作者感谢中国科学技术部国家重点技术研究开发项目 (2011BAK15B06) 的支持。感谢舒雅庄谁是我们的实验室的主学生帮助我们完成视频拍摄。

1. 水黾腿表面结构的观察
<ol><li>利用捕鱼着陆网从当地淡水池塘收集水黾。</li>
	<li>用剪刀剪掉至少5双中腿作为实验样品。小心地接触底部的腿, 以防止表面污染和中断的显微组织在前面的腿。</li>
	<li>自然地把腿晾在空中。</li>
	<li>用扫描电镜观察双腿的表面显微结构, 如图 1所示。</li>
	<li>观察 microsetae 的双腿使用扫描电镜与纳米级分辨率, 如图 1b所示。</li>
</ol>2. 准备动力测量系统的部件
<ol><li>购买 PVDF 薄膜传感器的尺寸为 14.9 x 10.2 毫米2 x 28 微米, 每微应变产生超过 10 mV。 注: PVDF 薄膜传感器是用来感知高灵敏度的动态接触力的。</li>
	<li>购买最大 1000 mV/pC 充电增益和低噪音小于5μV 的电荷放大器。 注: 电荷放大器用于放大 PVDF 薄膜传感器的信号, 从传感器的电荷输出转换为电压。</li>
	<li>购买一个数据采集设备, 其中模拟输入的采样率在一个范围从 1 s/秒到 102.4 kS/秒。 注: 数据采集装置用于读取电荷放大器的电压数据, 并将其发送到计算机进行进一步的处理和显示。</li>
	<li>购买几个高精度的位移阶段和伺服电机。 注: 双腿从水中以不同的速度从伺服电机驱动。</li>
	<li>购买 CCD 相机, 其聚焦长度在一个范围从5毫米到30毫米和帧速率是 30 fps。 注: 本相机用于记录和监测水面的变形和腿部与水面的距离。</li>
	<li>准备一台高性能的计算机。</li>
</ol>3. 动态力测量系统所有部件的装配
<ol><li>根据图 2a和图 2b所示的实际实验仪器, 装配动力测量系统。</li>
	<li>将 PVDF 薄膜传感器的一侧与电极固定在高精度位移级, 放置在水平框架上, 另一侧挂起。PVDF 薄膜传感器的安装方法有助于提高动态微力测量的分辨率。</li>
	<li>将 PVDF 薄膜传感器与电荷放大器、电荷放大器、数据采集装置和数据采集装置连接到计算机上。</li>
	<li>将摄像机固定在 PVDF 薄膜传感器左侧的高精度位移阶段。</li>
	<li>为了大致调整腿部与水之间的距离, 请将高精度位移阶段固定在 pvdf 薄膜传感器上方的框架上, 其与 pvdf 薄膜传感器的分离约为10厘米。</li>
	<li>要以精确的速度将腿从水面上抬开, 请将伺服电机固定在高精度位移阶段以下。</li>
</ol>4. 动态测力系统的标定
<ol><li>使用静电力系统26产生的微恒定力作用在 PVDF 薄膜传感器的自由端, 其大小应小于0.5 µN. 控制系统的静电力, 电压应用于内、外电极平行圆柱形电容器。 注意: 该力应在 pvdf 薄膜表面正常的方向行动, 应用点应该尽可能接近 pvdf 薄膜传感器的尖端, 以提高灵敏度。</li>
	<li>在短时间内释放该力以生成步骤输入。</li>
	<li>在计算机上使用软件 LabVIEW 读取步骤4.2 的电压时间信号, 这有助于读取 PVDF 薄膜传感器的输出电压信号。<ol>
<li>下载软件 LabVIEW 和硬件驱动程序 NI-DAQmx 在官方网站的国家文书。</li>
		<li>使用 LabVIEW 打开连续模拟电压测量的演示, 如图 3所示。</li>
		<li>选择通道设置模块中与电荷放大器连接的数据采集装置的物理通道。</li>
		<li>将采样速率设置为 100000, 在计时设置模块中将样本数设为100000。</li>
		<li>选择日志并读取为日志记录模式, 并编写文件路径以将电压数据存储在日志记录设置模块中。</li>
		<li>在触发器设置模块中选择 "无触发器"。</li>
		<li>单击工具栏中的箭头形状按钮以采样电压信号。</li>
	</ol>
</li>
	<li>分析电压曲线, 其中峰值电压对应于传感器的受力。</li>
	<li>重复步骤 4.1-4.4 在不同的力量输入, 其中一系列的电压-力点得到。</li>
	<li>确定校准结果中峰值输出电压和标准力的关系。</li>
</ol>5. 用一定速度测量粘附力
<ol><li>使用机械微将水滴 (5 µL) 放在 PVDF 薄膜传感器的自由端。 注: 液滴的位置应接近 PVDF 薄膜传感器的尖端。</li>
	<li>将一条腿粘在高精度位移级以下的伺服电机上。</li>
	<li>向下移动高精度位移阶段, 直到腿部与水面接触, 如图 4所示。通过安装在传感器左侧的摄像机系统监视腿部和水面之间的距离。</li>
	<li>通过伺服马达以恒定的速度将腿从水面上抬开。</li>
	<li>用步骤4.6 中建立的模型计算出离过程的每个电压曲线点对应的力, 然后绘制离开过程的力-时间曲线, 如图 4b所示。</li>
	<li>以一定的速度记录出发过程的峰值附着力。</li>
</ol>6. 以不同速度测量粘附力。
<ol><li>通过伺服电机改变腿的提升速度, 并根据步骤5测量粘附力。</li>
	<li>使用步骤6.1 中获得的数据绘制粘附力与提升速度曲线。</li>
	<li>通过曲线分析了粘附力与提升速度之间的关系。</li>
</ol>

