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

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>

<ol>
	<li>Gao, X., Jiang, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biophysics:+Water-repellent+legs+of+water+striders.">Biophysics: Water-repellent legs of water striders.</a> Nature. 432 (7013), 36 (2004).</li><li>Hu, D. L., Chan, B., Bush, J. W. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+hydrodynamics+of+water+strider+locomotion.">The hydrodynamics of water strider locomotion.</a> Nature. 424 (6949), 663-666 (2003).</li><li>Jiang, C. G., Xin, S. C., Wu, C. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Drag+reduction+of+a+miniature+boat+with+superhydrophobic+grille+bottom.">Drag reduction of a miniature boat with superhydrophobic grille bottom.</a> AIP Advances. 1 (3), 032148 (2011).</li><li>Su, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nano+to+micro+structural+hierarchy+is+crucial+for+stable+superhydrophobic+and+water-repellent+surfaces.">Nano to micro structural hierarchy is crucial for stable superhydrophobic and water-repellent surfaces.</a> Langmuir. 26 (7), 4984-4989 (2010).</li><li>Feng, X. Q., Gao, X., Wu, Z., Jiang, L., Zheng, Q. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Superior+water+repellency+of+water+strider+legs+with+hierarchical+structures:+experiments+and+analysis.">Superior water repellency of water strider legs with hierarchical structures: experiments and analysis.</a> Langmuir. 23 (9), 4892-4896 (2007).</li><li>Suter, R. B., Stratton, G., Miller, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Water+surface+locomotion+by+spiders:+distinct+gaits+in+diverse+families.">Water surface locomotion by spiders: distinct gaits in diverse families.</a> Journal of Arachnology. 31 (3), 428-432 (2003).</li><li>Yin, W., Zheng, Y. L., Lu, H. Y. <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+topographies+of+water+surface+dimples+formed+by+superhydrophobic+water+strider+legs.">Three-dimensional topographies of water surface dimples formed by superhydrophobic water strider legs.</a> Applied Physics Letters. 109 (16), 163701 (2016).</li><li>Liu, J. L., Feng, X. Q., Wang, G. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Buoyant+force+and+sinking+condition+of+a+hydrophobic+thin+rod+floating+on+water.">Buoyant force and sinking condition of a hydrophobic thin rod floating on water.</a> Physical Review E. 76 (6), 066103 (2007).</li><li>Ng, T. W., Panduputra, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamical+force+and+imaging+characterization+of+superhydrophobic+surfaces.">Dynamical force and imaging characterization of superhydrophobic surfaces.</a> Langmuir the Acs Journal of Surfaces &amp; Colloids. 28 (1), 453-458 (2012).</li><li>Zheng, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Elegant+Shadow+Making+Tiny+Force+Visible+for+Water-Walking+Arthropods+and+Updated+Archimedes'+Principle.">Elegant Shadow Making Tiny Force Visible for Water-Walking Arthropods and Updated Archimedes' Principle.</a> Langmuir. 32 (41), 10522-10528 (2016).</li><li>Zhao, J., Zhang, X., Chen, N., Pan, Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Why+superhydrophobicity+is+crucial+for+a+water-jumping+microrobot?+Experimental+and+theoretical+investigations.">Why superhydrophobicity is crucial for a water-jumping microrobot? Experimental and theoretical investigations.</a> Acs Appl Mater Interfaces. 4 (7), 3706-3711 (2012).</li><li>Shi, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Towards+Understanding+Why+a+Superhydrophobic+Coating+Is+Needed+by+Water+Striders.">Towards Understanding Why a Superhydrophobic Coating Is Needed by Water Striders.</a> Advanced Materials. 19 (17), 2257-2261 (2010).</li><li>Yang, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Water+striders+adjust+leg+movement+speed+to+optimize+takeoff+velocity+for+their+morphology.">Water striders adjust leg movement speed to optimize takeoff velocity for their morphology.</a> Nature communications. 7, 13698 (2016).</li><li>Liu, J. L., Sun, J., Mei, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biomimetic+mechanics+behaviors+of+the+strider+leg+vertically+pressing+water.">Biomimetic mechanics behaviors of the strider leg vertically pressing water.</a> Applied Physics Letters. 104 (23), 231607 (2014).</li><li>Kong, X. Q., Liu, J. L., Wu, C. