tubes under mechanical constraint display various circumferential buckling modes depending on dimension.

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 ...

Process of Making Three-dimensional Microstructures using Vaporization of a Sacrificial Component

Vascular structures in natural systems are able to provide high mass transport through high surface areas and optimized structure. Few synthetic material fabrication techniques are able to mimic the complexity of these structures while maintaining scalability. The Vaporization of a Sacrificial Component (VaSC) process is able to do so. This process uses sacrificial fibers as a template to form hollow, cylindrical microchannels embedded within a matrix. Tin (II) oxalate (SnOx) is embedded within poly(lactic) acid (PLA) fibers which facilitates the use of this process. The SnOx catalyzes the depolymerization of the PLA fibers at lower temperatures. The lactic acid monomers are gaseous at these temperatures and can be removed from the embedded matrix at temperatures that do not damage the matrix. Here we show a method for aligning these fibers using micromachined plates and a tensioning device to create complex patterns of three-dimensionally arrayed microchannels. The process allows the exploration of virtually any arrangement of fiber topologies and structures.

The Vaporization of a Sacrificial Component (VaSC) process is used to fabricate microvascular structures. This procedure uses sacrificial poly(lactic) acid fibers to form hollow microchannels with precise 3D geometric positioning provided by laser micromachined guide plates.

制作三维微结构，用牺牲部分汽化过程

Vascular structures in natural systems are able to provide high mass transport through high surface areas and optimized structure. Few synthetic material ...

Micro-masonry for 3D Additive Micromanufacturing

Transfer printing is a method to transfer solid micro/nanoscale materials (herein called &#8216;inks&#8217;) from a substrate where they are generated to a different substrate by utilizing elastomeric stamps. Transfer printing enables the integration of heterogeneous materials to fabricate unexampled structures or functional systems that are found in recent advanced devices such as flexible and stretchable solar cells and LED arrays. While transfer printing exhibits unique features in material assembly capability, the use of adhesive layers or the surface modification such as deposition of self-assembled monolayer (SAM) on substrates for enhancing printing processes hinders its wide adaptation in microassembly of microelectromechanical system (MEMS) structures and devices. To overcome this shortcoming, we developed an advanced mode of transfer printing which deterministically assembles individual microscale objects solely through controlling surface contact area without any surface alteration. The absence of an adhesive layer or other modification and the subsequent material bonding processes ensure not only mechanical bonding, but also thermal and electrical connection between assembled materials, which further opens various applications in adaptation in building unusual MEMS devices.

This paper introduces a 3D additive micromanufacturing strategy (termed &#8216;micro-masonry&#8217;) for the flexible fabrication of microelectromechanical system (MEMS) structures and devices. This approach involves transfer printing-based assembly of micro/nanoscale materials in conjunction with rapid thermal annealing-enabled material bonding techniques.

微砌筑的3D添加剂Micromanufacturing

Transfer printing is a method to transfer solid micro/nanoscale materials (herein called &#8216;inks&#8217;) from a substrate where they are generated to ...

Energy Dispersive X-ray Tomography for 3D Elemental Mapping of Individual Nanoparticles

Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial resolution, and is even capable of providing atomically resolved elemental maps. In this technique, a highly focused electron beam is incident upon a thin sample and the energy of emitted X-rays is measured in order to determine the atomic species of material within the beam path. This elementally sensitive spectroscopy technique can be extended to three dimensional tomographic imaging by acquiring multiple spectrum images with the sample tilted along an axis perpendicular to the electron beam direction.
Elemental distributions within single nanoparticles are often important for determining their optical, catalytic and magnetic properties. Techniques such as X-ray tomography and slice and view energy dispersive X-ray mapping in the scanning electron microscope provide elementally sensitive three dimensional imaging but are typically limited to spatial resolutions of &gt; 20 nm. Atom probe tomography provides near atomic resolution but preparing nanoparticle samples for atom probe analysis is often challenging. Thus, elementally sensitive techniques applied within the scanning transmission electron microscope are uniquely placed to study elemental distributions within nanoparticles of dimensions 10-100 nm.
Here, energy dispersive X-ray (EDX) spectroscopy within the STEM is applied to investigate the distribution of elements in single AgAu nanoparticles. The surface segregation of both Ag and Au, at different nanoparticle compositions, has been observed.

