Nanopumps based on high frequency electromagnetic travelling waves: A theoretical and experimental approach to the transport of fluids and particles in microchannels

在微制造的芯片实验室设备中，溶液的传输仍然主要是通过宏观泵来完成的。这限制了对这些设备潜力的充分利用。此外，理论预测，微通道的尺寸越来越小，将需要施加不合理的高压来产生流动。本项目旨在探索高频电磁行波（TWs）在微通道中控制溶液输运的理论和实践潜力。只要存在垂直于流动方向的任何介质性质的梯度，TWs就可以用来在溶液中诱导流动。这种梯度可以很容易地通过局部加热，通过将具有不同极化特性的粒子引入溶液或通过产生极化溶质的浓度梯度来产生。微结构电极阵列类似于介电电泳中使用的电极阵列，非常适合于产生TWs。令人惊讶的是，由于可以很容易地通过电磁场的幅度、频率和相位来控制波阱的特性，波阱泵送流体的潜力尚未得到充分的认识。结合产生介电梯度的各种可能性，有一系列的选择来微调电流体动力（EHD）泵送，并使其适应许多微通道几何形状和几乎任何流体。虽然初步的工作证明了这种方法的可行性，但对这一现象的严格理论描述还远远没有完成。它意味着对高度非线性场景的处理。特别是，热传导和扩散必须与电磁方程和流体基本方程结合起来，使用芯片结构中相当复杂的边界条件。鉴于我们在微流体和介质电泳方面的理论和实验专业知识，我们能够满足理论和实验方面的挑战，以便将TWs建立为微观和纳米环境中泵送的通用可靠工具。在一个迭代过程中，理论预测将导致二维和三维微纳米结构的产生，以产生微通道中TWs驱动的流动模式。从简单的几何形状开始，越来越多复杂的特征将被引入，以便最终到达作为技术设备基础的架构。将特别强调流体系统的生物应用，包括生物大分子和生物颗粒，如细胞，细菌或病毒的运输。

The transport of solutions in micro-fabricated lab-on-chip devices is still mostly performed with macroscopic pumps. This limits the full exploitation of the potential of these devices. In addition, theory predicts that the increasingly small dimensions of microchannels will necessitate the application of unreasonably high pressures in order to generate flow. Aim of this project is to explore the theoretical and practical potential of high frequency electromagnetic travelling waves (TWs) for the controlled transport of solutions in microchannels. TWs can be used to induce flow in solutions provided a gradient of any dielectric property of the fluid perpendicular to the flow direction is present. Such gradients can be easily produced through local heating, through the introduction of particles into the solution with contrasting polarization properties or through the generation of concentration gradients of polarisable solutes. Microstructured electrode arrays similar to what is used in dielectrophoresis are well suited for the generation of TWs. It is surprising that the potential of TWs for pumping fluids has not yet been fully appreciated, since the properties of the TWs can be easily controlled via amplitude, frequency and phase of the electromagnetic field. In combination with the various possibilities to generate dielectric gradients, there is a battery of options to fine-tune the electrohydrodynamic (EHD) pumping and to adapt it to many microchannel geometries and to almost any fluid. Although preliminary work demonstrated the feasibility of this approach, a rigorous theoretical description of this phenomenon is far from being complete. It implies the treatment of highly nonlinear scenarios. In particular, heat conduction and diffusion has to be combined with the electromagnetic equations and the basic equation of fluidics using rather complex boundary conditions present in chip architecture. Given our theoretical and experimental expertise of microfluidics and dielectrophoresis, we are ideally placed to meet the theoretical and experimental challenges in order to establish TWs as a versatile and reliable tool for the pumping in microscopic and nanoscopic environments. In an iterative process, theoretical predictions will lead to the production of 2D and 3D micro- and nanostructures for the generation of TWs driven flow patterns in microchannels. Starting with simple geometries, more and more complex features will be introduced in order to finally arrive at architectures that are the bases of technical devices. Special emphasis will be given to fluidic systems for biological applications including transport of biological macromolecules and biological particles such as cells, bacteria or viruses.