这项研究得到了由教育部 (2016R1D1A1B01006801) 资助的韩国国家研究基金会 (NRF) 的基础科学研究项目的支持, 并得到了 Soonchunhyang 大学研究基金的部分支持。.

为了健康和安全起见, 在使用任何墨水和清洁解决方案之前, 请参阅材料安全数据表 (MSDS)。
1. 按需 Electrohydrodynamic 喷墨印花用银纳米粒子墨水
<ol><li>将经过过滤的银纳米微粒 (AgNP) 墨水填充在 EHD 印刷系统的墨水库中。 注: 市面上可用的 AgNP 墨水可用于喷墨用途。该油墨应具有约 10 cP 的粘度和表面张力为 20 ~ 40 锰/米, 以获得需求下降喷射。</li>
	<li>使用热拉拔器制作用于国防部 EHD 打印的喷嘴。<ol>
<li>将玻璃毛细管 [内径 (ID) 的1毫米] 放在热拉拔器中。</li>
		<li>设置热拉拔器的参数;例如, 加热温度的范围为 580-590 摄氏度, 拉动速度约为18毫米/秒。 注: 热拉拔的参数应根据目标喷嘴 ID 和环境条件而异。</li>
		<li>使用设定参数操作热拉拔器, 在毛细管的中心处加热, 并在两端拉起, 使喷嘴的 ID 为5µm。 注: 根据基板上的目标点大小确定喷嘴 ID 的大小。为参考, 5 µm 的喷嘴 ID 可以打印5个µm 大小的点。</li>
		<li>通过玻璃刀具切割玻璃喷嘴, 调整玻璃喷嘴的长度。</li>
	</ol>
</li>
	<li>将喷嘴装配到喷嘴架和连接器上,通过聚四氟乙烯 (PTFE) 油管连接到油墨储层。</li>
	<li>应用气压向喷嘴尖端提供墨水。<ol>
<li>打开气压控制器, 将 15 ~ 20 帕的气压用于墨水库, 以向喷嘴尖端提供墨水。通过透明的玻璃喷嘴和油管监测墨水的流动, 以确保在供应墨水时, 管子和喷嘴内没有空气被困住。继续将气压应用到墨水库, 直到墨水出现在喷嘴尖端。 注: 不要在喷嘴尖端出现墨水之前减少压力, 因为这可能会导致喷嘴尖端气泡的诱捕。</li>
		<li>减少压力到约12帕, 以保持挤压半月板没有任何墨水滴水从喷嘴尖端。 注: 适当的气压取决于喷嘴的大小和油墨的粘度。不要增加30帕的气压, 以避免过度的空气压缩, 这是不可取的保持在稳定的条件下半月板。</li>
	</ol>
</li>
	<li>将组装好的喷嘴头固定在打印系统中。</li>
	<li>将玻璃基板放在衬底架的真空吸盘上, 然后打开真空泵以保持基体。</li>
	<li>移动 Z 轴舞台以调整间隔距离 (H)-喷嘴尖端和衬底位置之间的间隙-到大约100µm. 使用监视摄像机获取的侧面视图图像来估计距离, 方法是使用从喷嘴尖端的反射, 如图 2所示。 注意: 一个较小的站距离导致一个更高的电场, 这可能有助于打印与较低的 DC 和脉冲电压喷射。然而, 较低的离站距离可能导致更大的水滴。因此, 应相应降低电压的大小以获得所需的点大小。一般情况下, 建议使用较低的电压, 以获得较小的印刷点, 喷涂较少。但是, 如果µm 距离小于 50, 则需要进行仔细的操作, 因为喷嘴破损的几率越高, 与基体碰撞就越大。考虑射流能力与可靠性之间的权衡关系, 建议使用100µm 的离站距离。</li>
</ol><img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/57846/57846fig2.jpg"> 图 2: 使用侧面视图摄像机图像进行站距调整.从侧面摄像头的喷嘴图像可以用来估计的距离。从喷嘴尖端到基板的离站距离 (H) 可以很容易地估计为从喷嘴尖端到其阴影的一半距离。<a href="https://www.jove.com/files/ftp_upload/57846/57846fig2large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<ol start="8"><li>
应用直流和脉冲电压 注: 直流和脉冲电压可通过打印软件进行控制。<ol>
<li>逐步增加直流电压, 直到墨水从喷嘴尖端流出。 注意: 不要同时应用目标电压。增量电压应小于 100 V 一次。整体上, 不要应用直流电压超过 600 v。</li>
		<li>将直流电压稍稍从起始直流电压中减小, 直到未观察到喷嘴的进一步滴墨。 注: 在气压和直流电压调整后, 半月板应在适当的形状中喷射, 如补充图 S1所示。</li>
		<li>设置一个负脉冲电压与参数的t上升= 0 ~ 100 µs, t驻留= 300 µs, 和t下降= 0 µs7 (图 3) 在软件菜单中。</li>
		<li>将负脉冲电压应用于衬底架上。然后, 调整脉冲电压的幅度, V脉冲, 产生一滴每单脉冲电压。 注: 负脉冲电压的大小, V脉冲, 应低于 600 v。</li>
		<li>调整 DC 背景和脉冲电压, 以获得在基板上的目标雾滴大小, 同时观察侧面相机图像中基板上的喷点。 注: 为了在承印物上产生较少喷涂的小点, 脉冲电压的幅度, V脉冲, 应尽可能低。</li>
	</ol>
</li>
</ol><img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/57846/57846fig3.jpg"> 图 3: 国防部 EHD 喷射的脉冲电压.建议使用梯形波形电压来生产国防部 EHD 喷射7。<a href="https://www.jove.com/files/ftp_upload/57846/57846fig3large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<ol start="9"><li>
打印图案 注: 两种不同的模式可用于国防部 EHD 打印: 位图图像和 (基于 CAD) 的矢量信息。位图图像已广泛应用于基于 DOD 的喷墨打印。然而, 在印刷电子应用的情况下, 基于 CAD 的矢量信息比基于 DOD 的喷墨打印具有优势, 因为它在基于线的打印中使用单一的 EHD 头是有效的。同时, 矢量信息可以转换为位图图像, 用于位图图像的打印。<ol>