The use of energy dispersive X-ray tomography in the scanning transmission electron microscope to characterize elemental distributions within single nanoparticles in three dimensions is described.

能量色散X射线断层摄影术对个人纳米3D元素映射

Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial ...

Fabrication Process of Silicone-based Dielectric Elastomer Actuators

This contribution demonstrates the fabrication process of dielectric elastomer transducers (DETs). DETs are stretchable capacitors consisting of an elastomeric dielectric membrane sandwiched between two compliant electrodes. The large actuation strains of these transducers when used as actuators (over 300% area strain) and their soft and compliant nature has been exploited for a wide range of applications, including electrically tunable optics, haptic feedback devices, wave-energy harvesting, deformable cell-culture devices, compliant grippers, and propulsion of a bio-inspired fish-like airship. In most cases, DETs are made with a commercial proprietary acrylic elastomer and with hand-applied electrodes of carbon powder or carbon grease. This combination leads to non-reproducible and slow actuators exhibiting viscoelastic creep and a short lifetime. We present here a complete process flow for the reproducible fabrication of DETs based on thin elastomeric silicone films, including casting of thin silicone membranes, membrane release and prestretching, patterning of robust compliant electrodes, assembly and testing. The membranes are cast on flexible polyethylene terephthalate (PET) substrates coated with a water-soluble sacrificial layer for ease of release. The electrodes consist of carbon black particles dispersed into a silicone matrix and patterned using a stamping technique, which leads to precisely-defined compliant electrodes that present a high adhesion to the dielectric membrane on which they are applied.

This manuscript shows the fabrication process for the manufacture of dielectric elastomer soft actuators based on silicone membranes. The three key stages of production are presented in detail: blade casting of thin silicone membranes; pad printing of compliant electrodes; and the assembly of all the components.

有机硅为基础的介电弹性体致动器的制作工艺

This contribution demonstrates the fabrication process of dielectric elastomer transducers (DETs). DETs are stretchable capacitors consisting of an ...

Adsorption Device Based on a Langatate Crystal Microbalance for High Temperature High Pressure Gas Adsorption in Zeolite H-ZSM-5

We present a high-temperature and high-pressure gas adsorption measurement device based on a high-frequency oscillating microbalance (5 MHz langatate crystal microbalance, LCM) and its use for gas adsorption measurements in zeolite H-ZSM-5. Prior to the adsorption measurements, zeolite H-ZSM-5 crystals were synthesized on the gold electrode in the center of the LCM, without covering the connection points of the gold electrodes to the oscillator, by the steam-assisted crystallization (SAC) method, so that the zeolite crystals remain attached to the oscillating microbalance while keeping good electroconductivity of the LCM during the adsorption measurements. Compared to a conventional quartz crystal microbalance (QCM) which is limited to temperatures below 80 &#176;C, the LCM can realize the adsorption measurements in principle at temperatures as high as 200-300 &#176;C (i.e., at or close to the reaction temperature of the target application of one-stage DME synthesis from the synthesis gas), owing to the absence of crystalline-phase transitions up to its melting point (1,470 &#176;C). The system was applied to investigate the adsorption of CO2, H2O, methanol and dimethyl ether (DME), each in the gas phase, on zeolite H-ZSM-5 in the temperature and pressure range of 50-150 &#176;C and 0-18 bar, respectively. The results showed that the adsorption isotherms of these gases in H-ZSM-5 can be well fitted by Langmuir-type adsorption isotherms. Furthermore, the determined adsorption parameters, i.e., adsorption capacities, adsorption enthalpies, and adsorption entropies, compare well to literature data. In this work, the results for CO2 are shown as an example.

