Controlled Particle Transport in a Human Airway Replica

Abstract

The goal of this research is a proof-of-concept for targeted aerosol delivery and validation of computational results. Sodium chloride particles, with a monodisperse particle size of one micrometer are used to represent a drug aerosol in the experimental validation of computational results. A complex oral airway, including a mouth, larynx, pharynx, and trachea was constructed out of laser cured resin, using a three-dimensional printing method. A symmetric three generation (G0 to G3) bifurcating bronchial airway was constructed using the same process. Two-phase flow was conducted through these models to yield particle transport results. The bulk air flow was 2 liters per minute, the highest observed flow rate that will allow the flow to remain laminar throughout the airway model. The flow rate of the particle seeded flow was maintained at 20 milliliters per minute. The velocities of these two flow rates remain within an order of magnitude of each other to inhibit vortices created by shear forces when the two flows were introduced. A series of nozzles (constructed using SL) were used to control the particle injection location. A one millimeter inner diameter seed nozzle is offset, from the center, a given percent of the radius. There were five nozzles, with increasingly offset seed tubes, 0% (centerline of axisymmetric nozzle), 20%, 40%, 60%, and 80%. The airway model was attached to the nozzle so that the nozzle exit is in the same plane as the mouth entrance. The nozzle was rotated so that the seed tube exit can be positioned at various angles within the circular cross-section. By controlling the particle release position, the deposition efficiency can be increased, dramatically, as compared to the uniform injection of the drug. The results show the controlled particle release can determine which branch or branches of the third generation bifurcating bronchial airway the particles will exit. While numerous previous researchers have studied the deposition effects of a uniform injection of aerosol particles in the human airways, the controlled position of particle release is an original idea.