Kilohertz microfluidics as an analytical tool for determining dynamic characteristics of microfluidic systems

The advent in recent years of highly parallelized microfluidic chemical reaction systems necessitates an understanding of all fluid dynamic time scales including the often neglected millisecond time scale of the inertia of the liquid. We propose the use of harmonically oscillating microfluidics in the low kilohertz range as an analytical tool for the deduction of these time scales. Furthermore, we suggest the use of systems-level equivalent circuit theory as an adequate theory of the behavior of the system. A novel pressure source capable of operation in the desired frequency range is presented for this generic analysis. As a proof of concept, we study the fairly complex system of water-filled interconnected elastic microfluidic tubes containing a large, trapped air-bubble and driven by a pulsatile pressure difference. We demonstrate good agreement between the systems-level model and the experimental results, allowing us to determine the dynamic time scales of the system.