这项工作由新加坡教育部学术研究基金 (AcRF) 1 层 (RG171/15) 主办。

1. 微流控通道的制备
<ol><li>混合甲基 () 与弹性体基础的比例为10:1。</li>
	<li>将混合物放入真空烤箱中, 将其倒在硅晶片上, 上面有一个负色调的光刻胶图案。</li>
	<li>再次德加的图案硅晶片, 并加热它在70°c 3 小时, 在一个孵化器凝固。</li>
</ol>2. 叉指变换器的制作
<ol><li>在吴林波3晶片上沉积 20 nm 铬和 400 nm 的铝;图案20条, 宽度为150µm, 在塑料面罩上的光圈为2厘米, 通过将正光刻胶沉积在基板上进行光刻。</li>
	<li>用丙酮去除未暴露区域的 Cr 铝层。</li>
	<li>用氧等离子体 (氮气和氧比为 2:1) 将其表面处理为六十年代的 30 W 的功率。</li>
	<li>将该微通道对准, 并将其与吴林波3基板结合, 用拇指按压几秒钟。</li>
	<li>将集成设备放置在加热室中, 温度为60摄氏度, 为3小时。</li>
</ol>3. 双频励磁
<ol><li>同时应用两个频率分量 (f1 和f3, 其基本频率及其三次谐波分别) 与相差φ之间的 IDTs 对对, 使所生产的锯子可表示如下。 <img alt="Equation 1" src="/files/ftp_upload/58085/58085eq1.jpg"> 这里 <img alt="Equation 2" src="/files/ftp_upload/58085/58085eq2.jpg">和<img alt="Equation 3" src="/files/ftp_upload/58085/58085eq3.jpg"> = 声学压力。</li>
	<li>利用 ArbExpress 应用软件的方程编辑器在100毫秒/秒的采样频率上合成双频波形, 然后将其存储到函数发生器中, 作为任意输入的 SAW 励磁实验通过USB 电缆。</li>
	<li>改变基本频率的力量到总发射的力量<img alt="Equation 4" src="/files/ftp_upload/58085/58085eq4.jpg">从 100% (励磁在纯粹基本的频率) 到 0% (励磁在纯粹第三谐波);为了一个好的比较, 改变, 但保持总功率相同。</li>
	<li>将双频励磁的相位差改变为360°。</li>
</ol>4. 数值模拟
<ol><li>描述低雷诺 (即 Re 0.55) 和马赫数的不可压缩层流流的运动, 如下所示35。 <img alt="Equation 5" src="/files/ftp_upload/58085/58085eq5.jpg"> <img alt="Equation 6" src="/files/ftp_upload/58085/58085eq6.jpg"> 这里 <img alt="Equation 7" src="/files/ftp_upload/58085/58085eq7.jpg">= 流体速度, <img alt="Equation 8" src="/files/ftp_upload/58085/58085eq8.jpg">= 动态粘度, <img alt="Equation 9" src="/files/ftp_upload/58085/58085eq9.jpg">= 流体密度, <img alt="Equation 10" src="/files/ftp_upload/58085/58085eq10.jpg">= 流体的压力, <img alt="Equation 11" src="/files/ftp_upload/58085/58085eq11.jpg">= 标识矩阵和 <img alt="Equation 12" src="/files/ftp_upload/58085/58085eq12.jpg">= 外力。</li>
