(813c) Thermal Modeling of Wirelessly Heated Tissue Mimics

Roughly four percent of the 3.6 million medical devices implanted annually in the U.S. become infected and must be treated. Despite current prophylactic techniques, infection rates have decreased little over the past decade and existing treatments are limited to surgical explantation and replacement. One solution to treat and eliminate these infections is the use of thermal sterilization. Using heat inside the body to deactivate surface colonized bacteria is often overlooked because of the intense power requirements needed to induce effective thermal gradients and the risk of damaging surrounding, healthy tissue. In this work, magnetic hyperthermia is used to wirelessly deliver heat on implanted device surfaces with enough power to target deactivation time and temperature protocols. Remote surface heating is generated via a superparamagnetic iron oxide nanoparticle (SPION), poly(vinyl alcohol) composite coating exposed to an alternating magnetic field. Specific heating protocols using the coating are achieved by varying the SPION loading and the magnetic field strength. Additionally, experimental and theoretical thermal transport models are constructed to target a heating protocol that will eliminate infection while minimizing tissue damage. In the present work, these models quantify the thermal profiles generated from the SPION composite coating. Experimental heat transport models are produced through composite solid/liquid structures mimicking physiological constructs. These models provide results for the most extreme temperature gradients; including heat transport through mimicked bulk tissue, blood flow, and codependent bulk tissue/blood flow models. Experimental temperature profiles for both conductive and convective transport phenomena are measured using an in-house fabricated flow chamber and microscale thermistors.