Name: simultaneous multi-surface anodizations and stair-like reverse biases detachment of anodic aluminum oxides in sulfuric and oxalic acid electrolyte
Uploaded: 2017-10-05T14:00:00.000+00:00
Duration: 10 min 27 s
Description: Watch this Scientific Journal Video about Simultaneous Multi-surface Anodizations and Stair-like Reverse Biases Detachment of Anodic Aluminum Oxides in Sulfuric and Oxalic Acid Electrolyte at JoVE.com

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开始前请注意所有相关的材料安全数据表 (MSDS)。尽管该协议具有生态友好性, 但在相应的程序中使用了一些酸和氧化剂。此外, 使用所有适当的个人防护设备 (实验室大衣, 手套, 安全眼镜, 等 ). 
 1. 解决方案的准备 注意: 在解决方案包含的容器完全密封后, 在足够的时间内, 在室温下对所有溶液进行了强磁搅拌. 
<ol> <li> 高氯酸溶液的制备 <ol> <li> 将100毫升高氯酸 (HClO 4 , 60%) 与400毫升绝对乙醇 (C 2 H 5 OH, 100%) 在1到4的体积比. </li>
	</ol> </li> <li> 的制备铬酸溶液 <ol> <li> 溶解9.0 克铬氧化物 (cro 3 ) 和20.3 毫升磷酸 (H 3 PO 4 , 85%) 在479.7 毫升去离子 (直喷) 水中 (cro 3 : H 3 PO 4 = 0.18 m: 0.56 m) </li>
	</ol> </li> <li> 准备硫酸电解质 <ol> <li> 混合16.2 毫升硫酸 (H 2 所以 4 , 98%) 在983.8 毫升直喷水中导致摩尔浓度 0.3 m </li>
	</ol> </li> <li> 在 1 L 直喷水中制备草酸电解质 <ol> 27.012 克无水草酸 (C <li> 2 H 2 O 4 ), 导致摩尔浓度为 0.3 m 
	</ol> </li> </ol> 2。铝基板预处理 <ol> <li> 加工 al 试样 <ol> 将纯化的 al 试样 (和 #62; 99.99% 纯) 切成长方形方形状 (宽度 x 高度 x 厚度 = 20.0 mm x 50.0 mm x 1.0 mm), 所有的直角所述相邻曲面, 称为和 #34; 衬底和 #34; 以后. </li>
		<li> 抛光 multi-surfaces 的铝基板机械使用砂纸与适当的 ISO/FEPA 砂砾指定编号超过 P1000. 
		注: 有关详细信息, 请参阅 补充信息 . </li>
	</ol> </li> <li> 在 Al 基板的 multi-surfaces 上同时抛光 <ol> <li> 将大约350毫升的高氯酸乙醇溶液倒入双层夹克烧杯中, 最大容量为600毫升。然后, 将4/5 的铝基板浸入高氯酸溶液中. </li>
		<li> 将高氯酸溶液的温度设置为7和 #177; 0.1 和 #176; C 使用连接到双层护套烧杯的浴环行器. </li>
		<li> 在丙酮中通过超声波清洗 al 底物30-40 分钟, 用丙酮和 D 冲洗. 我用水几次, 以去除铝基板表面的有机残留物. </li>
		<li> 使用气枪或氮气 (N 2 ) 对铝基体进行干燥, 以消除残余溶剂的气体冲击. 
		注意: 不建议在大气环境下自然干燥, 因为溶剂的痕迹会对抛光的影响产生不利的影响. </li>
		<li> 将铝基板工作电极 (w) 连接到正极 (+) 端口和铂 (Pt) 线计数器电极 (.) 到可编程直流电源的负极 (-) 端口, 使用鳄鱼夹。铝基板和 Pt 线应相互平行 (请参见 图 S2 ). </li>
		<li> 对于 Pt., 平均适用于 2-4 min, 对 Al w 施加 +20.0 伏的前向偏差。根据表面条件, 如污染或粗糙度, 申请时间可保持在5分钟. 检查所有浸入溶液中的表面, 检查表面残留物是否脱落并滑入溶液。在这一步, 不建议磁搅拌, 因为检查是困难的搅拌下, 解决方案流可能会影响抛光的效果. 
