This work is supported by Ministry of Science and Technology under NSC-101-2923-M-002-001-MY3 and NSC-102-2112-M-002-018-MY3. This research is also supported by the Japan Society for the Promotion of Science (JSPS) through the &#8220;Funding Program for Next Generation World-Leading Researchers (NEXT Program),&#8221; initiated by the Council for Science and Technology Policy (CSTP) and JSPS Asian CORE Program.

1. GNS样品制备<ol><li>前在大约40千赫制备样品，声处理1 ml的GNS胶体溶液至少15分钟，以防止颗粒聚集，这可能会导致LSPR峰偏移。 </li><li>降100-200微升的GNS胶体在载玻片与商业硅酸镁铝（MAS）的涂层，以固定的GNSS。 </li><li>后至少1分钟，通过用蒸馏水冲洗除去多余的胶体。的等待时间取决于GNSS的所需分布密度。典型地，1-3分钟结果在合适的密度，使粒子能够容易地识别，因为他们最被彼此隔离。如果等待时间过长，可能会出现显著聚集。 </li><li>通过用氮气吹扫干燥样品。 </li><li> （可选的）要映射GNSS在玻璃上具有高分辨率，在此阶段23进行扫描电子显微镜（SEM）。一个例子的图像中FIGUR提供E 1，显示出全球导航卫星系统的特征密度。使用场发射SEM以获取图像。一旦油加入到样品（下一步骤），这将是很难除去的油，并观察用SEM样品。 </li><li>加一滴油具有相同的折射率到样品，以覆盖GNSS和消除从玻璃基板的强反射。 </li><li>放置的盖玻璃上的样品的顶部，并与指甲油密封。 </li><li>等待至少5分钟，直到指甲油干了。样品现已准备就绪。 </li></ol> 2.对准自制的共聚焦显微镜<ol><li> 图 2所示为安装的方案。对准显微镜体本身的白光照明的道路。打开显微镜的卤素光源，并按照显微镜制造商的手册，实现了科勒照明条件。以使白色卤素光束几乎平行于背面物镜的光圈，部分由50/50分束器反射，然后向激光传播。 </li><li>打开电流计反射镜，以确保它们保持在正确的初始位置，即，在扫描范围的中心。 </li><li>放置至少两个目标，由薄的纸，它同心环板制成，沿卤素光路，并与卤光束对齐。 </li><li>为了进行成像，选择532 nm激光。要执行光谱测量，选择超连续激光器。在对准中，激光的功率应小于10微瓦在物镜的后孔，以避免非线性。然后，准直入射激光束对面的向即将离任的卤素束的两个目标的援助。当这个过程完成后，将激光束的粗对准已经实现。 </li><li>透过物镜的后孔的中心对准的激光束。通常情况下，使用OIL-浸泡的目的。添加的油的油浸物镜与GNS样品之间的下降。使用的光电倍增管（PMT）作为检测器来收集GNSS的散射信号。 </li><li>放置在PMT的前面20微米直径的针孔来阻挡焦散射信号。打开电流计反射镜和PMT（经由家庭建造软件），调节样品台以最大化GNSS的反向散射信号的针孔位置和高度，然后观察个体GNS在计算机屏幕上。全球导航卫星系统与正确对准的样品的xy图像示于图2B。 </li><li>稍微改变样品台的高度，以检查聚焦的同心度。如果不是同心的，调整与扫描器直到GNS的中心的前部的两个反射镜的光束保持在同一位置，而试料台的高度被改变。确保该PSF的XZ图像类似于图2C以确保正确的光束对准。处理这两个图像与低通和高斯平滑滤波器。 </li></ol>散射非线性的3表征<ol><li>在低激发强度（小于10 4瓦/厘米2），通过以下方案获得2.6金纳米颗粒的图像。 </li><li>打开ImageJ的图像（或任何其它图像分析软件）。绘制横跨GNSS的图像中的一个的线（参见图2B），并使用分析- &gt;的ImageJ的工具绘图信息检索散射强度分布。适合所选择的PSF由一个高斯函数的轮廓: <img alt="公式（2）" src="/files/ftp_upload/53338/53338eq2.jpg" /> 其中 y是PMT读出，y值0是背景值（如果有的话），A是峰值幅度，w是宽度，x是空间坐标，而x c是中心coordinatE中的高斯函数。