Dresden 2014 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 12: Focus Session: Feedback Control of Nonlinear Soft and Hard Matter Systems (original: DY, joined by CPP)

CPP 12.4: Talk

Monday, March 31, 2014, 16:15–16:30, HÜL 186

Optimal control of particle separation in inertial microfluidics — •Christopher Prohm and Holger Stark — Institut für Theoretische Physik, Technische Universität Berlin, D-10623 Berlin

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 investigate the motion of a colloidal particle in microfluidic channels using mesoscopic simulations [3]. We show how the geometry of the channel influences inertial focussing. We also demonstrate that manipulating the axial or angular velocity of the particle modifies the inertial lift force profile which permits control of the lateral particle position. Finally we apply the theory of optimal control to the problem of particle sorting in inertial microfluidics [4]. We design optimal force profiles that are able to steer particles to desired lateral positions and, most importantly, to separate particles of similar size in a very robust fashion.

[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] C. Prohm, F. Tröltzsch, and H. Stark EPJE, 36, 118 (2013).