Physical cell separation using microfluidic funnel ratchets

The separation of biological cells using non-chemical methods is important to many areas of medicine and biology. Filtration through microstructured constrictions is one such method where cells can be separated by a combination of size and deformability. This technique, however, is limited by unpredictable variations of the filter hydrodynamic resistance as cells accumulate in the microstructure. Applying a reverse flow to unclog the filter will undo the separation and reduce filter selectivity because of the reversibility of low-Reynolds number flow. This work introduces a microfluidic structural ratchet mechanism to separate cells using oscillatory flow through a 2-dimensional array of funnel-shaped structures. Devices are fabricated using multi-layer soft lithography of polydimethylsiloxane (PDMS) and flow is controlled using pressure sources and on-chip membrane valves. An iterative procedure of design and testing is used to produce a final device which is characterized by the sorting and separation of L1210 mouse lymphoma cells (MLCs), peripheral blood mononuclear cells (PBMCs) from healthy donors, as well as polystyrene microparticles. The ability of this mechanism to sort and separate cells/particles based on size and deformability is investigated and confirmed. Additionally, the spatial distribution of cells after sorting is demonstrated to be repeatable and the separation process is shown to be irreversible. This mechanism can be applied generally to separate cells that differ by size and/or deformability.Applied Science, Faculty ofMechanical Engineering, Department ofGraduat

Psyc 2017 Lab Project: Trolling Behavior

Studying the effects of experience and personality traits on trolling behavio

Cell-­phoresis o fRed Blood Cells Revealing Biophysical Signatures in Falciparum Malaria

We describe the cell-phoresis mechanism for massively parallel analysis of red blood cell (RBC) deformability by transporting single cells through microstructures to measure their spatial dispersion. Analogous to gel electrophoresis, which transport molecules through nanostructures to measure their length, the spatial dispersion of RBCs within microstructures indicate their deformability. Similar to gel electrophoresis, cell-phoresis require minimal instrumentation, provide a simple image-based readout, and could be performed simultaneously on multiple samples as part of a biophysical assay. We applied the cell-phoresis mechanism to study the biophysical signatures of falciparum malaria where we demonstrate label-­‐free and calibration-­‐free detection of ring-­‐stage infection, as well as in vitro assessment of antimalarial drug efficacy. We show that all clinical antimalarial drugs rigidify RBCs infected P. falciparum and that recently discovered PfATP4 inhibitors show a distinct biophysical signature. We anticipate cell-phoresis to be a functional assay for screening new antimalarials and adjunctive agents, as well as for validating their mechanisms of action