Cell fusion is a ubiquitous process spontaneously occurs in organism development, tissue regeneration and genetic repair of damaged cells in vivo, which is normally defined as multiple individual cells form into one entirety by membrane rearrangement and cytoplasm exchange. Abnormal cell fusion could also occur in tumor progression as invasion and metastasis in which apoptosis and drug resistance is enhanced with increased proliferation and genetic mutant potential, result in difficulty to clinically cure the lethiferous diseases. Artificial cell fusion methods were deeply developed for in-vitro cancer model, antibodies production and cell therapies. However, the existed techniques were involved in exotic fusion intermediation which possess dysgenic to fusion products. Herein, a novel mechanical cell fusion method was introduced in this thesis implemented in microfluidic system.

Considering of the cell fusion process could be concluded as two steps: closefitting contact between target parental cell pairs and sufficient energy supply for energy barrier on plasma membrane breakdown. An initial validation on feasibility of viscous stress-induced cell fusion was performed in viscosity microsensor with suspending membrane. The analytical model of elasticity microstructure was designed to convert the biosample viscosity into displacement by fluid shear stress, which was then validated by simulations and experiments implemented with general liquid types for calibration. The available shear stress in microchannel was substituted into simplified strain energy on floating cell with general dimension, which prove the sufficient energy from hydrodynamic viscous force over first energy barrier of plasma membrane.

With the mechanical method feasibility, an integrated cell fusion microsystem was developed in microfluidics, consisting of the functionality of precise cell pairing, mechanical cell fusion and DLD-based isolation of process products. The critical microchamber structures constitute a high-throughput array, which was designed and optimized following the Darcy-Weisbach Equation for passive hydrodynamic cell capture and pairing. A novel strain energy model for cell extreme deformation in microchamber bypass was proposed and verified towards to membrane energy barrier. Homotypic and heterotypic cell pairs were attempted in fusion process also analyzed in biophysical behaviors and biological components.

Fused cell products could represent peculiar expression or behavior than parents, where the absolvent immune response for fused cancer cells could be interpreted. In consequence, a microfluidic co-culturing immunoassay was established for in-vitro profiling cytokine secretion of immune activities. The stimulus cells and immune cells were cocultured on topographic substrate and extracted cytokine samples profiled the dynamic balance in intercellular communications sptiotemporally. The amplification of cytokine detection sensitivity had validated the feasibility of fused cell immunophenotyping as in-vitro model for future biomedical applications.

Comparing with the traditional methods, we have proposed an integrated sample-sparing microfluidic system for sptiotemporal biophysical/biochemical sensing of bio-sample and artificial cell fusion process contribute to underlying phenotyping and downstream therapy in this thesis, which holds great prospect in practical applications of precise clinical diagnosis and biomedical research for disease cognition.