		注意: 不要 electropolish 超过5分钟, 这可能会使表面退化. 
		选项: 通过 PC 接口记录 current-time ( I - t ) 特性行为有助于监视抛光程序 (如果存在异常点). </li>
		<li> 停止应用偏倚并断开鳄鱼夹。从抛光溶液中仔细取铝基体和 Pt 电极。然后, 用乙醇 (95%) 和 D. 水来除去铝基板表面的残余溶液。如果抛光的执行正确, 可以识别铝基板的类似镜面的成品表面 (请参见 图 S1 和 图 S3 )。
		<li> 将 electropolished 铝基板储存在乙醇 (95%) 中, 直到下一道工序减少表面氧化. </li>
	</ol> </li> </ol> 3。草酸电解质下 AAOs 的大量制备 注意: 对于 AAOs 的纳米和 #39 的长程安排; 周期性, two-step SMSAs 程序被使用, 其中周期性纹理铝 multi-surfaces通过预 SMSA, 然后, 主要 SMSA 进行了制作高素质的 AAOs。重复应用的单位序列可以保持生产的复数和几乎相同的 AAOs, 直到铝基板保持。和 #34; n 和 #34; 表示应用的序列的编号. 
<ol> <li> n th 前 SMSA <ol> <li> 将大约650毫升的草酸水溶液倒入0.3 米的摩尔浓度为双套式烧杯, 最大能力为1.0 升。然后, 将约三季度的铝基板浸入草酸溶液中. </li>
		<li> 将草酸电解液的温度设置为15和 #177; 0.1 和 #176; C 使用连接到双层护套烧杯的浴环行器. </li>
		<li> 从乙醇中提取 electropolished 铝基板, 并使用气枪或 N 2 气体吹除残余溶剂. </li>
		<li> 使用鳄鱼夹将 electropolished 铝衬底与 w (+) 和 Pt 线连接到可编程直流电源的. (-)。铝基板和 Pt 导线应相互平行。然后, 将铝基板的 electropolished 部分浸入草酸电解质中. 
		注意: 要确保在酸性电解质的顶部和连接到 Al 衬底的鳄鱼夹底部之间存在足够的空间 ( 例如 , 大约1厘米), 否则在鳄鱼夹连接的位置会发生严重的腐蚀. </li>
		<li> 在 100-150 rpm 的适度磁性搅拌下, 在保持电解质温度的情况下, 将 +40.0 V 至 w 的阳极偏差应用于., 超过1-2 小时. 
		注意: 如果前 SMSA 时间太短, multi-surfaces 的铝基板将不会被正确地纹理. 
		选项: 通过 PC 接口记录 I - t 特性行为有助于理解 SMSA 中的典型行为。
		<li> 停止应用阳极偏置 af完成前 SMSA, 并断开鳄鱼剪辑。从酸性电解质中仔细提取样品, 用丙酮和 D 冲洗前 SMSAed 铝基板. 我喝水过几次. </li>
	</ol> </li> <li> n 前 AAOs 蚀刻 <ol> 将铬酸水溶液的温度设置为 60-#160; 65 和 #176; C. <li>
		<li> 将预 SMSAed 铝基板浸入 1 #160 的铬酸溶液中; 2 h 以去除铝基板上的预 AAOs. </li>
		<li> 用丙酮和直喷水冲洗前 AAOs 去除的铝基板几次。测量 Al 衬底的电阻, 以确定 AAOs 是否已在表面上完全移除。如果没有, 重复蚀刻程序 (步骤 3.2.2). </li>
	</ol> </li> <li> n th 主-SMSA <ol> <li> 将所有实验条件和连接都重新设置为步骤3.1 中使用的情况. 
		注: 应注意的是, 草酸电解质可以在几个序列中使用, 这不会影响主 AAOs 的质量。然而, 为了定量比较, 建议使用电解质在一个整体序列, 然后交换与一个新的. </li>
		<li> 对. 应用 +40.0 V 至 w 的阳极偏差; 适用时间可根据所需的阳极氧化铝厚度而变化。阳极氧化铝的生长率估计为8.0 和 7.5, #956; 在铝基板的前后表面, 在15和 #176 的电解质温度下, 分别为 (参考 57 ). </li>
	</ol> </li> <li> n srb-剥离 <ol> 停止应用阳极偏置并在完成主 SMSA 后搅拌, 并将主-SMSAed 铝基板与. (-) 和 Pt 线连接到可编程 DC 的 w (+)通过切换每个鳄鱼夹子来供电. </li>
