Date of Graduation

5-2014

Document Type

Thesis

Degree Name

Bachelor of Science in Biomedical Engineering

Degree Level

Undergraduate

Department

Biomedical Engineering

Advisor

Muldoon, Timothy J

Reader

Balachandran, Kartik

Second Reader

Wochok, Jeffrey C.

Abstract

We have introduced a method for creating thin-film PDMS optical phantoms that can be used to validate a bench-top optical device called a Diffuse Reflectance Microendoscope (DRME). The DRME is acquires data on cell surface morphology and sub-surface diffuse reflectance, which may provide clinicians with the tools to diagnose oral cancer at earlier stages. Phantoms were created with PDMS. Optical properties of the phantoms were controlled with the addition of nigrosin and titanium dioxide. Depth of phantoms was controlled by a spin coater. The DRME was built with a combination of filters and dichroic mirrors to separate electromagnetic radiation in the green and near-infrared wavelengths. Finally, results of phantom images acquired by the DRME were validated through Monte Carlo modeling. The absorption coefficient of PDMS phantoms is precisely controlled between 0.0 and 0.6 cm-1 through the addition of a 1% w/v nigrosin stock solution. Depth of thin-films is reproducibly controlled between 0.1 and 1 mm. Optimal source-detector fiber positioning of the DRME was tested between 1 and 3 mm by taking diffuse reflectance profiles of a phantom with scattering and absorbing coefficients of 100 cm-1 and 0.2 cm-1, respectively. The experiment was modeled through various Monte Carlo simulations. The ability to fine tune optical and geometric properties of PDMS optical phantoms will allow us to more accurately model oral epithelium for validation of the DRME in non-clinical trials. Results of our study demonstrate the concept of diffuse reflectance in distinguishing changes in optical properties of materials.

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