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Why+a+mosquito+leg+possesses+superior+load-bearing+capacity+on+water:+Experimentals.">Why a mosquito leg possesses superior load-bearing capacity on water: Experimentals.</a> Acta Mechanica Sinica. 32 (2), 335-341 (2016).</li><li>Liu, J. L., Mei, Y., Xia, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+wetting+mechanism+based+upon+triple+contact+line+pinning.">A new wetting mechanism based upon triple contact line pinning.</a> Langmuir. 27 (1), 196-200 (2011).</li><li>Lee, D. G., Kim, H. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+superhydrophobicity+in+the+adhesion+of+a+floating+cylinder.">The role of superhydrophobicity in the adhesion of a floating cylinder.</a> Journal of Fluid Mechanics. 624, 23-32 (2009).</li><li>Wei, P. J., Chen, S. C., Lin, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adhesion+forces+and+contact+angles+of+water+strider+legs.">Adhesion forces and contact angles of water strider legs.</a> Langmuir. 25 (3), 1526-1528 (2008).</li><li>Su, Y., Ji, B., Huang, Y., Hwang, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nature's+design+of+hierarchical+superhydrophobic+surfaces+of+a+water+strider+for+low+adhesion+and+low-energy+dissipation.">Nature's design of hierarchical superhydrophobic surfaces of a water strider for low adhesion and low-energy dissipation.</a> Langmuir. 26 (24), 18926-18937 (2010).</li><li>Shen, Y., Xi, N., Lai, K. W. C., Li, W. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+PVDF+microforce/force+rate+sensor+for+practical+applications+in+micromanipulation.">A novel PVDF microforce/force rate sensor for practical applications in micromanipulation.</a> Sensor Review. 24 (3), 274-283 (2004).</li><li>Wang, Y. R., Zheng, J. M., Ren, G. Y., Xu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+flexible+piezoelectric+force+sensor+based+on+PVDF+fabrics.">A flexible piezoelectric force sensor based on PVDF fabrics.</a> Smart Materials and Structures. 20 (4), 045009 (2011).</li><li>Liu, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Application+of+PVDF+film+to+stress+measurement+of+structural+member.">Application of PVDF film to stress measurement of structural member.</a> Journal of the Society of Naval Architects of Japan. 2002 (192), 591-599 (2002).</li><li>Fujii, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proposal+for+a+step+response+evaluation+method+for+force+transducers.">Proposal for a step response evaluation method for force transducers.</a> Measurement Science and Technology. 14 (10), 1741-1746 (2003).</li><li>Zheng, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improving+environmental+noise+suppression+for+micronewton+force+sensing+based+on+electrostatic+by+injecting+air+damping.">Improving environmental noise suppression for micronewton force sensing based on electrostatic by injecting air damping.</a> Review of Scientific Instruments. 85 (5), 055002 (2014).</li><li>Zheng, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+multi-position+calibration+of+the+stiffness+for+atomic-force+microscope+cantilevers+based+on+vibration.">The multi-position calibration of the stiffness for atomic-force microscope cantilevers based on vibration.</a> Measurement Science and Technology. 26 (5), 055001 (2015).</li><li>Sun, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Differential+Method+for+Force+Measurement+Based+on+Electrostatic+Force.">The Differential Method for Force Measurement Based on Electrostatic Force.</a> Journal of Sensors. 2017, 1857920 (2017).</li><li>Song, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Highly+Sensitive,+Precise,+and+Traceable+Measurement+of+Force.">Highly Sensitive, Precise, and Traceable Measurement of Force.</a> Instrumentation Science &amp; Technology. 44 (4), 386-400 (2016).</li><li>Kurata, M., Li, X., Fujita, K., Yamaguchi, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Piezoelectric+dynamic+strain+monitoring+for+detecting+local+seismic+damage+in+steel+buildings.">Piezoelectric dynamic strain monitoring for detecting local seismic damage in steel buildings.</a> Smart Materials and Structures. 22 (11), 115002 (2013).</li><li>Qasaimeh, M. A., Sokhanvar, S., Dargahi, J., Kahrizi, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PVDF-based+microfabricated+tactile+sensor+for+minimally+invasive+surgery.">PVDF-based microfabricated tactile sensor for minimally invasive surgery.</a> Journal of Microelectromechanical Systems. 18 (1), 195-207 (2009).</li></ol>

