Date of Award
Doctor of Philosophy (PhD)
Sound is a stress wave that carries energy and momentum flux. Scattered sound waves can generate acoustic radiation force that can be used to manipulate particles or cells. This dissertation demonstrates the physics behind cell manipulation by ultrasound. The work begins with a detailed analysis of the mechanics of using standing surface acoustic waves to fabricate acoustic tweezers for contactless particle manipulation using acoustic radiation force. Models to design and analyze acoustic radiation force have traditionally relied on plane wave theories that cannot predict how standing surface acoustic waves can levitate cells in the direction perpendicular to the substrate. We therefore developed a revised model for how standing surface acoustic waves lead to acoustic radiation force in three dimensions. The dissertation then explored use of ultrasound for manipulating mechanosensitive ion channels in both plant and animal cells. Although evidence that such manipulation can occur is strong, it is still unclear how ultrasound activates the mechanosensitive ion channels. The dissertation therefore developed mathematical models of these forces, of how they deform the cell membrane, and of how these membrane deformations activate mechanosensitive ion channels. The modeling approach was verified in an idealized system involving measuring ion channel currents in frog oocytes that were transfected with mechanosensitive ion channels and irradiated using ultrasound. The model predicted these currents, and a modified version of the approach was then used to predict the sensitivity of stress activated ion channels in tomato trichomes to the acoustic radiation force arising from acoustic emissions by insect and other animals. The integrated modeling approach shows promise for design and analysis of experiments and tools that probe and harness the function of stress activated ion channels via ultrasound.