Date of Award

Spring 5-10-2025

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science in Biomedical Engineering

Department

Biomedical Engineering

First Committee Advisor

Evan K. Wujcik

Second Committee Member

Caitlin Howell

Third Committee Member

Karissa Tilbury

Additional Committee Members

David J. Neivandt

Abstract

Electrically conductive polymers are a groundbreaking class of materials commonly examined in medical research focused on healthcare devices, such as biosensors. They share the mechanical properties of a classical polymer, as well as the electronic properties of metals. This allows them to function as flexible, lightweight, and highly efficient components in both wearable and implantable sensor technologies.

Though research has shown some brilliant findings, most of the polymer sensors presented are only partially, or not biologically compatible with the human body. Few polymer sensors have been tested or proven to be safe for wide applications outside of the lab. With its great features and potential for success, it has become crucial to ensure that the conductive polymer matrices used in bio-sensing are biocompatible and safe for the user. This work demonstrates a new electroconductive polymer matrix composed of bio-based materials–bovine gelatin, Whey Protein Isolate (WPI), Polyaniline (PANI) and Phytic Acid (PA)– as a soft, hydrogel-like material. Each polymer matrix sample contains varying amounts of WPI. A control sample without PANI was also included for comparison. The composition was designed to balance mechanical flexibility, conductivity, and biocompatibility. SEM testing showed fair homogeneity across all of the samples with the control sample being the least homogeneous. FTIR results confirmed a well-integrated polymer matrix where hydrogen bonding and electrostatic interactions contribute to the structural stability and charge transport in the matrix. TGA results revealed a distinct two-step degradation pattern: an initial mass loss corresponding to water evaporation, followed by a second drop associated with the depolymerization of the matrix. Based on the trend shown by the thermograms, samples containing higher amounts of WPI are more thermally stable compared to those that have lesser amounts of it in their matrix. The tensile testing revealed moderate stretchability across the samples with 1.5 g WPI samples exhibiting the highest elastic modulus ~ 153 kPa, with varying strain values. The electrical resistance testing revealed exquisitely low resistance, measuring as low as 5.1 kΩ for the 1 g WPI sample at rest. The resistance values were fully restored following the stretch test. The conductivity calculated based on the average length, thickness, and resistance of the samples was 160.5 mS/m, 259.1 mS/m, and 303 mS/m for samples 0.5 g WPI, 1 g WPI and 1.5 g WPI, respectively. The best optimal time for self-healing showed to be 48 hours or longer. The electrical resistance was fully restored to its initial value following self-healing, and even showed a slight decrease, indicating improved conductivity. The Zone of Inhibition results demonstrated that both control samples and PANI samples are resistant to S. aureus and E. coli, with inhibition zones diameters ranging from 15.3 mm and 19.5 mm. The aim of this study was to develop a new formulation of an electroconductive polymer matrix that is far more biocompatible, yet that still exhibits satisfactory mechanical properties like its predecessors, making it a great candidate for bio-sensing applications.

Download

Files over 10MB may be slow to open. For best results, right-click and select "save as..."

Share