A tunable, microfluidic filter for clog-free concentration and separation of complex algal cells
An inherent problem with microfluidic filters is the tendency to clog, especially when applied to cells due to their geometrical complexity, deformability, and tendency to adhere to surfaces. In this work, we handle live algal cells of high complexity without signs of clogging, achieved by exploiting hydrodynamic interactions around trilobite-shaped filtration units. To characterize the influence of cell complexity on the separation and concentration mechanisms, we compare the hydrodynamic interactions to those of synthetic, rigid microparticles. We discover that simple rolling along the filter structures, which prevents clogging for particles, cannot be applied to cells. Instead, we find that inertial effects must be employed to minimize the filter interactions and that this modification leads to only a minor reduction in device performance.
This project was funded by Trilobite Microsystems A/S and The Research Council of Norway—Project number 232148. Support was also received from the Norwegian micro- and nanofabrication Facility (NORFAB) infrastructure project. All measurements were conducted at the Hydrolab at the Department of Mathematics at the University of Oslo in Norway. Thanks to SINTEF MiNaLab for manufacturing the microfluidic chips, to Vladyslava Hostyeva at NIVA and Bente Edvardsen at Department of Biosciences, UiO, for providing the algal cultures and the growth media. Also thanks to Rita Amundsen at Department of Biosciences, UiO, for overlooking the cultures. Thanks to our lab engineer Olav Gundersen for assistance with the pressure system and to Dag Dysthe at the Department of Physics (UiO) for lending us the camera, and thanks to Lailai Zhu in the Complex Fluids group at Princeton University for general feedback on the manuscript.
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