Measurement of the Nonlinearity Parameter B/a in Biological Materials Using the Finite Amplitude and Thermodynamic Method

It is well-known that materials exhibit a decrease in compressibility when subjected to high compression. This decrease in compressibility may be described by the nonlinearity parameter B/A. Organic liquids have been shown to possess a wide variation of the parameter, ranging from 5 to 12. This thesis reports on the measurement of this parameter in biological materials, including tissue models and soft tissue. An acoustic method with the potential for in vivo measurements is developed for this purpose. The result of measurements is confirmed by a second method which determines the change of sound speed, and hence the compressibility, with changes in hydrostatic pressure and temperature. The measurements indicate that: (1) B/A increases approximately linearly with solute concentration for protein solutions; (2) B/A is relatively insensitive to the molecular weight of the solute for a fixed concentration; (3) B/A ranges from 6.5 to 11 for various soft tissues; and (4) B/A decreases when the cellular structure of a tissue is destroyed. It is felt that details of nonlinear ultrasonic propagation in living systems should contribute to the development of clinical diagnostic and therapeutic applications of ultrasound.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Electrical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Law, Wing Kong

• Physics, Acoustics

Identifier

(UMI)AAI8409800

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/69267