Finite Amplitude Measurements of the Nonlinear Parameter B/A for Liquid Mixtures Spanning a Range Relevant to Tissue Harmonic Mode

Abstract

The objective of this investigation was to measure the nonlinear parameter B/A using an enhanced finite amplitude distortion technique, based on nonlinear propagation effects analogous to those associated with tissue harmonic imaging. These measurements validate an improved method for measuring the nonlinear parameter B/A, the small-signal speed of sound, and the attenuation coefficient from a single set of ultrasonic measurements. To test the method, measurements were performed on 11 different mixtures of isopropyl alcohol (isopropanol) and water that span the range of concentrations from 0% to 100% isopropanol. Results for B/A ranging from approximately five to 11 were found to be reproducible and in good agreement with previously published values obtained using a thermodynamic method.

A novel method for extracting acoustic nonlinearity parameters with diffraction corrections

“…For solids, acoustic nonlinearity has been used to characterize material damage and microstructural changes [1][2][3]. For fluids, studies of acoustic nonlinearity are mainly focused on harmonic imaging of biological tissues [4,5]. In water, acoustic nonlinearity plays an important role in the development of parametric arrays for underwater sonar imaging [6].…”

Acoustic nonlinearity parameter measurements in a pulse-echo setup with the stress-free reflection boundary

“…[1][2][3][4] The practical implementation of the measurement technique has been limited to the through-transmission setup for determining the nonlinearity parameter (b) of the second harmonic wave. For the purpose of practical applications, a pulse-echo measurement technique is more desirable which enables the single-side access of test components.…”

Measured sound speeds and acoustic nonlinearity parameter in liquid water up to 523 K and 14 MPa

“…3,4 Acoustic nonlinearity is an inherent physical property of materials and has been targeted in technological applications such as harmonic imaging and parametric sonar imaging. [5][6][7][8][9] The acoustic nonlinearity of homogenous isotropic media is often described by the ratio of coefficients, B/A, in the isentropic equation of state. This EOS relates the pressure, P, and the mass density, ρ, through a simple expansion (subscript '0' indicates an unperturbed ambient quantity):…”

“…[9][10][11] In the FA method, an acoustic wave of a particular frequency, f 1 , is launched in a nonlinear medium and the amplitude of the second harmonic with frequency 2· f 1 is recorded. The more nonlinear a medium is, the higher the observed amplitude of the second (and higher) harmonic.…”