Geometrical optimization for motility-based microorganisms concentrator and sorter devices

I. BERDAKIN; Y. JEYARAM; A. V. SILHANEK; A. GUIDOBALDI; L.C. GIOJALAS; C. A. CONDAT; V. I. MARCONI

Villa Carlos Paz

Workshop; XIII Latin American Workshop on Nonlinear Physics, LAWNP; 2013

The use of soft lithography to build asymmetric micro-substrates makes it possible to control microorganisms motion and promises new and interesting applications in health industry and biotechnology. In this work, we investigate two ways in which these ratchet devices can be employed. First we show, experimentally and numerically, that it is possible to accumulate sperm cells in a region of space of our choice. Second, we study the most ecient way to sort out dierent subpopulations in a mixed culture of E. coli bacteria, that dier by their specic swimming strategies. In both cases, we develop models that incorporate the most relevant phenomenological aspects of the cellular motion using realistic parameters found in experiments, and integrate the equations of motion through molecular dynamics algorithms [1]. For E. coli, we study the diusion properties of each subpopulation along the sorter and dene a purity parameter for the extraction of each strain as a function of position. We obtain in this way a set of optimized parameters of the array geometry that maximizes the sorting eciency of the device. Our results show remarkably that it is possible to sort bacteria with 100% purity even for slightly dierent strains in experimentally reasonable times. We also conclude that a key element to consider when working with spermatozoa is that their interactions with walls and corners is remarkably dierent from run and tumble bacteria, because sperm cells tend to get trapped in acute angles. References [1] I. Berdakin, Y. Jeyaram, V.V. Moshchalkov, L. Venken, S. Dierckx, S.J. Vanderleyden, A.V. Silhanek, C.A. Condat, V.I. Marconi Phys. Rev. E 87 052702 (2013).