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.
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.
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.
","abstract_html":"<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>","abstract_has_math":false,"creators":["Hemphill, Brian D."],"institution":"Case Western Reserve University School of Graduate Studies","degree_name":"Master of Engineering","degree_level":"masters","degree_discipline":"Biomedical Engineering","degree_department":null,"school":null,"contributors":["Gratzl, Miklos"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2013,"date_issued":"2013-03-08","date_published":"2013-03-08","updated_at":"2026-07-24T03:35:52Z","subjects":["Biomedical Engineering","Optode","color detection"],"languages":["English"],"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."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://rave.ohiolink.edu/etdc/view?acc_num=case1354890395","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Gratzl, Miklos"]},{"key":"dc:creator","label":"Author","values":["Hemphill, Brian D."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2013-03-08"]},{"key":"dc:publisher","label":"Institution","values":["Case Western Reserve University School of Graduate Studies / OhioLINK"]},{"key":"dc:type","label":"Dc Type","values":["Electronic Thesis or Dissertation"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Biomedical Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Engineering"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Case Western Reserve University School of Graduate Studies"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Biomedical Engineering","Optode","color detection"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["English"]},{"key":"dc:rights","label":"Dc Rights","values":["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."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://rave.ohiolink.edu/etdc/view?acc_num=case1354890395"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["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.
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.
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.
"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf","p.73","1.19 MB"]},{"key":"dc:title","label":"Title","values":["Light Emitting Diodes and a Monochrome Camera to Measure Chemical Optode Response"]}]}],"canonical_facts":{"dc:contributor":["Gratzl, Miklos"],"dc:creator":["Hemphill, Brian D."],"dc:date":["2013-03-08"],"dc:description":["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.
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.
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.
"],"dc:format":["application/pdf","p.73","1.19 MB"],"dc:identifier":["http://rave.ohiolink.edu/etdc/view?acc_num=case1354890395"],"dc:language":["English"],"dc:publisher":["Case Western Reserve University School of Graduate Studies / OhioLINK"],"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."],"dc:subject":["Biomedical Engineering","Optode","color detection"],"dc:title":["Light Emitting Diodes and a Monochrome Camera to Measure Chemical Optode Response"],"dc:type":["Electronic Thesis or Dissertation"],"thesis:degree_discipline":["Biomedical Engineering"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Engineering"],"thesis:institution_name":["Case Western Reserve University School of Graduate Studies"]},"updated_at":"2026-07-24T03:35:52Z"}