PMUT-driven Acoustophoretic Particle and Cell Manipulation

This thesis advances acoustophoretic manipulation techniques at the cellular scale by employing Piezoelectric Micromachined Ultrasound Transducers (PMUTs). Through novel theoretical insights, numerical models, and experimental results, our work addresses the need for refined manipulation capabilities and caters to the growing interest in acoustophoretic techniques, particularly in the biomedical domain. 

We delve into the acoustic radiation force generated by various acoustic emitters, including piston, simply supported, and clamped configurations. Our study provides closed-form expressions for the forces acting on small, spherical objects in an ideal fluid, revealing the potential for a negative force that can trap an object close to the emitter's surface—a finding relevant for numerous practical applications. Extending our analysis to particles of all sizes, we assess the broad applicability of acoustic manipulation, supported by numerical studies that validate our theoretical models and highlight possible applications, including the manipulation of both synthetic spheres and biological cells.

A significant portion of this work focuses on developing PMUT-based devices tailored for acoustophoretic tasks. Through detailed Finite Element Method (FEM) modeling, we gain insights into PMUT behavior, which aids in designing more efficient devices. Notably, we demonstrate that a dual electrode, anti-phase actuation method offers a straightforward method to enhance acoustophoretic forces for more effective manipulation. We also examine the effects of acoustical crosstalk in PMUT arrays, revealing how it critically impacts device performance and underscores the need for careful design considerations.

Our research introduces a method that combines acoustophoretic and dielectrophoretic forces for dynamic manipulation of dielectric particles using PMUT arrays. This approach significantly extends the capabilities of PMUTs, enabling control over particle positioning through tailored actuation schemes. Additionally, we explore the use of PMUT arrays for manipulating biological cells, specifically focusing on dynamic patterning and handling of T-cells. This dual-force approach allows for dynamic control over cell positioning, showcasing the potential of PMUTs in biomedical applications.

While our work marks a significant step forward in PMUT-driven particle and cell manipulation, it also highlights the need for further research to fully realize the potential of this technology. It is our hope that this thesis will inspire continued development in this field, leading to new tools and techniques with wide-ranging implications for the life sciences and beyond.