	<li>描述在物体上产生的斯托克城拖曳力, 如下所示36。 <img alt="Equation 13" src="/files/ftp_upload/58085/58085eq13.jpg"> 这里 <img alt="Equation 14" src="/files/ftp_upload/58085/58085eq14.jpg">= 微粒的半径, <img alt="Equation 15" src="/files/ftp_upload/58085/58085eq15.jpg">= 流体的速度和 <img alt="Equation 16" src="/files/ftp_upload/58085/58085eq16.jpg">= 微粒的速度。</li>
	<li>在x轴 (横跨微通道宽度) 的微通道中, 根据16的频率推导出适用于所述微粒的声辐射力。 <img alt="Equation 17" src="/files/ftp_upload/58085/58085eq17.jpg"> 这里 <img alt="Equation 18" src="/files/ftp_upload/58085/58085eq18.jpg">= 微粒的容量, <img alt="Equation 19" src="/files/ftp_upload/58085/58085eq19.jpg">= 微粒的密度, <img alt="Equation 20" src="/files/ftp_upload/58085/58085eq20.jpg">= 介质的密度, <img alt="Equation 21" src="/files/ftp_upload/58085/58085eq21.jpg">= 微粒的压缩性, 和 <img alt="Equation 22" src="/files/ftp_upload/58085/58085eq22.jpg">= 介质的压缩性。</li>
	<li>推导了双频励磁产生的声辐射力如下。 <img alt="Equation 23" src="/files/ftp_upload/58085/58085eq23.jpg">
</li>
	<li>在声波辐射力和由牛顿第二定律所控制的斯托克斯拖曳力的情况下, 在通道宽度 (沿y轴) 上表达横向运动, 如下所示。 <img alt="Equation 24" src="/files/ftp_upload/58085/58085eq24.jpg">
</li>
	<li>在个人计算机上使用第四阶的朗格-库塔方法求解上述常微分方程。分别将时间步长和总工期设置为1µs 和二十年代。</li>
</ol>5. 实验观察
<ol><li>旋转溶液集中 5.9 x 107与4µm 绿色荧光聚苯乙烯珠每1毫升的漩涡约 2-3 分钟, 然后浸泡在超声波 sonicator 10 分钟, 以扰乱任何团聚之前, 每次测试。</li>
	<li>将混合物装入3毫升注射器, 然后用注射器泵驱动, 流速为 3-5 µL/分钟。</li>
	<li>驱动与双频信号从一个功能发生器后跟功率放大器。</li>
	<li>在40X 放大的光镜下观察下游微通道中的稳定微粒, 并用数码相机记录图像。</li>
	<li>用 ImageJ 和建立的尺度测量捕获数字图像中累积微粒的位置, 然后用规范化的荧光亮度定量测定累积微粒的浓度。每个压力节点。</li>
</ol>