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作者没有什么可透露的。

在该协议中, 成功地设计了一种基于 PVDF 薄膜传感器的动态力测量系统, 并对其进行了标定, 以测量离水表面的粘附力。在整个步骤中, 重要的是, 通过从水面上抬起腿, 以不同的速度测量粘附力, 因为这项研究集中在水快速机动的显著特征上。实验结果表明, 当提升速度增加时, 粘结力降低。这些澄清说, 水黾会感到放松, 如果他们在高速移动的水。
基于 PVDF 的动态力测量方法是传统方法的重要补充。在过去的研究中, 水黾在分离过程中的粘附力通常用原子力显微镜 (AFM) 在准静态模式下测量。与 AFM 方法相比, 尽管测量精度略低, 但 PVDF 薄膜传感器能够测量较大宏观物体的力。此外, 由于其具有较大的频率响应特性, PVDF 薄膜传感器可以测量腿与水面之间的动态相互作用, 而 AFM 只能在准静态条件下使用。
所提出的动态力测量方法仅限于微力检测。如果对悬挂式传感器施加较大的力, 会引起 PVDF 薄膜传感器的较大变形, 导致不精确的结果。此外, PVDF 薄膜传感器的敏感区域较小, 限制了测量对象的尺寸。然而, 与传统的方法相比, 所提出的方法能够测量动力, 而不是仅仅测量静力, 这可以表现出整个相互作用过程。
基于 PVDF 薄膜传感器的这种方法在许多领域有着广泛的应用, 因为它在动态力传感方面具有很高的灵敏度和明显的灵活性。例如, 通过监测建筑物在振动或大议案27、28中的反应, 人们非常重视结构健康监测的应用。此外, PVDF 薄膜传感器用于直接测量聚结过程中两个无粘性水滴之间的相互作用, 其中流体力学没有得到充分的理解。此外, PVDF 薄膜传感器在29的机器人触觉传感中也起着重要的作用。传感器嵌入机器人的指尖, 测量物体的接触力和接触温度。在生物研究领域, 基于 PVDF 的力传感器有助于提高单细胞操作的成功率, 如 DNA 注射和基因治疗, 通过精确的机械反馈控制, 灵敏度高。