		<li> 应用 srb, 并检查典型的起泡效果沿 multi-edges 的铝基板覆盖的主-AAOs。srb 条件的详细情况, 如开始 RB 的强度, 楼梯的数量, 以及每个台阶的持续时间, 都与主-AAOs 的厚度紧密相关。对于主-AAOs 厚度大于60和 #956; m, srb 的台阶由-21 v 到-24 v 控制, 增量-1 v 并且没有时间间隔在毗邻台阶之间。-21 v、-22 v 和-23 v 的持续时间固定在10分钟, 并且在分离过程完成之前保持-24 v 的最后一个台阶 (有关详细信息, 请参阅参考 57 , 以了解更详细的情况, 包括 AAOs). 
		注意: 强烈建议初学者使用 srb 的 PC 接口控制, 并在此过程中记录 I - t 特征曲线. </li>
		<li> 完成剥离后停止应用 srb, 并断开鳄鱼夹。从酸性电解液中仔细拿起样品, 用丙酮和 D 仔细冲洗. 我的水有足够的次数. </li>
		<li> 完全从相应的 Al 表面分离每个阳极氧化铝。在步3.4.3 之后, 分离的 AAOs 的上部部分仍然连接到 Al 基体, 应该手工地打破. </li>
	</ol> </li> <li> n 残余氧化铝蚀刻 <ol> <li> 将铬酸溶液的温度设置为60-65 和 #176; C, 将 AAOs 分离的铝基板浸泡约30分钟, 以消除残余氧化铝. </li>
		<li> 拿起蚀刻铝基体, 用丙酮和直喷水冲洗几次。测量电阻以确认残余氧化铝的完全去除。如果没有, 请重复步骤 3.5.2. </li>
	</ol> </li> <li> n+1 th 序列 <ol> <li> 进入步骤 3.1, 并使用剩余的氧化铝蚀刻铝基板重复整个序列. </li>
	</ol> </li> </ol> 4。硫酸电解质 AAOs 的大量制备 注意: 在本节中, 明确指出了步骤3中的不同条件. 
<ol> <li> n 第 前 SMSA <ol> <li> 将大约650毫升的硫酸水溶液 (0.3 米) 倒入双层套式烧杯中, 最大容量为1.0 升。然后, 约三季度的铝基板浸入硫酸溶液中. </li>
		<li> 设置0和 #177 的电解液温度; 0.1 和 #176; C. </li>
		<li> 使用气枪或 N 2 气体吹除 electropolished 铝基板上的残余溶剂, 并使用鳄鱼夹子将 Al 衬底连接到可编程直流电源 (请参阅步骤 3.1.4) </li>
		<li> 在中等磁性搅拌 (100-150 rpm) 下, 对. 施加超过 1-2 h 的 +25.0 V 至 w 的阳极偏差. </li>
		<li> 在完成预 SMSA 后停止应用阳极偏差, 并断开鳄鱼夹。用丙酮和 D 冲洗前 SMSAed 铝基板. 我喝水过几次. 
		注意: 对于 n th 前 AAOs 蚀刻, 请参阅步骤 3.2. </li>
	</ol> </li> <li> n th 主-SMSA <ol> <li> 将所有实验条件和连接都重新设置为步骤4.1 中使用的情况. </li>
		<li> 应用相同的阳极偏差。应用时间可根据需要的氧化铝厚度而变化。阳极氧化铝的生长率估计为5.3 和 #956; m/小时 (参见参考 56 以了解更多详细信息). </li>
	</ol> </li> <li> n srb-剥离 <ol> 在完成主 SMSA 后停止应用阳极偏置和搅拌, 并将主-SMSAed 铝基板与. (-) 和 Pt 线连接到可编程直流电源的 w (+)通过切换每个鳄鱼夹子提供. </li>
		<li> 应用 srb, 并检查典型的冒泡效果和样品的 multi-edges。台阶在 srb 被控制从-15 v 到-17 v 以增量-1 v 并且没有时间间隔在毗邻台阶之间。-15 v 和-16 v 的持续时间固定在10分钟, 并且在分离过程完成之前保持-17 v 的最后台阶. 
		注: 基于在硫酸电解质下制备的 AAOs 更脆的性质, 在分离时刻, 伴随着明显的咔嗒声, 电流水平突然增加. </li>
		<li> 停止应用 srb 后完成剥离, 并断开鳄鱼剪辑。从酸性电解液中仔细拿起样品, 用丙酮和 D 仔细冲洗. 我的水有足够的次数. </li>
		<li> 通过断开分离的 AAOs 的上部, 机械地将每个阳极氧化铝从相应的 Al 表面分离出来. 
		注: 对于 n th 剩余氧化铝蚀刻参考步骤 3.5. </li>
	</ol> </li> <li> n+1 th 序列 <ol> <li> 进入步骤 4.1, 并使用剩余的氧化铝蚀刻铝基板重复整个序列. </li>
	</ol>
	</li>
</ol>

