Name: a novel method for in situ electromechanical characterization of nanoscale specimens
Uploaded: 2017-06-02T14:00:00.000+00:00
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Description: Watch this Scientific Journal Video about A Novel Method for In Situ Electromechanical Characterization of Nanoscale Specimens at JoVE.com

这项工作得到了美国海军研究实验室基础研究计划的ASEE-NRL博士后研究金和海军研究部的支持。作者感谢C. Kindle在NRL的技术支持。

Si框架的微加工<ol><li>在180μm厚的Si晶片上的旋涂（3000rpm和30s）SPR220-7光致抗蚀剂（PR）。使用足够的PR完全涂覆晶片。晶圆的晶面取向并不重要。 </li><li>在60℃下用PR层（约7.5μm厚）将晶片烘烤2分钟，然后在115℃下在热板上烘烤90秒。 </li><li>通过图案化的铬/玻璃光掩模将PR层暴露于紫外线，允许光通过它来限定Si框架的形状。对本步骤和下一步使用标准光刻设备和工艺（ 图2a-b ）。 </li><li>通过在未稀释的MF 24A或MF 319中将具有PR的Si晶片浸入其中约1分钟（ 图2c ）来显影通过光掩模曝光的图案。在步骤1.6期间，图案化的PR层用作掩模。 </li><li>将180μm厚的Si晶片结合到厚度为500μm的支撑Si wafer使用低熔点临时粘合剂以便于处理（详见材料表 ）。使用热板（70°C）在玻璃皿中加热粘合剂，并使用足够的粘合剂涂覆支撑晶片。然后轻轻地将180μm厚的Si晶片压在500μm厚的晶片上（ 图2d ）。 </li><li> 从上方蚀刻顶部的硅晶片，制成独立的结构。使用任何数量的市售电感耦合等离子体反应离子蚀刻系统，其使用Bosch工艺与SF 6和C 4 F 8气体进行蚀刻步骤。在博世工艺中，钝化层沉积和等离子体蚀刻的交替循环导致深刻蚀刻的沟槽，具有大多数完好的侧壁）（图2e）。 <ol><li>开始沉积期间SF 6和C 4 F 8的3和100sccm流动5秒和100和2.5sccm的SF 6和C 4 F <sub蚀刻时分别为8s，7s。根据需要调整仪器相关参数（流速，气体之间的比例和沉积和蚀刻步骤的时间间隔）。 </li></ol></li><li>每20分钟，使用轮廓仪测量蚀刻沟槽的深度，以校准特定于仪器和蚀刻配方的蚀刻速率。 </li><li>通过使用过夜丙酮浸泡去除临时粘合剂和PR，分离支撑硅晶片并清洁薄Si晶片（ 图2f ）。然后用去离子（DI）水彻底冲洗薄晶片。 </li><li>使用任何市售的具有SiH 4 ，N 2 O和N 2气体的等离子体增强化学气相沉积（PECVD）系统（ 图2g ），在Si框架两侧在300℃下沉积SiO 2绝缘层。使用标准SiO 2沉积配方， 例如 ，使用170sccm的5％SiH 4和710sccm的N 2 O沉积2-3μm厚的SiO 2层。 </li><li>打破将各个矩形Si框架连接到周围结构的接头。在光学显微镜下使用尖锐的镊子（ 图2h ）。 </li></ol> 2.金属样品的激光图案<ol><li>切成5.0厘米×5.0厘米的铜箔（纯度99.99％;参见表格材料 ），并用胶带将其粘贴到载玻片上。双面旋涂一层厚1公分的PR。虽然可以通过激光技术切割宽范围厚度（高达100μm）的箔片，但是这里使用两种不同的厚度（13μm和25μm）进行演示。使用足够的PR完全涂覆表面。将PR在115°C烘烤2分钟。需要PR以便保护铜箔的表面免受在激光切割步骤期间产生的碎屑，并允许对样品束进行化学蚀刻（参见步骤2.4）而不影响第e表面的箔。 </li><li>使用具有约90ns脉冲宽度的50kHz的355nm，10瓦，固态，三倍频Nd:YVO 4脉冲激光，切割5个4个单独样品的阵列，每个样品由4mm长的铜框架1 mm宽（ 图3b ）。 </li><li>在铜箔表面调整激光束的能量为65 mJ / cm 2 。这提供足够的激光能量以两次通过铜切割，而不会过度加热和/或损坏相邻的铜。每个样品的图案由Galvo扫描镜产生，该扫描镜扫描激光束以切割每次产生20个样品的铜箔（ 图3a ）。将激光切割样品光束的宽度从30μm（对于13μm厚的箔）调整到50μm（对于25μm厚的箔）。 </li><li>通过将样品阵列浸入40-60℃的40％液体氯化铁中30秒（对于13微米厚的箔）或40秒（对于t他25微米厚的箔）以去除潜在损坏的激光切割边缘，减小单个样品波束在20微米以下的宽度（ 图3c ），并产生光滑的边缘轮廓。 </li><li>将阵列浸入第一丙酮分离的溶剂浴中，然后用甲醇，然后用异丙醇，然后用氮气干燥，除去保护性光致抗蚀剂。将样品阵列存放在干燥氮气干燥器中。上述制造步骤的截面示意图如图3d所示。 </li><li>使用激光切割样品阵列周围的盒子，将其从铜箔的其余部分释放出来。 </li></ol>装配和原位 TEM实验<ol><li>用小型剪刀分离个体标本（包括铜框）。在硅框架上放置少量银环氧树脂，并在光学显微镜下小心地对准样品，使样品计数器跨越中心的窄间隙e框架（ 图4a ）。 </li><li>与步骤3.1类似，用银环氧树脂将银线（直径50μm）连接到样品的两端（ 图5c ）。 </li><li>使用聚焦离子束（FIB）铣削，以创建具有多个肩部的纳米尺度表面（100nm×10μm×10μm）。逐渐变厚的横截面远离规格部分意味着产生电流密度的平滑过渡，在规格部分中更均匀的电流密度，并且使任何给定肩部处的局部加热最小化。为了最小化损坏，在铜样品的最终铣削过程中，使用降低的加速电压（5 kV）和电流（&lt;80 pA）。使用扫描电子显微镜（SEM）图像（ 图4b-e和5b ）测量量规的横截面面积。 </li><li>通过激光切割，FIB或小型剪刀去除标本框架（参见图4a的插图）。虽然不是在图像的情况下，位置o切割应理想地远离仪表部分，以尽可能减少仪表部分的材料损坏。 </li><li>在光学显微镜下将MEMTS安装到单个倾斜应变TEM支架（参见表格 ）上，然后使用螺栓和非导电垫圈将其连接。垫圈用于防止装配过程中的不必要的扭转。使用50 W CO 2激光系统使用硬质纤维电气级片材图案化的垫圈（0.5毫米厚）（ 参见表中激光切割中的具体参数）。 </li><li>使用银导电环氧树脂将步骤3.2中的银线连接到TEM支架上的金属针（ 图5a ）上。 </li><li>使用手持式或台式万用表检查MEMTS（ 图1中的 B和C）上的电阻，以验证仪表部分是否损坏。电阻应小于100Ω。还测量MEMT之间的电阻S和电接地的TEM样品架，以确认样品和TEM支架之间没有电气串扰。如果样品隔离，测得的电阻应大于10MΩ。 </li><li>将具有MEMTS的TEM支架放入TEM进行原位实验。 </li><li>将外部直流电源（见材料表 ）连接到TEM支架内部的电气馈通，以从TEM室外部向样品施加直流输入信号，以控制电流。电气连接位置取决于TEM支架制造商，但是对于本研究，连接位于支架手柄上，并且销连接器用于将电源从电源施加到TEM样品。通过将输入电流除以横截面积（从图5b中的SEM图像获得）获得在量规部分的标称电流密度。 注意:单次倾斜培训TEM支架包含由单独的位移控制器（材料表 ）控制的内置致动器。 </li><li>在控制机械和电气负载的同时，在以下步骤中获取TEM图像。也可以使用其他应变和电流负载。 </li><li>根据内置的压电致动器的分辨率（在本例中为〜0.34nm），以小的步长逐步施加拉伸应变，直到同时观察到一个或多个位错的运动。这是一个关键的步骤，所以热和/或电能的任何额外的增加产生额外的运动。 </li><li>让样品平衡一分钟。 </li><li>对样品施加输入电流密度。由于横截面积小，即使在大电流密度下，电流应足够低，不会导致显着的温升（ <img alt="方程" src="/files/ftp_upload/55735/55735eq2.jpg" /> ）在t他衡量部分。量规部分中心的最大温升取决于样品几何形状和材料特性，如下所述。 </li><li>为了在稳态条件下对样品进行成像，将其保持在电子束下一分钟，同时在获取图像之前保持电流稳定。允许样品以这种方式平衡应用于机械或电负载的任何改变之后。 </li></ol>

