Inversion of ultrasonic scattering data for red blood cell suspensions under different flow conditions

Area of Science:

• Biophysics
• Acoustics
• Fluid Dynamics

Background:

• Low-frequency scattering principles apply to complex particle distributions.
• Nonspherical particle scattering requires orientation averaging for accurate analysis.
• Ultrasonic data from red blood cell suspensions can reveal cellular behavior.

Purpose of the Study:

• To apply low-frequency scattering theory to invert ultrasonic data for red blood cell suspensions.
• To investigate red blood cell interactions and population dynamics under varying flow conditions.
• To determine correlation and cell population parameters from scattering data.

Main Methods:

• Utilizing recent advancements in low-frequency scattering by correlated random distributions of nonspherical particles.
• Applying orientation averaging techniques to scattering data.
• Inverting ultrasonic data using a generalized fluctuation function S(c;w)P.

Main Results:

• The inversion procedure successfully isolated a correlation parameter (c) and a cell population parameter (P).
• Peak scattering occurred at volume fractions (w) between 0.15 and 0.25, corresponding to c values from 0.4 to 2.1.
• These results contrast with hard spheres (w ≈ 0.13, c = 3), indicating weaker repulsion and potential aggregation in red blood cells.

Conclusions:

• Lower c values suggest weaker repulsion and possible interparticle attraction (aggregative trends) between deformable red blood cells.
• The correlation parameter c may also reflect flow alignment of discoid red blood cells.
• Ultrasonic scattering provides insights into the micro dynamics of red blood cell suspensions.