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作者没有什么可透露的。

本文研究了双频激励下的螺旋埋弧焊微通道中的微粒运动, 并对双频励磁信号进行了有效的可调谐图形技术的开发和测试。这种波形的产生很容易由大多数函数发生器实现, 调整方法非常方便。12和 s 的11频率响应的捏造 IDTs 说明了几个共振模式34。测量的基本频率为6.1 兆赫和17.8 兆赫的第三次谐波接近那些被设计的价值 (6.2 和18.6 兆赫) 以相似的传输系数,-8.34 </...

在生物、化学、生物物理学和医学过程中, 中控技术将一个或多个功能集成在微芯片上。通量允许实验室设置的规模小于亚毫米, 快速反应速度, 短响应时间, 高过程控制, 低容量消耗 (减少浪费, 较低的试剂成本, 和较少的样品量), 高吞吐量由于并行化, 在未来大规模生产和经济高效的一次性耗材的低成本, 化学, 放射性, 或生物研究的高安全性, 以及紧凑和便携设备1,2的优势。精确的细胞操作 (即积累和分离) 在基于控制的分析和诊断3,4中是至关重要的。然而, 微粒操纵的准确性和重现性有各种各样的挑战。许多技术, 如电渗透5, 介电泳 (DEP)6, magnetophoresis7, thermophoresis8,9, 光学方法10, 光电方法11, 开发了水动力方法12和 acoustophoresis13、14、15。相比之下, 声学方法是适用于一个应用, 因为理论上, 许多类型的微粒/细胞可以有效地操纵和无创性与足够高的对比度 (密度和压缩性) 比较周围的液体。因此, 与它们的对应物相比, 声学方法天生符合大多数微粒和生物物体的条件, 不管它们的光学、电学和磁性特性16。
根据斯内尔定律17, IDTs 的表面声波 (锯) 主要传播在压电基底的表面, 在几个波长的厚度上, 然后在瑞利角向微通道中的流体泄漏. 18,19,20,21,22。由于其能量的定位, 在高频率下具有很好的设计灵活性, 具有良好的微流控通道和小型化的系统集成, 使其在表面上具有高能量效率的技术优势。微电子-机械系统 (MEMS) 技术, 具有很高的大批量生产潜力23。在这个协议中, 锯是由一对相同的 IDTs 产生的, 并以相反的方向传播, 在微通道中产生驻波, 或螺旋弧, 悬浮微粒被推到压力节点, 主要由应用的声学辐射力24。这种合力的振幅由激发频率、微粒大小和声学对比系数22、25决定。
这样的 acoustophoresis 限制了预先设定的操作模式, 而这些方式不易调整。IDTs 的激发频率由它们的周期距离决定, 因此带宽相当有限。为了提高调谐和操纵能力, 开发了一些策略。在微通道的不同部位应用的声驻波的第一和第二模态, 可以根据不同的运动速度将微粒更有效地分离到节点线26。这两种模式也可应用于微通道的整个部分, 并交替切换27、28、29。然而, 为此, 需要大量的设备 (即三个函数发生器、两个阻抗匹配单元和一个电磁继电器), 由于不同的实验装置的成本和控制复杂性的增加,电阻抗在压电陶瓷板的基本频率和第三次谐波30。此外, 倾斜手指叉指变换器 (SFITs) 可以用来调整细胞和微粒模式的刺激一段时间的倾斜手指为某一共振20,31。然而, 带宽与倾斜的手指的数量成反比。与传统的螺旋型磁粉分离器的单节线相比, 多压力节线具有较高的分离效率和灵敏度。另外, 压力节点的位置也可以通过调整在设计32,33中应用到两个 IDTs 的相位差来改变。
IDTs 的基本频率和第三次谐波具有相似的频率响应, 使它们能够同时激发, 为微粒操作34提供了更多的调谐。与传统的单频励磁相比, 调整双频励磁的声压和两者之间的相位提供了技术的唯一性, 例如高达2倍的缩短运动时间到压力节点线或中心的微通道, 不同数量和位置的压力节点线, 和微粒浓度。

<table border="0" cellpadding="0" cellspacing="0" width="689">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">poly-dimethylsiloxane</td>
			<td style="width:147px;">Dow Corning</td>
			<td style="width:119px;">Sylgard 184</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">poly-dimethylsiloxane elastomer base</td>
			<td>Dow Corning</td>
			<td>Sylgard 184</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">silicon wafer</td>
			<td>Bonda Technology</td>
			<td>SI8PSPD</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">negative tone photoresist</td>
			<td>Microchem</td>
			<td>SU-8</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">double-side polished LiNbO3 wafer</td>
			<td>University Wafer</td>
			<td style="width:119px;">Y-128&#176;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">positive photoresist</td>
			<td>Nicolaus-Otto-Stra&#223;e</td>
			<td>AZ 9260</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">oxygen plasma</td>
			<td>Harrick Plasma</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">plastic mask</td>
			<td>Infinite Graphics</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

microparticle manipulation by standing surface acoustic waves with dual-frequency excitations

本文演示了一种提高驻面声波 (螺旋埋弧) 在单片机系统中微粒操作的调谐能力的方法。同时激发的基本频率和它的第三次谐波, 这被称为双频励磁, 对一对交叉传感器 (IDTs) 可以产生一种新的类型的驻声波在微流控通道。改变双频励磁信号中的功率和相位, 可重构应用于微通道内微粒的声辐射力 (例如, 压力节点的数量和位置, 以及在相应的压力节点上的微粒浓度)。本文表明, 微粒子的运动时间只有一个压力节点可以减少2倍的功率比的基本频率大于90%。相比之下, 微通道中有三个压力节点, 如果小于这个阈值。此外, 调整基本频率与第三次谐波之间的初始相位, 会导致三个螺旋埋弧压力节点的不同运动速率, 以及微通道中每个压力节点的微粒百分比。实验观测与数值预测有很好的一致性。这种新颖的励磁方法能够很容易地、无创性地集成到系统中, 具有广泛的可维持, 对实验装置的改动也只有少数。

