可缩放邮票印刷及不堪砌面的制作
概要
为制造不同尺寸、形状和材料的半排汗结构提供了一个简单的协议。该协议采用物理冲压、pdms 成型和薄膜表面修改的组合, 通过常用的材料沉积技术。
Abstract
半眨眼是一个过程, 流体湿的图案表面超出其正常的润湿长度, 由于毛细管作用和吸收的组合。这种润湿现象在从生理学到航天工程的许多技术领域都很重要。目前, 有几种不同的技术可以制造半排汗结构。但是, 这些传统方法通常非常耗时, 并且很难针对大面积进行扩展, 或者难以针对特定的非均匀图案几何进行自定义。该协议为研究人员提供了一种简单、可扩展且经济高效的方法, 用于制造微图案的半排汗表面。该方法通过邮票印刷、聚二甲基硅氧烷 (pdms) 成型和薄膜表面涂层的方法来制造吸水结构。该方案在 pdms 微柱阵列上涂覆了70纳米厚的铝薄膜, 并对其进行了偏斜抽吸。
Introduction
最近, 人们越来越感兴趣能够主动和被动地控制液体的润湿、蒸发和混合。独特的纹理半湿滑表面为冷却技术提供了一种新的解决方案, 因为这些纹理表面起到流体 (和/或热) 泵的作用, 没有运动部件。这种流体运动是由与液体薄膜的动态曲率相关的毛细管作用事件的级联驱动的。一般来说, 当液体使固体表面变湿时, 弯曲的液体薄膜 (即液体半月板) 会迅速形成。流体厚度和曲率分布不断变化, 直到达到自由能量最小值。作为参考, 这种动态润湿剖面可以在只有几十微米的跨越 (流体润湿) 长尺度内迅速衰减到几十纳米的厚度。因此, 这个过渡 (液膜) 区域可以发生显著的变化, 液体界面曲率。过渡 (薄膜) 区域几乎是所有动态物理和化学的发源地。特别是过渡 (薄膜) 区域是最大 (1) 蒸发速率、(2) 分离压力梯度和 (3) 静压梯度的区域, 为1,2。因此, 弯曲液膜在热输运、相分离、流体不稳定性和多组分流体混合中起着至关重要的作用。例如, 在传热方面, 在这个高度弯曲的过渡薄膜区域3、4、5、6、7中观察到了最高的壁面热流。
最近的半注浆研究表明, 几何形状 (如高度、直径等) 和支柱的位置决定了流体在结构中的润湿前轮廓和速度8。当流体前部从阵列中最后一个结构的末端蒸发时, 流体前部保持在恒定的距离和曲率上, 因为蒸发的流体被储存在排裁结构中的流体所取代。在热管和沸腾表面也采用了半湿结构来分析和增强不同的传热机制。10,11,12岁
目前用于创建抽吸结构的一种方法是热压印13。这种方法是通过用热塑性聚合物邮票将所需的布局冲压到硅模具样品上的抵抗层, 然后取下邮票来保持微观结构。一旦去除, 样品通过反应离子蚀刻过程中取出任何多余的抵抗层14,15。然而, 这个过程可以对排汗结构的制造温度敏感, 并包括多个步骤, 利用各种涂层, 以确保排汗结构的准确性 16.也存在着光刻技术对于宏观尺度模式的实用性;虽然它们仍然提供了一种在表面上创建微结构模式的方法, 但这一过程的吞吐量远远低于大规模复制的理想。考虑到大规模、可重复的纹理, 如自旋或浸渍涂层, 固有地缺乏可控的图案。这些方法在目标表面创建了一个随机的微结构阵列, 但可以缩放到比传统光刻技术大得多的区域17。
本报告概述的议定书试图结合传统纹理方法的优点, 同时消除每种方法的具体弱点;它定义了一种在宏观尺度上制造各种高度、形状、方向和材料的自定义半排义结构的方法, 并具有潜在的高吞吐量。为了优化排汗特性, 可以快速创建各种抽吸模式, 例如流体速度的定向控制、传播和不同流体的混合。不同的抽吸结构的使用还可以提供不同的薄膜厚度和曲率分布, 可用于系统地研究不同厚度和曲率分布的传热与传质之间的耦合半。
Protocol
Representative Results
Discussion
介绍了一种用于半抽吸结构的图案柱阵的方法;这是通过在塑料晶片上留下凹槽, 并带有雕刻装置, 该雕刻装置遵循用户创建的位图图案来实现。然后, pdms 混合物通过沉积进行浇注、固化和涂覆一层铝薄膜。可以根据此协议下的位图中分配的灰度值自定义支柱数组特征。图案的这一关键方面可以创建广泛的可能的排汗结构来测试, 可用于各种应用, 包括薄膜研究和热系统的直接应用。代?…
開示
The authors have nothing to disclose.