<li>
位图图像打印
		<ol>
<li>在打印软件的 "打印" 选项卡中加载位图图像, 并将其转换为二进制图像。</li>
			<li>设置二进制图像打印的参数。例如, 将放置间隔 (即2 个连续像素之间的距离) 设置为10µm。 注意: 位图图像没有任何物理尺寸。打印图像的物理尺寸将与放置间隔相关。例如, 如果使用较大的放置间隔, 则打印的图像会变大。在传统的喷墨打印中, 每英寸点 (DPI) 通常用于这个目的。但是, 应该注意的是, 较小的 DPI 意味着更大的下降间隔。为了确定放置间隔, 应考虑打印点的大小。一般情况下, EHD 国防部印刷的下降间隔明显小于传统喷墨打印。</li>
			<li>使用所选位图在基板上的目标位置开始打印。</li>
		</ol>
</li>
		<li>
基于 CAD 信息的矢量打印
		<ol>
<li>加载 CAD 信息以进行打印。 注意: 文件格式 DXF 是基于文本的 CAD 信息, 可用于打印信息。</li>
			<li>设置矢量打印参数;例如, 将放置间隔设置为3µm, 在10赫兹处喷射频率。 注意: 要打印连接的线条图案, 应选择放置间隔, 以便相邻沉积滴略有重叠。但是, 过多的重叠可能会导致更大的线条宽度。对于任何实用的线打印, 建议重叠约30%。在矢量印刷的情况下, 运动速度 (v) 如下方程式。 v = d x f 这里 d = 放置间隔, 并 f = 喷射频率。</li>
			<li>使用预先确定的打印参数 (如放置间隔、打印速度、电压等) 打印基板上加载的图案. 注: 印刷后, 可能需要烧结过程, 以获得所需的导电性的印刷模式, 这是超出了本文的范围。</li>
		</ol>
</li>
	</ol>
</li>
</ol>2. 采用近场静电纺丝的精细导电线图案
<ol><li>为导电线印刷制作近场静电纺丝 (NFES) 油墨。<ol>
<li>将乙醇和去离子 (di) 水混合, 容积比为 3 (乙醇) 到 1 (di 水), 以制备溶剂1。例如, 混合9毫升乙醇和3毫升的 DI 水, 使12毫升溶剂1。</li>
		<li>将0.3 克的聚 (环氧乙烷) (乙烯基, M重量= 40万) 和9.7 克的制备溶剂 1, 通过搅拌, 在室温下使用磁力搅拌器超过3小时 (6 °c), 使聚合物溶液与 wt% 的25。</li>
		<li>混合银纳米糊墨, 其粘度约为 1.1万 cP, 并制备聚合物溶液, 其重量比为 5 (银纳米糊墨) 至 1 (聚合物溶液), 采用涡旋搅拌机10分钟获得油墨的 NFES.例如, 10 克的银纳米浆料油墨和2克聚合物溶液可以混合获得 NFES 油墨。 注: 在本协议中, 混合料的配比一般比材料的具体用量更重要。商业上可用的银纳米浆料油墨为丝网印刷目的, 具有 Ag 固体含量约 85.5 wt%, 可用于此目的。请注意, 溶剂和聚合物的选择可能根据所用墨水的成分而不同。</li>
	</ol>
</li>
	<li>在注射器中填充准备好的 NFES 墨水。</li>
	<li>通过连接管将注射器与喷嘴连接起来。 注: 可用于喷嘴的商用注射器针, 其 ID 为100µm。</li>
	<li>手动推注射器, 向喷嘴提供墨水。</li>
	<li>将注射器安装在注射器马达中, 连接到打印系统。</li>
	<li>在真空吸盘上放置基板, 在打印过程中打开真空泵以保持基体。</li>
	<li>控制 Z 位置 (舞台) 以调整离站距离。 注: 建议的离站距离应约2毫米, 这是一个显着较小的站距相比, 与传统的静电纺丝使用。</li>
	<li>
调整流量
	<ol>
<li>操作注射器泵, 以填充喷嘴组件中的 NFES 墨水, 并生成一个墨水流, 其初始流量为50µL/分钟, 高于目标流速。</li>
		<li>当墨水流出喷嘴尖端时, 设定目标流速为1µL/分钟。 注意: 较小的流量会导致图案宽度变小。然而, 它可能导致线断裂。在确定目标流速时, 应考虑线宽与直线延伸之间的权衡。</li>
	</ol>
</li>
	<li>
应用电压
	<ol>
<li>将直流电压源连接至喷嘴连接器, 并将接地电压连接到衬底架上。</li>
		<li>将直流电压逐步提高到1.5 伏。 注: 由于离站距离在几毫米范围内, 直流电压可提高2伏, 高于国防部 EHD 喷墨打印。然而, 应该避免直流电压高于2伏, 因为它可能会损坏功能材料, 特别是银糊墨水, 添加到聚合物溶液。一般来说, 当需要较薄的印制线时, 建议使用较低的直流电压。然而, 当使用低电压时, 印制线很容易断开, 因为连续油墨印刷的拉力与直流电压有关。考虑到权衡, 我们建议使用直流电压范围从1伏到2伏。</li>
	</ol>
</li>
	<li>以300毫米/秒的打印速度启动空闲打印, 以获得稳定状态的流。在空闲打印期间, 调整打印参数, 如直流电压和流量, 以获得所需的打印结果。 注: 由于粘性墨水在输送到喷嘴尖端时的长油管中可以被压缩, 因此需要10分钟以上的空闲打印才能获得稳态流量。如果不进行空闲打印, 打印线的宽度可能随时间而变化。因此, 怠速打印速度应与实际打印速度相同, 以便在打印过程中可以调整喷射参数。这样, 在空闲打印期间调整直流电压以获得目标线宽。请注意, 流量和直流电压应该是平衡的, 使注射器泵推的墨水量可以等于由电场拉下的墨水量。</li>
	<li>选择打印图案, 如连续线和网格图案。 注: 由于所生产的纤维容易偏转, 并且可以随机沉积, 因为印刷线产生的电荷排斥力, 印刷速度应大于300毫米/秒, 以使图案与印刷方向一致, 以及建议打印线间距大于100µm, 以打印网格或线条图案。</li>
	<li>使用预先确定的打印参数在基板上打印所选图案。 注: 可能需要烧结过程来获得印刷图案的目标功能, 这超出了本文的范围。</li>
</ol>