在双频励磁 (6.2 和18.6 兆赫) 下, 螺旋埋弧焊的声压和声辐射力分布在图 1中。在这里, 双频励磁发生在聚苯乙烯微粒 (直径4µm) 在微通道, 宽度为300µm 在一个声学功率146兆瓦。在P1 > 90% 的情况下, 产生的声学压力总是处于阶段, 因此只有一个压力节点存在于y = 150 µm。相比之下, 三压力节点存在于y = 75, 150, 225 µm 在p1</s...

Watch this Scientific Journal Video about Microparticle Manipulation by Standing Surface Acoustic Waves with Dual-frequency Excitations at JoVE.com

Microparticle Manipulation by Standing Surface Acoustic Waves with Dual-frequency Excitations

提出了一种用双频励磁微流控通道处理微粒的协议。

双频激励下驻面声波的微粒操纵

We demonstrate a method for increasing the tuning ability of a standing surface acoustic wave (SSAW) for microparticles manipulation in a lab-on-a-chip ...

microparticle-manipulation-standing-surface-acoustic-waves-with-dual

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Application of Newton's Laws of Motion

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6.9K 次观看.  Nanyang Technological University. 提出了一种用双频励磁微流控通道处理微粒的协议。

视频: Microparticle Manipulation by Standing Surface Acoustic Waves with Dual-frequency Excitations

Synthesis of Phase-shift Nanoemulsions with Narrow Size Distributions for Acoustic Droplet Vaporization and Bubble-enhanced Ultrasound-mediated Ablation

High-intensity focused ultrasound (HIFU) is used clinically to thermally ablate tumors. To enhance localized heating and improve thermal ablation in tumors, lipid-coated perfluorocarbon droplets have been developed which can be vaporized by HIFU. The vasculature in many tumors is abnormally leaky due to their rapid growth, and nanoparticles are able to penetrate the fenestrations and passively accumulate within tumors. Thus, controlling the size of the droplets can result in better accumulation within tumors. In this report, the preparation of stable droplets in a phase-shift nanoemulsion (PSNE) with a narrow size distribution is described. PSNE were synthesized by sonicating a lipid solution in the presence of liquid perfluorocarbon. A narrow size distribution was obtained by extruding the PSNE multiple times using filters with pore sizes of 100 or 200 nm. The size distribution was measured over a 7-day period using dynamic light scattering. Polyacrylamide hydrogels containing PSNE were prepared for in vitro experiments. PSNE droplets in the hydrogels were vaporized with ultrasound and the resulting bubbles enhanced localized heating. Vaporized PSNE enables more rapid heating and also reduces the ultrasound intensity needed for thermal ablation. Thus, PSNE is expected to enhance thermal ablation in tumors, potentially improving therapeutic outcomes of HIFU-mediated thermal ablation treatments.

Phase-shift nanoemulsions (PSNE) can be vaporized using high intensity focused ultrasound to enhance localized heating and improve thermal ablation in tumors. In this report, the preparation of stable PSNE with a narrow size distribution is described. Furthermore, the impact of vaporized PSNE on ultrasound-mediated ablation is demonstrated in tissue-mimicking phantoms.

相移窄粒度分布的纳米乳液的合成声波液滴蒸发和泡增强的超声介导消融

High-intensity  focused ultrasound (HIFU) is used clinically to thermally ablate tumors. To  enhance localized heating and improve thermal ablation in ...