在自然界中, 水黾具有非凡的能力跳跃或滑翔容易和迅速在水面上的帮助下细长和 nonwetting 腿1,2,3,4,5,但很少移动缓慢, 这是不像陆地昆虫。水黾的层次结构稳定了超疏水性状态, 使接触面积和水与腿6、7、8之间的粘附力显著降低,9. 然而, 水黾从水面快速脱离的水力优势仍然不太解释10、11、12。
从水面跳跃的过程主要分为三阶段13、14、15、16。首先, 水黾用中、后腿向下推水面, 将生物能量转化为水的表面能量, 直至下沉至最大深度, 使昆虫能够初始化跳跃方向并确定分离速度。其次是上升阶段, 昆虫被弯曲的水表面的毛细管力量推挤向上, 直到到达最大速度。在最后的脱离接触阶段, 水黾持续上升的惯性, 直到打破从水面, 但速度大大减少, 由于与水的粘附力, 这对能源消耗的主要影响水黾。因此, 本文提出了在接触阶段不同起飞速度下的粘附力的测量方法, 并说明了快速运动的特点。
研究了水黾在水面推进时的粘附力。李 & 金在理论和实验上证实, 当接触角增加到160度17时, 黾的腿的粘附力和能量需要大大降低。潘仁伟设计了一个静水压实验, 以测量 TriboScope 系统的粘附力, 被发现是其重量的 1/5 18。Kehchih 分析了2D 模型分离水腿的准静态过程, 发现腿部 superhydrophobicity 对降低粘附力和耗能19起着重要作用。然而, 以往研究中的粘附力的测量只是在一个准静态过程的条件下, 在快速跳跃过程中无法监测粘附力的变化。
在本研究中, 我们设计了一种使用聚偏氟乙烯 (PVDF) 薄膜传感器和其它辅助仪器的动态力测量系统。与其它压电材料相比, PVDF 更适于测量灵敏度为20、21、22的动态 microforce。通过将 PVDF 薄膜传感器集成到系统中, 当腿部从水面23、24、25处拉出时, 可检测和处理实时粘附力。

<table border="0" cellpadding="0" cellspacing="0" style="width:559px;" width="559">
	<tbody>
		<tr height="32">
			<td height="32" style="height:32px;width:87px;">PVDF film sensor</td>
			<td style="width:111px;">TE Connectivity</td>
			<td style="width:87px;">DT1-028K/L</td>
			<td style="width:275px;">The PVDF film sensor is used to sense the dynamic contact force .</td>
		</tr>
		<tr height="48">
			<td height="48" style="height:48px;width:87px;">Charge amplifier</td>
			<td style="width:111px;">Wuxi Shiao Technology co.,Ltd</td>
			<td style="width:87px;">YE5852B</td>
			<td style="width:275px;">The charge amplifier&#160;is an electronic current integrator that produces a voltage output proportional to the integrated value of the input</td>
		</tr>
		<tr height="48">
			<td height="48" style="height:48px;width:87px;">Data acquisition device</td>
			<td style="width:111px;">National Instruments</td>
			<td style="width:87px;">USB-4431</td>
			<td style="width:275px;">The data acquisition device is used to read the voltage data.</td>
		</tr>
		<tr height="48">
			<td height="48" style="height:48px;width:87px;">Displacement stage</td>
			<td style="width:111px;">ZOLIXINSTRUMENTS CO.LTD</td>
			<td style="width:87px;">KSAV1010-ZF</td>
			<td style="width:275px;">KSAV1010/2030-ZF is a wedge vertical stage with high-resolution, high-stability and high-load.</td>
		</tr>
		<tr height="48">
			<td height="48" style="height:48px;width:87px;">CCD camera</td>
			<td style="width:111px;">Shenzhen Andonstar Tech Co., Ltd</td>
			<td style="width:87px;">digital microscope A1</td>
			<td style="width:275px;">Frame rate: 30 frames/sec;Focal distance: 5mm - 30mm</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:87px;">Computer</td>
			<td style="width:111px;">Lenovo</td>
			<td style="width:87px;">G480</td>
			<td style="width:275px;"></td>
		</tr>
		<tr height="32">
			<td height="32" style="height:33px;width:87px;">Servomotor</td>
			<td style="width:111px;">EMAX US Inc.</td>
			<td style="width:87px;">ES08MD</td>
			<td style="width:275px;">It&#39;s not bad this servo with speed varying from 0.10 sec/60&#176; / 4.8v to 0.08 sec/60&#176;/6.0v.</td>
		</tr>
		<tr height="48">
			<td height="48" style="height:48px;width:87px;">Mechanical Pipettes</td>
			<td style="width:111px;">Dragon Laboratory Instruments Limited</td>
			<td style="width:87px;">YE5K693181</td>
			<td style="width:275px;">The pipettes cover volume range of 0.1 &#956;l to 2.5 &#956;l</td>
		</tr>
	</tbody>
</table>

measurement of dynamic force acted on water strider leg jumping upward by the pvdf film sensor

