Abstract
The physical environment of microorganisms is governed by the low-Reynolds-number regime where viscous forces overwhelm inertia, and locomotion requires non-reciprocal kinematic strategies. Understanding and controlling the behavior of these biological microswimmers is critical for advancements in biophysics, targeted drug delivery, and bio-inspired microrobotics. While traditional manipulation techniques often compromise biocompatibility or natural cell behavior, acoustofluidics provides a powerful, contactless, and label-free alternative. By integrating ultrasonic waves within microfluidic platforms, precisely controlled acoustic radiation forces and acoustic streaming flows can be deployed to trap, manipulate, and analyze motile cells without diminishing their physiological viability. This dissertation details the investigation of fundamental physical interactions between active biological microswimmers and applied acoustic fields. Using the biciliate green alga Chlamydomonas reinhardtii as a foundational model organism and active biophysical probe, this work leverages acoustofluidic tools to assess the factors influencing motile cell behavior. The research is driven by three specific aims: (1) analyzing individual cell swimming metrics and transient ciliary beating dynamics during the photoshock response via acoustic trap-and-release techniques; (2) examining the nature and limitations of hydrodynamic synchronization and cell-cell interactions between acoustically confined microswimmer pairs; and (3) characterizing microswimmer kinematics and orientation within acoustic streaming vortices. Ultimately, this work advances the development of acoustofluidic methodologies for active matter manipulation and deepens the biophysical understanding of how microscale forces and flow fields shape the behavior of swimming microorganisms.
Committee Chair
J. Mark Meacham
Committee Members
Philip V. Bayly; Matthew Bersi; Susan K. Dutcher; Chad Pearson
Degree
Doctor of Philosophy (PhD)
Author's Department
Mechanical Engineering & Materials Science
Document Type
Dissertation
Date of Award
4-29-2026
Language
English (en)
DOI
https://doi.org/10.7936/j48n-ey95
Recommended Citation
Narayan, Advaith, "Elucidating cell-cell and cell-field interactions in acoustically confined microswimmers" (2026). McKelvey School of Engineering Graduate Student Theses & Dissertations. 1368.
The definitive version is available at https://doi.org/10.7936/j48n-ey95