利用计算机模拟设计和研究胶体微观器件

Microfluidic technology controls a very small amount of fluid to perform specific tasks by using microscale devices, which has the potential to change our life. Because the size of the colloidal particle is comparable to that of the microchannel, colloidal particles are particularly suitable for designing micro-devices. This idea has attracted considerable interests. In microfluidic environment, surface physical effects and thermal fluctuations are significant, and the Reynolds number is very low, which is essentially different from the macroscopic situations. However, the existing colloidal micro-devices do not exploit these important physical properties quite well, such that there is still a huge space for improvement. In this project, we will employ the mesoscale dynamics simulation method to design and investigate novel, controllable and efficient colloidal micro-devices, on the basis of the surface physical effects. In particular, we will exploit the gradient-driven (temperature or concentration gradient) phoresis to explore new schemes for designing colloidal micro-devices, develop effective mechanisms of overcoming or utilizing the thermal fluctuations to improve the performance of the colloidal micro-motors, and design colloidal microfluidic pump without moving part to flexibly and precisely manipulate the flow field. It is expected that these studies will provide the theoretical basis for further experimental investigation of the colloidal micro-devices, provide more choices and possibilities for the development of the microfluidic technology, and hence be helpful to promote the extensive applications of the microfluidics.

微流技术通过利用多种微观器件来操控极少量的流体执行特定的任务，它是一个有潜力改变我们生产与生活的重要技术。由于与微流通道在尺寸上的天然匹配，胶体粒子特别适合用来设计微观器件，这一研究思路已经引起了人们广泛的兴趣。与宏观尺度截然不同,微流环境具有显著的表面效应、热涨落和微小的雷诺数等重要物理特征,但现有胶体微器件对此并没有非常好地开发和利用，仍存在着巨大的改进空间。本项目将采用介观动力学模拟方法，基于表面物理效应来设计和研究新颖、可控、高效的胶体微观器件。我们将重点开发梯度场（温度或浓度梯度）驱动的泳效应来探索设计胶体器件的新方案，发展能有效克服或利用热涨落的机制来提高胶体微马达的性能，设计没有移动部分的胶体微流泵来实现对流场精确灵活的操控等。本项目将为胶体微器件的实验研发奠定重要的理论基础与依据，为微流技术的发展提供更多的选择性与可能性，进而有助于推动微流技术的普遍应用。

本项目采用了计算机模拟和理论分析的方法，基于表面物理效应设计和研究了新颖、高效的胶体微观器件。我们重点开发了梯度场（温度或浓度梯度）驱动的泳效应来探索设计胶体器件的新方案。该项目开展的研究内容包括以下几个方面：（1）设计了不同类型的胶体微马达,考察了基底障碍物对胶体微马达运动行为的影响,研究了胶体微马达的趋光行为；（2）基于对单个胶体微马达的认识，我们研究了由多个胶体马达所组成的活性物质体系的集体行为，包括活性物质中的熵力、噪声和动态自组装，以及手性活性物质的边缘流；（3）系统地考察了非对称胶体粒子的各向异性泳效应，并利用其设计了外界梯度场驱动的微观涡轮机；（4）基于泳渗透边界设计了多种全新的微流泵，并利用泳渗透流开发了控制胶体粒子的有效方案。截止到目前，我们已经在国内外知名学术期刊上发表了18篇学术论文，而且仍有三个相关工作正在进行之中。我们所取得的研究成果不仅为胶体微器件的实验研发奠定了重要的理论基础与依据，为微流技术的发展提供了更多的选择性与可能性，也有助于理解活性物质体系的集体行为。