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

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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.