相应PSF的FWHM为（½ln2） 瓦特基于所述物镜的数值孔径（NA），共焦PSF的FWHM的理论可以被估计为近似0.43升/ NA，其中λ是激励波长。比较这两个数来检查成像系统的对准。 </li><li>增加激发强度通过手动改变中性密度（ND）滤光器在图2A中，并在每个强度电平记录后向散射图像。采取从每个GNS在不同激发强度的中心的散射信号的值，并绘制散射信号与激励强度的曲线。检查前几个点，这应当表现出一种线性关系时的激发强度是足够低的线性度。绘制基于第一几个点的线性拟合的线。如果随后的点散射强度下降低于该线性趋势，saturatioN有发生。 </li><li>观察饱和散射后，逐渐减小低于饱和阈值的强度，和图像相同GNSS再次确保了非线性行为的可逆性。 </li></ol> 4.测量单个金纳米球的散射光谱<ol><li>为了测量从一个单一的GNS的散射光谱，使用超连续激光器作为激光源。激光器的初始波长范围为450纳米至1750纳米。以除去可能会损坏样品和光学部件的过量红外线功率，放置一个或两个反射镜的超连续激光后的权利，以反映可见光，并用光束转储收集过量的红外光。 </li><li>按照第2对准程序直接超连续激光在激光扫描共聚焦显微镜。使用宽带50/50 BS，以确保在整个可见光范围光谱覆盖范围。 </li><li>获得一个像玻璃的全球导航卫星系统。定位单个GNS的图像中，并固定在颗粒上的入射光的宽带光的焦点。 </li><li>使用翻转镜在PMT以引导反向散射信号朝向分光计，其配备了一个电荷耦合器件的前方，然后取所选择的单一的GNS的频谱。请注意，这里的频谱是GNS散射和背景的混合由于来自其他表面的反射。 </li><li>切换回PMT检测，并拍摄图像，以确定粒子的位置没有改变。然后，转移焦点，以在这一点，没有粒子存在。切换回光谱仪，走多了一个频谱，它代表了背景。 </li><li>从频谱从步骤4.4减去4.5步的背景光谱，以获得单个GNS一个明确的散射光谱。 </li></ol> 5.对准SAX显微镜<ol><li> 参见图3用于该SAX显微镜，其中，从拍频获得的两个声光调制器（AOM）之间的理想正弦瞬时调制的方案。首先，调整激光的光束尺寸满足随后的声光调制器的需要。通过使用50/50分束器分裂532nm的激光光分成两个光束。 </li><li>通过两个声光调制器引导两束，其中一个光束穿过各AOM。两个声光调制器的调制频率必须是不同的。例如，一种可能是在40.000兆赫，另一个在40.010兆赫，得到10千赫的频率差。这个差频将是用于该SAX信号的基本调制频率 f 米 。 </li><li>取第一级衍射光束从两个声光调制器，并且通过使用另一个50/50的束分离器结合两个光束。该声光调制器之后调整镜子使准直两个光束。 </li><li>加，其连接到示波器的光电检测器来监视颞modulatioñ。分割用滑动玻璃的激光的一小部分，并将其发送到光检测器， 如图3。随着正确的调制和光束重叠，观察正弦强度调制的主频率 f 米 ，类似于所示的波形的在图4中。 注意:调制的背景需要尽可能低，以获得最大的调制深度。此外，使用示波器的傅立叶分析函数来检查所述调制的谐波失真减少。为了实现成功的SAX实现，保证了完美的正弦激励强度调制以最小的初始非线性。 </li><li>断开光检测器的电输出从示波器并连接到锁定放大器的参考输入。 </li><li> 如图3，对准激光束分成共焦系统按照前面的协议。 HERE，PMT的电输出连接到锁定放大器作为信号输入。 </li><li>使用空白盖玻璃作为样品，并检查电检测系统的线性度，通过逐渐增加励磁电源,, 如图5，其中所述检测器是低于1-V的读出值的线性。在所有的后续测量，小心抑制读数低于此值。 </li><li>设置锁定放大器的输出导出的电压信号的绝对幅度。通过改变高次谐波分量在参考信道设置，获取SAX信号，A 1，A 2的振幅，并依此类推。 </li><li>从锁定放大器的线性和非线性的信号输出到一个数据采集卡，还接收的光栅扫描电流反射镜的驱动电压信号。用一个定制的Labview程序的帮助下，同步锁定放大器和的信号电流镜以形成图像。 </li><li>为了优化信噪比中的图像中，选择适当的锁定放大器的像素获取和积分时间。例如，当激励的主调制频率 f m为 10千赫，也就是说，当周期为100微秒，设置锁定放大器的积分时间为比周期长至少三次。加入检测镜移动时，采集速度被设定在与SAX摄像模式每秒1500个像素。 </li></ol>