科研

工程学

Characterization of Surface Modifications by White Light Interferometry: Applications in Ion Sputtering, Laser Ablation, and Tribology Experiments

In materials science and engineering it is often necessary to obtain quantitative measurements of surface topography with micrometer lateral resolution. From the measured surface, 3D topographic maps can be subsequently analyzed using a variety of software packages to extract the information that is needed.
In this article we describe how white light interferometry, and optical profilometry (OP) in general, combined with generic surface analysis software, can be used for materials science and engineering tasks. In this article, a number of applications of white light interferometry for investigation of surface modifications in mass spectrometry, and wear phenomena in tribology and lubrication are demonstrated. We characterize the products of the interaction of semiconductors and metals with energetic ions (sputtering), and laser irradiation (ablation), as well as ex situ measurements of wear of tribological test specimens.
Specifically, we will discuss:
<ol class="lroman">
	<li>Aspects of traditional ion sputtering-based mass spectrometry such as sputtering rates/yields measurements on Si and Cu and subsequent time-to-depth conversion.</li>
	<li>Results of quantitative characterization of the interaction of femtosecond laser irradiation with a semiconductor surface. These results are important for applications such as ablation mass spectrometry, where the quantities of evaporated material can be studied and controlled via pulse duration and energy per pulse. Thus, by determining the crater geometry one can define depth and lateral resolution versus experimental setup conditions.</li>
	<li>Measurements of surface roughness parameters in two dimensions, and quantitative measurements of the surface wear that occur as a result of friction and wear tests.</li>
</ol>
Some inherent drawbacks, possible artifacts, and uncertainty assessments of the white light interferometry approach will be discussed and explained.

White light microscope interferometry is an optical, noncontact and quick method for measuring the topography of surfaces. It is shown how the method can be applied toward mechanical wear analysis, where wear scars on tribological test samples are analyzed; and in materials science to determine ion beam sputtering or laser ablation volumes and depths.

白光干涉表面改性中的应用离子溅射，激光烧蚀，与摩擦学实验表征

In materials science and engineering it is often necessary to obtain quantitative measurements of surface topography with micrometer lateral resolution. ...

Fabrication, Operation and Flow Visualization in Surface-acoustic-wave-driven Acoustic-counterflow Microfluidics

Surface acoustic waves (SAWs) can be used to drive liquids in portable microfluidic chips via the acoustic counterflow phenomenon. In this video we present the fabrication protocol for a multilayered SAW acoustic counterflow device. The device is fabricated starting from a lithium niobate (LN) substrate onto which two interdigital transducers (IDTs) and appropriate markers are patterned. A polydimethylsiloxane (PDMS) channel cast on an SU8 master mold is finally bonded on the patterned substrate. Following the fabrication procedure, we show the techniques that allow the characterization and operation of the acoustic counterflow device in order to pump fluids through the PDMS channel grid. We finally present the procedure to visualize liquid flow in the channels. The protocol is used to show on-chip fluid pumping under different flow regimes such as laminar flow and more complicated dynamics characterized by vortices and particle accumulation domains.

In this video we first describe fabrication and operation procedures of a surface acoustic wave (SAW) acoustic counterflow device. We then demonstrate an experimental setup that allows for both qualitative flow visualization and quantitative analysis of complex flows within the SAW pumping device.

制造，操作和表面声波驱动声逆流微流体流动可视化

Surface acoustic waves (SAWs) can be used to drive liquids in portable microfluidic chips via the acoustic counterflow phenomenon. In this video we ...