本研究旨在解释自然界中水黾通常在水面上容易地跳跃或滑行的现象, 其峰值运动速度达到150厘米/秒。首先, 用扫描电镜观察了水黾的显微组织和层次。根据双腿的观察形态学, 建立了水表面脱离的理论模型, 解释了水黾在降低能量方面的能力。其次, 利用具有良好灵敏度的 PVDF 薄膜传感器, 设计了一种动态力测量系统, 可以检测整个交互过程。随后, 一条与水接触的单腿以不同的速度向上拉, 同时测量粘附力。实验结果表明, 对水黾的快速跳跃有了深刻的认识。

举升速度与粘附力的关系见表 1。当提升速度从0.01 米/秒增加到0.3 米/秒时, 水表面和腿部之间的粘附力从0.10 降到0.03。实验结果表明, 当提升速度增加时, 峰值粘附力会显著降低, 这表明水黾在水面上快速移动会感到舒适。
本文建立了基于双腿显微组织和刚毛形状的水下腿的模型, 阐明了低能量还原水表面容易跳跃的机理。刚毛的腿是一个锥形的柱子, 前面部分薄, 后方非常厚, 如图 1所示, 导致前面部分的刚度大大低于后方。因此, 刚毛的前部倾向于容易弯曲, 而后方没有由于优秀刚性。当腿从水中拉出时, 腿上的刚毛会因粘附力而弯曲, 最后垂直于水面, 如图 5所示。水会沿刚毛自然地下降, 耗能低, 可以忽略。刚毛的弯曲会使接触线明显减小到直径为0.2 米的圆, 能量减少可以表示为:
<img alt="Equation 1" src="/files/ftp_upload/58221/58221eq1.jpg"> 在那里, y是表面张力系数, 72 mJ/米2和 D 是直径的刚毛的尖端, 分别。因此, 水黾可以很容易地跳进水里。
通过前向模型对粘接力与升力速度的关系进行了深入的解释。根据能量守恒, 由于粘附力的提高, 所提水的总能量约等于腿E的能量减少。在该模型中, E在不同的提升速度下是恒定的。因此, 水的能量被拉起来, 包括势能ep 和动能ek, 是不变的。高提升速度将导致小势能ep 和大动能ek。因此, 随着提升速度的增加, 与势能成正比的粘附力会急剧下降。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/58221/58221fig1.jpg"> 图 1: nonwetting 水黾腿.(a) 超疏水性腿上的刚毛。(b) 刚毛上的纳米级凹槽。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/58221/58221fig1large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/58221/58221fig2.jpg"> 图 2:动态力测量系统。(a) 动态力测量系统的示意图由 PVDF 薄膜传感器、CCD 摄像机、电荷放大器、数据采集装置和计算机组成。(b) 动态力测量系统的实际实验仪器。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/58221/58221fig2large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/58221/58221fig3.jpg"> 图 3: 前面板演示的连续模拟电压测量.虚拟仪器的演示是用来采样 PVDF 薄膜传感器的电压信号。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/58221/58221fig3large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/58221/58221fig4.jpg"> 图 4: 以一定的速度离开腿部的实验.(a) 腿离水面的脱离。(b) 用 PVDF 薄膜传感器测量的实时粘附力。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/58221/58221fig4large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/58221/58221fig5.jpg"> 图 5:水黾从水面离开的理论模型.该模型表明, 刚毛是弯曲剥离远离水面。<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/58221/58221fig5large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Table 1" src="/files/ftp_upload/58221/58221table1.jpg"> 表 1: 在不同的提升速度下测量的峰值粘附力.从0.10 μN 到0.03 μN 的粘附力显著降低, 提升速度从0.01 米/秒增加到0.3 米/秒。

