Light Emitting Diodes and a Monochrome Camera to Measure Chemical Optode Response

<p>Bulk chemical optodes employing chromoionophores respond to the analyte of interest by altering their color. Accordingly it is necessary to have a means of measuring that color in a quantitative manner. In this work a pH-sensitive optode sensor is used as a basis for comparing two different methods of measuring a sensor’s color.</p><p> A system using three different colored LEDs as illuminators and a monochrome camera as a detector has been designed to measure optode sensor response. Three images of the sensor are taken, each with a different color LED providing illumination, to record information about the sensor’s spectral reflectance characteristics. The system’s performance is measured and the results are compared to a color camera with white light illumination under the same measurement conditions. The narrow spectral emission profile of LEDs provides superior wavelength selectivity compared to a color camera’s red, green and blue filters, resulting in the expectation of improved performance.</p><p> Multiple images are taken of an optode using both systems. Pixels of interest are extracted from each, normalized to a color-constant reference, and various parameters calculated. The color is represented as three-dimensional vectors in a Cartesian coordinate system, where the angle between measured vectors represents the color change of the sensor. Sensitivity is calculated for both systems in terms of radians per pH, and standard deviation is computed over nine trials and used to calculate signal-to-noise ratio for the two compared measurement systems, and the monochrome/LED system exhibits superior performance.</p>

Name thesis:degree_name

Master of Engineering

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Biomedical Engineering

Grantor dc:publisher

Case Western Reserve University School of Graduate Studies

Year dc:date

2013

Author dc:creator

• Hemphill, Brian D.

Contributors dc:contributor

• Gratzl, Miklos

• Biomedical Engineering
• Optode
• color detection

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=case1354890395

OAI identifier oai:identifier

oai:etd.ohiolink.edu:case1354890395