Ultrasonic method to characterize shear wave propagation in micellar fluids

Abstract

Viscoelastic micellar fluid characteristics have been measured with mechanically generated shear waves and showed good agreement to shear oscillatory methods. In this paper, shear waves in wormlike micellar fluids using ultrasound were successfully generated and detected. Micellar fluids of different concentrations (100, 200, 300, and 400 mM) were studied with ultrasound-based and conventional rheology methods. The measured micellar fluid complex modulus from oscillatory shear tests between 0.001 and 15.91 Hz was characterized with an extended Maxwell fluid model. The elastic and viscous parameters found using rheological testing were used to estimate shear wave phase velocity over a frequency range from 100 to 500 Hz, and compared to shear wave velocity measured with ultrasound-based methods with a mean absolute error 0.02 m/s. The shear wave frequency content was studied and an increase in shear wave center frequency was found as a function of micellar fluid concentration. Moreover, the bias found in the shear wave group velocity with respect to rheological measurement is attributed to the micellar fluid viscous component. Finally, the shear wave phase velocity evaluated at the center frequency agreed well with the rheological measurements.

Acoustic radiation force optical coherence elastography for evaluating mechanical properties of soft condensed matters and its biological applications

“…In Gladden et al, the shear wave speeds in micellar fluids with concentrations of 100, 200, 300 and 400 mM were 0.25, 0.45, 0.54 and 0.65 m/s by using a mechanical shaker and measurements of the motion with a camera operating at 2000 frames/sec . Amador et al reported that the group velocity in 100, 200, 300 and 400 mM were 0.24, 0.44, 0.56 and 0.71 m/s by using SWE, respectively . Our results are comparable (Figure 2A‐D) with both reported studies and OCE has ability to measure Rayleigh wave behaviors in the soft condensed matters.…”

“…In fact, the appearance and macroscopic behavior of the micellar fluids is that of a semisolid, like biological mucus rather than fluids although it bears the name micellar fluid. Two similar studies reported the viscosity in micellar 200 mM using Maxwell models and the results are not in the good agreement, 0.48 vs 0.12 Pa·s . On the contrary, the Kelvin‐Voigt model is more reliable to be used especially as storage modulus is significantly larger than loss modulus , which can be reasonably associated with our experimental cases illustrated in Figure .…”

“…The relationship between shear waves and Rayleigh waves has been well‐defined and demonstrated in previous literatures: that Rayleigh wave velocity is approximately 95.5% of shear wave velocity under the circumstance of a solid‐air interface . On the other hand, the elasticity and viscosity of micellar fluids were measured by classical mechanical test methods in previous papers reported by Gladden et al and Amador et al . In Gladden et al, the shear wave speeds in micellar fluids with concentrations of 100, 200, 300 and 400 mM were 0.25, 0.45, 0.54 and 0.65 m/s by using a mechanical shaker and measurements of the motion with a camera operating at 2000 frames/sec .…”

“…Soft condensed matter has high similarity with characteristics of biological tissues; therefore, these have been exploited to investigate tissue mechanics and have been successful in explaining dynamical tissue behaviors such as surface tension, elasticity and viscosity . Micelles have been identified to have representative complexity of soft matter systems and have attracted much attention in areas such as nanocarriers for drug delivery , mechanical responses , and cancer treatment due to the versatility of the rheological properties with small amphiphilic molecules and their spontaneous self‐assembly in a simplicity of the design with surfactant, salt and water .…”

“…Furthermore, OCE is able to deal with biological mucus and tissues with thin thickness or transparent status for differentiating low viscosity of bile with colecystectomized patients from normal subjects sampled the via bile duct . In contrast, it would be difficult for ultrasonic shear wave elastography (SWE) technology to investigate these materials because extra scatterers would be required and the materials are of limited thickness .…”