Regensburg 2013 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 44: Wetting, Micro- and Nanofluidics

CPP 44.2: Vortrag

Donnerstag, 14. März 2013, 15:30–15:45, H39

Optimal Particle Separation in Microfluidic Systems Using Inertial Lift Forces — •Christopher Prohm and Holger Stark — Institut für Theoretische Physik, TechnischeUniversität Berlin, D-10623 Berlin, Germany

At intermediate Reynolds numbers, particles in a microfluidic channel assemble at fixed distances from the channel axis and bounding walls [1]. This Segré-Silberberg effect can be described in terms of an effective lift force acting on the particles.

Devices utilizing inertial lift forces for the separation of bacteria and red blood cells have recently been demonstrated [2]. The separation is most efficient for large size differences since the inertial lift force scales with the third power of the particle radius.

Here, we show that one can use external forces generated, for example, by optical tweezers to separate particles similar in size. We determine the inertial lift force by mesoscopic simulations [3] and use it to set up a Smoluchowski equation which describes the particle motion in lateral direction. We then employ the formalism of optimal control [4] to determine profiles of the external force, which help to steer particles and thereby maximize particle separation.

[1] G. Segré and A. Silberberg, Nature, 189, 209 (1961).

[2] A. J. Mach and D. Di Carlo, Biotechnol. Bioeng., 107, 302 (2010).

[3] C. Prohm, M. Gierlak, and H. Stark EPJE, 35, 80 (2012).

[4] F. Tröltzsch, Optimal Control of Partial Differential Equations, American Mathematical Society, first edition (2010).