Authors: A. Ahmadi, H. Najjaran, J. Holzman, M. Hoorfar
Affilation: University of British Columbia, Canada
Pages: 561 - 564
Keywords: microdroplet, digital microfluidic multiplexer, contact-angle hysteresis, CFD
This paper introduces a computationally efficient numerical modeling approach for microdroplet motion on an innovative Digital Microfluidic Multiplexer structure which enables the pilot synthesis and study of nanoparticles. This structure offers an enhanced level of controllability and flexibility in drop actuation compared to the existing digital microfluidic systems that rely on addressable cell structures. Unlike the cell structures, the Digital Microfluidic Multiplexer has the capability of serving a massively parallel microfluidic system while being scaled down to a few microns without increasing the hardware complexity. Beside the electrowetting on dielectric (EWOD) mechanism, the proposed structure can accommodate an alternative actuation mechanism caused by an external magnetic field on a small current passing thru the droplet. The real-time control of microdroplets under the influence of electrical, magnetic and hydrodynamic effects requires a reliable and computationally efficient model. The model developed in this work approximates a time-variant average velocity using a computational-fluid-dynamic (CFD) code that solves the Navier-Stokes equation for velocity and pressure distributions inside the microdroplet using upwind finite volume method. Then, the estimated average velocity is modified using the contact-angle hysteresis effect and the magnetic field induced force in a converging iterative computational procedure.