Watch this Scientific Journal Video about Measurement of Dynamic Force Acted on Water Strider Leg Jumping Upward by the PVDF Film Sensor at JoVE.com

Measurement of Dynamic Force Acted on Water Strider Leg Jumping Upward by the PVDF Film Sensor

PVDF 薄膜传感器对水黾腿跳起动力的测量

这里的协议专门研究水黾在水面上的自由和快速机动。该协议包括观察腿的显微组织和测量不同速度离开水面时的粘附力。

This study aimed to make an explanation for the phenomenon in nature that water strider usually jumps or glides on the water surface easily but quickly, ...

measurement-dynamic-force-acted-on-water-strider-leg-jumping-upward

Nanyang Technological University

Research

JoVE Journal

Engineering

5.9K 次观看.  Tianjin University. 这里的协议专门研究水黾在水面上的自由和快速机动。该协议包括观察腿的显微组织和测量不同速度离开水面时的粘附力。

视频: Measurement of Dynamic Force Acted on Water Strider Leg Jumping Upward by the PVDF Film Sensor

The Preparation of Electrohydrodynamic Bridges from Polar Dielectric Liquids

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

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

高压直流电桥从极地介电液的制备

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

科研

工程学

Investigating Single Molecule Adhesion by Atomic Force Spectroscopy

Atomic force spectroscopy is an ideal tool to study molecules at surfaces and interfaces. An experimental protocol to couple a large variety of single molecules covalently onto an AFM tip is presented. At the same time the AFM tip is passivated to prevent unspecific interactions between the tip and the substrate, which is a prerequisite to study single molecules attached to the AFM tip. Analyses to determine the adhesion force, the adhesion length, and the free energy of these molecules on solid surfaces and bio-interfaces are shortly presented and external references for further reading are provided. Example molecules are the poly(amino acid) polytyrosine, the graft polymer PI-g-PS and the phospholipid POPE (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine). These molecules are desorbed from different surfaces like CH3-SAMs, hydrogen terminated diamond and supported lipid bilayers under various solvent conditions. Finally, the advantages of force spectroscopic single molecule experiments are discussed including means to decide if truly a single molecule has been studied in the experiment.

A protocol to couple a large variety of single molecules covalently onto an AFM tip is presented. Procedures and examples to determine the adhesion force and free energy of these molecules on solid supports and bio-interfaces are provided.

调查单分子粘附的原子力谱

Atomic force spectroscopy is an ideal tool to study molecules at surfaces and interfaces. An experimental protocol to couple a large variety of single ...

How to Build a Vacuum Spring-transport Package for Spinning Rotor Gauges

The spinning rotor gauge (SRG) is a high-vacuum gauge often used as a secondary or transfer standard for vacuum pressures in the range of 1.0 x 10-4 Pa to 1.0 Pa. In this application, the SRGs are frequently transported to laboratories for calibration. Events can occur during transportation that change the rotor surface conditions, thus changing the calibration factor. To assure calibration stability, a spring-transport mechanism is often used to immobilize the rotor and keep it under vacuum during transport. It is also important to transport the spring-transport mechanism using packaging designed to minimize the risk of damage during shipping. In this manuscript, a detailed description is given on how to build a robust spring-transport mechanism and shipping container. Together these form a spring-transport package. The spring-transport package design was tested using drop-tests and the performance was found to be excellent. The present spring-transport mechanism design keeps the rotor immobilized when experiencing shocks of several hundred g (g = 9.8 m/sec2 and is the acceleration due to gravity), while the shipping container assures that the mechanism will not experience shocks greater than about 100 g during common shipping mishaps (as defined by industry standards).

Here we describe how to build a robust spring-transport mechanism for a spinning rotor gauge. This device securely immobilizes the rotor and keeps it under vacuum during transportation. We also describe packaging that minimizes the risk of damage during transport. Tests show our design works for typical shocks during transport.

如何建立一个真空Spring的运输包装为纺转子规

The spinning rotor gauge (SRG) is a high-vacuum gauge often used as a secondary or transfer standard for vacuum pressures in the range of 1.0 x 10-4 Pa to ...

