制造，操作和表面声波驱动声逆流微流体流动可视化
Summary
在这段视频中，我们首先描述的表面声波（SAW）声逆流装置的制造和运行程序。然后，我们证明实验装置，允许流量可视化进行定性和定量分析复杂的流量泵送装置内的SAW。
Abstract
表面声波（声表面波）可用于驱动便携式微流体芯片中的液体通过声学逆流现象。在这个视频中，我们提出了一个多层的SAW声逆流装置的制造协议。该设备制作从铌酸锂（LN）的图案化基板上两个叉指式换能器（叉指换能器）和适当的标记。聚二甲基硅氧烷（PDMS）通道蒙上上SU8主的模具终于结合图案的衬底上。随着制造过程中，我们显示技术，让声逆流装置以液体泵通过的PDMS通道电网的特性和操作。我们终于提出的程序可视化的通道中的液体流。该协议是用于显示根据不同的流型，其特征在于由涡流和颗粒堆积域的层流和更加复杂的动态芯片上的流体排出。
Introduction
微社会面临的一个持续挑战是需要有一个高效的抽水机制，可以小型化，融入真正的便携式微计分析系统（μTAS）。标准的宏观泵送系统根本无法提供所需的可移植性μTAS，由于体积流速的不利缩放通道的大小减小到微米范围内或低于。相反，锯已获得了越来越大的兴趣，流体驱动机制，并出现一些这些问题1,2的解决方案作为一个有前途的途径。
锯进行能源运输到流体3提供了非常高效的机制。到一个压电基片上， 例如铌酸锂（LN） 的SAW传播时，波将被辐射到的任何流体在其路径中以一个角度被称为瑞利角θR =罪722 1（三F / C），由于在衬底中，C S，流体C F声速的不匹配。这种辐射泄漏到流体中产生的压力波在流体驱动声流 。根据适用于该设备上的设备的几何形状和功率，这种机制被示出致动片上的过程，如流体混合，颗粒的分选，雾化，抽水1,4各种各样的。尽管SAW微流体驱动的简单性和有效性，也有只有少数锯驱动微泵机制已被证明日期。第一个示范的免费的液滴放置在表面声波传播路径上的压电基片3的简单的翻译。这种新方法产生了很大兴趣在使用锯作为一种微流体驱动方法，但仍然是一个需要流体被驱动通过封闭的渠道，更艰巨的任务。 Tan 等人泵内的微通道，激光烧蚀成在压电基片直接显示。的几何与通道和IDT尺寸修改，他们能够表现出均匀混合流5。 Glass 等人最近展示了移动，作为一个示范，值得信赖的小型化流行的实验室上的一个CD概念6,7组合SAW驱动旋转离心力的微流体通过微流体和微流体元件的方法。然而，唯一的完全封闭的声表面波驱动泵送机构已被证明仍然是切基尼等。的SAW驱动声逆流8此影片的焦点。它利用流体的雾化和聚结了的传播方向相对的方向通过一个封闭的通道泵波coustic。该系统可以产生令人惊讶的复杂微通道内流动。此外，根据设备的几何形状，它可以提供流量计划的范围内，从层流的涡流和颗粒积累域的特征在于，更复杂的制度。设备内部流动特性的能力，很容易影响显示了先进的片上粒子操纵的机会。
在这个协议中，我们希望澄清实用的基于SAW的微流体设备制造，实验操作，和流量可视化的主要方面。虽然我们明确说明这些程序驱动的SAW声逆流设备的制造和操作，这些部分可以很容易地修改他们的应用的范围SAW驱动微政权的。
Protocol
1。设备制造设计光掩模的图案化中，第一表面声波（SAW）层，和第二的聚二甲基硅氧烷（PDMS）微流道模具。 的第一光掩模具有一对相对的叉指式换能器（叉指换能器），也被称为一个SAW延迟线和信道对应的标记和空间参考，在显微镜。在我们的标准设备，我们有单电极叉指换能器与P = 10微米，孔径为750微米，25个直手指对手指 的宽度。产生所得到的IDT的声表面波的波长…
Representative Results
图2示出的移动设备的RF测试之前采取对LN层键合到微通道层的有代表性的结果：典型的S 11和S 12光谱分别面板a）和b）中报告。在S 11的频谱的中心频率的谷的深度相关的RF功率转换效率，声表面波的机械功率。因此，对于IDT手指对固定数量的，在山谷中的最低的减少将导致操作设备所需的功率减少。在这个最低的频率，该装置将最有效…
Discussion
微社区所面临的最大挑战之一是实现真正的便携式点护理设备驱动平台。其中所提出的集成微型泵23，基于表面声波（声表面波）是特别有吸引力，因为其相关功能流体混合，雾化和粒子浓度和分离4。在本文中，我们已经演示了如何制作和运行流体芯片上的实验室设备是在一个封闭的PDMS微流芯片上集成转向执行器SAW首次描述切基尼等。8。
关于…
Disclosures
The authors have nothing to disclose.
