Zhang, Chris2021-09-082021-09-082021-072021-09-08July 2021https://hdl.handle.net/10388/13557Currently, multiple functions are performed in microfluidic devices in a separate manner or in a manner that needs unnecessary transportation from one location, where one function is performed, to another, where another function is performed. There is a need to integrate these functions holistically to eliminate unnecessary steps and improve the performance of microfluidic system. This thesis was devoted to design and fabricate a microfluidic device that allows pumping, mixing, and particle separating functions to be performed simultaneously (or by eliminating any unnecessary transportation). A design concept by introducing membranes into microfluidic devices was proposed based on Axiomatic design theory. Simulation was performed via the multi-physics software COMSOL and was validated with acceptable accuracy by experiments. The UV light lithography and soft lithography were employed to fabricate the device. A microfluidic device consisting of a main channel height of 50 μm, a main channel width of 30 μm, and membranes with a thickness of 10 μm, lengths of 300 μm and 200 μm was fabricated using Polydimethylsiloxane (PDMS). The experiments were conducted to test the feasibility of the expected functions. The microbeads with diameters of 15 μm, 3 μm, and 200 nm were used to mimic the circulating tumor cells (CTC), normal blood cells and anti-cancer drugs, respectively. The experiment demonstrated the device effectiveness in terms of the mixing and particle separating functions. Unfortunately, the pumping function was not measured with the instrument available. There are two main contributions. First, in the field of microfluidics, especially microfluidic device technology, the device is novel to the best of the author’s knowledge. Existing devices perform more than one function but have a distinct time stamp to each of the functions and unnecessary transportations between each function unit. Second, in the field of biomedical engineering, this thesis provides a proof that the size- and deflection-based principle to separate two groups of particles, CTCs from the blood stream in this case, is working. Subsequently, it is promising to further shape it to a practically viable device to separate CTCs from the blood stream.application/pdfMulti-functional microfluidcsPumpingSeparatingMixingThesis2021-09-08