Magnetostatic Modeling for Microfluidic Device Design

For several years, biologists have used superparamagnetic beads to facilitate biological separations. More recently, researchers have adopted this approach in microfluidic devices [1-3]. This recent development and use of superparamagnetic particles in biomedical and biological applications have resulted in a necessity for methods that enable the understanding and prediction of their properties and actions during use. Typically, such methods would involve simple experimentation prior to in vitro experimentation, animal testing, and finally clinical testing. To better understand and unleash this technology, COMSOL®, which is a finite element analysis and multiphysics simulation software, has recently been used to model superparamagnetic particles in several applications. Two COMSOL® models were created based on a magnetic trapping system consisting of a stationary permanent magnet and a microfluidics channel. The first model, known as the Particle Motion Model, simulates the movement of an individual superparamagnetic particle flowing through a fluidic channel beneath a permanent magnet by coupling the Moving Mesh Arbitrary Lagrange-Eulerian (ALE), Incompressible Navier-Stokes, Plane Strain, and Magnetostatics physics modes. The second model, which will be referred to as the Mixture Model, simulates the bulk flow of a superparamagnetic particle fluid in an identical system using the Mixture and Magnetostatics physics modes. The Mixture Model was then applied to the optimization of the design of the magnetic trapping system using a defined geometry and velocity.