(388c) Deposition of Non-Spherical Particles in a Bifurcating Airway

Title: Deposition of Non-Spherical Particles in a Bifurcating Airway

Poom Bunchatheeravate
and Jennifer Curtis

Department of Chemical
Engineering, University of Florida, Gainesville, FL 32611. USA

Particles between the
sizes of 1-10um are more susceptible to deposition in the human lung.
Previous investigations of particle deposition in the human airways
focus on the deposition of spherical particles. Only a handful of
studies focus on the effect of particle morphology. These studies
include the deposition of fibrous particles in response to pollutants
such as asbestos, deposition of porous particles for higher drug
loadings, as well as deposition of nano-size particles. The current
study seeks to quantify the deposition of different shaped particles
and establish a relationship between particle shape and deposition.
The airway model used in this study is that of a triple bifurcating
airway that was glass blown with the dimensions similar to that of
Weibel's Model A. The simplicity of the airway model helps to isolate
the effect of particle morphology on deposition patterns. The
particles used in this study were classified into three general
shapes - spherical, rod-like, and flake-like. The effect of particle
density was also studied for spherical particles and flake particles. All of the particles studied had a mean aerodynamic diameter between
1-10 microns. Particles were dyed using a near-infrared dye and sent
into the airway model with a fixed volumetric flowrate. After the
deposition, the particle were visualized using IVIS Lumina
fluorescence imaging machine. The IVIS Lumina provides two essential
pieces of information - the fluorescence image showing the position
of particle and the photon counts emitted in each region of the
airway model relating to the local concentration. The deposition in
each individual airway was quantified for each type of particle. The
deposition associated with each type of particle is compared and an
empirical model was developed relating the deposition efficiency in
each branching airway with the particle properties. It was found that
the particle properties that influence the deposition are the
particle Stokes number, the diffusion coefficient, the density and
the sphericity.