| Description |
TITLE: TITLE: INFERRING ELASTIC MODULI OF DROPLETS IN ACOUSTIC FIELDS
ABSTRACT: The acoustic radiation force, as seen in apparatuses such as in an acoustic levitator, continues to find applications in materials science, manufacturing, and medical fields. One example of
the utilization of an acoustic levitator is measuring the progress of clotting blood droplets. One of the largest advantages of using acoustic levitation is that the process is a minimal contact method. In some biological and chemical processes, surface contact can corrupt measurements,
and acoustic levitation avoids these issues by using the acoustic radiation force to contain and
manipulate the blood drop. The deformation of Newtonian liquid droplets via acoustic levitation has been well studied. In that case, the shape of the droplet is governed by the surface
tension and shape curvature (Young-Laplace equilibrium). The quasi-static deformation of elastic droplets in acoustic levitators, however, has not yet been investigated. In this thesis, we
explore the application of acoustic levitation to the characterization of the deformation of soft
elastic droplets.
This thesis consists of three main efforts. To start, the history of the acoustic radiation
force and the impacts they have made are discussed. These studies however, deal with droplets
much smaller than the acoustic wavelength, such that the scattered components may be greatly
simplifed, thus simplifying the whole system. Next, a generalized theory for the acoustic radiation pressure acting on droplets of sizes similar to the length scale of the acoustic wavelength is
developed. We model the droplet as an incompressible, isotropic, linear elastic solid undergoing
small deformations, under the conditions that the deformation is axisymmetric, with a purely
radial traction condition, where the traction condition is derived from the acoustic radiation
pressure. The displacement and stress within the droplet is then solved for utilizing two potentials developed by Love (1926). We finish off by testing the validity of the theory by measuring
the deformation and location of soft alginate gels with known material properties in an acoustic
levitator.
COMMITTEE: Advisor R. Glynn Holt, ME; Co-advisor Paul Barbone, ME/MSE; Raymond Nagem, ME |
