M.Sc Thesis

M.Sc StudentLevy Ayalon
SubjectMicrofluidic chip for cell pairing toward communication
analysis at the single cell level
DepartmentDepartment of Mechanical Engineering
Supervisor ASSOCIATE PROF. Moran Bercovici
Full Thesis textFull thesis text - English Version


The interaction and communication between individual cells plays a central role in virtually all fields of biology, from the cooperative work of cells in the immune system, through the differentiation of stem cells, and to the proliferation of cancer cells. In recent years it has been shown that these processes are fundamentally coupled to cell-to-cell heterogeneity and variability, which manifests itself in all cell functions, from the level of the genome, transcriptome, and proteome, to the level of proliferation, migration, differentiation and apoptosis. Studying cellular ensembles masks these differences, and may yield observations that are not representative of any individual cell type or subpopulation. Despite this, most current studies consider cell population, largely due to technological limitations in the ability to dynamically compartmentalize, manipulate, and analyze single cells.

In this work, we focused on the development of a cell-pairing mechanism with the ultimate goal of realizing a microfluidic platform enabling the study of cell communication at the single-cell level. We present a new concept based on sequential trapping of two cell types and their delivery to individual and isolated micro-chambers. We study two mechanisms for trapping - hydrodynamic and dielectrophoretic (DEP). For the hydrodynamic trapping we present numerical simulations which allow us to optimize the tradeoff between the capture rate for cells and the overall flow rate of the system, as well as ensure that the environment of the micro-chambers remains isolated and unaffected by the flow of the main channel. We then present the design and fabrication of multiple PDMS (Polydimethylsiloxane) based microfluidic devices used for testing the concept. We show that while cell capturing is indeed feasible in such devices their adherence to the device walls prevent their release, despite the use of several coating materials. To avoid the adherence issues associated with physical traps, we designed multi-layer DEP traps and demonstrated their application towards trapping and releasing of cells. While the ultimate goal of cell pairing was not yet achieved within the scope of this work, we believe that the elements presented provide the necessary background for accomplishing this task in the future.