A Chaotic Micro-Mixer Using Magnetic Beads

Abstract

A MEMS-based micro mixer is developed to be integrated into a bio-molecule sorting system, in which efficient mixing of magnetic beads with target bio-molecules is crucial. The mixer consists of embedded micro-conductors, which produce a time-dependent magnetic field, and a micro channel, which guides the streams of working fluid and suspension. It is demonstrated that integrated 2-D micro conductors provide a magnetic field strong enough to attract nearby magnetic beads. Numerical simulation helps to design the arrangement of channel and embedded electrodes that can generate chaotic motion of beads. It is found that the serpentine channel geometry with the transverse electrodes is able to create the stretching and folding of material lines, which lead to chaotic mixing. Similar mixing pattern is confirmed experimentally in the chaotic mixer fabricated. The fast mixing thus achieved facilitates the attachment of beads onto the target bio-molecules.