这项研究得到了韩国国家研究基金会 (NRF) 资助的韩国政府 (MSIP) (No. 2016R1C1B1016344 和 2016R1E1A2915664) 的部分支持。

在本文中, 我们成功地展示了一种简便、高产、环保的方法, 通过 SMSA 和 srb 分离制备纳米多孔 AAOs, 可以重复到相同的铝基板, 从而显著提高质量性以及有限的天然资源的可用性。如图 1a的流程图所示, 我们的氧化铝制造策略是基于传统的 two-step 阳极氧化, 在 multi-surfaces 情况下进行了修改。因为电场在抛光和 two-step SMSAs 规程在正常方向被形成了在 multi-surfaces, 电化学反应发生,...

在酸性电解质中由阳极氧化 Al 基体形成的 AAOs, 引起了对各种基础科学和工业的极大兴趣, 例如, 纳米管/纳米线的硬模板1,2,3,4,5, 能量存储设备6,7,8,9, 生物传感10,11, 过滤应用程序12,13,14, 用于蒸发和/或蚀刻的掩码15,16,17, 和电容式湿度传感器18,19,20,21 ,22, 由于其 self-ordered 蜂窝结构, 高宽比纳米, 和优异的机械性能23。为了将纳米多孔 AAOs 应用于这些不同的应用, 它们应该是具有高度和长程有序排列的纳米的独立形式。在这方面, 获得 AAOs 的战略必须考虑形成 (阳极氧化) 和分离 (剥离) 程序。
从阳极氧化铝的形成角度来看, 轻度阳极氧化 (以下简称 MA) 是在硫酸、草酸和磷酸电解质下很好地建立的23,24,25,26 ,27。然而, ma 过程展示了 low-yields 氧化铝制造由于他们的缓慢的成长率取决于相对地低强度的阳极电压, 将进一步恶化通过 two-step ma 过程改进纳米的周期性28 ,29。因此, 采用更高的阳极电压 (草酸/硫酸电解质) 或使用更浓的电解质 (磷酸)30,31, 将硬阳极化 (HA) 技术作为替代 MA 的方法. 32,33,34,3536373839HA 进程显示了不同的增长速率和周期性安排, 而结果 AAOs 变得更加脆弱, 而纳米的密度则降低了30。此外, 需要一个昂贵的冷却系统, 以驱散由高电流密度引起的焦耳的加热31。这些结果限制了 AAOs 通过 HA 过程的潜在适用性。
在铝板的相应表面分离出一个阳极氧化铝时, 在 MA 和 HA 过程中使用有毒化学物质, 如氯化铜35,39, 对剩余铝基板的选择性化学蚀刻得到了最广泛的应用. 、41、42或水银氯161743444547,48,49. 然而, 这种方法会产生不利的副作用,如: 如, 较长的反应时间与 Al 的剩余厚度成正比, 重金属离子对阳极氧化铝的污染, 对人体/自然环境的有害残留物。, 而且有价值的资源使用效率低下。因此, 许多试图实现直接剥离的阳极氧化铝。虽然两个阴极电压分层50,51和阳极电压脉冲剥离7,41,42,52, 53,54,55目前的优点是, 剩余的铝基板可以被重用, 前者的技术在化学蚀刻方法中需要几乎可比的时间50。尽管处理时间明显减少, 有害和高活性化学品, 例如二和/或高氯酸, 被用作分离电解质在后者的技术55, 其中一个额外的清洁由于阳极氧化和分离过程中电解质的变化, 需要进行工艺过程。特别是分离 AAOs 的分离行为和质量严重影响了其厚度。在具有相对较薄厚度的阳极氧化铝的情况下, 分离的一个可能含有裂纹和/或孔径。
上述所有试验方法都已应用于 Al 试样的 "单面", 不包括表面保护/工程用途, 而传统技术的这一特性也显示了氧化铝制造的关键局限性。在产量和加工方面, 这也影响了 AAOs56,57的潜在适用性。
为了满足日益增长的需求, 在氧化铝相关领域的轻便, 高产, 绿色技术的方法, 我们先前报告的 SMSA 和直接支队通过 srb 在硫酸56和草酸57酸电解质, 分别。这是一个众所周知的事实, 复数 AAOs 可以形成多表面的铝基板浸入酸性电解质。然而, srb, 一个关键的区别, 我们的方法, 使这些 AAOs 从相应的铝基板的 multi-surfaces 在相同的酸性电解质用于 SMSAs 指示 mass-production, 简单, 和绿色技术特征.我们想指出的是, SRBs-based 支队是 SMSAs56,57的复数 AAOs 的最佳策略, 并且与 AAOs57的相对较薄的厚度相比, 更有效。单面上的阴极分层 (即, 恒定反向偏置)f ">> 51。最后, 由 SMSAs 顺序组合而成的 SRBs-based 分离器的单元序列可以重复地应用到相同的 Al 衬底, 避免复杂的程序和有毒/活性化学品, 从而强化了我们战略, 并保证自然资源的有效利用。

