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Theoretical and experimental investigations in acoustofluidic manipulation of bioparticles

Wang, Hanlin 2022. Theoretical and experimental investigations in acoustofluidic manipulation of bioparticles. PhD Thesis, Cardiff University.
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With the maturation of micro and nano processing technologies and the development of microchip laboratories, the acoustofluidic manipulation of particles has been developed rapidly. Microfluidic chips as miniature experimental platforms are revolutionizing research tools in several disciplines. Acoustically driven microfluidic chips is a current research hotspot with the advantages of non-invasiveness, high strength, and good biocompatibility. This thesis demonstrates acoustofluidic platforms based on static surface acoustic waves for particle manipulation, including the design of interdigital transducers (IDTs), cleaning room fabrication and integration with microfluidic technologies, electronics, and mechanical systems. I present a numerical model to predict the motion of particles under microfluidic manipulation. I employ a perturbation approach where the flow variables are divided into first and second-order fields. Impedance boundary conditions are used to model microchannel walls and displacement boundary conditions are used to model acoustic actuation. This model is verified to be accurate by comparison with published numerical studies. Furthermore, to extend the generalizability of the model, I present two microfluidic systems, conventional PDMS-SAW system, and the GaN system. By comparing numerical predictions with experimental results, I validate the GaN system's ability to manipulate particles with high throughput and verify the accuracy of the model for different piezoelectric materials and working frequencies. Based on this simulation model, I developed two new acoustic fluid configurations: a microchannel sandwiched between two identical surfaces acoustic wave (SAW) transducers (SAW-SAW) or between a piezoelectric transducer (PZT) and a SAW transducer (PZT-SAW). I have numerically simulated the distribution of acoustic pressure, time-averaged flow velocity, and particle trajectories in these devices and compared the simulation results for different acoustic fluid configurations. The results show that the SAW-SAW and PZT-SAW configurations produce significantly higher acoustic pressures and particle velocities in the microchannel. In addition, I have developed a novel Filled Tilt Angle (FTA) acoustic fluidic device to be applied to the mechanophenotyping of live cells. The FTA 3 device consists of an interdigital transducer placed at an angle along the microfluidic channel in the direction of fluid flow. Pressure nodes formed within the acoustic fluid field of the microchannel cause biological cells to deviate from their original flow pattern based on their mechanical properties, including volume, compressibility, and density. The threshold power that allows the cells to converge to the pressure node fully is used to calculate the acoustic contrast factor. To demonstrate the role of FTA in the mechanophenotyping of cells and to distinguish between different cell types, further experiments were performed by using A549 (lung cancer cells), MDB-MA-231 (breast cancer cells), and leukocytes. The obtained acoustic contrast factors for lung and breast cancer cells differed from those of leukocytes by 55.1% and 17.8%, respectively. These results show that this method can successfully distinguish between different cell types based on the acoustic contrast factors, which has tremendous clinical implications for identifying, for example, epithelial cells in the circulation. Finally, this thesis extends the understanding of acoustofluidic units through the study of innovative microfluidic systems. It will further advance the knowledge of SSAW based cell manipulation techniques and enable further development for high precision cell manipulation and biosensor applications.

Item Type: Thesis (PhD)
Date Type: Completion
Status: Unpublished
Schools: Engineering
Uncontrolled Keywords: 1).________________acoustofluidics______________________________ 2). _______________bioparticles_________________________________ 3).________________surface acoustic wave_______________________ 4).________________phenomechaotyping_________________________ 5).________________Microfluidic chips ___________________________ 6)._________________Piezoelectric effect__________________________
Date of First Compliant Deposit: 23 May 2023
Last Modified: 23 May 2023 09:36

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