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?...

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><tbody><tr><td>PVDF film sensor</td><td>TE Connectivity</td><td>DT1-028K/L</td><td>The PVDF film sensor is used to sense the dynamic contact force .</td></tr><tr><td>Charge amplifier</td><td>Wuxi Shiao Technology co.,Ltd</td><td>YE5852B</td><td>The charge amplifier&amp;nbsp;is an electronic current integrator that produces a voltage output proportional to the integrated value of the input</td></tr><tr><td>Data acquisition device</td><td>National Instruments</td><td>USB-4431</td><td>The data acquisition device is used to read the voltage data.</td></tr><tr><td>Displacement stage</td><td>ZOLIXINSTRUMENTS CO.LTD</td><td>KSAV1010-ZF</td><td>KSAV1010/2030-ZF is a wedge vertical stage with high-resolution, high-stability and high-load.</td></tr><tr><td>CCD camera</td><td>Shenzhen Andonstar Tech Co., Ltd</td><td>digital microscope A1</td><td>Frame rate: 30 frames/sec;Focal distance: 5mm - 30mm</td></tr><tr><td>Computer</td><td>Lenovo</td><td>G480</td><td></td></tr><tr><td>Servomotor</td><td>EMAX US Inc.</td><td>ES08MD</td><td>It&#039;s not bad this servo with speed varying from 0.10 sec/60&amp;deg; / 4.8v to 0.08 sec/60&amp;deg;/6.0v.</td></tr><tr><td>Mechanical Pipettes</td><td>Dragon Laboratory Instruments Limited</td><td>YE5K693181</td><td>The pipettes cover volume range of 0.1 &amp;mu;l to 2.5 &amp;mu;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?...

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

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

Quantitatively Measuring In situ Flows using a Self-Contained Underwater Velocimetry Apparatus (SCUVA)

The ability to directly measure velocity fields in a fluid environment is necessary to provide empirical data for studies in fields as diverse as oceanography, ecology, biology, and fluid mechanics. Field measurements introduce practical challenges such as environmental conditions, animal availability, and the need for field-compatible measurement techniques. To avoid these challenges, scientists typically use controlled laboratory environments to study animal-fluid interactions. However, it is reasonable to question whether one can extrapolate natural behavior (i.e., that which occurs in the field) from laboratory measurements. Therefore, in situ quantitative flow measurements are needed to accurately describe animal swimming in their natural environment.
We designed a self-contained, portable device that operates independent of any connection to the surface, and can provide quantitative measurements of the flow field surrounding an animal. This apparatus, a self-contained underwater velocimetry apparatus (SCUVA), can be operated by a single scuba diver in depths up to 40 m. Due to the added complexity inherent of field conditions, additional considerations and preparation are required when compared to laboratory measurements. These considerations include, but are not limited to, operator motion, predicting position of swimming targets, available natural suspended particulate, and orientation of SCUVA relative to the flow of interest. The following protocol is intended to address these common field challenges and to maximize measurement success.

Quantitatively Measuring In situ Flows using a Self-Contained Underwater Velocimetry Apparatus SCUVA

This protocol provides instructions on how to use a self-contained underwater velocimetry apparatus (SCUVA), which is designed for quantification of in situ animal-generated flows. In addition, this protocol addresses challenges posed by field conditions, and includes operator motion, predicting position of animals, and orientation of SCUVA.

