Electronic Thesis and Dissertation Repository

Degree

Master of Engineering Science

Program

Biomedical Engineering

Supervisor

Mequanint, Kibret

Abstract

Hydrogels contain high amount of water allowing their use as surrogates to human tissues with specific properties that can be tuned by additives. Gellan gum is a gel-forming material of interest and is a replacement for other common gelling agent with limited use as a tissue phantom. Therefore, this thesis examines the application of gellan gum gels as a novel magnetic resonance imaging (MRI) phantom with a design of experiments model to obtain tunable properties. The analysis was extended to include mechanical and electrical properties with a separate design of experiment. Gels doped with synthesized superparamagnetic iron oxide nanoparticles (SPIONs) and MnCl2 or GdCl3 were scanned using magnetic strengths ranging from 230 μT to 3 T. Nineteen distinct gel samples were formulated determining the linear, quadratic, and interactive effects of each contrast agent by a central composite design of experiments. For mechanical and electrical characterization, the gellan gum gels were doped with LiCl to induce crosslinking and to match the electrical properties of tissues. Additionally, the concentration of gellan gum and propylene glycol (PG) were varied. The models were analyzed with ANOVA and was able to accurately predict the desired properties from the concentration seen by the adjusted R2 values. Therefore, novel gellan gum gels were prepared with controllable magnetic relaxation, electrical conductivity, and mechanical strength.

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