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A., Kamino, T., Michael, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=TEM+sample+preparation+and+FIB-induced+damage.">TEM sample preparation and FIB-induced damage.</a> MRS Bulletin. 32 (5), 400-407 (2007).</li></ol>

作者宣称他们没有竞争的经济利益。

Micro / nanotechnology提供了强大的工具来表征分析室中的材料行为，包括扫描16,18,19,20,21和透射电子显微镜13,22,23,24。这种原位测试能力对材料科学和工程界来说是非常有吸引力的，因为可以使用高分辨率电子显微镜25,26直接观察到基本的微观结构和潜在的变形机制。 在这里，我们提出了一种基于微设备的方法来利用独特的辅助来研究材料样品的耦合电和机械行为原位 TEM的原理。这种方法中的步骤需要使用光刻，反应离子蚀刻设备，电子显微镜的平均经验，以及在这里使用的高质量激光加工系统的访问和训练。虽然采用银环氧树脂和碱性光学显微镜，使用简单的手段来完成标本和硅胶支架的组装，但要注意不要损坏样品计量部分。在处理样品时始终是这样。在铜样品的最终FIB研磨过程中也必须注意。在最终抛光期间减少加速电压（5kV）和电流（&lt;80pA） 27将减少可能的样品损伤28并产生平滑的，无缺陷的量规部分。要记住的另一个重要项目是检查与TEM夹具电隔离的样品，以确保施加的电流通过仪表部分一旦实验开始。 晶片蚀刻工艺包括对于制造EAD样品的良好框架至关重要的一些步骤。将500μm支撑晶片临时粘合到180μm晶片之间，在晶片之间具有均匀的临时粘合剂涂层是重要的，不仅有助于处理脆弱的蚀刻晶片，而且支撑晶片也有利于等离子体蚀刻工艺期间的热传递。传热不足可能导致PR掩模的蚀刻和硅框架的后续非目标蚀刻。定期测量蚀刻沟槽深度也很重要。必须完全蚀刻较薄的顶部硅晶片，但对支撑晶片应进行最小蚀刻，以使其能够作为较薄晶片的均匀散热器。最后，重要的是用丙酮彻底清洁蚀刻的晶圆，然后在SiO 2沉积之前用去离子水冲洗，以最小化任何剩余的重量sidues。 这里显示的EAD实验图像是可以预期的代表，但可以对分辨率，剂量和帧速率进行修改，以允许更好地观察和定量位错。此外，图像处理软件可以用于分析一系列具有增强分辨率的TEM图像。 MEMTS为研究机电材料行为提供了几个独特的优势。该系统能够直接观察在机电负载下控制宏观材料变形的纳米尺度现象。其次，具有小截面的样品计量部分提供了使用低电流大小施加大量电流密度的能力，从而消除了使用高功率仪器所固有的安全问题。例如，将1,000A / mm 2的电流密度施加到1mm 2计量段将仅需要1kA如果量规横截面减小到1μm2，则为1 mA。更重要的是，使用较低的电流有助于热管理。 MEMTS也是独特的，因为其对准和组装不需要昂贵的设备，并且与其他基于微型设备的组装方法相比并不是时间密集的。 这里描述的方法很好地适用于金属，陶瓷和聚合物的机电测试，但它也可用于探索每种材料类别内的微观结构依赖的机电行为。例如，可以通过制备代表性样品来研究单晶和多晶结晶度，晶粒取向，晶粒尺寸，相分布和缺陷密度对机电行为的影响。从这样一个全面的研究中获得的见解可以提供进一步了解EAD驱动机制和提高EAD制造能力所需的理解。说更多的布拉dly，MEMTS可能是研究利用热电耦合的其他设备的有用平台。例如，它可以用于观察热电冷却器中使用的材料，其通过塞贝克效应将施加的电压转换为温度差。 尽管使用本文概述的工艺进行的实验还没有显示出电辅助的变形发生在没有显着的焦耳加热的情况下，需要进一步的实验。这里描述的过程利用了一小组实验条件并集中在局部区域上。需要使用多种材料，电流密度和时间尺度的更全面的一组实验来更确定地验证EAD中是否存在纯粹的电气效应。当前的MEMTS方法的一个技术限制是在原位实验中缺乏量化作用于样品的力的能力。力量是至关重要的以获得应力应变数据（ 例如 ，定量鉴定样品何时达到流动应力），并且当与原位观察结合时，直接提供微观结构性质关系。为了实现这一独特的研究机会，我们正在努力修改Si框架以集成力传感器。

