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TitlePolarized Light Applications towards Biomedical Diagnosis and Monitoring
File Size8.8 MB
Total Pages239
Document Text Contents
Page 1

A Dissertation



Submitted to the Office of Graduate and Professional Studies of
Texas A&M University

in partial fulfillment of the requirements for the degree of


Chair of Committee, Gerard L. Coté
Committee Members, Javier Jo

Kristen Maitland
Prasad Enjeti

Head of Department, Gerard L. Coté

August 2015

Major Subject: Biomedical Engineering

Copyright 2015 Casey William-Munz Pirnstill

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Utilization of polarized light for improved specificity and sensitivity in disease

diagnosis is occurring more often in fields of sensing, measurement, and medical

diagnostics. This dissertation focuses on two distinct areas where polarized light is

applied in biomedical sensing/monitoring: The first portion of worked reported in this

dissertation focuses on addressing several major obstacles that exist prohibiting the use

of polarized light as a means of developing an optical based non-invasive polarimetric

glucose sensor to improve the quality of life and disease monitoring for millions of

people currently afflicted by diabetes mellitus. In this work there are two key areas,

which were focused on that require further technical advances for the technology to be

realized as a viable solution.

First, in vivo studies performed on New Zealand White (NZW) rabbits using a dual-

wavelength polarimeter were conducted to allow for performance validation and

modeling for predictive glucose measurements accounting for the time delay associated

with blood aqueous humor glucose concentrations in addition to overcoming motion

induced birefringence utilizing multiple linear regression analysis. Further, feasibility of

non-matched index of refraction eye coupling between the system and corneal surface

was evaluated using modeling and verified with in vitro testing validation. The system

was initially modeled followed by construction of the non-matched coupling

configuration for testing in vitro.

The second half of the dissertation focuses on the use of polarized light microscopy

designed, built, and tested as a low-cost high quality cellphone based polarimetric

imaging system to aid medical health professionals in improved diagnosis of disease in

the clinic and in low-resource settings. Malaria remains a major global health burden and

new methods for, low-cost, high-sensitivity diagnosis of malaria are needed particularly

in remote low-resource areas throughout the world. Here, a cost effective optical cell-

phone based transmission polarized light microscope system is presented utilized for

imaging the malaria pigment known as hemozoin. Validation testing of the optical

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(3). For tuning the PID controller for optimal response profile and speed the gain values

are adjusted by the user, shown in section 4 on front panel.

Figure G5: A screen capture of the front panel for the FPGA VI.

The block diagram and front panel schematic for the host PC PID control VI is

shown in Figures G6 and G7 below. The section marked (1) in the block diagram is used

to connect this VI with the FPGA VI and cRio chassis. This section opens a reference to

the FPGA VI, initializes important variable values of the loop, and then runs the FPGA

VI embedded on the cRio device. The bulk of the host PC VI function is shown in the

section marked (2) on the block diagram. This section allows the user to specify changes

in the PID parameters in real-time during operation of the PID controller. The second

function of the host VI is illustrated in section (3) on the block diagram. This portion of

the VI takes the data acquired from FPGA modules, organizes the data into a desired

output format and generates the output file containing the PID feedback values

calculated by the PID controller.

Figure G6: A screen capture of the block diagram schematic for the host PC PID control VI.

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The front panel of the VI is shown in Figure G7. To tune the PID gain settings in

real-time while operating the VI the user can vary the control boxes in section (1) of the

front panel. The path specified in section (2) of the front panel and file name provided in

the control box specify the path and filename for the output data file for the PID

controller. A graph of the process variable and desired set-point are plotted in section

(3). The frequency control specified in section (5) determines the duration the output

voltage is supplied via the cRio module. The indicators on the front panel in section (6)

provide real-time values for the operating frequency, output voltages, and the remaining

number of elements that need to be written to the host PC.

Figure G7: A screen capture of the front panel schematic for the host PC PID control VI.

For the dual-wavelength polarimeter setup the diagram shown above was essentially

duplicated allowing for two PID loops to run simultaneously, for the respective

wavelengths lasers in the system.

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