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Q., Bates, M., Zhuang, X. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+super-resolution+imaging+by+stochastic+optical+reconstruction+microscopy.">Three-dimensional super-resolution imaging by stochastic optical reconstruction microscopy.</a> Science. 319 (5864), 810-813 (2008).</li><li>Heintzmann, R., Jovin, T. M., Cremer, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Saturated+patterned+excitation+microscopy+-+a+concept+for+optical+resolution+improvement.">Saturated patterned excitation microscopy - a concept for optical resolution improvement.</a> J. Opt. Soc. Am. A. 19 (8), 1599-1609 (2002).</li><li>Tzang, O., Pevzner, A., Marvel, R. E., Haglund, R. F., Cheshnovsky, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Super-Resolution+in+Label-Free+Photomodulated+Reflectivity.">Super-Resolution in Label-Free Photomodulated Reflectivity.</a> Nano Lett. 15 (2), 1362-1367 (2015).</li></ol>

The authors declare that they have no competing financial interests.

在协议中，有几个关键步骤。首先，制备样品时，纳米颗粒的密度不应太高，以避免颗粒之间电浆耦合。如果两个或多个颗粒非常接近彼此，耦合导致LSPR波长偏移到更长的波长，从而显著降低非线性。然而，这种成像技术实际上映射，代替微粒本身电浆模式的分布。因此，可以预期，与适当的激发波长中，耦合电浆模式也可以显示强散射的非线性，并且可以具有增强的分辨率进行成像。第二，这...

等离子体的研究已经引起了极大的兴趣，因为它在许多不同的领域1-4的应用。一种在等离子体中研究最多的领域是表面等离子体激元，其中的传导电子夫妇在金属和电介质之间的界面的外部电磁波的集体振荡。表面等离子体激元已探索其在亚波长光学，生物光子学，以及显微镜5,6潜在的应用。在由于局部表面等离子共振（LSPR）金属纳米颗粒的超小体积的强场增强吸引，不仅是因为它的优异的敏感性，颗粒大小，颗粒形状，以及周围介质 7的介电性质的广泛关注，因为它能够提高固有的弱非线性光学效应11 -10的能力，而且还。 LSPR的特殊敏感性是生物传感和近外商投资企业有价值LD成像技术12,13。另一方面，电浆结构的增强非线性可以利用在光子集成电路中的应用，如光交换和全光信号处理14,15。众所周知的电浆吸收线性正比于在低强度电平的激发强度。当激励足够强，吸收达到饱和。有趣的是，在较高的强度，在吸收再次增大。这些非线性效应被称为饱和吸收（SA），15-17和反向可饱和吸收（RSA）18。 据了解，由于LSPR，散射特别强烈的电浆结构。根据基本的电磁散射与入射强度的反应应该是线性的。然而，在纳米粒子，散射和吸收紧密通过米氏理论联系在一起，都可以通过电子邮件xpressed中的介电常数的实部和虚部条款。下，一个单一的GNS表现为下光照偶极的假设下，从一个单一的等离子纳米颗粒根据米氏理论的散射系数（Q SCA）和吸收系数（Q 绝对）可以表示为19 <img alt="式（1）" src="/files/ftp_upload/53338/53338eq1.jpg" /> 其中 x是2πa/λ，a是球体的半径，并且m 2 为 ε 米 /εð。这里，ε 米 和 εD分别对应于金属的介电常数和周围的电介质，分别。因为散射系数的形式是类似的第Ë吸收系数，因此它被期望遵守饱和散射在一个电浆纳米粒子20。 最近，在一个孤立的电浆粒子非线性饱和散射证实首次21。值得注意的是，在深度饱和，其实散射强度略有下降，当激发强度增加。更值得注意的是，当激励强度继续后散射趋于饱和增加，散射强度再次上升，呈现出反饱和散射20的效果。 Wavelength-和尺寸相关的研究表明散射21 LSPR和非线性之间有紧密的关系。电浆散射的强度和波长的依赖性非常类似于那些吸收，这表明这些非线性行为基础的共同机制。 在应用方面，它是很好KNOWN该非线性有助于改善光学显微镜的分辨率。在2007年，饱和励磁提出（SAX）显微镜，其可以通过经由激励光束22的时间正弦调制提取饱和信号提高分辨率。 SAX显微镜是基于这样，对于一个激光焦斑，强度在中心处比在外围更强的概念。如果信号（或者荧光或散射）呈现饱和特性，饱和必须从中心开始，而线性响应保持在外围。因此，如果有一种方法，以仅提取饱和部分，它将只离开中心部分，同时抑制周边部，从而有效地增强了空间分辨率。原则上，存在的SAX显微镜没有更低分辨率极限，只要深达到饱和并且有由于强烈照明没有样品的损伤。 已经表明，该resolutioÑ​​荧光成像可以通过利用SAX技术来显著增强。然而，荧光遭受的漂白效果。结合散射非线性的发现和SAX的概念，是根据散射超分辨率显微镜可以实现21。相对于传统的超分辨率显微技术，散射为基础的技术提供了一种新颖的非漂白对比法。在本文中，一步一步的描述给出概述获得和提取等离子散射的非线性要求的程序。识别通过改变入射强度引入散射非线性的方法进行了描述。详情将提供解开这些非线性如何影响单个纳米粒子的图像，以及如何空间分辨率可以相应地由SAX技术来增强。