电辅助变形（EAD）是锻造，冲压，挤压等金属变形过程的有用工具。 EAD过程包括在变形期间通过金属工件施加电流，通过减少流动应力，增加应变到失效，有时消除形成1,2,3之后的回弹，显着提高金属成形性。尽管其使用增长，但对于EAD提高金属成形性的机制尚未达成共识。本文介绍了实验的样品制备和测试程序，其中可以分离潜在的竞争性EAD机制，并在测试过程中实现原位显微结构检查。 EAD对金属成形的影响有两个假设。第一个假设，焦耳加热效应，sta所施加的电流在成形金属中遇到电阻，导致温度升高并导致材料软化和膨胀。第二个假设被称为电塑性，其中电流通过降低位错活化能而增加变形。这两个假设都是从20世纪70年代的实验中产生的，涉及应用于机械变形金属4,5的短时电流脉冲。最近的研究通常涉及较低的电流直流脉冲，这与制造应用更相关，但是研究人员在对EAD数据的解释方面仍然不同意。 由于施加的电流的高度耦合性质和增加的热能，解释EAD数据是困难的。高导电性金属中的电流密度即使很小也能显着提高材料的温度; 例如 ，130-240℃，电流密度为33-120A / mm 2 ，用于各种铝和铜合金6,7,8,9 。这种温度变化可以显着影响弹性模量，屈服强度和流动应力，使得区分热和电致塑性效应变得具有挑战性。突出这个困难，可以发现最近的研究支持焦耳加热假说或电塑假说。例如，研究铝，铜和钛的各种合金中的机电变形，研究人员已经报道，电致塑性有助于增强变形，因为这种效果不能仅仅通过焦耳加热来解释1,6,7。与这些报告相反的是研究表明EAD减轻压力钛，不锈钢和Ti-6Al-4V热效应10,11 。 热管理不是EAD研究的具体内容，而是调查机电材料性质时的一般问题。特别是在大型样品中，质心与其周围深度绝缘，保持均匀的温度可能具有挑战性。与样品尺寸相关的另一个机电测试挑战是能够进行与机电应力相关的基本微结构变化的原位和实时观测。常规地在标准试样12上进行原位 TEM机械试验，但是样品的不均匀横截面会在测量段附近产生电流密度和热传递的几何依赖性变化。总而言之，观察和解释EA的主要挑战<html> D机制与样品尺寸有关，可概括如下:1）热偶耦合影响样品温度，使得难以分离单一提出的EAD机制; 2）标准测试样品和程序不存在于原位实时在施加的电流下研究张力材料。通过在透射电子显微镜（TEM）中用超低体积计量部分的样品进行EAD实验，同时控制电流，机械负载和温度，可以克服这些挑战。 在本文中，我们描述了EAD实验的样品制备和测试程序，其中通过使用附着到较大的微/纳米尺度部分（10μm×10μm×100nm）的样品结构使焦耳加热效应可忽略不计稳定支撑框架。通过分析和数值模拟，已经显示出来在这种配置下，甚至高电流密度（〜3,500A / mm 2 ）导致样品温度（&lt;0.02℃）几乎没有增加。基于微器件的机电测试系统的三维示意图（MEMTS） 如图 1所示，这里提出的另一个重要的优点是，不像检查样品那样检查样品，如通常做的那样，样品结构和支撑框架被设计成直接配合到透射电子显微镜TEM）样品架同时具有同时施加电气和机械载荷的能力，该设置可实现原子级分辨率下的材料变形的实时原位观察，尽管单晶铜样品用于本文概述的步骤，该方法具有足够的柔性以适用于其他材料试样ing金属，陶瓷和聚合物15,16 。

