DOI: https://doi.org/10.15368/theses.2011.203
Available at: https://digitalcommons.calpoly.edu/theses/643
Date of Award
12-2011
Degree Name
MS in Biomedical Engineering
Department/Program
Biomedical and General Engineering
Advisor
Lily Laiho
Abstract
Melanoma skin cancer is the abnormal growth of the melanocytes – the pigmented cells located in the epidermis. The current gold standard diagnostic technique for determining whether a lesion is cancerous involves subjectively examining suspicious lesions and performing an invasive biopsy to confirm melanoma. This method may neglect some lesions or cause scarring from biopsies that turn out to be benign. Thus, impedance-based detection using a multi-electrode device was investigated as a noninvasive technique to diagnose melanoma skin cancer. The multi-electrode device was designed with 8 equally spaced Ag/AgCl electrodes surrounding one central electrode at a 5 mm radius. The electrodes were held in place by a vice-like mechanism using three circular Delrin sections. The electrodes were interfaced to an 8:1 multiplexer and National Instruments Educational Laboratory Virtual Instrumentation Suite (ELVIS) for measurement control and impedance analysis. The ELVIS system, multiplexer, and electrode device were validated for accuracy with various values of resistors and capacitors. Raw and cooked chicken thigh meat and skin were tested to evaluate the capabilities of the electrode device to discern different tissue types and tissue moisture contents by impedance measurements. EpidermTM and Melanoma tissue-engineered skin analogues, provided by MatTek Corporation, were tested to mimic the in situ disease state. The electrode device was found to produce reliable measurements for known electrical components with resistances between 10 ohms and 100 k-ohms and capacitances between 10 nF and 10 uF. The measurements from the chicken tissues and tissue-engineered skin constructs – excluding cooked chicken skin data – fell within the reliable range of the electrode device and were thus considered reliable as well. All analyses concluded that a statistical difference between the impedances of raw meat and raw skin, cooked meat and raw meat, and EpidermTM and Melanoma existed. Therefore, the hypothesis that a multi-electrode device could differentiate between melanoma and healthy skin tissues based on impedance measurements was satisfied.