<table>
	<tbody>
		<tr>
			<td>microscope body</td>
			<td>Olympus, Japan</td>
			<td>BX-51</td>
			<td></td>
		</tr>
		<tr>
			<td>objective lens</td>
			<td>Olympus, Japan</td>
			<td>UPlanSapo, 100X, NA 1.4</td>
			<td></td>
		</tr>
		<tr>
			<td>80-nm gold colloid</td>
			<td>BBI Solutions, UK</td>
			<td>EM.GC80</td>
			<td></td>
		</tr>
		<tr>
			<td>supercontinuum laser</td>
			<td>Fianium, United Kingdom</td>
			<td>SC400-2-PP</td>
			<td></td>
		</tr>
		<tr>
			<td>broadband dielectric mirrors</td>
			<td>Thorlabs, USA</td>
			<td>BB1-E02</td>
			<td></td>
		</tr>
		<tr>
			<td>field emission SEM</td>
			<td>JEOL, Japan</td>
			<td>JSM-6330F</td>
			<td>optional</td>
		</tr>
		<tr>
			<td>spectrometer</td>
			<td>Andor Technology, UK</td>
			<td>Shamrock 163</td>
			<td></td>
		</tr>
		<tr>
			<td>&#160;charge-coupled device</td>
			<td>Andor Technology, UK</td>
			<td>iDus DV420A-OE</td>
			<td></td>
		</tr>
		<tr>
			<td>acousto-optic modulators</td>
			<td>&#160;IntraAction Corp., USA</td>
			<td>AOM-402AF1</td>
			<td></td>
		</tr>
		<tr>
			<td>lock-in amplifier</td>
			<td>Stanford Research Systems, USA</td>
			<td>SR-830</td>
			<td></td>
		</tr>
		<tr>
			<td>MAS-coated slide glass</td>
			<td>Matsunami Glass, Japan,</td>
			<td>S9215</td>
			<td></td>
		</tr>
	</tbody>
</table>

measurement of scattering nonlinearities from a single plasmonic nanoparticle

Plasmonics, which are based on the collective oscillation of electrons due to light excitation, involve strongly enhanced local electric fields and thus have potential applications in nonlinear optics, which requires extraordinary optical intensity. One of the most studied nonlinearities in plasmonics is nonlinear absorption, including saturation and reverse saturation behaviors. Although scattering and absorption in nanoparticles are closely correlated by the Mie theory, there has been no report of nonlinearities in plasmonic scattering until very recently. 
Last year, not only saturation, but also reverse saturation of scattering in an isolated plasmonic particle was demonstrated for the first time. The results showed that saturable scattering exhibits clear wavelength dependence, which seems to be directly linked to the localized surface plasmon resonance (LSPR). Combined with the intensity-dependent measurements, the results suggest the possibility of a common mechanism underlying the nonlinear behaviors of scattering and absorption. These nonlinearities of scattering from a single gold nanosphere (GNS) are widely applicable, including in super-resolution microscopy and optical switches. 
In this paper, it is described in detail how to measure nonlinearity of scattering in a single GNP and how to employ the super-resolution technique to enhance the optical imaging resolution based on saturable scattering. This discovery features the first super-resolution microscopy based on nonlinear scattering, which is a novel non-bleaching contrast method that can achieve a resolution as low as l/8 and will potentially be useful in biomedicine and material studies.