Acknowledgements
作者有没有人承认。
Materials
| Name | Company | Catalog Number | Comments |
| Double side polished 128° YX lithium niobate wafer | Crystal Technology, LLC | ||
| Silicon wafer | Siegert Wafers | We use <100> | |
| IDT Optical lithography mask with alignment marks (positive) | Any vendor | ||
| Channel Optical lithography mask (negative) | Any vendor | ||
| Positive photoresist | Shipley | S1818 | |
| Positive photoresist developer | Microposit | MF319 | |
| Negative tone photoresist | Allresist | AR-N-4340 | |
| Negative tone photoresist developer | Allresist | AR 300-475 | |
| SU8 thick negative tone photoresist | Microchem | SU-8 2000 Series | |
| SU8 thick negative tone photoresist developer | Microchem | SU-8 developer | |
| Hexadecane | Sigma-Aldrich | H6703 | |
| Carbon tetrachloride (CCl4) | Sigma-Aldrich | 107344 | |
| Octadecyltrichlorosilane (OTS) | Sigma-Aldrich | 104817 | |
| Acetone CMOS grade | Sigma-Aldrich | 40289 | |
| 2-propanol CMOS grade | Sigma-Aldrich | 40301 | |
| Titanium | Any vendor | 99.9% purity | |
| Gold | Any vendor | 99.9% purity | |
| PDMS | Dow Corning | Sylgard 184 silicone elastomer kit with curing agent | |
| Petri dish | Any vendor | ||
| 5 mm ID Harris Uni-Core multi-purpose coring tool | Sigma-Aldrich | Z708895 | Any diameter greater than 2 mm is suitable |
| Acoustic absorber | Photonic Cleaning Technologies | First Contact regular kit | |
| RF-PCB | Any vendor | ||
| Spinner | Laurell technologies corporation | WS-400-6NPP | Any spinner can be used |
| UV Mask aligner | Karl Suss | MJB 4 | Any aligner can be used |
| Thermal evaporator | Kurt J. Lesker | Nano 38 | Any thermal, e-beam evaporator or sputtering system can be used |
| Oxygen plasma asher | Gambetti Kenologia Srl | Colibrì | Any plasma asher or RIE machine can be used |
| Centrifuge | Eppendorf | 5810 R | Any centrifuge can be used |
| Wire bonder | Kulicke & Soffa | 4523AD | Any wire bonder can be used if the PCB is used without pogo connectors |
| Contact Angle Meter | KSV | CAM 101 | Any contact angle meter can be used |
| Spectrum analyzer | Anristu | 56100A | Any spectrum or network analyzer can be used |
| RF signal generator | Anristu | MG3694A | Any RF signal generator can be used |
| RF high power amplifier | Mini Circuits | ZHL-5W-1 | Any RF high power amplifier can be used |
| Microbeads suspension | Sigma-Aldrich | L3280 | Depending on the experimental purpose different suspension of different diameter and different material properties can be used |
| Optical microscope | Nikon | Ti-Eclipse | Any optical microscope with spatial resolution satisfying experimental purposes can be used |
| Video camera | Basler | A602-f | Any video camera that has enough frame rate and sensitivity satisfying experimental purposes can be used |
| Camera acquisition software | Advanced technologies | Motion Box | Any software enabling high and controlled frame rate acquisition can be used |
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Cite This Article
Travagliati, M., Shilton, R., Beltram, F., Cecchini, M. Fabrication, Operation and Flow Visualization in Surface-acoustic-wave-driven Acoustic-counterflow Microfluidics. J. Vis. Exp. (78), e50524, doi:10.3791/50524 (2013).