<table><tbody><tr><td>Sulfuric Acid &gt;98%</td><td>DUKSAN reagent</td><td>5950</td><td></td></tr><tr><td>Oxalic Acid Anhydrous, 99.5-100.2%</td><td>KANTO chemical</td><td>31045-73</td><td></td></tr><tr><td>Phosphoric Acid, 85%</td><td>SAMCHUN chemical</td><td>P0463</td><td></td></tr><tr><td>Perchloric Acid, 60%</td><td>SAMCHUN chemical</td><td>P0181</td><td>Highly Reactive</td></tr><tr><td>Chromium(VI) Oxide</td><td>Sigma Aldrich</td><td>232653</td><td>Strong Oxidizer</td></tr><tr><td>Ethanol, 95%</td><td>SAMCHUN chemical</td><td>E0219</td><td></td></tr><tr><td>Absolute Ethanol, 99.9%</td><td>SAMCHUN chemical</td><td>E1320</td><td></td></tr><tr><td>Double Jacket Beaker</td><td>iNexus</td><td>27-00292-05</td><td></td></tr><tr><td>Low Temperature Bath Circulator</td><td>JEIO TECH</td><td>AAH57052K</td><td></td></tr><tr><td>Programmable DC Power Supply</td><td>PNCYS</td><td>EDP-3001&amp;nbsp;</td><td></td></tr><tr><td>Aluminum Plate, &gt;99.99%</td><td>Goodfellow</td><td></td><td></td></tr><tr><td>Platinum Cylinder</td><td>Whatman</td><td>444685</td><td></td></tr><tr><td>Pure &amp;amp; Ultra Pure Water System (Deionized Water)</td><td>Human Science</td><td>Pwer II &amp;amp; HIQ II</td><td></td></tr></tbody></table>

simultaneous multi-surface anodizations and stair-like reverse biases detachment of anodic aluminum oxides in sulfuric and oxalic acid electrolyte

在报告了 two-step 阳极氧化后, 纳米多孔阳极氧化铝 (AAOs) 在基础科学和工业应用领域得到广泛的利用, 因为它们的纳米周期排列相对较高纵横比。然而, 迄今为止所报告的技术, 这可能只适用于单表面阳极氧化, 显示严重的缺点,即, 耗时, 以及复杂的程序, 需要有毒化学品, 浪费宝贵的自然资源.本文介绍了一种简便、高效、环保的制备硫酸和草酸电解质纳米 AAOs 的方法, 克服了传统的氧化铝制备方法的局限性。首先, 通过同时 multi-surfaces 阳极氧化 (SMSA) 同时产生复数 AAOs, 表明 AAOs 具有可比性质的质量性。其次, 这些 AAOs 可以与铝 (铝) 基板分离, 在相同的电解质中应用楼梯样的反向偏置 (srb), 这意味着简单和绿色技术特性。最后, 将 SMSAs 连续组合与 SRBs-based 剥离的单元序列重复应用于同一 Al 衬底, 从而强化了该策略的优点, 同时保证了自然资源的有效利用。

nth的流程图主要由 two-step SMSAs、srb 剥离和相关化学蚀刻组成, 在图 1a中作了概要介绍。每个插图显示一个扫描电子显微镜 (SEM) 图像的对应的表面形貌在每个单独的程序和一张照片后立即采取 srb-支队。在单元序列的总 5th重复之后的示意图说明显示了 SMSA 和 SRBs-based 策略的优点 (图 1b)。分别在<strong class="xf...

Watch this Scientific Journal Video about Simultaneous Multi-surface Anodizations and Stair-like Reverse Biases Detachment of Anodic Aluminum Oxides in Sulfuric and Oxalic Acid Electrolyte at JoVE.com

Simultaneous Multi-surface Anodizations and Stair-like Reverse Biases Detachment of Anodic Aluminum Oxides in Sulfuric and Oxalic Acid Electrolyte

阳极氧化铝在硫酸和草酸电解质中的同时多表面 Anodizations 和阶梯式反向偏置剥离

提出了一种通过同时 multi-surfaces 阳极氧化制备多孔阳极氧化铝的协议, 并给出了阶梯式反向偏置分遣队。它可以反复应用于相同的铝基板, 表现出轻便、高产、环保的战略。

After reporting on the two-step anodization, nanoporous anodic aluminum oxides (AAOs) have been widely utilized in the versatile fields of fundamental ...

simultaneous-multi-surface-anodizations-stair-like-reverse-biases

Research

JoVE Journal

Engineering

7.2K 次观看.  Sungkyunkwan University. 提出了一种通过同时 multi-surfaces 阳极氧化制备多孔阳极氧化铝的协议, 并给出了阶梯式反向偏置分遣队。它可以反复应用于相同的铝基板, 表现出轻便、高产、环保的战略。

视频: Simultaneous Multi-surface Anodizations and Stair-like Reverse Biases Detachment of Anodic Aluminum Oxides in Sulfuric and Oxalic Acid Electrolyte

Ultrahigh Density Array of Vertically Aligned Small-molecular Organic Nanowires on Arbitrary Substrates

