Separation of circulating tumor cells (CTCs) is crucial for diagnosis and therapeutic purposes since metastasis is leading cause of cancer-deaths. Many separation methods are proposed in the literature to purify the CTCs. The study purposes a novel size based micro particle separation using a novel acoustophoresis based microfluidic system. The separation speed and sensitivity are optimized using the optimized F-IDT structure. The system is tested through simulation studies and the design is optimized. The simulation studies and the results are reported in the study. The fabrication study and characterization results are also presented by the study.

Label free active separation systems has four main methods, electrokinetics, optics, acoustophoresis and magnetophoresis. Magnetophoresis or electrokinetics separates the particle according to its magnetic or electrical properties while acoustophoresis uses volume or density. Acoustophoresis was used as the active system since volume and the shape are the characteristic property of the CTCs. Focused IDT electrodes generates a standing wave to create the nodes around the focal area. F-IDT structure decreases the power requirement of the system and increases the speed of the separation. The structure used in the simulations has 1 node to observe the particle behavior. The system structure is simulated using COMSOL 5.3 multiphysics. Acoustophoresis based separation system model is built according to the optimized design parameters. The channel is simulated as a PDMS channel wall and fluid flowing inside. It is observed that the particles alignment duration is 5 secs after SAW is on. Therefore, the separation capability of the overall system is demonstrated through numerical simulations.

The Fabrication of the active system and the electrical characterization is performed. The results show that, the operating frequency is 15.02 MHz as expected, and about 10 dB response is observed. The F-IDT structures are created using the lithography process applied on a LiNbO3 wafer coated by 200 nm of chromium layer. The microchannel was fabricated out of PDMS by SU-8 molding. The PDMS microchannel was bonded to the quartz wafer using plasma cleaner. Channel widthheight is 400μmx200μm.