定量测量原位流动，使用一个自包含的水下测速仪（SCUVA）

The ability to directly measure velocity fields in a fluid environment is necessary to provide empirical data for studies in fields as diverse as ...

科研

生物工程

Concurrent Quantitative Conductivity and Mechanical Properties Measurements of Organic Photovoltaic Materials using AFM

Organic photovoltaic (OPV) materials are inherently inhomogeneous at the nanometer scale. Nanoscale inhomogeneity of OPV materials affects performance of photovoltaic devices. Thus, understanding of spatial variations in composition as well as electrical properties of OPV materials is of paramount importance for moving PV technology forward.1,2 In this paper, we describe a protocol for quantitative measurements of electrical and mechanical properties of OPV materials with sub-100 nm resolution. Currently, materials properties measurements performed using commercially available AFM-based techniques (PeakForce, conductive AFM) generally provide only qualitative information. The values for resistance as well as Young's modulus measured using our method on the prototypical ITO/PEDOT:PSS/P3HT:PC61BM system correspond well with literature data. The P3HT:PC61BM blend separates onto PC61BM-rich and P3HT-rich domains. Mechanical properties of PC61BM-rich and P3HT-rich domains are different, which allows for domain attribution on the surface of the film. Importantly, combining mechanical and electrical data allows for correlation of the domain structure on the surface of the film with electrical properties variation measured through the thickness of the film.

Organic photovoltaic (OPV) materials are inherently inhomogeneous at the nanometer scale. Nanoscale inhomogeneity of OPV materials affects performance of photovoltaic devices. In this paper, we describe a protocol for quantitative measurements of electrical and mechanical properties of OPV materials with sub-100 nm resolution.

并行定量的导电性和力学性能测试的有机光伏材料利用原子力显微镜

Organic photovoltaic  (OPV) materials are inherently inhomogeneous at the nanometer scale. Nanoscale  inhomogeneity of OPV materials affects performance ...

工程学

Kinematics and Ground Reaction Force Determination: A Demonstration Quantifying Locomotor Abilities of Young Adult, Middle-aged, and Geriatric Rats

Behavior, in its broadest definition, can be defined as the motor manifestation of physiologic processes. As such, all behaviors manifest through the motor system. In the fields of neuroscience and orthopedics, locomotion is a commonly evaluated behavior for a variety of disease models. For example, locomotor recovery after traumatic injury to the nervous system is one of the most commonly evaluated behaviors 1-3. Though locomotion can be evaluated using a variety of endpoint measurements (e.g. time taken to complete a locomotor task, etc), semiquantitative kinematic measures (e.g. ordinal rating scales (e.g. Basso Beattie and Bresnahan locomotor (BBB) rating scale, etc)) and surrogate measures of behaviour (e.g. muscle force, nerve conduction velocity, etc), only kinetics (force measurements) and kinematics (measurements of body segments in space) provide a detailed description of the strategy by which an animal is able to locomote 1. Though not new, kinematic and kinetic measurements of locomoting rodents is now more readily accessible due to the availability of commercially available equipment designed for this purpose. Importantly, however, experimenters need to be very familiar with theory of biomechanical analyses and understand the benefits and limitations of these forms of analyses prior to embarking on what will become a relatively labor-intensive study. The present paper aims to describe a method for collecting kinematic and ground reaction force data using commercially available equipment. Details of equipment and apparatus set-up, pre-training of animals, inclusion and exclusion criteria of acceptable runs, and methods for collecting the data are described. We illustrate the utility of this behavioral analysis technique by describing the kinematics and kinetics of strain-matched young adult, middle-aged, and geriatric rats.

Locomotion is often examined as a behavioural outcome in various models of disease in fields such as neuroscience and orthopedics. This video paper intends to describe a method for collecting ground reaction forces and kinematics from rats during unrestrained locomotion.

运动学与地面反作用力的测定：一个示范量化青年，中年和老年大鼠的运动能力能力

Behavior, in its broadest definition, can be defined as the motor manifestation of physiologic processes.  As such, all behaviors manifest through the ...