Selective Area Modification of Silicon Surface Wettability by Pulsed UV Laser Irradiation in Liquid Environment

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of biosensing devices. We report on a protocol of using KrF and ArF lasers irradiating Si (001) samples immersed in a liquid environment with low number of pulses and operating at moderately low pulse fluences to induce Si wettability modification. Wafers immersed for up to 4 hr in a 0.01% H2O2/H2O solution did not show measurable change in their initial contact angle (CA) ~75&#176;. However, the 500-pulse KrF and ArF lasers irradiation of such wafers in a microchamber filled with 0.01% H2O2/H2O solution at 250 and 65 mJ/cm2, respectively, has decreased the CA to near 15&#176;, indicating the formation of a superhydrophilic surface. The formation of OH-terminated Si (001), with no measurable change of the wafer&#8217;s surface morphology, has been confirmed by X-ray photoelectron spectroscopy and atomic force microscopy measurements. The selective area irradiated samples were then immersed in a biotin-conjugated fluorescein-stained nanospheres solution for 2 hr, resulting in a successful immobilization of the nanospheres in the non-irradiated area. This illustrates the potential of&#160;the method for selective area biofunctionalization and fabrication of advanced Si-based biosensing architectures. We also describe a similar protocol of irradiation of wafers immersed in methanol (CH3OH) using ArF laser operating at pulse fluence of 65 mJ/cm2 and in situ formation of a strongly hydrophobic surface of Si (001) with the CA of 103&#176;. The XPS results indicate ArF laser induced formation of Si&#8211;(OCH3)x compounds responsible for the observed hydrophobicity. However, no such compounds were found by XPS on the Si surface irradiated by KrF laser in methanol, demonstrating the inability of the KrF laser to photodissociate methanol and create -OCH3 radicals.

We report on a process of in situ alteration of HF treated Si (001) surface into a hydrophilic or hydrophobic state by irradiating samples in microfluidic chambers filled with&#160;H2O2/H2O solution (0.01%-0.5%) or methanol solutions using pulsed UV laser of a relative low pulse fluence.

硅表面润湿性的选择区域改性脉冲紫外激光照射在液体环境

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of ...

Characterization of Full Set Material Constants and Their Temperature Dependence for Piezoelectric Materials Using Resonant Ultrasound Spectroscopy

During the operation of high power electromechanical devices, a temperature rise is unavoidable due to mechanical and electrical losses, causing the degradation of device performance. In order to evaluate such degradations using computer simulations, full matrix material properties at elevated temperatures are needed as inputs. It is extremely difficult to measure such data for ferroelectric materials due to their strong anisotropic nature and property variation among samples of different geometries. Because the degree of depolarization is boundary condition dependent, data obtained by the IEEE (Institute of Electrical and Electronics Engineers) impedance resonance technique, which requires several samples with drastically different geometries, usually lack self-consistency. The resonant ultrasound spectroscopy (RUS) technique allows the full set material constants to be measured using only one sample, which can eliminate errors caused by sample to sample variation. A detailed RUS procedure is demonstrated here using a lead zirconate titanate (PZT-4) piezoceramic sample. In the example, the complete set of material constants was measured from room temperature to 120 &#176;C. Measured free dielectric constants <img alt="Equation 1" src="/files/ftp_upload/53461/image001.jpg" /> and&#160;<img alt="Equation 2" src="/files/ftp_upload/53461/image002.jpg" /> were compared with calculated ones based on the measured full set data, and piezoelectric constants d15 and d33 were also calculated using different formulas. Excellent agreement was found in the entire range of temperatures, which confirmed the self-consistency of the data set obtained by the RUS.

This protocol describes the procedure of measuring the temperature dependence of the full set material constants of piezoelectric materials using resonant ultrasound spectroscopy (RUS).

全套材料常数表征及其温度依赖性的压电材料使用共振超声波谱

During the operation of high power electromechanical devices, a temperature rise is unavoidable due to mechanical and electrical losses, causing the ...