图6显示了从一个80纳米的GNS测量光谱。一组基于米氏理论计算出的曲线给出了相同的情节，表现出良好的协议。该LSPR峰值大约是580纳米。在以下的实验中，激光波长为532纳米，这被选择，因为它位于电浆频带内，以提高光散射与电浆效果和使散射饱和21。 图7呈现在不同的激发强度的散射单个金纳米颗粒的图像，且最底行提供每个粒子以突?...

Watch this Scientific Journal Video about Measurement of Scattering Nonlinearities from a Single Plasmonic Nanoparticle at JoVE.com

Measurement of Scattering Nonlinearities from a Single Plasmonic Nanoparticle

Saturable and reverse saturable scattering were discovered in isolated plasmonic particles and adopted as a novel non-bleaching contrast method in super-resolution microscopy. Here the experimental procedures of detecting and extracting nonlinear scattering are explained in detail, as well as how to enhance resolution with the aid of saturated excitation microscopy.

从单电浆纳米粒子散射非线性测量

Plasmonics, which are based on the collective oscillation of electrons due to light excitation, involve strongly enhanced local electric fields and thus ...

measurement-scattering-nonlinearities-from-single-plasmonic

Research

JoVE Journal

Engineering

12.8K 次观看.  National Taiwan University. Saturable and reverse saturable scattering were discovered in isolated plasmonic particles and adopted as a novel non-bleaching contrast method in super-resolution microscopy. Here the experimental procedures of detecting and extracting nonlinear scattering are explained in detail, as well as how to enhance resolution with the aid of saturated excitation microscopy. 

视频: Measurement of Scattering Nonlinearities from a Single Plasmonic Nanoparticle

Measuring Spatially- and Directionally-varying Light Scattering from Biological Material

Light interacts with an organism's integument on a variety of spatial scales. For example in an iridescent bird: nano-scale structures produce color; the milli-scale structure of barbs and barbules largely determines the directional pattern of reflected light; and through the macro-scale spatial structure of overlapping, curved feathers, these directional effects create the visual texture. Milli-scale and macro-scale effects determine where on the organism's body, and from what viewpoints and under what illumination, the iridescent colors are seen. Thus, the highly directional flash of brilliant color from the iridescent throat of a hummingbird is inadequately explained by its nano-scale structure alone and questions remain. From a given observation point, which milli-scale elements of the feather are oriented to reflect strongly? Do some species produce broader "windows" for observation of iridescence than others? These and similar questions may be asked about any organisms that have evolved a particular surface appearance for signaling, camouflage, or other reasons.
In order to study the directional patterns of light scattering from feathers, and their relationship to the bird's milli-scale morphology, we developed a protocol for measuring light scattered from biological materials using many high-resolution photographs taken with varying illumination and viewing directions. Since we measure scattered light as a function of direction, we can observe the characteristic features in the directional distribution of light scattered from that particular feather, and because barbs and barbules are resolved in our images, we can clearly attribute the directional features to these different milli-scale structures. Keeping the specimen intact preserves the gross-scale scattering behavior seen in nature. The method described here presents a generalized protocol for analyzing spatially- and directionally-varying light scattering from complex biological materials at multiple structural scales.

We present a non-destructive method for sampling spatial variation in the direction of light scattered from structurally complex materials. By keeping the material intact, we preserve gross-scale scattering behavior, while concurrently capturing fine-scale directional contributions with high-resolution imaging. Results are visualized in software at biologically-relevant positions and scales.

从生物材料空间定向变化的光散射测量

Light interacts with an organism's integument on a variety of spatial scales. For example in an iridescent bird: nano-scale structures produce color; the ...

科研

工程学

Design, Fabrication, and Experimental Characterization of Plasmonic Photoconductive Terahertz Emitters