<table><tbody><tr><td>Silicon wafers</td><td></td><td></td><td>Any high-quality polished wafers of the correct thickness will work</td></tr><tr><td>Photoresist</td><td>Dow</td><td>SR220-7</td><td></td></tr><tr><td>Photoresist developer</td><td>Shipley</td><td>MF 24A</td><td></td></tr><tr><td>Photoresist developer</td><td>Rohm and Haas</td><td>MF 319</td><td></td></tr><tr><td>Temporary wafer adhesive</td><td></td><td>Crystalbond 509</td><td>Available from a variety of sources</td></tr><tr><td>Iductively Coupled Plasma Reactive Ion Etching (CP-RIE) system</td><td>Oxford</td><td>Plasmalab system 100 ICP RIE</td><td></td></tr><tr><td>Profilometer</td><td>Veeco</td><td>Dektak 150</td><td></td></tr><tr><td>Plasma-Enhanced Chemical Vapor Deposition (PECVD) system</td><td>Oxford</td><td>Plasmalab system 100 PECVD</td><td></td></tr><tr><td>Thin specimen sheet</td><td>Surepure Chemetals</td><td>3702, 3703, 3704 or 2236</td><td>13 &amp;micro;m and 25 &amp;micro;m-thick copper, 99.99% 4N Pure</td></tr><tr><td>Photoresist</td><td>Shipley</td><td>1818</td><td></td></tr><tr><td>355 nm, 10 W, solid-state, frequency tripled Nd:YVO&lt;sub&gt;4&lt;/sub&gt; pulsed laser</td><td>JDSU</td><td>Q301-HD</td><td></td></tr><tr><td>Liquid ferric chloride</td><td>Sigma-Aldrich</td><td>157740</td><td></td></tr><tr><td>Conductive silver epoxy</td><td>Chemtronics</td><td>CW2400</td><td></td></tr><tr><td>Silver wires</td><td></td><td></td><td>Any highly conductive metallic wires will work (&amp;lt;100 &amp;micro;m in diameter)</td></tr><tr><td>Focused Ion Beam (FIB)</td><td>FEI</td><td>Nova 600</td><td></td></tr><tr><td>Single tilt straining TEM holder</td><td>Gatan</td><td>654</td><td></td></tr><tr><td>Displacement controller</td><td>Gatan</td><td>902 Accutroller</td><td>May be sold with the TEM holder</td></tr><tr><td>CO&lt;sub&gt;2&lt;/sub&gt; laser cutter</td><td>Universal Laser Systems</td><td>VLS 3.50</td><td>Use 50% power and 15% speed</td></tr><tr><td>Electrical insulation sheet</td><td></td><td>0.5 mm-thick Hard Fiber Electrical Grade Sheet (Fishpaper)</td><td>Available from a variety of sources</td></tr><tr><td>Transmission Electron Microscope (TEM)</td><td>FEI</td><td>Tecnai G2</td><td></td></tr><tr><td>External power supply</td><td>Keithley</td><td>2400 SourceMeter</td><td></td></tr></tbody></table>

a novel method for in situ electromechanical characterization of nanoscale specimens

电子辅助变形（EAD）越来越多地被用于提高金属在诸如钣金轧制和锻造的过程中的成形性。尽管对负责EAD的潜在机制有不同意见，仍采用这种技术。与先前的EAD研究相比，本文所述的实验程序能够进行更明确的研究，通过消除导致以前EAD结果的不一致的热效应。此外，由于这里描述的方法使得能够在透射电子显微镜（TEM）中实时地进行EAD观察，所以它优于现有的在测试后观察EAD效应的验尸方法。测试样品由使用激光和离子束研磨的组合制造的具有纳米级厚度的独立拉伸试验部分的单晶铜（SCC）箔组成。 SCC安装到提供给我的蚀刻硅基底板上机电支持和电气隔离，同时用作散热器。即使在高电流密度（〜3,500 A / mm 2 ）下，使用这种几何形状，测试部分的温度升高可以忽略不计（&lt;0.02°C），从而消除了焦耳加热效应。通过获取和分析一系列TEM图像来实现材料变形监测和识别对微观结构（ 如位错）的相应变化。我们的样品制备和原位实验程序是坚固的和通用的，因为它们可以容易地用于测试具有不同微结构的材料， 例如单晶和多晶铜。

