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UBC Theses and Dissertations

Magnetically actuated MEMS devices for active control of cell migration Khademolhosseini, Farzad


The ability of living cells to sense and respond to mechanical cues from the surrounding environment has been the subject of much study. Over the past two decades, a variety of techniques have been used to apply mechanical stimuli and investigate cell response. Recently, with advances in the field of Microelectromechanical Systems, devices incorporating microscale actuators have been developed to apply forces and study the cell response of individual cells. Among these microdevices, micropillar arrays incorporating remotely actuated magnetic pillars have shown some success as combined actuation and sensing platforms for cell strain studies. However, issues associated with the complex fabrication techniques used, the low actuation forces generated and the high magnetic field gradients required for pillar actuation have hindered the wide-scale adoption of these devices by the general research community. Consequently, investigation into the use of these active micropatterned surfaces in eliciting or controlling specific cellular response on a multicellular level has yet to be undertaken. This thesis aims to investigate the application of remotely actuated micropillar surfaces in controlling the migration behavior of cells on a multicellular level. First, using a novel custom-made magnetically actuated cell strain assessment tool, conventional tests are performed on endothelial cells to determine the minimum strain requirements for eliciting cell response. Then, a new technique for fabrication and patterning of magnetic micropillar arrays is developed to overcome the complexities of previous fabrication methods. Using the newly developed fabrication technique, magnetic micropillar arrays of various dimensions are fabricated and their mechanical, magnetic and material properties are characterized. The fabricated magnetic micropillars generate forces of several hundred nanonewtons at moderate magnetic fields of 100mT and are favorable to previous state-of-the-art. Finally, a cell migration chip comprising various micropillar topologies is developed and the migration behavior and migration rates of sheets of cells on the micropillar surfaces in the presence and absence of micropillar actuation is studied using in-vitro experiments. We show that actuated micropillar surfaces significantly impede cell migration, reducing cell migration rates by up to 85%. The magnetically actuated micropillar surfaces could have possible in-vivo applications for preventing cell-migration induced biofouling of medical implants.

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Attribution-NonCommercial-NoDerivs 2.5 Canada