Emission Spectroscopic Boundary Layer Investigation during Ablative Material Testing in Plasmatron

Ablative Thermal Protection Systems (TPS) allowed the first humans to safely return to Earth from the moon and are still considered as the only solution for future high-speed reentry missions. But despite the advancements made since Apollo, heat flux prediction remains an imperfect science and engineers resort to safety factors to determine the TPS thickness. This goes at the expense of embarked payload, hampering, for example, sample return missions. 
Ground testing in plasma wind-tunnels is currently the only affordable possibility for both material qualification and validation of material response codes. The subsonic 1.2MW Inductively Coupled Plasmatron facility at the von Karman Institute for Fluid Dynamics is able to reproduce a wide range of reentry environments. This protocol describes a procedure for the study of the gas/surface interaction on ablative materials in high enthalpy flows and presents sample results of a non-pyrolyzing, ablating carbon fiber precursor. With this publication, the authors envisage the definition of a standard procedure, facilitating comparison with other laboratories and contributing to ongoing efforts to improve heat shield reliability and reduce design uncertainties.
The described core techniques are non-intrusive methods to track the material recession with a high-speed camera along with the chemistry in the reactive boundary layer, probed by emission spectroscopy. Although optical emission spectroscopy is limited to line-of-sight measurements and is further constrained to electronically excited atoms and molecules, its simplicity and broad applicability still make it the technique of choice for analysis of the reactive boundary layer. Recession of the ablating sample further requires that the distance of the measurement location with respect to the surface is known at all times during the experiment. Calibration of the optical system of the applied three spectrometers allowed quantitative comparison. At the fiber scale, results from a post-test microscopy analysis are presented.

Development of new ablative materials and their numerical modeling requires extensive experimental investigation. This protocol describes procedures for material response characterization in plasma flows with the core techniques being non-intrusive methods to track the material recession along with the chemistry in the reactive boundary layer by emission spectroscopy.

烧蚀材料在试验过程中等离子体发生器发射光谱边界层研究

Ablative Thermal Protection Systems (TPS) allowed the first humans to safely return to Earth from the moon and are still considered as the only solution ...

Fabrication and Operation of Acoustofluidic Devices Supporting Bulk Acoustic Standing Waves for Sheathless Focusing of Particles

Acoustophoresis refers to the displacement of suspended objects in response to directional forces from sound energy. Given that the suspended objects must be smaller than the incident wavelength of sound and the width of the fluidic channels are typically tens to hundreds of micrometers across, acoustofluidic devices typically use ultrasonic waves generated from a piezoelectric transducer pulsating at high frequencies (in the megahertz range). At characteristic frequencies that depend on the geometry of the device, it is possible to induce the formation of standing waves that can focus particles along desired fluidic streamlines within a bulk flow. Here, we describe a method for the fabrication of acoustophoretic devices from common materials and clean room equipment. We show representative results for the focusing of particles with positive or negative acoustic contrast factors, which move towards the pressure nodes or antinodes of the standing waves, respectively. These devices offer enormous practical utility for precisely positioning large numbers of microscopic entities (e.g., cells) in stationary or flowing fluids for applications ranging from cytometry to assembly.

Acoustofluidic devices use ultrasonic waves within microfluidic channels to manipulate, concentrate and isolate suspended micro and nanoscopic entities. This protocol describes the fabrication and operation of such a device supporting bulk acoustic standing waves to focus particles in a central streamline without the aid of sheath fluids.

制造和Acoustofluidic设备的运营支撑体声波驻波的聚焦鞘颗粒

Acoustophoresis refers to the displacement of suspended objects in response to directional forces from sound energy. Given that the suspended objects must ...

Hand Controlled Manipulation of Single Molecules via a Scanning Probe Microscope with a 3D Virtual Reality Interface