A protocol for high-temperature and high-pressure gas adsorption measurements on zeolite H-ZSM-5 using an adsorption measurement device based on a langatate crystal microbalance is presented. Prior to the adsorption measurements, the synthesis of zeolite H-ZSM-5 on the langatate crystal microbalance sensor by the steam-assisted crystallization (SAC) method is demonstrated.

基于一个Langatate体微天平的高温高压气体吸附在分子筛吸附器H-ZSM-5

We present a high-temperature and high-pressure gas adsorption measurement device based on a high-frequency oscillating microbalance (5 MHz langatate ...

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.

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 ...

Predicting Catalyst Extrudate Breakage Based on the Modulus of Rupture

The mechanical strength of extruded catalysts and their natural or forced breakage by either collision against a surface or by a compressive load in a fixed bed are important phenomena in catalyst technology. The mechanical strength of the catalyst is measured here by its bending strength or flexural strength. This technique is relatively new from the perspective of applying it to commercial catalysts of typical sizes used in the industry. Catalyst breakage by collision against a surface is measured after a fall of the extrudates through the ambient air in a vertical pipe. Quantifying the impact force is done theoretically by applying Newton's second law. Measurement of catalyst breakage due to stress in a fixed bed is done following the standard procedure of the bulk crush strength test. Novel here is the focus on measuring the reduction in the length to diameter ratio of the extrudates as a function of the stress.

Here we present a protocol to measure the modulus of rupture of an extruded catalyst and the breakage of said catalyst extrudates by collision against a surface or by compression in a fixed bed.

基于断裂模量的催化剂挤出断裂预测

The mechanical strength of extruded catalysts and their natural or forced breakage by either collision against a surface or by a compressive load in a ...

Combining Microfluidics and Microrheology to Determine Rheological Properties of Soft Matter during Repeated Phase Transitions

The microstructure of soft matter directly impacts macroscopic rheological properties and can be changed by factors including colloidal rearrangement during previous phase changes and applied shear. To determine the extent of these changes, we have developed a microfluidic device that enables repeated phase transitions induced by exchange of the surrounding fluid and microrheological characterization while limiting shear on the sample. This technique is &#181;2rheology, the combination of microfluidics and microrheology. The microfluidic device is a two-layer design with symmetric inlet streams entering a sample chamber that traps the gel sample in place during fluid exchange. Suction can be applied far away from the sample chamber to pull fluids into the sample chamber. Material rheological properties are characterized using multiple particle tracking microrheology (MPT). In MPT, fluorescent probe particles are embedded into the material and the Brownian motion of the probes is recorded using video microscopy. The movement of the particles is tracked and the mean-squared displacement (MSD) is calculated. The MSD is related to macroscopic rheological properties, using the Generalized Stokes-Einstein Relation. The phase of the material is identified by comparison to the critical relaxation exponent, determined using time-cure superposition. Measurements of a fibrous colloidal gel illustrate the utility of the technique. This gel has a delicate structure that can be irreversibly changed when shear is applied. &#181;2rheology data shows that the material repeatedly equilibrates to the same rheological properties after each phase transition, indicating that phase transitions do not play a role in microstructural changes. To determine the role of shear, samples can be sheared prior to injection into our microfluidic device. &#181;2rheology is a widely applicable technique for the characterization of soft matter enabling the determination of rheological properties of delicate microstructures in a single sample during phase transitions in response to repeated changes in the surrounding environmental conditions.

We demonstrate the fabrication and use of a microfluidic device that enables multiple particle tracking microrheology measurements to study the rheological effects of repeated phase transitions on soft matter.

微流体和 Microrheology 相结合测定软物质在重复相变过程中的流变特性

The microstructure of soft matter directly impacts macroscopic rheological properties and can be changed by factors including colloidal rearrangement ...