In recent years &pi;-conjugated organic semiconductors have emerged as the active material in a number of diverse applications including large-area, low-cost displays, photovoltaics, printable and flexible electronics and organic spin valves. Organics allow (a) low-cost, low-temperature processing and (b) molecular-level design of electronic, optical and spin transport characteristics. Such features are not readily available for mainstream inorganic semiconductors, which have enabled organics to carve a niche in the silicon-dominated electronics market. The first generation of organic-based devices has focused on thin film geometries, grown by physical vapor deposition or solution processing. However, it has been realized that organic nanostructures can be used to enhance performance of above-mentioned applications and significant effort has been invested in exploring methods for organic nanostructure fabrication.	
A particularly interesting class of organic nanostructures is the one in which vertically oriented organic nanowires, nanorods or nanotubes are organized in a well-regimented, high-density array. Such structures are highly versatile and are ideal morphological architectures for various applications such as chemical sensors, split-dipole nanoantennas, photovoltaic devices with radially heterostructured "core-shell" nanowires, and memory devices with a cross-point geometry. Such architecture is generally realized by a template-directed approach. In the past this method has been used to grow metal and inorganic semiconductor nanowire arrays. More recently &pi;-conjugated polymer nanowires have been grown within nanoporous templates. However, these approaches have had limited success in growing nanowires of technologically important &pi;-conjugated small molecular weight organics, such as tris-8-hydroxyquinoline aluminum (Alq3), rubrene and methanofullerenes, which are commonly used in diverse areas including organic displays, photovoltaics, thin film transistors and spintronics.	
Recently we have been able to address the above-mentioned issue by employing a novel "centrifugation-assisted" approach. This method therefore broadens the spectrum of organic materials that can be patterned in a vertically ordered nanowire array. Due to the technological importance of Alq3, rubrene and methanofullerenes, our method can be used to explore how the nanostructuring of these materials affects the performance of aforementioned organic devices. The purpose of this article is to describe the technical details of the above-mentioned protocol, demonstrate how this process can be extended to grow small-molecular organic nanowires on arbitrary substrates and finally, to discuss the critical steps, limitations, possible modifications, trouble-shooting and future applications.

We report a simple method for fabricating an ultrahigh density array of vertically ordered small-molecular organic nanowires. This method allows for synthesis of complex heterostructured hybrid nanowire geometries, which can be inexpensively grown on arbitrary substrates. These structures have potential applications in organic electronics, optoelectronics, chemical sensing, photovoltaics and spintronics.

超高密度垂直对齐的任意基质的小分子有机纳米线阵列

In  recent years &pi;-conjugated  organic semiconductors have emerged as the active material in a number of  diverse applications including large-area, ...

科研

工程学

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

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

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

实时直流偏置的动态法切换时间改善严重欠阻尼边缘化场静电MEMS致动器

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

A Method to Manipulate Surface Tension of a Liquid Metal via Surface Oxidation and Reduction

Controlling interfacial tension is an effective method for manipulating the shape, position, and flow of fluids at sub-millimeter length scales, where interfacial tension is a dominant force. A variety of methods exist for controlling the interfacial tension of aqueous and organic liquids on this scale; however, these techniques have limited utility for liquid metals due to their large interfacial tension.
Liquid metals can form soft, stretchable, and shape-reconfigurable components in electronic and electromagnetic devices. Although it is possible to manipulate these fluids via mechanical methods (e.g., pumping), electrical methods are easier to miniaturize, control, and implement. However, most electrical techniques have their own constraints: electrowetting-on-dielectric requires large (kV) potentials for modest actuation, electrocapillarity can affect relatively small changes in the interfacial tension, and continuous electrowetting is limited to plugs of the liquid metal in capillaries.
Here, we present a method for actuating gallium and gallium-based liquid metal alloys via an electrochemical surface reaction. Controlling the electrochemical potential on the surface of the liquid metal in electrolyte rapidly and reversibly changes the interfacial tension by over two orders of magnitude ( &#820;500 mN/m to near zero). Furthermore, this method requires only a very modest potential (&#60; 1 V) applied relative to a counter electrode. The resulting change in tension is due primarily to the electrochemical deposition of a surface oxide layer, which acts as a surfactant; removal of the oxide increases the interfacial tension, and vice versa. This technique can be applied in a wide variety of electrolytes and is independent of the substrate on which it rests.

We present a method to control the interfacial energy of a liquid metal in an electrolyte via electrochemical deposition (or removal) of a surface oxide layer. This simple method can control the capillary behavior of gallium-based liquid metals by tuning the interfacial energy rapidly, significantly, and reversibly using modest voltages.

方法通过表面氧化还原操纵液态金属的表面张力

Controlling interfacial tension is an effective method for manipulating the shape, position, and flow of fluids at sub-millimeter length scales, where ...