如上所述的准备和测试应该导致样品在其规格上断裂，类似于图 6a所示的单晶铜（SCC）样品。机械故障应伴随着电阻的大幅度增加，证实SCC试样通过绝缘垫圈和氧化物涂覆的硅框架电隔离。应使用聚焦在区域轴附近的TEM的亮场模式观察样品中的平面位错。通过逐渐增加应变直到达到流动应力（后期平衡状态），位错运动应该是可见的（ 图 6b）。随着额外的应变和/或施加的电流，可以连续监测相应的位错运动。 数字图7示出了在SCC标本13的EAD实验期间的代表性图像。在将样品拉伸至其后产量平衡状态之后，施加额外的应变而不施加任何电流（参见图 7b）。这导致了新的位错回路（或可能的第二位错滑行）， 如图 7 b 2中的箭头所示 。不改变应变，然后施加500A / mm 2的电流密度，但是在任何位错中都不会产生明显的运动（ 图 7b）。将电流除去，将样品保持恒定1分钟，再次增加菌株，再次产生由图 7b中箭头所示的位错回路的显着变化</st荣&gt; 4 。该结果说明了该过程隔离电辅助变形中涉及的热和电效应的潜力。还使用这种技术进行了涉及更高电流密度（高达5kA / mm 2 ）的实验，产生类似的结果 - 在没有额外的应变的情况下，没有观察到的额外位错运动。使用更高的电流密度强调了这种技术去除焦耳加热引起的热应力的能力，这些复杂的以前的EAD数据集是复杂的。 考虑到样品规格尺寸小，选择高品质材料至关重要。例如，在规格部分附近的微观材料缺陷（ 例如空隙）将导致样品在材料制备过程中的灾难性故障（ 图 4g ）。这是特别的<html>具有挑战性，因为难以知道量规部分中是否存在看不见的材料缺陷，而不进行附加的非破坏性测试，例如X射线衍射形貌。 激光或聚焦离子研磨期间的另一个关键挑战是可能的表面损伤，包括Ga离子注入，离子束诱导位错以及激光诱导加热形成非晶结构。通过使用温和的FIB研磨工艺可以除去大部分的表面伪影（步骤3.3）。然而，使用这种微细加工技术仍然需要仔细考虑，因为这些表面缺陷可能改变样品的微结构并且极大地影响EAD实验结果。在我们的工作中，我们利用高分辨率的TEM图像和衍射图来证实我们的样品确实是原始的单晶铜图 6 c 。 内容"fo:keep-together.within-page ="1"&gt;值得注意的是，仪表部分中心的最大温升可以使用以下公式计算13 : <img alt="方程" src="/files/ftp_upload/55735/55735eq3.jpg" />哪里<img alt="方程" src="/files/ftp_upload/55735/55735eq4.jpg" />是目前的密度， <img alt="方程" src="/files/ftp_upload/55735/55735eq5.jpg" />是仪表长度， <img alt="方程" src="/files/ftp_upload/55735/55735eq6.jpg" />是电阻率， <img alt="方程" src="/files/ftp_upload/55735/55735eq7.jpg" />是热导率。该方程式表明，仪表部分的温度升高对于非常敏感<img alt="方程" src="/files/ftp_upload/55735/55735eq8.jpg" />因为最大试样温度升高与量规长度的平方直接相关。例如，将测量段长度增加一个数量级，从10μ<html> m（在本研究中使用）至100μm，会使温度升高两个数量级。而不是温度上升约0.02°C，温度会升高约2°C，这可能在本研究中有显着差异。此外，材料选择也会影响温升。在本研究中使用的铜具有相对低的电阻和高导热系数，因此，对于给定的电流密度，铜样品中的预期温度升高将比其他材料样品小得多。作为示例，与铜相比，铂具有6倍大的电阻率和5倍的电导率17 ，因此，当铂长度和给定的电流密度是铂时，铂壳的温度上升（约30倍）将大大增加相同。 / p&gt; &lt;/ p&gt; 图1:基于微型设备的机电测试系统（MEMTS）。该图像是三维（3D）原理图，显示了重要组件以及样本如何与TEM支架相配合。没有显示将样品连接到TEM支架上的针的线。 <a href="http://ecsource.jove.com/files/ftp_upload/55735/55735fig1large.jpg" target="_blank">请点击此处查看此图的较大版本。</a> <img alt="图2" src="/files/ftp_upload/55735/55735fig2.jpg" /> 图2:硅框架制造工艺。裸光子晶片（ a ）被光刻胶（ b ）旋涂，然后使用光刻将其图案化。暴露的光致抗蚀剂被开发出以暴露下面的Si晶片（ c ）。晶片临时结合到较厚的支撑晶片上并具有反应性离子蚀刻（RIE）用于蚀刻通过较薄的顶部晶片（ d - e ）。丙酮用于去除光致抗蚀剂并分离支撑晶片（ f ）。然后在蚀刻的晶片（ g ）的所有表面上沉积氧化硅层。最后，通过小心地将它们从支撑片（ h ）中小心地拉出来，将各个框架与晶片分离。 <a href="http://ecsource.jove.com/files/ftp_upload/55735/55735fig2large.jpg" target="_blank">请点击此处查看此图的较大版本。</a> <img alt="图3" src="/files/ftp_upload/55735/55735fig3.jpg" /> 图3:金属样品制造。 （ a ）铜样品阵列的光学图像（ b ）单个样品，（ c ）测量仪器部分的放大视图。制造工艺步骤如（ d </strong&gt;），这是（ b ）中A --- A的横截面。激光切割（ d ，顶部）时，薄膜的两面都涂有光致抗蚀剂以保护样品。结构被激光加工（ d ，第二），然后蚀刻以产生平滑的边缘（ d ，第三）。许多标本可以由（ a ）所示的单个制造运行生产。最后，剥离光致抗蚀剂，并从样品片（ d ，底部）中轻轻取出各个样品。 <a href="http://ecsource.jove.com/files/ftp_upload/55735/55735fig3large.jpg" target="_blank">请点击此处查看此图的较大版本。</a> <img alt="图4" src="/files/ftp_upload/55735/55735fig4.jpg" /> 图4:聚焦离子束（FIB）研磨图像。图（ a ）示出了附着在Si框架上的样本和特写视图（插图）激光切割后的样品支架。图像（ b ） - （ e ）显示在连续的FIB通过期间，测量仪部分变得越来越薄。每次通过除去较少的材料以改善表面光洁度并减少由于研磨过程而导致的材料性质变化。然而，仪表部分缺陷可能保留（ f ），甚至在施加任何应变之前也可能导致材料故障（ g ）。 <a href="http://ecsource.jove.com/files/ftp_upload/55735/55735fig4large.jpg" target="_blank">请点击此处查看此图的较大版本。</a> <img alt="图5" src="/files/ftp_upload/55735/55735fig5.jpg" /> 图5:安装在TEM支架上的样品。 （ a ）和（ b ）显示了TEM保​​持器中的组装样品，使用gen的表面光滑表面的最终尺寸tle FIB铣削。一旦试样接合到Si框架上，并且使用导电环氧树脂（ c ）连接银线，则Si框架中的两个圆形孔用于将试样安装在TEM支架中。非导电垫圈用于使样品与TEM支架绝缘。最后，使用导电环氧树脂将银线连接到TEM支架销。经修改13 ，经AIP出版许可。 <a href="http://ecsource.jove.com/files/ftp_upload/55735/55735fig5large.jpg" target="_blank">请点击此处查看此图的较大版本。</a> <img alt="图6" src="/files/ftp_upload/55735/55735fig6.jpg" /> 图6:代表性的单晶铜（SSC）样品。 （ a ）显示了仪表部分故障后测量的部分（ 图 1中的位置A）。 （ b </strong&gt;）是显示平面位错的量规部分的亮场图像。 （ c ）示出了在测量部分处的衍射图。经修改13 ，经AIP出版许可。 <a href="http://ecsource.jove.com/files/ftp_upload/55735/55735fig6large.jpg" target="_blank">请点击此处查看此图的较大版本。</a> <img alt="图7" src="/files/ftp_upload/55735/55735fig7.jpg" /> 图7: 原位 EAD实验TEM图像。这些图像显示了对位错运动的机械和电荷负载效应。 （ b1 ） - （ b4 ）示出（ a ）中的区域（ b ）的放大视图。 （ b1 ）显示出产后平衡状态下的样品。 （ b2 ）识别出由超过（（ <strong&gt; b1）。当施加电流时没有观察到变化（ b3 ）。一旦应变再次增加，再次发现进一步的脱位变化（ b4 ）。经AIP出版许可转载13 。 <a href="http://ecsource.jove.com/files/ftp_upload/55735/55735fig7large.jpg" target="_blank">请点击此处查看此图的较大版本。</a>

Watch this Scientific Journal Video about A Novel Method for In Situ Electromechanical Characterization of Nanoscale Specimens at JoVE.com

A Novel Method for In Situ Electromechanical Characterization of Nanoscale Specimens

