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

在微型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执行的。这限制了对这些设备潜力的充分开发。此外，理论预测，由于微通道的尺寸越来越小，为了产生流量，必须施加不合理的高压。本项目的目的是探索高频电磁行波(TW)在微通道中控制溶液传输的理论和实践潜力。TWS可用于在溶液中诱导流动，只要存在垂直于流动方向的流体的任何介电性质的梯度。这种梯度可以通过局部加热、通过向溶液中引入具有不同极化性质的粒子或通过产生可极化溶质的浓度梯度来容易地产生。微结构电极阵列类似于用于介电的电极阵列，非常适合于行波管的产生。令人惊讶的是，行波管用于泵送流体的潜力尚未得到充分认识，因为行波管的特性可以很容易地通过电磁场的幅度、频率和相位来控制。与产生介电梯度的各种可能性相结合，有一系列选项可以微调电流体动力(EHD)泵，并使其适应多种微通道几何形状和几乎任何流体。虽然初步工作证明了这一方法的可行性，但对这一现象的严格理论描述还远远不完整。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，使用芯片体系结构中存在的相当复杂的边界条件。鉴于我们在微流控和介电方面的理论和实验专业知识，我们处于理想的位置来应对理论和实验挑战，以便将TW建立为在微观和纳米环境中泵浦的多功能和可靠的工具。在迭代过程中，理论预测将导致产生2D和3D微纳结构，以产生微通道中的行波驱动流型。从简单的几何开始，将引入越来越多的复杂特征，以最终达到作为技术设备基础的体系结构。将特别强调生物应用的流体系统，包括生物大分子和生物粒子的运输，如细胞、细菌或病毒。

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.