A microfluidic chaotic mixer using ferrofluid

A novel micromixer which utilizes chaotic mixing induced by ferrofluid actuation is developed. The micromixer is fabricated by a polydimethylsiloxane micromolding technique. The micromixer consists of a T-shaped main mixing channel and two parallel sub-channels that intersect the main channel. Oscillation of a couple of ferrofluid slugs in the sub-channels, induced by external permanent magnet actuation, generates chaotic advection in the main channel flow. To visualize the mixing, red fluorescent particles are supplied to one of the inlets of a T-shaped channel, and mixing flow is observed by a fluorescence microscope and an intensified CCD camera. The mixing experiments are performed with various ferrofluid perturbation frequencies and main stream flow velocities. The optimal mixing conditions determining the upper and lower limits of the most effective Strouhal numbers are found from the experimental results.