神经科学

Microfabricated Post-Array-Detectors (mPADs): an Approach to Isolate Mechanical Forces

In this video, we will present our approach to measure cellular traction forces using a microfabricated array of posts.  Traction forces are generated through myosin-actin interactions and play an important role in our physiology.  During development, they enable cells to move from one location to the next in order to form the early structures of tissue.  Traction forces help in the healing processes.  They are necessary for the proper closure of wounds or the migration and crawling of leukocytes through our body.  These same forces can be detrimental to our health in the case of cancer metastasis or vascular growth towards a tumor.  The most common method by which to study cells in vitro has been to use a glass or polystyrene dish.  However, the rigidity of the substrates makes it impossible to physically measure cell traction forces, and there are relatively few methods to study traction forces.  Our lab has developed a technique to overcome these limitations.  The method is based on a vertical array of flexible cantilevers, the stiffness and size scale of which are such that individual cells spread across many cantilevers and deflect them in the process.  The pillars we use are 3 &mu;m in diameter, 10 &mu;m tall, and are configured in a regular array with 9 &mu;m center-to-center spacing.  But these physical dimensions can be readily varied to accommodate a variety of studies.  We start with a silicon master, but the final posts are made out of silicone rubber called poly (dimethyl siloxane), or PDMS.  We can measure the deflections under a microscope and calculate the magnitude and direction of traction forces required to produce the observed deflections.  We call these substrates microfabricated post-array-detectors, or mPADs.  Here, we will show you how we fabricate and use the mPADs to assess modulations of cellular contractility.

Microfabricated Post-Array-Detectors mPADs: an Approach to Isolate Mechanical Forces

In this video, we demonstrate how to fabricate and utilize microfabricated post array detectors (mPADs) to assess modulations of cellular contractility.

微阵列后探测器（mPADs）：机械力的方法来隔离

In this video, we will present our approach to measure cellular traction forces using a microfabricated array of posts.  Traction forces are generated ...

生物学

Studying the Neural Basis of Adaptive Locomotor Behavior in Insects

Studying the neural basis of walking behavior, one often faces the problem that it is hard to separate the neuronally produced stepping output from those leg movements that result from passive forces and interactions with other legs through the common contact with the substrate. If we want to understand, which part of a given movement is produced by nervous system motor output, kinematic analysis of stepping movements, therefore, needs to be complemented with electrophysiological recordings of motor activity. The recording of neuronal or muscular activity in a behaving animal is often limited by the electrophysiological equipment which can constrain the animal in its ability to move with as many degrees of freedom as possible. This can either be avoided by using implantable electrodes and then having the animal move on a long tether (i.e. Clarac et al., 1987; Duch &amp; Pfl&uuml;ger, 1995; B&ouml;hm et al., 1997; Gruhn &amp; Rathmayer, 2002) or by transmitting the data using telemetric devices (Kutsch et al, 1993; Fischer et al., 1996; Tsuchida et al. 2004; Hama et al., 2007; Wang et al., 2008). Both of these elegant methods, which are successfully used in larger arthropods, often prove difficult to apply in smaller walking insects which either easily get entangled in the long tether or are hindered by the weight of the telemetric device and its batteries. In addition, in all these cases, it is still impossible to distinguish between the purely neuronal basis of locomotion and the effects exerted by mechanical coupling between the walking legs through the substrate. One solution for this problem is to conduct the experiments in a tethered animal that is free to walk in place and that is locally suspended, for example over a slippery surface, which effectively removes most ground contact mechanics. This has been used to study escape responses (Camhi and Nolen, 1981; Camhi and Levy, 1988), turning (Tryba and Ritzman, 2000a,b; Gruhn et al., 2009a), backward walking (Graham and Epstein, 1985) or changes in velocity (Gruhn et al., 2009b) and it allows the experimenter easily to combine intra- and extracellular physiology with kinematic analyses (Gruhn et al., 2006).
We use a slippery surface setup to investigate the timing of leg muscles in the behaving stick insect with respect to touch-down and lift-off under different behavioral paradigms such as straight forward and curved walking in intact and reduced preparations.