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S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrospinning:+A+fascinating+fiber+fabrication+technique.">Electrospinning: A fascinating fiber fabrication technique.</a> Biotechnology Advances. 28, 325-347 (2010).</li><li>He, X., 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=Near-Field+Electrospinning:+Progress+and+Applications.">Near-Field Electrospinning: Progress and Applications.</a> The Journal of Physical Chemistry C. 121, 8663-8678 (2017).</li><li>Yang, T. L., 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=Synthesis+and+fabrication+of+silver+nanowires+embedded+in+PVP+fibers+by+near-field+electrospinning+process.">Synthesis and fabrication of silver nanowires embedded in PVP fibers by near-field electrospinning process.</a> Optical Materials. 39, 118-124 (2015).</li><li>Chang, C., Limkrailassiri, K., Lin, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continuous+near-field+electrospinning+for+large+area+deposition+of+orderly+nanofiber+patterns.">Continuous near-field electrospinning for large area deposition of orderly nanofiber patterns.</a> Applied Physics Letters. 93 (12), (2008).</li></ol>

作者没有什么可透露的。

在本协议中, 我们将重点放在使用 AgNP 墨迹打印精细图案的两种模式: DOD EHD 打印和 NFES。然而, EHD 喷墨印花的应用并不局限于使用 AgNP 的导电油墨。在这里, 我们将讨论的一般准则, 选择的墨水, 系统配置, 和其他打印参数需要使用 EHD 喷墨打印的各种精细模式的应用。
EHD 印刷的第一个也是最重要的步骤是油墨的选择和准备。传统喷墨印花中使用的墨水可用于国防部 EHD 印刷。?...