使用宏观样品，隔离电气和热效应对电辅助变形（EAD）是非常困难的。已经开发了金属样品微观和纳米结构以及定制测试程序，以评估施加的电流对形成的影响，而不会有焦耳加热和这些样品上位错的演变。

一种新的方法<em&gt;原位</em&gt;纳米级样品的机电表征

Electrically assisted deformation (EAD) is increasingly being used to improve the formability of metals during processes such as sheet metal rolling and ...

a-novel-method-for-situ-electromechanical-characterization-nanoscale

Research

JoVE Journal

Engineering

A Novel Method for In Situ Electromechanical Characterization of Nanoscale Specimens

9.1K 次观看.  US Naval Research Laboratory. 使用宏观样品，隔离电气和热效应对电辅助变形（EAD）是非常困难的。已经开发了金属样品微观和纳米结构以及定制测试程序，以评估施加的电流对形成的影响，而不会有焦耳加热和这些样品上位错的演变。 

视频: A Novel Method for In Situ Electromechanical Characterization of Nanoscale Specimens

Quantitative and Qualitative Examination of Particle-particle Interactions Using Colloidal Probe Nanoscopy

Colloidal Probe Nanoscopy (CPN), the study of the nano-scale interactive forces between a specifically prepared colloidal probe and any chosen substrate using the Atomic Force Microscope (AFM), can provide key insights into physical interactions present within colloidal systems. Colloidal systems are widely existent in several applications including, pharmaceuticals, foods, paints, paper, soil and minerals, detergents, printing and much more.1-3 Furthermore, colloids can exist in many states such as emulsions, foams and suspensions. Using colloidal probe nanoscopy one can obtain key information on the adhesive properties, binding energies and even gain insight into the physical stability and coagulation kinetics of the colloids present within. Additionally, colloidal probe nanoscopy can be used with biological cells to aid in drug discovery and formulation development. In this paper we describe a method for conducting colloidal probe nanoscopy, discuss key factors that are important to consider during the measurement, and show that both quantitative and qualitative data that can be obtained from such measurements.

Colloidal probe nanoscopy can be used within a variety of fields to gain insight into the physical stability and coagulation kinetics of colloidal systems and aid in drug discovery and formulation sciences using biological systems. The method described within provides a quantitative and qualitative means to study such systems.

粒子粒子相互作用采用胶体探针纳米显微定量和定性检查

Colloidal Probe Nanoscopy (CPN), the study of the nano-scale interactive forces between a specifically prepared colloidal probe and any chosen substrate ...

科研

化学

Remote Magnetic Actuation of Micrometric Probes for in situ 3D Mapping of Bacterial Biofilm Physical Properties

Bacterial adhesion and growth on interfaces lead to the formation of three-dimensional heterogeneous structures so-called biofilms. The cells dwelling in these structures are held together by physical interactions mediated by a network of extracellular polymeric substances. Bacterial biofilms impact many human activities and the understanding of their properties is crucial for a better control of their development &#8212; maintenance or eradication &#8212; depending on their adverse or beneficial outcome. This paper describes a novel methodology aiming to measure in situ the local physical properties of the biofilm that had been, until now, examined only from a macroscopic and homogeneous material perspective. The experiment described here&#160;involves introducing magnetic particles into a growing biofilm to seed local probes that can be remotely actuated without disturbing the structural properties of the biofilm. Dedicated magnetic tweezers were developed to exert a defined force on each particle embedded in the biofilm. The setup is mounted on the stage of a microscope to enable the&#160;recording of time-lapse images of the particle-pulling period. The particle trajectories are then extracted from the pulling sequence and the local viscoelastic parameters are derived from each particle displacement curve, thereby providing the 3D-spatial distribution of the parameters. Gaining insights into the biofilm mechanical profile is essential from an engineer&#39;s point of view for biofilm control purposes but also from a fundamental perspective to clarify the relationship between the architectural properties and the specific biology of these structures.

Remote Magnetic Actuation of Micrometric Probes for in situ 3D Mapping of Bacterial Biofilm Physical Properties

This paper shows an original methodology based on the remote actuation of magnetic particles seeded in a bacterial biofilm and the development of dedicated magnetic tweezers to measure in situ the local mechanical properties of the complex living material built by micro-organisms at interfaces.

测微探针进行远程磁驱动<em&gt;原位</em&gt; 3D细菌生物膜物理性质的映射

Bacterial adhesion and growth on interfaces lead to the formation of three-dimensional heterogeneous structures so-called biofilms. The cells dwelling in ...

生物工程

Characterization Of Multi-layered Fish Scales (Atractosteus spatula) Using Nanoindentation, X-ray CT, FTIR, and SEM

The hierarchical architecture of protective biological materials such as mineralized fish scales, gastropod shells, ram&#8217;s horn, antlers, and turtle shells provides unique design principles with potentials for guiding the design of protective materials and systems in the future. Understanding the structure-property relationships for these material systems at the microscale and nanoscale where failure initiates is essential. Currently, experimental techniques such as nanoindentation, X-ray CT, and SEM provide researchers with a way to correlate the mechanical behavior with hierarchical microstructures of these material systems1-6. However, a well-defined standard procedure for specimen preparation of mineralized biomaterials is not currently available. In this study, the methods for probing spatially correlated chemical, structural, and mechanical properties of the multilayered scale of A. spatula using nanoindentation, FTIR, SEM, with energy-dispersive X-ray (EDX) microanalysis, and X-ray CT are presented.

Characterization Of Multi-layered Fish Scales Atractosteus spatula Using Nanoindentation, X-ray CT, FTIR, and SEM

This paper presents the methods used for probing spatially correlated chemical, structural, and mechanical properties of the multilayered scale of Atractosteus spatula (A. spatula) using nanoindentation, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and X-ray computed tomography (X-ray CT). The experimental results have been used to investigate the design principles of protective biological materials.

表征多层鱼鳞（中<em&gt; Atractosteus锅铲</em&gt;）基于纳米压痕技术，X射线CT，红外光谱和SEM

The hierarchical architecture of protective biological materials such as mineralized fish scales, gastropod shells, ram&#8217;s horn, antlers, and turtle ...