Quantitative Hardness Measurement by Instrumented AFM-indentation

In this work, a combination of amplitude-modulated non-contact atomic force microscopy and atomic force spectroscopy is applied for instrumented hardness measurements on an Au(111) surface with atomistic resolution of single plasticity events. A careful experimental procedure is described that includes the force sensor selection, its calibration, the calibration of the cantilever deflection detection system, and the minimization of instrumental drift for accurate and reproducible force-distance measurements. Also, a method for the data analysis is presented that allows the extraction of force-penetration curves from recorded force-distance curves. A typical curve displays a clear elastic deformation regime up to the first plasticity event, or pop-in, with a length in the range of one to two Burger's vectors. Later plasticity events exhibit the same magnitude. The work of plasticity is further extracted from the measurements. Finally, the hardness is determined in combination with the indentation curve using non-contact atomic force microscopy images of the remaining indents.

This experimental protocol describes how atomic force microscopy can be used to measure hardness at the true nanometer scale and to detect single atomistic plasticity events.

通过仪表AFM压痕硬度定量测量

In this work, a combination of amplitude-modulated non-contact atomic force microscopy and atomic force spectroscopy is applied for instrumented hardness ...

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 ...

Measurement of Quantum Interference in a Silicon Ring Resonator Photon Source

Silicon photonic chips have the potential to realize complex integrated quantum information processing circuits, including photon sources, qubit manipulation, and integrated single-photon detectors. Here, we present the key aspects of preparing and testing a silicon photonic quantum chip with an integrated photon source and two-photon interferometer. The most important aspect of an integrated quantum circuit is minimizing loss so that all of the generated photons are detected with the highest possible fidelity. Here, we describe how to perform low-loss edge coupling by using an ultra-high numerical aperture fiber to closely match the mode of the silicon waveguides. By using an optimized fusion splicing recipe, the UHNA fiber is seamlessly interfaced with a standard single-mode fiber. This low-loss coupling allows the measurement of high-fidelity photon production in an integrated silicon ring resonator and the subsequent two-photon interference of the produced photons in a closely integrated Mach-Zehnder interferometer. This paper describes the essential procedures for the preparation and characterization of high-performance and scalable silicon quantum photonic circuits.

Silicon photonic chips have the potential to realize complex integrated quantum systems. Presented here is a method for preparing and testing a silicon photonic chip for quantum measurements.

量子干涉效应在硅谐振环光子源测量

Silicon photonic chips have the potential to realize complex integrated quantum information processing circuits, including photon sources, qubit ...

Generation of Size-controlled Poly (ethylene Glycol) Diacrylate Droplets via Semi-3-Dimensional Flow Focusing Microfluidic Devices

Uniform and size-controllable poly (ethylene glycol) diacrylate (PEGDA) droplets could be produced via the flow focusing process in a microfluidic device. This paper proposes a semi-three-dimensional (semi-3D) flow-focusing microfluidic chip for droplet formation. The polydimethylsiloxane (PDMS) chip was fabricated using the multi-layer soft lithography method. Hexadecane containing surfactant was used as the continuous phase, and PEGDA with the ultraviolet (UV) photo-initiator was the dispersed phase. Surfactants allowed the local surface tension to drop and formed a more cusped tip which promoted breaking into tiny micro-droplets. As the pressure of dispersed phase was constant, the size of droplets became smaller with increasing continuous phase pressure before dispersed phase flow was broken off. As a result, droplets with size variation from 1 &#181;m to 80 &#181;m in diameter could be selectively achieved by changing the pressure ratio in two inlet channels, and the average coefficient of variation was estimated to be below 7%. Furthermore, droplets could turn into micro-beads by UV exposure for photo-polymerization. Conjugating biomolecules on such micro-beads surface have many potential applications in the fields of biology and chemistry.

Generation of Size-controlled Poly ethylene Glycol Diacrylate Droplets via Semi-3-Dimensional Flow Focusing Microfluidic Devices

Here, we present a protocol to illustrate the fabrication processes and verifying experiments of a semi-three-dimensional (semi-3D) flow-focusing microfluidic chip for droplet formation.

Semi-3-Dimensional 流聚焦微流控装置产生尺寸控制的聚乙二醇二丙烯酸酯液滴

Uniform and size-controllable poly (ethylene glycol) diacrylate (PEGDA) droplets could be produced via the flow focusing process in a microfluidic device. ...