EHD 喷墨印花已广泛应用于各种领域, 如印刷电子、生物技术和先进材料应用, 因为它能够高分辨率和低成本直接模式1。印制线宽度或印刷网点尺寸可降至1µm, 大大小于传统的压电式喷墨打印1。
在 EHD 印刷中, 一小部分墨水 (或半月板) 被推出喷嘴尖端, 并通过控制流速1、2、3、4、5或正气压1来维持. ,6,7。挤出半月板是充电, 可以很容易地从喷嘴尖端拉到基板的电场, 如图 1所示。锥形半月板在喷射过程中形成, 产生比喷嘴尺寸更薄的墨流。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/57846/57846fig1.jpg"> 图 1: EHD 打印.图中显示了 EHD 喷墨打印的原理。墨水通过压力推挤并且通过电场拉扯从喷嘴形成一个被挤出的半月板。然后, 带电的墨水可以很容易地通过直流或脉冲电压喷射到基板。<a href="https://www.jove.com/files/ftp_upload/57846/57846fig1large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
尽管单 EHD 打印机可用于两种不同的模式, 近场静电纺丝 (NFES) 和需求下降 (DOD) EHD 喷墨打印, 实现方法在油墨, 射流系统和驱动电压方面有显著差异1,2,3. 例如, NFES4、5使用相对高粘度的墨水 [超过 1000 centipoises (cP)] 形成连续的微线图案, 高速打印可达1米/秒。另一方面, 国防部 EHD 喷墨打印6,7,8使用低粘性墨水与粘度约 10 cP, 以打印点为基础的复杂模式, 低打印速度小于10毫米/秒。
由于对每种模式的要求都有很大的不同, 对缺乏经验的研究人员来说, 达到预期的结果可能会有挑战性。经验上的 "专门知识" 在实践中可能很重要。为了帮助研究人员习惯于印刷方法, 我们提出了用银纳米粒子墨水进行精细导电图案的 EHD 印刷协议。然而, 我们增加了对协议的评论, 使它们不限于使用银纳米粒子墨水的导电图案。最后, 讨论部分介绍了打印和准备指南。

<table><tbody><tr><td>EHD integrated printing system</td><td>Psolution Ltd., South Korea</td><td>PS300</td><td></td></tr><tr><td>Harima Ag Nanoparticle ink</td><td>Harima Inc., Japan</td><td>Harima NPS-JL</td><td>Ag solid content: ~ 53 wt%, Viscosity: ~10 cP, Surface tension: ~30 mN/m</td></tr><tr><td>Glass capillary</td><td>Narishige Scientific Instrument Lab</td><td>G-1</td><td>Inner diameter: 1 mm; Used to make nozzle for DOD EHD jet printing using thermal puller</td></tr><tr><td>Nozzle thermal puller</td><td>Sutter Instrument, USA</td><td>Sutter P-1000</td><td></td></tr><tr><td>Microscope Slides (Glass subtrate)</td><td>Paul-Marienfeld &amp;amp; Co.KG, Germany</td><td>10 006 12</td><td>Dimension (L x W x T): 76 mm x 26 mm x 1 mm</td></tr><tr><td>Magnetic Stirrer</td><td>Barnstead Thermolyne Corp., USA</td><td>Cimarec SP131635</td><td></td></tr><tr><td>Vortex Stirrer</td><td>Jeiotech, South Korea</td><td>Lab Companion VM-96T</td><td></td></tr><tr><td>Ag nanopaste&amp;nbsp;</td><td>NPK, South Korea</td><td>ES-R001</td><td>Ag solid content: ~85.5 wt%, Viscosity: ~11000 cP</td></tr><tr><td>Poly ethylene oxide (PEO)</td><td>Sigma-Aldrich, USA</td><td>372773-500G</td><td>Mw = 400000</td></tr><tr><td>Ethanol</td><td>Sigma-Aldrich, USA</td><td>459836-500ML</td><td></td></tr></tbody></table>

high-resolution patterning using two modes of electrohydrodynamic jet: drop on demand and near-field electrospinning