A Standard and Reliable Method to Fabricate Two-Dimensional Nanoelectronics

Two-dimensional (2D) materials have attracted huge attention due to their unique properties and potential applications. Since wafer scale synthesis of 2D materials is still in nascent stages, scientists cannot fully rely on traditional semiconductor techniques for related research. Delicate processes from locating the materials to electrode definition need to be well controlled. In this article, a universal fabrication protocol required in manufacturing nanoscale electronics, such as 2D quasi-heterojunction bipolar transistors (Q-HBT), and 2D back-gated transistors are demonstrated. This protocol includes the determination of material position, electron beam lithography (EBL), metal electrode definition, et al. A step by step narrative of the fabrication procedures for these devices are also presented. Furthermore, results show that each of the fabricated devices has achieved high performance with high repeatability. This work reveals a comprehensive description of process flow for preparing 2D nano-electronics, enables the research groups to access this information, and pave the way toward future electronics.

The article aims to introduce a standard and reliable fabrication procedure for the development of future low dimensional nanoelectronics.

制造二维电子学的标准可靠方法

Two-dimensional (2D) materials have attracted huge attention due to their unique properties and potential applications. Since wafer scale synthesis of 2D ...

工程学

Probing Surface Electrochemical Activity of Nanomaterials using a Hybrid Atomic Force Microscope-Scanning Electrochemical Microscope (AFM-SECM)

Scanning electrochemical microscopy (SECM) is used to measure the local electrochemical behavior of liquid/solid, liquid/gas and liquid/liquid interfaces. Atomic force microscopy (AFM) is a versatile tool to characterize micro- and nanostructure in terms of topography and mechanical properties. However, conventional SECM or AFM provides limited laterally resolved information on electrical or electrochemical properties at nanoscale. For instance, the activity of a nanomaterial surface at crystal facet levels is difficult to resolve by conventional electrochemistry methods. This paper reports the application of a combination of AFM and SECM, namely, AFM-SECM, to probe nanoscale surface electrochemical activity while acquiring high-resolution topographical data. Such measurements are critical to understanding the relationship between nanostructure and reaction activity, which is relevant to a wide range of applications in material science, life science and chemical processes. The versatility of the combined AFM-SECM is demonstrated by mapping topographical and electrochemical properties of faceted nanoparticles (NPs) and nanobubbles (NBs), respectively. Compared to previously reported SECM imaging of nanostructures, this AFM-SECM enables quantitative assessment of local surface activity or reactivity with higher resolution of surface mapping.

Probing Surface Electrochemical Activity of Nanomaterials using a Hybrid Atomic Force Microscope-Scanning Electrochemical Microscope AFM-SECM

Atomic force microscopy (AFM) combined with scanning electrochemical microscopy (SECM), namely, AFM-SECM, can be used to simultaneously acquire high-resolution topographical and electrochemical information on material surfaces at nanoscale. Such information is critical to understanding heterogeneous properties (e.g., reactivity, defects, and reaction sites) on local surfaces of nanomaterials, electrodes and biomaterials.

使用混合原子力显微镜扫描电化学显微镜（AFM-SECM）探测纳米材料的表面电化学活性

Scanning electrochemical microscopy (SECM) is used to measure the local electrochemical behavior of liquid/solid, liquid/gas and liquid/liquid interfaces. ...

Micromechanical Tension Testing of Additively Manufactured 17-4 PH Stainless Steel Specimens

This study presents a methodology for the rapid fabrication and micro-tensile testing of additively manufactured (AM) 17-4PH stainless steels by combining photolithography, wet-etching, focused ion beam (FIB) milling, and modified nanoindentation. Detailed procedures for proper sample surface preparation, photo-resist placement, etchant preparation, and FIB sequencing are described herein to allow for high throughput (rapid) specimen fabrication from bulk AM 17-4PH stainless steel volumes. Additionally, procedures for the nano-indenter tip modification to allow tensile testing are presented and a representative micro specimen is fabricated and tested to failure in tension. Tensile-grip-to-specimen alignment and sample engagement were the main challenges of the micro-tensile testing; however, by reducing the indenter tip dimensions, alignment and engagement between the tensile grip and specimen were improved. Results from the representative micro-scale in situ SEM tensile test indicate a single slip plane specimen fracture (typical of a ductile single crystal failure), differing from macro-scale AM 17-4PH post-yield tensile behavior.

Presented here is a procedure for measuring fundamental material properties through micromechanical tension testing. Described are the methods for micro-tensile specimen fabrication (allowing rapid micro-specimen fabrication from bulk material volumes by combining photolithography, chemical etching, and focused ion beam milling), indenter tip modification, and micromechanical tension testing (including an example).

增材制造的17-4 PH不锈钢试样的微机械张力测试

This study presents a methodology for the rapid fabrication and micro-tensile testing of additively manufactured (AM) 17-4PH stainless steels by combining ...

Optimizing Magnetic Force Microscopy Resolution and Sensitivity to Visualize Nanoscale Magnetic Domains

Magnetic force microscopy (MFM) enables mapping local magnetic fields across a sample surface with nanoscale resolution. To perform MFM, an atomic force microscopy (AFM) probe whose tip has been magnetized vertically (i.e., perpendicular to the probe cantilever) is oscillated at a fixed height above the sample surface. The resultant shifts in the oscillation phase or frequency, which are proportional to the magnitude and sign of the vertical magnetic force gradient at each pixel location, are then tracked and mapped. Although the spatial resolution and sensitivity of the technique increases with decreasing lift height above the surface, this seemingly straightforward path to improved MFM images is complicated by considerations such as minimizing topographical artifacts due to shorter range van der Waals forces, increasing the oscillation amplitude to further improve sensitivity, and the presence of surface contaminants (in particular water due to humidity under ambient conditions). In addition, due to the orientation of the probe's magnetic dipole moment, MFM is intrinsically more sensitive to samples with an out-of-plane magnetization vector. Here, high-resolution topographical and magnetic phase images of single and bicomponent nanomagnet artificial spin-ice (ASI) arrays obtained in an inert (argon) atmosphere glovebox with &lt;0.1 ppm O2 and H2O are reported. Optimization of lift height and drive amplitude for high resolution and sensitivity while simultaneously avoiding the introduction of topographical artifacts is discussed, and detection of the stray magnetic fields emanating from either end of the nanoscale bar magnets (~250 nm long and &lt;100 nm wide) aligned in the plane of the ASI sample surface is shown. Likewise, using the example of a Ni-Mn-Ga magnetic shape memory alloy (MSMA), MFM is demonstrated in an inert atmosphere with magnetic phase sensitivity capable of resolving a series of adjacent magnetic domains each ~200 nm wide.

