Thesis Examination Committee
Prof Zhiyong FAN, ECE/HKUST (Chairperson)
Prof Levent YOBAS, ECE/HKUST (Thesis Supervisor)
Prof Shuhuai YAO, MAE/HKUST
Cell lysis for intracellular contents extraction is critical for biomedical sciences and clinical diagnostics. Many chemical and physical cell lysis methods have been developed to achieve higher lysis efficiency and usability. In recent years, the emergence of microfluidic techniques has opened the possibility of integrating cell lysis and downstream analytical procedures into a small device. The miniaturization and integration result in plentiful advantages, such as time savings and convenience of use. Among all the microfluidic devices for cell lysis, those utilizing mechanical forces are superior due to their exemption from reagent residue and heating issues. Various mechanical cell lysis devices for targeting different contents have been demonstrated.
This thesis presents a microfluidic device for mechanical cell lysis and intracellular contents extraction. The device features point constrictions that are quite short and highly localized. Little backpressure is generated and a local high stress field is created at the point constriction. Therefore, cells are deformed and lysed by the high shear force when approaching the point constriction. Numerical simulation is conducted and the results indicate that cells suffer from tremendous deformation when passing the constriction. The cell lysis process is recorded and lysis mechanisms are studied. The cell membrane is damaged and the nucleus is found to be isolated after the cell passes the constriction. The analysis of cell lysates by flow cytometer and microscope further confirms the existence of membrane debris and the nucleus extraction efficiency. Nucleus purification methods are developed to remove membrane debris. Device performances over protein and DNA extraction are investigated under different loading cell densities and device types. Quantification results of released protein and DNA from different types of cells further validate the wide applicability of the device.