Near-Infrared Temperature Measurement Technique for Water Surrounding an Induction-heated Small Magnetic Sphere

A technique to measure the temperature of water and non-turbid aqueous media surrounding an induction-heated small magnetic sphere is presented. This technique utilizes wavelengths of 1150 and 1412 nm, at which the absorption coefficient of water is dependent on temperature. Water or a non-turbid aqueous gel containing a 2.0-mm- or 0.5-mm-diameter magnetic sphere is irradiated with 1150 nm or 1412 nm incident light, as selected using a narrow bandpass filter; additionally, two-dimensional absorbance images, which are the transverse projections of the absorption coefficient, are acquired via a near-infrared camera. When the three-dimensional distributions of temperature can be assumed to be spherically symmetric, they are estimated by applying inverse Abel transforms to the absorbance profiles. The temperatures were observed to consistently change according to time and the induction heating power.

A technique utilizing wavelengths of 1150 and 1412 nm to measure the temperature of water surrounding an induction-heated small magnetic sphere is presented.

感应加热小磁球周围水近红外测温技术

A technique to measure the temperature of water and non-turbid aqueous media surrounding an induction-heated small magnetic sphere is presented. This ...

Fabrication of Flexible Image Sensor Based on Lateral NIPIN Phototransistors

Flexible photodetectors have been intensely studied for the use of curved image sensors, which are a crucial component in bio-inspired imaging systems, but several challenging points remain, such as a low absorption efficiency due to a thin active layer and low flexibility. We present an advanced method to fabricate a flexible phototransistor array with an improved electrical performance. The outstanding electrical performance is driven by a low dark current owing to deep impurity doping. Stretchable and flexible metal interconnectors simultaneously offer electrical and mechanical stabilities in a highly deformed state. The protocol explicitly describes the fabrication process of the phototransistor using a thin silicon membrane. By measuring I-V characteristics of the completed device in deformed states, we demonstrate that this approach improves the mechanical and electrical stabilities of the phototransistor array. We expect that this approach to a flexible phototransistor can be widely used for the applications of not only next-generation imaging systems/optoelectronics but also wearable devices such as tactile/pressure/temperature sensors and health monitors.

We present a detailed method to fabricate a deformable lateral NIPIN phototransistor array for curved image sensors. The phototransistor array with an open mesh form, which is composed of thin silicon islands and stretchable metal interconnectors, provides flexibility and stretchability. The parameter analyzer characterizes the electrical property of the fabricated phototransistor.

基于侧向 NIPIN Phototransistors 的柔性图像传感器的研制

Flexible photodetectors have been intensely studied for the use of curved image sensors, which are a crucial component in bio-inspired imaging systems, ...

O-cresol Concentration Online Measurement Based On Near Infrared Spectroscopy Via Partial Least Square Regression

Unlike macroscopic process variables, near-infrared spectroscopy provides process information at the molecular level and can significantly improve the prediction of the components in industrial processes. The ability to record spectra for solid and liquid samples without any pretreatment is advantageous and the method is widely used. However, the disadvantages of analyzing high-dimensional near-infrared spectral data include information redundancy and multicollinearity of the spectral data. Thus, we propose to use partial least squares regression method, which has traditionally been used to reduce the data dimensionality and eliminate the collinearity between the original features. We implement the method for predicting the o-cresol concentration during the production of polyphenylene ether. The proposed approach offers the following advantages over component regression prediction methods: 1) partial least squares regression solves the multicollinearity problem of the independent variables and effectively avoids overfitting, which occurs in a regression analysis due to the high correlation between the independent variables; 2) the use of the near-infrared spectra results in high accuracy because it is a non-destructive and non-polluting method to obtain information at microscopic and molecular scales.

The protocol describes a method of predicting o-cresol concentration during the production of polyphenylene ether using near-infrared spectroscopy and partial least squares regression. To describe the process more clearly and completely, an example of predicting the o-cresol concentration during the production of polyphenylene is used to clarify the steps.

O-cresol 浓度在线测量基于近红外光谱通过部分最小平方回归

Unlike macroscopic process variables, near-infrared spectroscopy provides process information at the molecular level and can significantly improve the ...