Electrohydrodynamic (EHD) 喷墨打印在各个领域引起了广泛的关注, 因为它可以作为一种高分辨率、低成本的直接图形工具。EHD 印刷使用射流供应商, 以保持挤出的半月板, 通过推动墨水出喷嘴尖端。然后用电场将半月板拉到基板上以产生高分辨率的图案。EHD 印刷的两种模式被用于精细模式: 连续近场静电纺丝 (NFES) 和基于点的需求下降 (DOD) EHD 印刷。根据印刷方式, 对印刷设备和油墨黏度的要求将有所不同。尽管采用单 EHD 打印机可以实现两种不同的模式, 但在油墨、射流系统和驱动电压方面, 实现方法有显著差异。因此, 如果不正确理解射流的要求和限制, 就很难取得预期的结果。本文的目的是提出一个指导方针, 使经验不足的研究人员可以减少试验和错误的努力, 使用 EHD 喷气机的具体研究和开发目的。为了演示精细模式的实现, 我们使用 Ag 纳米粒子墨水来实现协议中的导电模式。此外, 我们还提出了通用的印刷准则, 可用于其他类型的墨水为各种精细模式的应用。

基于点的按需打印: 国防部印刷是基于一滴喷射每一个喷射触发器。要生产国防部喷射, 应使用粘度约为 10 cP 的低粘性墨水。EHD 国防部印刷的墨水要求与传统的国防部喷墨打印机的需求相似, EHD 印刷方法与传统的国防部喷墨打印法是一样的。在传统的喷墨打印中, 光栅印刷技术被广泛应用, 因为它适用于使用多喷嘴头的位图图像打印。然而, 在 EHD 喷墨打印的...

Watch this Scientific Journal Video about High-resolution Patterning Using Two Modes of Electrohydrodynamic Jet: Drop on Demand and Near-field Electrospinning at JoVE.com

High-resolution Patterning Using Two Modes of Electrohydrodynamic Jet: Drop on Demand and Near-field Electrospinning

采用两种 Electrohydrodynamic 射流的高分辨率模式: 需求下降和近场静电纺丝

在这里, 我们提出了一个协议, 以产生高分辨率导电模式使用 electrohydrodynamic (EHD) 喷墨打印。该协议包括两种 EHD 喷墨打印模式: 连续近场静电纺丝 (NFES) 和基于点的需求下降 (DOD) EHD 打印。

Electrohydrodynamic (EHD) jet printing has drawn attention in various fields because it can be used as a high-resolution and low-cost direct patterning ...

high-resolution-patterning-using-two-modes-electrohydrodynamic-jet

Research

JoVE Journal

Bioengineering

9.6K 次观看.  Soonchunhyang University. 在这里, 我们提出了一个协议, 以产生高分辨率导电模式使用 electrohydrodynamic (EHD) 喷墨打印。该协议包括两种 EHD 喷墨打印模式: 连续近场静电纺丝 (NFES) 和基于点的需求下降 (DOD) EHD 打印。

视频: High-resolution Patterning Using Two Modes of Electrohydrodynamic Jet: Drop on Demand and Near-field Electrospinning

Electrospinning Fundamentals: Optimizing Solution and Apparatus Parameters

Electrospun nanofiber scaffolds have been shown to accelerate the maturation, improve the growth, and direct the migration of cells in vitro. Electrospinning is a process in which a charged polymer jet is collected on a grounded collector; a rapidly rotating collector results in aligned nanofibers while stationary collectors result in randomly oriented fiber mats. The polymer jet is formed when an applied electrostatic charge overcomes the surface tension of the solution. There is a minimum concentration for a given polymer, termed the critical entanglement concentration, below which a stable jet cannot be achieved and no nanofibers will form - although nanoparticles may be achieved (electrospray). A stable jet has two domains, a streaming segment and a whipping segment. While the whipping jet is usually invisible to the naked eye, the streaming segment is often visible under appropriate lighting conditions. Observing the length, thickness, consistency and movement of the stream is useful to predict the alignment and morphology of the nanofibers being formed. A short, non-uniform, inconsistent, and/or oscillating stream is indicative of a variety of problems, including poor fiber alignment, beading, splattering, and curlicue or wavy patterns. The stream can be optimized by adjusting the composition of the solution and the configuration of the electrospinning apparatus, thus optimizing the alignment and morphology of the fibers being produced. In this protocol, we present a procedure for setting up a basic electrospinning apparatus, empirically approximating the critical entanglement concentration of a polymer solution and optimizing the electrospinning process. In addition, we discuss some common problems and troubleshooting techniques.