Magnetic force microscopy (MFM) employs a vertically magnetized atomic force microscopy probe to measure sample topography and local magnetic field strength with nanoscale resolution. Optimizing MFM spatial resolution and sensitivity requires balancing decreasing lift height against increasing drive (oscillation) amplitude, and benefits from operating in an inert atmosphere glovebox.

优化磁力显微镜分辨率和灵敏度，以可视化纳米级磁畴

Magnetic force microscopy (MFM) enables mapping local magnetic fields across a sample surface with nanoscale resolution. To perform MFM, an atomic force ...

Atomic Force Microscopy Cantilever-Based Nanoindentation: Mechanical Property Measurements at the Nanoscale in Air and Fluid

An atomic force microscope (AFM) fundamentally measures the interaction between a nanoscale AFM probe tip and the sample surface. If the force applied by the probe tip and its contact area with the sample can be quantified, it is possible to determine the nanoscale mechanical properties (e.g., elastic or Young&#39;s modulus) of the surface being probed. A detailed procedure for performing quantitative AFM cantilever-based nanoindentation experiments is provided here, with representative examples of how the technique can be applied to determine the elastic moduli of a wide variety of sample types, ranging from kPa to GPa. These include live mesenchymal stem cells (MSCs) and nuclei in physiological buffer, resin-embedded dehydrated loblolly pine cross-sections, and Bakken shales of varying composition.
Additionally, AFM cantilever-based nanoindentation is used to probe the rupture strength (i.e., breakthrough force) of phospholipid bilayers. Important practical considerations such as method choice and development, probe selection and calibration, region of interest identification, sample heterogeneity, feature size and aspect ratio, tip wear, surface roughness, and data analysis and measurement statistics are discussed to aid proper implementation of the technique. Finally, co-localization of AFM-derived nanomechanical maps with electron microscopy techniques that provide additional information regarding elemental composition is demonstrated.

Quantifying the contact area and force applied by an atomic force microscope (AFM) probe tip to a sample surface enables nanoscale mechanical property determination. Best practices to implement AFM cantilever-based nanoindentation in air or fluid on soft and hard samples to measure elastic modulus or other nanomechanical properties are discussed.

原子力显微镜悬臂式纳米压痕:空气和流体中纳米级机械性能测量

An atomic force microscope (AFM) fundamentally measures the interaction between a nanoscale AFM probe tip and the sample surface. If the force applied by ...

A Virtual Simulation Experiment of Mechanics: Material Deformation and Failure Based on Scanning Electron Microscopy

This work presents a set of comprehensive virtual experiments to detect material deformation and failure. The most commonly used pieces of equipment in mechanics and material disciplines, such as a metallographic cutting machine and a high-temperature universal creep testing machine, are integrated into a web-based system to provide different experimental services to users in an immersive and interactive learning environment. The protocol in this work is divided into five subsections, namely, the preparation of the materials, molding the specimen, specimen characterization, specimen loading, nanoindenter installation, and SEM in situ experiments, and this protocol aims to provide an opportunity for users regarding the recognition of different equipment and the corresponding operations, as well as the enhancement of laboratory awareness, etc., using a virtual simulation approach. To provide clear guidance for the experiment, the system highlights the equipment/specimen to be used in the next step and marks the pathway that leads to the equipment with a conspicuous arrow. To mimic the hands-on experiment as closely as possible, we designed and developed a three-dimensional laboratory room, equipment, operations, and experimental procedures. Moreover, the virtual system also considers interactive exercises and registration before using chemicals during the experiment. Incorrect operations are also allowed, resulting in a warning message informing the user. The system can provide interactive and visualized experiments to users at different levels.

This work presents a three-dimensional virtual simulation experiment for material deformation and failure that provides visualized experimental processes. Through a set of experiments, users can become familiar with the equipment and learn the operations in an immersive and interactive learning environment.

力学虚拟仿真实验:基于扫描电镜的材料变形与失效

This work presents a set of comprehensive virtual experiments to detect material deformation and failure. The most commonly used pieces of equipment in ...

High-Speed Magnetic Tweezers for Nanomechanical Measurements on Force-Sensitive Elements

Single-molecule magnetic tweezers (MTs) have served as powerful tools to forcefully interrogate biomolecules, such as nucleic acids and proteins, and are therefore poised to be useful in the field of mechanobiology. Since the method commonly relies on image-based tracking of magnetic beads, the speed limit in recording and analyzing images, as well as the thermal fluctuations of the beads, has long hampered its application in observing small and fast structural changes in target molecules. This article describes detailed methods for the construction and operation of a high-resolution MT setup that can resolve nanoscale, millisecond dynamics of biomolecules and their complexes. As application examples, experiments with DNA hairpins and SNARE complexes (membrane-fusion machinery) are demonstrated, focusing on how their transient states and transitions can be detected in the presence of piconewton-scale forces. We expect that high-speed MTs will continue to enable high-precision nanomechanical measurements on molecules that sense, transmit, and generate forces in cells, and thereby deepen our molecular-level understanding of mechanobiology.

Here, we describe a high-speed magnetic tweezer setup that performs nanomechanical measurements on force-sensitive biomolecules at the maximum rate of 1.2 kHz. We introduce its application to DNA hairpins and SNARE complexes as model systems, but it will be also applicable to other molecules involved in mechanobiological events.

高速磁镊，用于力敏元件的纳米力学测量

Single-molecule magnetic tweezers (MTs) have served as powerful tools to forcefully interrogate biomolecules, such as nucleic acids and proteins, and are ...

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