In this video article we present a detailed demonstration of a highly efficient method for generating terahertz waves. Our technique is based on photoconduction, which has been one of the most commonly used techniques for terahertz generation 1-8. Terahertz generation in a photoconductive emitter is achieved by pumping an ultrafast photoconductor with a pulsed or heterodyned laser illumination. The induced photocurrent, which follows the envelope of the pump laser, is routed to a terahertz radiating antenna connected to the photoconductor contact electrodes to generate terahertz radiation. Although the quantum efficiency of a photoconductive emitter can theoretically reach 100%, the relatively long transport path lengths of photo-generated carriers to the contact electrodes of conventional photoconductors have severely limited their quantum efficiency. Additionally, the carrier screening effect and thermal breakdown strictly limit the maximum output power of conventional photoconductive terahertz sources. To address the quantum efficiency limitations of conventional photoconductive terahertz emitters, we have developed a new photoconductive emitter concept which incorporates a plasmonic contact electrode configuration to offer high quantum-efficiency and ultrafast operation simultaneously. By using nano-scale plasmonic contact electrodes, we significantly reduce the average photo-generated carrier transport path to photoconductor contact electrodes compared to conventional photoconductors 9. Our method also allows increasing photoconductor active area without a considerable increase in the capacitive loading to the antenna, boosting the maximum terahertz radiation power by preventing the carrier screening effect and thermal breakdown at high optical pump powers. By incorporating plasmonic contact electrodes, we demonstrate enhancing the optical-to-terahertz power conversion efficiency of a conventional photoconductive terahertz emitter by a factor of 50 10.

We describe methods for the design, fabrication, and experimental characterization of plasmonic photoconductive emitters, which offer two orders of magnitude higher terahertz power levels compared to conventional photoconductive emitters.

电浆光电导太赫兹发射器的设计，制造和实验表征

In this video article we present a detailed demonstration of a highly efficient method for generating terahertz waves. Our technique is based on ...

Visible-light Induced Reduction of Graphene Oxide Using Plasmonic Nanoparticle

Present work demonstrates the simple, chemical free, fast, and energy efficient method to produce reduced graphene oxide (r-GO) solution at RT using visible light irradiation with plasmonic nanoparticles. The plasmonic nanoparticle is used to improve the reduction efficiency of GO. It only takes 30 min&#160;at RT by illuminating the solutions with Xe-lamp, the r-GO solutions can be obtained by completely removing gold nanoparticles through simple centrifugation step. The spherical gold nanoparticles (AuNPs) as compared to the other nanostructures is the most suitable plasmonic nanostructure for r-GO preparation. The reduced graphene oxide prepared using visible light and AuNPs was equally qualitative as chemically reduced graphene oxide, which was supported by various analytical techniques such as UV-Vis spectroscopy, Raman spectroscopy, powder XRD and XPS. The reduced graphene oxide prepared with visible light shows excellent quenching properties over the fluorescent molecules modified on ssDNA and excellent fluorescence recovery for target DNA detection. The r-GO prepared by recycled AuNPs is found to be of same quality with that of chemically reduced r-GO. The use of visible light with plasmonic nanoparticle demonstrates the good alternative method for r-GO synthesis.

A simple protocol for the preparation of reduced graphene oxide using visible light and plasmonic nanoparticle is described.

可见光诱导的还原氧化石墨烯的使用电浆纳米粒子

Present work demonstrates the simple, chemical free, fast, and energy efficient method to produce reduced graphene oxide (r-GO) solution at RT using ...

A System to Create Stable Nanoparticle Aerosols from Nanopowders

Nanoparticle aerosols released from nanopowders in workplaces are associated with human exposure and health risks. We developed a novel system, requiring minimal amounts of test materials (min. 200 mg), for studying powder aerosolization behavior and aerosol properties. The aerosolization procedure follows the concept of the fluidized-bed process, but occurs in the modified volume of a V-shaped aerosol generator. The airborne particle number concentration is adjustable by controlling the air flow rate. The system supplied stable aerosol generation rates and particle size distributions over long periods (0.5-2 hr and possibly longer), which are important, for example, to study aerosol behavior, but also for toxicological studies. Strict adherence to the operating procedures during the aerosolization experiments ensures the generation of reproducible test results. The critical steps in the standard protocol are the preparation of the material and setup, and the aerosolization operations themselves. The system can be used for experiments requiring stable aerosol concentrations and may also be an alternative method for testing dustiness. The controlled aerosolization made possible with this setup occurs using energy inputs (may be characterized by aerosolization air velocity) that are within the ranges commonly found in occupational environments where nanomaterial powders are handled. This setup and its operating protocol are thus helpful for human exposure and risk assessment.

We designed and developed an effective nanopowder aerosolization setup and operating protocol. The system generated nanoparticle aerosols with stable number concentrations and size distributions for long durations, requiring only small quantities of test material (min. 200 mg).

系统创建从纳米粉体纳米稳定气溶胶

Nanoparticle aerosols released from nanopowders in workplaces are associated with human exposure and health risks. We developed a novel system, requiring ...