Electrospinning techniques can create a variety of nanofibrous scaffolds for tissue engineering or other applications. We describe here a procedure to optimize the parameters of the electrospinning solution and apparatus to obtain fibers with the desired morphology and alignment. Common problems and troubleshooting techniques are also presented.

静电基础：优化解决方案和设备参数

Electrospun nanofiber scaffolds have been shown to accelerate the maturation, improve the growth, and direct the migration of cells in vitro. ...

科研

生物工程

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 ...

The Preparation of Electrohydrodynamic Bridges from Polar Dielectric Liquids

Horizontal and vertical liquid bridges are simple and powerful tools for exploring the interaction of high intensity electric fields (8-20 kV/cm) and polar dielectric liquids. These bridges are unique from capillary bridges in that they exhibit extensibility beyond a few millimeters, have complex bi-directional mass transfer patterns, and emit non-Planck infrared radiation. A number of common solvents can form such bridges as well as low conductivity solutions and colloidal suspensions. The macroscopic behavior is governed by electrohydrodynamics and provides a means of studying fluid flow phenomena without the presence of rigid walls. Prior to the onset of a liquid bridge several important phenomena can be observed including advancing meniscus height (electrowetting), bulk fluid circulation (the Sumoto effect), and the ejection of charged droplets (electrospray). The interaction between surface, polarization, and displacement forces can be directly examined by varying applied voltage and bridge length. The electric field, assisted by gravity, stabilizes the liquid bridge against Rayleigh-Plateau instabilities. Construction of basic apparatus for both vertical and horizontal orientation along with operational examples, including thermographic images, for three liquids (e.g., water, DMSO, and glycerol) is presented.

Horizontal and vertical electrohydrodynamic liquid bridges are simple and powerful tools for exploring the interaction of high intensity electric fields and polar dielectric liquids. The construction of basic apparatus and operational examples, including thermographic images, for three liquids (e.g., water, DMSO, and glycerol) is presented.

高压直流电桥从极地介电液的制备

Horizontal and vertical liquid bridges are simple and powerful tools for exploring the interaction of high intensity electric fields (8-20 kV/cm) and ...

工程学

Prescribed 3-D Direct Writing of Suspended Micron/Sub-micron Scale Fiber Structures via a Robotic Dispensing System

A 3-axis dispensing system is utilized to control the initiating and terminating fiber positions and trajectory via the dispensing software. The polymer fiber length and orientation is defined by the spatial positioning of the dispensing system 3-axis stages. The fiber diameter is defined by the prescribed dispense time of the dispensing system valve, the feed rate (the speed at which the stage traverses from an initiating to a terminating position), the gauge diameter of the dispensing tip, the viscosity and surface tension of the polymer solution, and the programmed drawing length. The stage feed rate affects the polymer solution&#8217;s evaporation rate and capillary breakup of the filaments. The dispensing system consists of a pneumatic valve controller, a droplet-dispensing valve and a dispensing tip. Characterization of the direct write process to determine the optimum combination of factors leads to repeatedly acquiring the desired range of fiber diameters. The advantage of this robotic dispensing system is the ease of obtaining a precise range of micron/sub-micron fibers onto a desired, programmed location via automated process control. Here, the discussed self-assembled micron/sub-micron scale 3D structures have been employed to fabricate suspended structures to create micron/sub-micron fluidic devices and bioengineered scaffolds.

Here, we present a protocol to fabricate freely-suspended, micron/sub-micron scale polymer fibers and &#8220;web-like&#8221; structures generated via automated direct writing procedure by means of a 3-axis dispensing system.

暂停规定微米/亚微米尺度的纤维结构的3-D直写经全自动点胶系统

A 3-axis dispensing system is utilized to control the initiating and terminating fiber positions and trajectory via the dispensing software. The polymer ...

Scalable Stamp Printing and Fabrication of Hemiwicking Surfaces

Hemiwicking is a process where a fluid wets a patterned surface beyond its normal wetting length due to a combination of capillary action and imbibition. This wetting phenomenon is important in many technical fields ranging from physiology to aerospace engineering. Currently, several different techniques exist for fabricating hemiwicking structures. These conventional methods, however, are often time consuming and are difficult to scale-up for large areas or are difficult to customize for specific, nonhomogeneous patterning geometries. The presented protocol provides researchers with a simple, scalable, and cost-effective method for fabricating micro-patterned hemiwicking surfaces. The method fabricates wicking structures through the use of stamp printing, polydimethylsiloxane (PDMS) molding, and thin-film surface coatings. The protocol is demonstrated for hemiwicking with ethanol on PDMS micropillar arrays coated with a 70 nm thick aluminum thin-film.