化学

Growth and Electrostatic/chemical Properties of Metal/LaAlO3/SrTiO3 Heterostructures

The quasi 2D electron system (q2DES) that forms at the interface between LaAlO3 (LAO) and SrTiO3 (STO) has attracted much attention from the oxide electronics community. One of its hallmark features is the existence of a critical LAO thickness of 4 unit-cells (uc) for interfacial conductivity to emerge. Although electrostatic mechanisms have been proposed in the past to describe the existence of this critical thickness, the importance of chemical defects has been recently accentuated. Here, we describe the growth of metal/LAO/STO heterostructures in an ultra-high vacuum (UHV) cluster system combining pulsed laser deposition (to grow the LAO), magnetron sputtering (to grow the metal) and X-ray photoelectron spectroscopy (XPS). We study step by step the formation and evolution of the q2DES and the chemical interactions that occur between the metal and the LAO/STO. Additionally, magnetotransport experiments elucidate on the transport and electronic properties of the q2DES. This systematic work not only demonstrates a way to study the electrostatic and chemical interplay between the q2DES and its environment, but also unlocks the possibility to couple multifunctional capping layers with the rich physics observed in two-dimensional electron systems, allowing the fabrication of new types of devices.

Growth and Electrostatic/chemical Properties of Metal/LaAlO3/SrTiO3 Heterostructures

We fabricate metal/LaAlO3/SrTiO3 heterostructures using a combination of pulsed laser deposition and in situ magnetron sputtering. Through magnetotransport and in situ X-ray photoelectron spectroscopy experiments, we investigate the interplay between electrostatic and chemical phenomena of the quasi two-dimensional electron gas formed in this system.

金属/LaAlO 的生长和静电/化学性质3/SrTiO3异

The quasi 2D electron system (q2DES) that forms at the interface between LaAlO3 (LAO) and SrTiO3 (STO) has attracted much attention from the oxide ...

Multiscale Structures Aggregated by Imprinted Nanofibers for Functional Surfaces

Multiscale surface structures have attracted increasing interest owing to several potential applications in surface devices. However, an existing challenge in the field is the fabrication of hybrid micro-nano structures using a facile, cost-effective, and high-throughput method. To overcome these challenges, this paper proposes a protocol to fabricate multiscale structures using only an imprint process with an anodic aluminum oxide (AAO) filter and an evaporative self-aggregation process of nanofibers. Unlike previous attempts that have aimed to straighten nanofibers, we demonstrate a unique fabrication method for multiscale aggregated nanofibers with high aspect ratios. Furthermore, the surface morphology and wettability of these structures on various liquids were investigated to facilitate their use in multifunctional surfaces.

Presented is an easy method to fabricate nano-micro multiscale structures, for functional surfaces, by aggregating nanofibers fabricated using an anodic aluminum oxide filter.

功能表面用印迹纳米纤维聚合的多尺度结构

Multiscale surface structures have attracted increasing interest owing to several potential applications in surface devices. However, an existing ...

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. ...

Rendering SiO2/Si Surfaces Omniphobic by Carving Gas-Entrapping Microtextures Comprising Reentrant and Doubly Reentrant Cavities or Pillars

We present microfabrication protocols for rendering intrinsically wetting materials repellent to liquids (omniphobic) by creating gas-entrapping microtextures (GEMs) on them comprising cavities and pillars with reentrant and doubly reentrant features. Specifically, we use SiO2/Si as the model system and share protocols for two-dimensional (2D) designing, photolithography, isotropic/anisotropic etching techniques, thermal oxide growth, piranha cleaning, and storage towards achieving those microtextures. Even though the conventional wisdom indicates that roughening intrinsically wetting surfaces (&#952;o &#60; 90&#176;) renders them even more wetting (&#952;r &#60; &#952;o &#60; 90&#176;), GEMs demonstrate liquid repellence despite the intrinsic wettability of the substrate. For instance, despite the intrinsic wettability of silica &#952;o &#8776; 40&#176; for the water/air system, and &#952;o &#8776; 20&#176; for the hexadecane/air system, GEMs comprising cavities entrap air robustly on immersion in those liquids, and the apparent contact angles for the droplets are &#952;r &#62; 90&#176;. The reentrant and doubly reentrant features in the GEMs stabilize the intruding liquid meniscus thereby trapping the liquid-solid-vapor system in metastable air-filled states (Cassie states) and delaying wetting transitions to the thermodynamically-stable fully-filled state (Wenzel state) by, for instance, hours to months. Similarly, SiO2/Si surfaces with arrays of reentrant and doubly reentrant micropillars demonstrate extremely high contact angles (&#952;r &#8776; 150&#176;&#8211;160&#176;) and low contact angle hysteresis for the probe liquids, thus characterized as superomniphobic. However, on immersion in the same liquids, those surfaces dramatically lose their superomniphobicity and get fully-filled within &#60;1 s. To address this challenge, we present protocols for hybrid designs that comprise arrays of doubly reentrant pillars surrounded by walls with doubly reentrant profiles. Indeed, hybrid microtextures entrap air on immersion in the probe liquids. To summarize, the protocols described here should enable the investigation of GEMs in the context of achieving omniphobicity without chemical coatings, such as perfluorocarbons, which might unlock the scope of inexpensive common materials for applications as omniphobic materials. Silica microtextures could also serve as templates for soft materials.

