Controlled particle placement through convective and capillary assembly
Controlled particle placement through convective and capillary assembly
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DOI：
10.1021/la700852c
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发表时间：
2007-11-06
期刊：
影响因子：
3.9
通讯作者：
Wolf, Heiko
中科院分区：
文献类型：
--
作者：
Malaquin, Laurent;Kraus, Tobias;Wolf, Heiko
d现在有很多种方法可用于合成具有受控形状、结构和尺寸的胶体颗粒。在利用微米和纳米颗粒的设备的开发中的主要挑战之一仍然是在表面上的颗粒放置和集成。所需的是工程方法，以控制这些积木的组装在准确的位置和高产量。在这里，我们研究了两种互补的方法来创建从金和聚苯乙烯颗粒的胶体悬浮液开始的从完整层到单个颗粒的稀疏阵列的颗粒组装体。在亲水性基底上进行对流组装，以使用由溶液的三相接触线处的溶剂蒸发引起的纳米颗粒的对流来产生结晶单层或多层。在疏水表面上，研究了毛细管组装以使用毛细管力来在模板的凹进区域中捕获和组织颗粒来创建稀疏阵列和复杂的三维结构。在这两种方法中，悬浮液中施加在颗粒上的流体动力学阻力在组装过程中起着关键作用。我们首次证明，悬浮液中的颗粒的速度和方向可以控制执行组装或拆卸的颗粒。这是通过将胶体悬浮液的温度设置为高于或低于露点来实现的。其他参数的影响，如基板速度，润湿性能，和图案的几何形状，也进行了研究。对于毛细管组装的特定情况下，我们提出了一种机制，考虑到这些参数对粒子运动的相对影响，并描述了温度对组装效率的影响。
dA wide variety of methods are now available for the synthesis of colloidal particle having controlled shapes, structures, and dimensions. One of the main challenges in the development of devices that utilize micro- and nanoparticles is still particle placement and integration on surfaces. Required are engineering approaches to control the assembly of these building blocks at accurate positions and at high yield. Here, we investigate two complementary methods to create particle assemblies ranging from full layers to sparse arrays of single particles starting from colloidal suspensions of gold and polystyrene particles. Convective assembly was performed on hydrophilic substrates to create crystalline mono- or multilayers using the convective flow of nanoparticles induced by the evaporation of solvent at the three-phase contact line of a solution. On hydrophobic surfaces, capillary assembly was investigated to create sparse arrays and complex three-dimensional structures using capillary forces to trap and organize particles in the recessed regions of a template. In both methods, the hydrodynamic drag exerted on the particle in the suspension plays a key role in the assembly process. We demonstrate for the first time that the velocity and direction of particles in the suspension can be controlled to perform assembly or disassembly of particles. This is achieved by setting the temperature of the colloidal suspension above or below the dew point. The influence of other parameters, such as substrate velocity, wetting properties, and pattern geometry, is also investigated. For the particular case of capillary assembly, we propose a mechanism that takes into account the relative influences of these parameters on the motion of particles and that describes the influence of temperature on the assembly efficiency.