A simple protocol is provided for the fabrication of hemiwicking structures of varying sizes, shapes, and materials. The protocol uses a combination of physical stamping, PDMS molding, and thin-film surface modifications via common materials deposition techniques.

可缩放邮票印刷及不堪砌面的制作

Hemiwicking is a process where a fluid wets a patterned surface beyond its normal wetting length due to a combination of capillary action and imbibition. ...

Fabricating Superhydrophobic Polymeric Materials for Biomedical Applications

Superhydrophobic materials, with surfaces possessing permanent or metastable non-wetted states, are of interest for a number of biomedical and industrial applications. Here we describe how electrospinning or electrospraying a polymer mixture containing a biodegradable, biocompatible aliphatic polyester (e.g., polycaprolactone and poly(lactide-co-glycolide)), as the major component, doped with a hydrophobic copolymer composed of the polyester and a stearate-modified poly(glycerol carbonate) affords a superhydrophobic biomaterial. The fabrication techniques of electrospinning or electrospraying provide the enhanced surface roughness and porosity on and within the fibers or the particles, respectively. The use of a low surface energy copolymer dopant that blends with the polyester and can be stably electrospun or electrosprayed affords these superhydrophobic materials. Important parameters such as fiber size, copolymer dopant composition and/or concentration, and their effects on wettability are discussed. This combination of polymer chemistry and process engineering affords a versatile approach to develop application-specific materials using scalable techniques, which are likely generalizable to a wider class of polymers for a variety of applications.

Two- and three-dimensional superhydrophobic polymeric materials are prepared by electrospinning or electrospraying biodegradable polymers blended with a lower surface energy polymer of similar composition.

制造超疏水高分子材料生物医学应用

Superhydrophobic materials, with surfaces possessing permanent or metastable non-wetted states, are of interest for a number of biomedical and industrial ...

Electrospinning Fibrous Polymer Scaffolds for Tissue Engineering and Cell Culture

As the field of tissue engineering evolves, there is a tremendous demand to produce more suitable materials and processing techniques in order to address the requirements (e.g., mechanics and vascularity) of more intricate organs and tissues. Electrospinning is a popular technique to create fibrous scaffolds that mimic the architecture and size scale of the native extracellular matrix. These fibrous scaffolds are also useful as cell culture substrates since the fibers can be used to direct cellular behavior, including stem cell differentiation (see extensive reviews by Mauck et al. and Sill et al. for more information). In this article, we describe the general process of electrospinning polymers and as an example, electrospin a reactive hyaluronic acid capable of crosslinking with light exposure (see Ifkovits et al. for a review on photocrosslinkable materials). We also introduce further processing capabilities such as photopatterning and multi-polymer scaffold formation. Photopatterning can be used to create scaffolds with channels and multi-scale porosity to increase cellular infiltration and tissue distribution. Multi-polymer scaffolds are useful to better tune the properties (mechanics and degradation) of a scaffold, including tailored porosity for cellular infiltration. Furthermore, these techniques can be extended to include a wide array of polymers and reactive macromers to create complex scaffolds that provide the cues necessary for the development of successful tissue engineered constructs.

The process of electrospinning polymers for tissue engineering and cell culture is addressed in this article. Specifically, the electrospinning of photoreactive macromers with additional processing capabilities of photopatterning and multi-polymer electrospinning is described.

静电纤维聚合物支架用于组织工程和细胞培养

As the field of tissue engineering evolves, there is a tremendous demand to produce more suitable materials and processing techniques in order to address ...

生物学

Expanding Nanopatterned Substrates Using Stitch Technique for Nanotopographical Modulation of Cell Behavior

Substrate nanotopography has been shown to be a potent modulator of cell phenotype and function. To dissect nanotopography modulation of cell behavior, a large area of nanopatterned substrate is desirable so that enough cells can be cultured on the nanotopography for subsequent biochemical and molecular biology analyses. However, current nanofabrication techniques have limitations to generate highly defined nanopatterns over a large area. Herein, we present a method to expand nanopatterned substrates from a small, highly defined nanopattern to a large area using stitch technique. The method combines multiple techniques, involving soft lithography to replicate poly(dimethylsiloxane) (PDMS) molds from a well-defined mold, stitch technique to assemble multiple PDMS molds to a single large mold, and nanoimprinting to generate a master mold on polystyrene (PS) substrates. With the PS master mold, we produce PDMS working substrates and demonstrate nanotopographical modulation of cell spreading. This method provides a simple, affordable yet versatile avenue to generate well-defined nanopatterns over large areas, and is potentially extended to create micro-/nanoscale devices with hybrid components.