Rendering SiO2/Si Surfaces Omniphobic by Carving Gas-Entrapping Microtextures Comprising Reentrant and Doubly Reentrant Cavities or Pillars

This work presents microfabrication protocols for achieving cavities and pillars with reentrant and doubly reentrant profiles on SiO2/Si wafers using photolithography and dry etching. Resulting microtextured surfaces demonstrate remarkable liquid repellence, characterized by robust long-term entrapment of air under wetting liquids, despite the intrinsic wettability of silica.

通过雕刻包含可重入和双重入的腔或柱的气体镶入微纹理来渲染 SiO2/Si 曲面全功能性

We present microfabrication protocols for rendering intrinsically wetting materials repellent to liquids (omniphobic) by creating gas-entrapping ...

The Effect of Anodization Parameters on the Aluminum Oxide Dielectric Layer of Thin-Film Transistors

Aluminum-oxide (Al2O3) is a low cost, easily processable and high dielectric constant insulating material that is particularly appropriate for use as the dielectric layer of thin-film transistors (TFTs). Growth of aluminum-oxide layers from anodization of metallic aluminum films is greatly advantageous when compared to sophisticated processes such as atomic layer deposition (ALD) or deposition methods that demand relatively high temperatures (above 300 &#176;C) such as aqueous combustion or spray-pyrolysis. However, the electrical properties of the transistors are highly dependent on the presence of defects and localized states at the semiconductor/dielectric interface, which are strongly affected by the manufacturing parameters of the anodized dielectric layer. To determine how several fabrication parameters influence the device performance without performing all possible combination of factors, we used a reduced factorial analysis based on a Plackett-Burman design of experiments (DOE). The choice of this DOE permits the use of only 12 experimental runs of combinations of factors (instead of all 256 possibilities) to obtain the optimized device performance. The ranking of the factors by the effect on device responses such as the TFT mobility is possible by applying analysis of variance (ANOVA) to the obtained results.

Anodization parameters for growth of the aluminum-oxide dielectric layer of zinc-oxide thin-film transistors (TFTs) are varied to determine the effects on the electrical parameter responses. Analysis of variance (ANOVA) is applied to a Plackett-Burman design of experiments (DOE) to determine the manufacturing conditions that result in optimized device performance.

阳极化参数对薄膜晶体管氧化铝介电层的影响

Aluminum-oxide (Al2O3) is a low cost, easily processable and high dielectric constant insulating material that is particularly appropriate for use as the ...

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

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

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

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

基于混合相位a-VOx的不对称横杆的偏置和制造现场传输电子显微镜

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

Versatile Technique to Produce a Hierarchical Design in Nanoporous Gold

The potential to generate variable pore sizes, simplistic surface modification, and a breadth of commercial uses in the fields of biosensors, actuators, drug loading and release, and the development of catalysts have unquestionably accelerated the usage of nanoporous gold (NPG)-based nanomaterials in research and development. This article describes the process of the generation of hierarchical bimodal nanoporous gold (hb-NPG) by employing a step-wise procedure involving electrochemical alloying, chemical dealloying techniques, and annealing to create both macro- and mesopores. This is done to improve the utility of NPG by creating a bicontinuous solid/void morphology. The area available for surface modification is enhanced by smaller pores, while molecular transport benefits from the network of larger pores. The bimodal architecture, which is the result of a series of fabrication steps, is visualized using scanning electron microscopy (SEM) as a network of pores that are less than 100 nm in size and connected by ligaments to larger pores that are several hundred nanometers in size. The electrochemically active surface area of the hb-NPG is assessed using cyclic voltammetry (CV), with a focus on the critical roles that both dealloying and annealing play in creating the necessary structure. The adsorption of different proteins is measured by solution depletion technique, revealing the better performance of hb-NPG in terms of protein loading. By changing the surface area to volume ratio, the created hb-NPG electrode offers tremendous potential for biosensor development. The manuscript discusses a scalable method to create hb-NPG surface structures, as they offer a large surface area for the immobilization of small molecules and improved transport pathways for faster reactions.

Nanoporous gold with a hierarchical and bimodal pore size distribution can be produced by combining electrochemical and chemical dealloying. The composition of the alloy can be monitored via EDS-SEM examination as the dealloying process advances. The material's loading capacity can be determined by studying protein adsorption onto the material.

在纳米多孔金中产生分层设计的多功能技术

The potential to generate variable pore sizes, simplistic surface modification, and a breadth of commercial uses in the fields of biosensors, actuators, ...

阳极氧化铝在硫酸和草酸电解质中的同时多表面 Anodizations 和阶梯式反向偏置剥离

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