Acknowledgements
这些材料是根据美国海军研究办公室根据第1号批准部分赞助的研究编写的。n00014-15-1-2481 和国家科学基金会根据1653396号赠款。本文所包含的观点和结论是作者的观点和结论, 不应解释为必然代表官方政策或美国海军研究办公室、国家科学基金会或美国政府。
Materials
| NI-DAQ 9403 | National Instruments | 370466AE-01 | The communication interface between the camera and the control switch for the laser. |
| Control Switch | Crouzet | GN84134750 | A controller to use for the laser that activates the laser based on the voltage sent by the DAQ. |
| Flea Camera | FLIR | FL3-U3-120S3C-C | A flea camera used for imaging the drill bit on the plastic mold. |
| Flea Imaging Camera | Point Grey | FL3-U3-20E4M-C | A flea camera used for obtaining the side images of the pillars. |
| 200 Steps/rev, 12V-350mA Stepper Motor (x2) | AdaFruit | 324 | The stepper motors are used to control the depth and angle of the end mill. |
| 10x Infinity Corrected Long Working Distance Objective | Mitutoyo | #46-144 | The objective used to get the image of the side of the pillars. |
| 15x Infinite Conjugate, UV Coated, ReflX Objective | TechSpec | #58-417 | The objective used to get the image of the top of the pillars. |
| 72002 0.002D X 0.006 LOC Carbide SQ 2FL Miniature End Mill | Harvey Tools | 72002 | The drill bit that was used to create holes in the plastic mold. |
| DC Power Delivery at 1 kW | Advanced Energy | MDX-1K | Used to power the deposition sputterer. |
| Turbo-V 70LP Nacro Torr Pump | Varian | 9699336 | Turbo Pump used to reduce pressure inside deposition chamber. |
| 2000mw, 405nm High-Power Blue Light Focus Laser | WDLasers | KREE | Sample Heating Laser |
| 5.875" I.D. Dessicator w/ 0.25" Tube Connections | McMaster-Carr | 2204K5 | PDMS Dessicator |
| SYLGARD 184 Silicone Elastomer, 0.5kg Kit | Dow-Corning | 4019862 | The PDMS Kit used to make the base. |
| Diaphragm Air Compressor / Vacuum Pump | Gast | DOL-701-AA | Dessicator Vacuum Pump |
| Motorized Linear Stages (2x) | Standa | 8MT175 | The stepper motors used to control the sample plate in the x- and y- direction. |
| 2" Diameter Unmounted Poistive Achromatic Doublets, AR Coated: 400-700 nm | ThorLabs | AC508-150-A | The achromat was ued in order to obtain the images of the side of the pillars. |
| Flea 3 Mono Camera, 2448 X 2048 Pixels | Point Grey | FL3-GE-50S5M-C | A flea camera used for imiaging the top of the pillars. |
| Digital Vacuum Transducer | Thyrcont Vacuum Instruments | 4940-CF-212734 | Used for monitoring pressure inside deposition chamber. |
| Pressurized Argon Tank Resovoir | Airgas | AR RP300 | Gas used in deposition process. |
| 1-D Translation Stage | Newport Corporation | TSX-1D | A translation stage used to move the camera to focus on the end mill. |
| Cylindrical Laser Mount (x2) | Newport Corporation | ULM-TILT-M | The laser mount was used to move the camera to focus on the end mill. |
| Benchtop Chiller with Centrifugal Pump, 120V, 60Hz | Polyscience | LS51MX1A110C | A chiller used for the deposition assembly. |
| Alcatel Adixen 2010SD XP, Explosion Proof Motor, Rotary Vane Vacuum Pump, 1-Phase | Ideal Vacuum Products | 210SDMLAM-XP | A vacuum pump used for the deposition assembly. |
| Fan, 105 CFM, 115 V (x2) | Comair Rotron | MU2A1 | A fan used for cooling certain aspects of the deposition assembly. |
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