Multi-Mode PMUT Actuation for Reconfigurable Particle & Fluid Manipulation

This thesis investigates how higher‑order flexural modes in Piezoelectric Micromachined Ultrasonic Transducers (PMUTs) can be used to create reconfigurable acoustic fields for manipulating particles and fluids. Traditional PMUT-based acoustofluidic systems typically operate in the fundamental mode, but recent studies suggest that higher‑order modes can generate far more complex and versatile force patterns. Despite this potential, multi‑mode PMUT actuation has not yet been explored in a systematic way.

The project begins with a theoretical study combining a focused literature review, analytical modeling, and finite element simulations. These tools are used to predict the acoustic force landscapes produced by different flexural modes. Special attention is given to how higher‑order modes modify trap positions, trap stiffness, and overall force topology, enabling new capabilities such as reconfigurable patterning, selective sorting, localized mixing, or multi‑scale particle control.

In the experimental part of the thesis, the student will verify these predictions using impedance measurements, laser Doppler vibrometry (LDV), and benchtop manipulation tests with microspheres suspended in liquid. Measured mode shapes will be compared directly to FEM simulations to evaluate accuracy and understand how each mode influences particle behavior.

The expected outcome is a deeper understanding of how individual PMUT modes can be selectively excited or combined to produce distinct, controllable manipulation regimes. These insights can support future developments in multi‑PMUT arrays and may directly contribute to ongoing research in cell patterning, as well as broader applications such as microscale sorting, mixing, and reconfigurable assembly.