Testing of Nanoparticle Release from a Composite Containing Nanomaterial Using a Chamber System

With the rapid development of nanotechnology as one of the most important technologies in the 21st century, interest in the safety of consumer products containing nanomaterials is also increasing. Evaluating the nanomaterial release from products containing nanomaterials is a crucial step in assessing the safety of these products, and has resulted in several international efforts to develop consistent and reliable technologies for standardizing the evaluation of nanomaterial release. In this study, the release of nanomaterials from products containing nanomaterials is evaluated using a chamber system that includes a condensation particle counter, optical particle counter, and sampling ports to collect filter samples for electron microscopy analysis. The proposed chamber system is tested using an abrasor and disc-type nanocomposite material specimens to determine whether the nanomaterial release is repeatable and consistent within an acceptable range. The test results indicate that the total number of particles in each test is within 20% from the average after several trials. The release trends are similar and they show very good repeatability. Therefore, the proposed chamber system can be effectively used for nanomaterial release testing of products containing nanomaterials.

Nanoparticle release is tested using a chamber system that includes a condensation particle counter, an optical particle counter and sampling ports to collect filter samples for microscopy analysis. The proposed chamber system can be effectively used for nanomaterial release testing with a repeatable and consistent data range.

从使用室系统一个复合含纳米材料的纳米颗粒释放测试

With the rapid development of nanotechnology as one of the most important technologies in the 21st century, interest in the safety of consumer products ...

Optical Trap Loading of Dielectric Microparticles In Air

We demonstrate a method to trap a selected dielectric microparticle in air using radiation pressure from a single-beam gradient optical trap. Randomly scattered dielectric microparticles adhered to a glass substrate are momentarily detached using ultrasonic vibrations generated by a piezoelectric transducer (PZT). Then, the optical beam focused on a selected particle lifts it up to the optical trap while the vibrationally excited microparticles fall back to the substrate. A particle may be trapped at the nominal focus of the trapping beam or at a position above the focus (referred to here as the levitation position) where gravity provides the restoring force. After the measurement, the trapped particle can be placed at a desired position on the substrate in a controlled manner. 
In this protocol, an experimental procedure for selective optical trap loading in air is outlined. First, the experimental setup is briefly introduced. Second, the design and fabrication of a PZT holder and a sample enclosure are illustrated in detail. The optical trap loading of a selected microparticle is then demonstrated with step-by-step instructions including sample preparation, launching into the trap, and use of electrostatic force to excite particle motion in the trap and measure charge. Finally, we present recorded particle trajectories of Brownian and ballistic motions of a trapped microparticle in air. These trajectories can be used to measure stiffness or to verify optical alignment through time domain and frequency domain analysis. Selective trap loading enables optical tweezers to track a particle and its changes over repeated trap loadings in a reversible manner, thereby enabling studies of particle-surface interaction.

A protocol for launching and stably trapping selected dielectric microparticles in air is presented.

介电微粒的光阱装载在空气中

We demonstrate a method to trap a selected dielectric microparticle in air using radiation pressure from a single-beam gradient optical trap. Randomly ...

Plasmonic Trapping and Release of Nanoparticles in a Monitoring Environment

Plasmonic tweezers use surface plasmon polaritons to confine polarizable nanoscale objects. Among the various designs of plasmonic tweezers, only a few can observe immobilized particles. Moreover, a limited number of studies have experimentally measured the exertable forces on the particles. The designs can be classified as the protruding nanodisk type or the suppressed nanohole type. For the latter, microscopic observation is extremely challenging. In this paper, a new plasmonic tweezer system is introduced to monitor particles, both in directions parallel and orthogonal to the symmetric axis of a plasmonic nanohole structure. This feature enables us to observe the movement of each particle near the rim of the nanohole. Furthermore, we can quantitatively estimate the maximal trapping forces using a new fluidic channel.

A microchip fabrication process that incorporates plasmonic tweezers is presented here. The microchip enables the imaging of a trapped particle to measure maximal trapping forces.

电浆捕获和纳米粒子的释放在监控环境

Plasmonic tweezers use surface plasmon polaritons to confine polarizable nanoscale objects. Among the various designs of plasmonic tweezers, only a few ...