A protocol for producing a large area of nanopatterned substrate from small nanopatterned molds for study of nanotopographical modulation of cell behavior is presented.

扩大奈米基材使用缝合技术的细胞行为Nanotopographical调制

Substrate nanotopography has been shown to be a potent modulator of cell phenotype and function. To dissect nanotopography modulation of cell behavior, a ...

Melt Electrospinning Writing of Three-dimensional Poly(&#949;-caprolactone) Scaffolds with Controllable Morphologies for Tissue Engineering Applications

This tutorial reflects on the fundamental principles and guidelines for electrospinning writing with polymer melts, an additive manufacturing technology with great potential for biomedical applications. The technique facilitates the direct deposition of biocompatible polymer fibers to fabricate well-ordered scaffolds in the sub-micron to micro scale range. The establishment of a stable, viscoelastic, polymer jet between a spinneret and a collector is achieved using an applied voltage and can be direct-written. A significant benefit of a typical porous scaffold is a high surface-to-volume ratio which provides increased effective adhesion sites for cell attachment and growth. Controlling the printing process by fine-tuning the system parameters enables high reproducibility in the quality of the printed scaffolds. It also provides a flexible manufacturing platform for users to tailor the morphological structures of the scaffolds to their specific requirements. For this purpose, we present a protocol to obtain different fiber diameters using melt electrospinning writing (MEW) with a guided amendment of the parameters, including flow rate, voltage and collection speed. Furthermore, we demonstrate how to optimize the jet, discuss often experienced technical challenges, explain troubleshooting techniques and showcase a wide range of printable scaffold architectures.

This protocol serves as a comprehensive guideline to fabricate scaffolds via electrospinning with polymer melts in a direct writing mode. We systematically outline the process and define the appropriate parameter settings for achieving targeted scaffold architectures.

用于组织工程应用的三维聚 (ε-内) 支架的熔体静电纺丝

This tutorial reflects on the fundamental principles and guidelines for electrospinning writing with polymer melts, an additive manufacturing technology ...

Vapor Phase Deposition of Electroactive Poly(3,4-ethylenedioxythiophene) onto Electrospun Commodity Polymer Nanofibers

This study investigates the preparation of polyacrylonitrile (PAN) nanofibers through electrospinning to create highly porous and strong materials for applications in water purification, electrocatalysis, and biomedicine. The uniformly white PAN nanofiber mats were cut into 2 cm x 2 cm coupons to ensure consistency. After electrospinning, these nanofibers were coated with an electroactive polymer (EAP) using chemical vapor deposition, with iron (III) chloride (FeCl3) serving as an oxidant for polymerizing 3,4-ethylenedioxythiophene (EDOT) into poly(3,4-ethylenedioxythiophene) (PEDOT). The study examined the impact of different FeCl3 concentrations on PEDOT deposition on the PAN coupons. PEDOT deposition led to an increase in coupon weight. Scanning electron microscopy (SEM) revealed increases in the diameter of the nanofibers treated with increasing FeCl3 oxidant concentration, although higher FeCl3&#160;concentrations caused inter-fiber bridging, implying a concomitant decrease in inter-fiber spacing. Energy dispersive X-ray spectroscopy (EDS) was used to confirm the presence of Fe, Cl, and S in the nanofibers, with sulfur content rising with FeCl3&#160;concentration used, suggesting increased PEDOT deposition efficiency with increasing oxidant concentration. Mechanical testing showed that PEDOT-coated PAN fibers had improved tensile strength and toughness in the hydrated state compared to pure PAN nanofibers. These results highlight the crucial role of FeCl3&#160;concentration in influencing the morphology and properties of PAN-PEDOT composites, enhancing their suitability for applications such as water purification, tissue engineering, biosensing, catalysis, and energy storage.

This paper describes a simple technique for coating electrospun PAN nanofibers with electroactive polymers using vapor deposition. The effects of the oxidant FeCl&#8323; on the deposition of poly(3,4-ethylenedioxythiophene) coatings on PAN were investigated to understand and optimize polymer growth, fiber diameter, and overall mechanical strength of the nanofiber mats.

电活性聚（3,4-乙烯二氧噻吩）在电纺商品聚合物纳米纤维上的气相沉积

This study investigates the preparation of polyacrylonitrile (PAN) nanofibers through electrospinning to create highly porous and strong materials for ...