Mierofluidic mixer using magnetic beads

In this paper, we present a novel, simple and low-cost micromixer that is based on the manipulation of self-assembled structures by an alternating magnetic field of magnetic microbeads over the section of a microfluidic channel. The principle is demonstrated using a microfluidic chip of polymethylmetacrylate (PMMA) that contains a 200 pm wide Y-shaped microchannel and is integrated with soft ferromagnetic plate structures. The latter are part of an electromagnetic circuit and serve to locally apply a magnetic field over the section of the microchannel. The mixing efficiency depends on the fluid perfusion through the magnetic structure. Starting from a laminar flow pattern of parallel fluorescent and non-fluorescent liquid streams, we demonstrate a 95 % mixing efficiency using a mixing length of only 200 l..trn and at liquid flows of the order of 0.5