MNT, Electronic Engineering Department, Universitat Politècnica de Catalunya, Jordi Girona 1-3, Barcelona, 08034, Spain.
Nanoscale Res Lett. 2013 Jan 12;8(1):26. doi: 10.1186/1556-276X-8-26.
This work introduces the electrospray technique as a suitable option to fabricate large-scale colloidal nanostructures, including colloidal crystals, in just a few minutes. It is shown that by changing the deposition conditions, different metamaterials can be fabricated: from scattered monolayers of polystyrene nanospheres to self-assembled three-dimensional ordered nanolayers having colloidal crystal properties. The electrospray technique overcomes the main problems encountered by top-down fabrication approaches, largely simplifying the experimental setup. Polystyrene nanospheres, with 360-nm diameter, were typically electrosprayed using off-the-shelf nanofluids. Several parameters of the setup and deposition conditions were explored, namely the distance between electrodes, nanofluid conductivity, applied voltage, and deposition rate. Layers thicker than 20 μm and area of 1 cm2 were typically produced, showing several domains of tens of microns wide with dislocations in between, but no cracks. The applied voltage was in the range of 10 kV, and the conductivity of the colloidal solution was in the range of 3 to 4 mS. Besides the morphology of the layers, the quality was also assessed by means of optical reflectance measurements showing an 80% reflectivity peak in the vicinity of 950-nm wavelength.
这项工作介绍了电喷雾技术，作为在短短几分钟内制造大规模胶体纳米结构（包括胶体晶体）的合适选择。结果表明，通过改变沉积条件，可以制造出不同的超材料：从聚苯乙烯纳米球的分散单层到具有胶体晶体性质的自组装三维有序纳米层。电喷雾技术克服了自上而下制造方法遇到的主要问题，大大简化了实验装置。典型地，使用市售的纳米流体来电喷雾 360nm 直径的聚苯乙烯纳米球。探索了设置和沉积条件的几个参数，即电极之间的距离、纳米流体的电导率、施加的电压和沉积速率。典型地，生产出厚度超过 20μm 且面积为 1cm2 的层，显示出几个几十微米宽的畴，畴之间存在位错，但没有裂纹。施加的电压在 10kV 范围内，胶体溶液的电导率在 3 到 4mS 范围内。除了层的形态之外，还通过光学反射率测量来评估质量，在 950nm 波长附近显示出 80%的反射率峰值。