Scanning Light Scattering Profiler (SLPS) Based Methodology to Quantitatively Evaluate Forward and Backward Light Scattering from Intraocular Lenses

The scanning light scattering profiler (SLSP) methodology has been developed for the full-angle quantitative evaluation of forward and backward light scattering from intraocular lenses (IOLs) using goniophotometer principles. This protocol describes the SLSP platform and how it employs a 360&#176; rotational photodetector sensor that is scanned around an IOL sample while recording the intensity and location of scattered light as it passes through the IOL medium. The SLSP platform can be used to predict, non-clinically, the propensity for current and novel IOL designs and materials to induce light scatter. Non-clinical evaluation of light scattering properties of IOLs can significantly reduce the number of patient complaints related to unwanted glare, glistening, optical defects, poor image quality, and other phenomena associated with the unintended light scattering. Future studies should be conducted to correlate SLSP data with clinical results to help identify which measured light scatter is most problematic for patients that have undergone cataract surgery subsequent to IOL implantation.

Scanning Light Scattering Profiler SLPS Based Methodology to Quantitatively Evaluate Forward and Backward Light Scattering from Intraocular Lenses

This protocol describes the scanning light scattering profiler (SLSP) that enables the full-angle quantitative evaluation of forward and backward scattering of light from intraocular lenses (IOLs) using goniophotometer principles.

基于扫描光散射分析器（SLPS）的方法来量化评估来自眼内镜的前向和后向光散射

The scanning light scattering profiler (SLSP) methodology has been developed for the full-angle quantitative evaluation of forward and backward light ...

Standardized Method for Measuring Collection Efficiency from Wipe-sampling of Trace Explosives

One of the limiting steps to detecting traces of explosives at screening venues is effective collection of the sample. Wipe-sampling is the most common procedure for collecting traces of explosives, and standardized measurements of collection efficiency are needed to evaluate and optimize sampling protocols. The approach described here is designed to provide this measurement infrastructure, and controls most of the factors known to be relevant to wipe-sampling. Three critical factors (the applied force, travel distance, and travel speed) are controlled using an automated device. Test surfaces are chosen based on similarity to the screening environment, and the wipes can be made from any material considered for use in wipe-sampling. Particle samples of the explosive 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) are applied in a fixed location on the surface using a dry-transfer technique. The particle samples, recently developed to simulate residues made after handling explosives, are produced by inkjet printing of RDX solutions onto polytetrafluoroethylene (PTFE) substrates. Collection efficiency is measured by extracting collected explosive from the wipe, and then related to critical sampling factors and the selection of wipe material and test surface. These measurements are meant to guide the development of sampling protocols at screening venues, where speed and throughput are primary considerations.

Optimized sampling protocols and the development of new wipe materials can be facilitated by standardized measurements of collection efficiency from wipe-sampling. Our approach for sampling trace explosives uses an automated device to control speed, force, and distance during wipe-sampling followed by extraction of collected explosives.

从微量炸药的擦拭取样测量收集效率的标准化方法

One of the limiting steps to detecting traces of explosives at screening venues is effective collection of the sample. Wipe-sampling is the most common ...

Micro/Nano-scale Strain Distribution Measurement from Sampling Moir&#233; Fringes

This work describes the measurement procedure and principles of a sampling moir&#233; technique for full-field micro/nano-scale deformation measurements. The developed technique can be performed in two ways: using the reconstructed multiplication moir&#233; method or the spatial phase-shifting sampling moir&#233; method. When the specimen grid pitch is around 2 pixels, 2-pixel sampling moir&#233; fringes are generated to reconstruct a multiplication moir&#233; pattern for a deformation measurement. Both the displacement and strain sensitivities are twice as high as in the traditional scanning moir&#233; method in the same wide field of view. When the specimen grid pitch is around or greater than 3 pixels, multi-pixel sampling moir&#233; fringes are generated, and a spatial phase-shifting technique is combined for a full-field deformation measurement. The strain measurement accuracy is significantly improved, and automatic batch measurement is easily achievable. Both methods can measure the two-dimensional (2D) strain distributions from a single-shot grid image without rotating the specimen or scanning lines, as in traditional moir&#233; techniques. As examples, the 2D displacement and strain distributions, including the shear strains of two carbon fiber-reinforced plastic specimens, were measured in three-point bending tests. The proposed technique is expected to play an important role in the non-destructive quantitative evaluations of mechanical properties, crack occurrences, and residual stresses of a variety of materials.

A sampling moir&#233; technique featuring 2-pixel and multi-pixel sampling methods for high-accuracy strain distribution measurements at the micro/nano-scale is presented here.

微米/纳米尺度应变分布测量从采样莫尔条纹

This work describes the measurement procedure and principles of a sampling moir&#233; technique for full-field micro/nano-scale deformation measurements. ...