We describe a method to record motor activity, timed to the electrically recorded tarsal contact signal in a tethered insect, walking on a slippery surface. This is used to study the neural basis of adaptive behavior under reduced influence of mechanical interaction between legs through the substrate.

研究昆虫的自适应运动能力行为的神经基础

Studying the neural basis of walking behavior, one often faces the problem that it is hard to separate the neuronally produced stepping output from those ...

Image-based Lagrangian Particle Tracking in Bed-load Experiments

Image analysis has been increasingly used for the measurement of river flows due to its capabilities to furnish detailed quantitative depictions at a relatively low cost. This manuscript describes an application of particle tracking velocimetry (PTV) to a bed-load experiment with lightweight sediment. The key characteristics of the investigated sediment transport conditions were the presence of a covered flow and of a fixed rough bed above which particles were released in limited number at the flume inlet. Under the applied flow conditions, the motion of the individual bed-load particles was intermittent, with alternating movement and stillness terms. The flow pattern was preliminarily characterized by acoustic measurements of vertical profiles of the stream-wise velocity. During process visualization, a large field of view was obtained using two action-cameras placed at different locations along the flume. The experimental protocol is described in terms of channel calibration, experiment realization, image pre-processing, automatic particle tracking, and post-processing of particle track data from the two cameras. The presented proof-of-concept results include probability distributions of the particle hop length and duration. The achievements of this work are compared to those of existing literature to demonstrate the validity of the protocol.

The manuscript presents a protocol for the conduction of bed-load sediment transport experiments where the moving particles are tracked by image analysis. The experimental facility, the procedures for run realization and data processing, and finally some proof-of-concept results are presented here.

基于图像的拉格朗日粒子跟踪在床载荷实验

Image analysis has been increasingly used for the measurement of river flows due to its capabilities to furnish detailed quantitative depictions at a ...

环境科学

Simulation of Human-induced Vibrations Based on the Characterized In-field Pedestrian Behavior

For slender and lightweight structures, vibration serviceability is a matter of growing concern, often constituting the critical design requirement. With designs governed by the dynamic performance under human-induced loads, a strong demand exists for the verification and refinement of currently available load models. The present contribution uses a 3D inertial motion tracking technique for the characterization of the in-field pedestrian behavior. The technique is first tested in laboratory experiments with simultaneous registration of the corresponding ground reaction forces. The experiments include walking persons as well as rhythmical human activities such as jumping and bobbing. It is shown that the registered motion allows for the identification of the time variant pacing rate of the activity. Together with the weight of the person and the application of generalized force models available in literature, the identified time-variant pacing rate allows to characterize the human-induced loads. In addition, time synchronization among the wireless motion trackers allows identifying the synchronization rate among the participants. Subsequently, the technique is used on a real footbridge where both the motion of the persons and the induced structural vibrations are registered. It is shown how the characterized in-field pedestrian behavior can be applied to simulate the induced structural response. It is demonstrated that the in situ identified pacing rate and synchronization rate constitute an essential input for the simulation and verification of the human-induced loads. The main potential applications of the proposed methodology are the estimation of human-structure interaction phenomena and the development of suitable models for the correlation among pedestrians in real traffic conditions.

A protocol is presented for the characterization of the in-field pedestrian behavior and the simulation of the resulting structural response. Field-tests demonstrate that the in situ identified pacing rate and synchronization rate among the participants constitute an essential input for the simulation and verification of the human-induced loads.

基于该特征场行人行为人类引起的振动模拟

For slender and lightweight structures, vibration serviceability is a matter of growing concern, often constituting the critical design requirement. With ...