Considering organic molecules as the functional building blocks of future nanoscale technology, the question of how to arrange and assemble such building blocks in a bottom-up approach is still open. The scanning probe microscope (SPM) could be a tool of choice; however, SPM-based manipulation was until recently limited to two dimensions (2D). Binding the SPM tip to a molecule at a well-defined position opens an opportunity of controlled manipulation in 3D space. Unfortunately, 3D manipulation is largely incompatible with the typical 2D-paradigm of viewing and generating SPM data on a computer. For intuitive and efficient manipulation we therefore couple a low-temperature non-contact atomic force/scanning tunneling microscope (LT NC-AFM/STM) to a motion capture system and fully immersive virtual reality goggles. This setup permits &#34;hand controlled manipulation&#34; (HCM), in which the SPM tip is moved according to the motion of the experimenter&#39;s hand, while the tip trajectories as well as the response of the SPM junction are visualized in 3D. HCM paves the way to the development of complex manipulation protocols, potentially leading to a better fundamental understanding of nanoscale interactions acting between molecules on surfaces. Here we describe the setup and the steps needed to achieve successful hand-controlled molecular manipulation within the virtual reality environment.

We demonstrate the precise manipulation of individual organic molecules on a metal surface with the tip of a scanning probe microscope driven in 3D by the experimenter's hand using a motion capture system and fully immersive virtual reality goggles.

通过手扫描探针显微镜用三维虚拟现实接口控制单分子的操作

Considering organic molecules as the functional building blocks of future nanoscale technology, the question of how to arrange and assemble such building ...

Scanning SQUID Study of Vortex Manipulation by Local Contact

Local, deterministic manipulation of individual vortices in type 2 superconductors is challenging. The ability to control the position of individual vortices is necessary in order to study how vortices interact with each other, with the lattice, and with other magnetic objects. Here, we present a protocol for vortex manipulation in thin superconducting films by local contact, without applying current or magnetic field. Vortices are imaged using a scanning superconducting quantum interference device (SQUID), and vertical stress is applied to the sample by pushing the tip of a silicon chip into the sample, using a piezoelectric element. Vortices are moved by tapping the sample or sweeping it with the silicon tip. Our method allows for effective manipulation of individual vortices, without damaging the film or affecting its topography. We demonstrate how vortices were relocated to distances of up to 0.8 mm. The vortices remained stable at their new location up to five days. With this method, we can control vortices and move them to form complex configurations. This technique for vortex manipulation could also be implemented in applications such as vortex based logic devices.

We present a protocol for manipulation of individual vortices in thin superconducting films, using local mechanical contact. The method does not include applying current, magnetic field or additional fabrication steps.

由当地接触式扫描涡操纵SQUID研究

Local, deterministic manipulation of individual vortices in type 2 superconductors is challenging. The ability to control the position of individual ...

Enhanced Electron Injection and Exciton Confinement for Pure Blue Quantum-Dot Light-Emitting Diodes by Introducing Partially Oxidized Aluminum Cathode

Stable and efficient red (R), green (G), and blue (B) light sources based on solution-processed quantum dots (QDs) play important roles in next-generation displays and solid-state lighting technologies. The brightness and efficiency of blue QDs-based light-emitting diodes (LEDs) remain inferior to their red and green counterparts, due to the inherently unfavorable energy levels of different colors of light. To solve these problems, a device structure should be designed to balance the injection holes and electrons into the emissive QD layer. Herein, through a simple autoxidation strategy, pure blue QD-LEDs which are highly bright and efficient are demonstrated, with a structure of ITO/PEDOT:PSS/Poly-TPD/QDs/Al:Al2O3. The autoxidized Al:Al2O3 cathode can effectively balance the injected charges and enhance radiative recombination without introducing an additional electron transport layer (ETL). As a result, high color-saturated blue QD-LEDs are achieved with a maximum luminance over 13,000 cd m-2, and a maximum current efficiency of 1.15 cd A-1. The easily controlled autoxidation procedure paves the way for achieving high-performance blue QD-LEDs.

A protocol is presented for fabricating high-performance, pure blue ZnCdS/ZnS-based quantum dots light-emitting diodes by employing an autoxidized aluminum cathode.

采用部分氧化铝阴极增强电子注入和激子约束的纯蓝色量子点发光二极管

Stable and efficient red (R), green (G), and blue (B) light sources based on solution-processed quantum dots (QDs) play important roles in next-generation ...