PVDF 薄膜传感器对水黾腿跳起动力的测量
Summary
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。
Abstract
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。
Introduction
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。
Protocol
1. 水黾腿表面结构的观察 利用捕鱼着陆网从当地淡水池塘收集水黾。 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。 自然地把腿晾在空中。 用扫描电镜观察双腿的表面显微结构, 如图 1所示。 观察 microsetae 的双腿使用扫描电镜与纳米级分辨率, 如?…
Representative Results
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?…
Discussion
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?…
Divulgations
The authors have nothing to disclose.
Acknowledgements
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。
Materials
| PVDF film sensor | TE Connectivity | DT1-028K/L | The PVDF film sensor is used to sense the dynamic contact force . |
| Charge amplifier | Wuxi Shiao Technology co.,Ltd | YE5852B | The charge amplifier is an electronic current integrator that produces a voltage output proportional to the integrated value of the input |
| Data acquisition device | National Instruments | USB-4431 | The data acquisition device is used to read the voltage data. |
| Displacement stage | ZOLIXINSTRUMENTS CO.LTD | KSAV1010-ZF | KSAV1010/2030-ZF is a wedge vertical stage with high-resolution, high-stability and high-load. |
| CCD camera | Shenzhen Andonstar Tech Co., Ltd | digital microscope A1 | Frame rate: 30 frames/sec;Focal distance: 5mm – 30mm |
| Computer | Lenovo | G480 | |
| Servomotor | EMAX US Inc. | ES08MD | It's not bad this servo with speed varying from 0.10 sec/60° / 4.8v to 0.08 sec/60°/6.0v. |
| Mechanical Pipettes | Dragon Laboratory Instruments Limited | YE5K693181 | The pipettes cover volume range of 0.1 μl to 2.5 μl |
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Citer Cet Article
Zhang, L., Zhao, M., Wang, Z., Li, Y., Huang, Y., Zheng, Y. Measurement of Dynamic Force Acted on Water Strider Leg Jumping Upward by the PVDF Film Sensor. J. Vis. Exp. (138), e58221, doi:10.3791/58221 (2018).