Measuring the Interaction Force Between a Droplet and a Super-hydrophobic Substrate by the Optical Lever Method

The goal of this paper is to investigate the interaction force between droplets and super-hydrophobic substrates in the air. A measurement system based on an optical lever method is designed. A millimetric cantilever is used as a force sensitive component in the measurement system. Firstly, the force sensitivity of the optical lever is calibrated using electrostatic force, which is the critical step in measuring interaction force. Secondly, three super-hydrophobic substrates with different grid fractions are prepared with nanoparticles and copper grids. Finally, the interaction forces between droplets and super-hydrophobic substrates with different grid fractions are measured by the system. This method can be used to measure the force on the scale of sub-micronewton with a resolution on the scale of nanonewton. The in-depth study of the contact process of droplets and super-hydrophobic structures can help to improve the production efficiency in coating, film and printing. The force measurement system designed in this paper can also be used in other fields of microforce measurement.

The protocol aims to investigate the interaction between droplets and super-hydrophobic substrates in the air. This includes calibrating the measurement system and measuring the interaction force at super-hydrophobic substrates with different grid fractions.

用光学杠杆方法测量液滴和超疏水基板之间的相互作用力

The goal of this paper is to investigate the interaction force between droplets and super-hydrophobic substrates in the air. A measurement system based on ...

Comparison of Kinetic Characteristics of Footwork during Stroke in Table Tennis: Cross-Step and Chasse Step

The cross-step and chasse step are the basic steps of table tennis. This study presents a protocol to investigate the ground reaction force characteristics between cross-step and chasse step during stroke in table tennis. Sixteen healthy male national level 1 table tennis players (Age: 20.75 &plusmn; 2.06 years) volunteered to participate in the experiment after understanding the purpose and details of the experiment. All participants were asked to hit the ball into the target zone by cross-step and chasse step, respectively. The ground reaction force in the anterior-posterior, medial-lateral, and vertical directions of the participant was measured by a force platform. The key finding of this study was that: the posterior ground reaction force of cross-step footwork (0.89 &plusmn; 0.21) was significantly large (P = 0.014) than the chasse step footwork (0.82 &plusmn; 0.18). However, the lateral ground reaction force of cross-step footwork (-0.38 &plusmn; 0.21) was significantly lower (P &lt; 0.001) than chasse step footwork (-0.46 &plusmn; 0.29) as well as the vertical ground reaction force of cross-step footwork (1.73 &plusmn; 0.19) was significantly lower (P &lt; 0.001) than chasse step footwork (1.9 &plusmn; 0.33). Based on the mechanism of the kinetic chain, the better lower limb dynamic performance of sliding stroke may be conducive to energy transmission and thus bring gain to the swing speed. Beginners should start from the chasse step to hit the ball technically, and then practice the skill of cross-step.

This study presents a protocol to investigate the ground reaction force characteristics between cross-step and chasse step during stroke in table tennis.

乒乓球击球时步法动力学特性比较:跨步和追逐步

The cross-step and chasse step are the basic steps of table tennis. This study presents a protocol to investigate the ground reaction force ...

行为学

A Micro-Displacement Measurement Based on the Shadow Technique

The precision measurement of micro displacement is important in scientific and industrial fields. However, it is a tough challenge due to the complex design and the high cost of measuring instruments. Inspired by the shadow formed from water striders walking on a water surface under sunlight, a micro-displacement measurement method was proposed. Water strider legs with superhydrophobic properties bend the water surface. The curved surface of the water refracts sunlight, creating a shadow with a bright edge at the bottom of the pond. The shadow size is generally larger than the indentation depth of the legs from the water surface. In the micro-displacement measurement system, the applied displacement is proportional to the change in the diameter of the shadow. The presented study proposes a micro-displacement measurement procedure based on this shadow technique. The displacement sensitivity can reach 10.0 nm/pixel in the range of 5 &#181;m. This system is simple to construct, low cost, and has high precision with good linear performance. The method provides a convenient additional option to measure micro-displacement.

High-precision micro-displacement measurement is significant in the field of aerospace engineering, ultra-precision machining, and micro-assembly. The present protocol describes measuring micro displacements based on the shadow technique.

The precision measurement of micro displacement is important in scientific and industrial fields. However, it is a tough challenge due to the complex ...