Dynamics of Morphological Wetting Transitions on Topographic Substrates

我们建议利用在拓扑结构的衬底上形成的各种液体形态来操纵该衬底上的少量液体(开放式微流体)。利用电润湿效应，我们计划通过在自由液体表面的各种平衡形态之间切换，在带有适当台阶和凹槽的衬底上传输液体。地形衬底的独特优势是出现的液体形态的拉普拉斯压力的可变性，因此即使是从零压力储罐中也可以提取液体。我们想要研究各种参数对液体形貌的影响，如施加(交流)电压、其频率、绝缘衬底涂层的厚度和衬底的表面形貌。将特别强调由于接触线附近的电场引起的表面轮廓的内部变形和由于凹槽中的限制而引起的外部变形的相互作用。用原子力显微镜和共聚焦荧光显微镜观察液体的形貌。

We propose to exploit the variety of liquid morphologies forming on topographically structured substrates for manipulating small amounts of liquids on that substrate (open microfluidics). Using the electrowetting effect, we plan to transport liquids on a substrate bearing appropriate steps and grooves, by switching between various equilibrium morphologies of the free liquid surface. The particular advantage of topographic substrates is the variability in the Laplace pressure of the emerging liquid morphologies, such that liquid may be taken even from a zero pressure reservoir. We want to study the impact of a variety of parameters on the liquid morphologies, such as the applied (ac-) voltage, its frequency, the thickness of the insulating substrate coating, and the topography of the substrate. Particular emphasis will be on the interplay of the intrinsic deformation of the surface profile due to electric fields in the vicinity of the contact line and the external deformation due to the confinement in a groove. The liquid morphologies will be observed using atomic force microscopy and confocal fluorescence microscopy.