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X-APPLE-TRAVEL-ADVISORY-BEHAVIOR:AUTOMATIC
234751
20260415T082930Z
DTSTART;TZID=America/New_York:20260427T090000
DTEND;TZID=America/New_York:2
 0260427T103000
URL;TYPE=URI:https://www.wpi.edu/news/calendar/events/ece-m
 s-thesis-presentation-maria-bechwati
ECE MS Thesis Presentation by: Maria Bechwati
\n\nImage\n  \n\n\n\nTitle:\nAssessing Integrated Photonic Measurement Meth
 ods to Sense the pH of Saliva\n\nAbstract:\nPhotonic integrated circuits (
 PICs) are a rapidly growing technology. Currently, PICs are being explored
  for sensing. Fiber-based optical sensors are a well-established and commo
 n technology. PIC sensors, however, are more compact, scalable, and consum
 e less power. In addition, since the components are integrated onto a chip
 , integrated sensors are generally less affected by environmental factors 
 like temperature and mechanical stress.\nThis thesis assesses methods of m
 easuring the pH of a transparent substance in the visible spectrum using P
 ICs for the eventual purpose of measuring the pH of saliva. Measuring the 
 pH of saliva is important as a diagnostic factor, where the pH is the desi
 red sensed parameter, and as an environmental factor, where the pH may int
 erfere with accurately sensing other target analytes.\nMeasurements were t
 aken by applying the analyte onto a passive integrated photonic component 
 where the upper cladding was etched away to create a sensing trench. The a
 nalyte becomes the cladding of the waveguide, and the evanescent fields of
  the guided light interact with the analyte, affecting the spectra. Two ma
 in parameters’ correlation to pH were examined: absorption and refractiv
 e index. To assess absorption, analyte solutions of varying pHs were mixed
  with bromothymol blue, a pH-sensitive dye, and these solutions were depos
 ited on trenched straight-through waveguides. A shift in the maximum loss 
 correlated to pH was observed, although the measurement method demonstrate
 d issues with resolution. Both of the refractive index measurements, Fresn
 el reflections on trenched straight-through waveguides and interferometry 
 on trenched Mach-Zehnder interferometers, showed no correlation to pH, whi
 ch may be due to the sensitivity and design of these structures.\nIn addit
 ion, an optimization-based program to assess fabrication errors was briefl
 y explored. This could offer the chance to further enhance sensing capabil
 ities, as fabrication errors could be estimated to account for changes in 
 the spectra caused by them, as opposed to the desired sensing parameter.\n
 This work provides insights into promising PIC measurement methods of pH. 
 It also demonstrates hurdles in resolution and sensitivity, which may be o
 f interest to future research.\n\nResearch Advisor:\nProf. Doug Petkie\nPh
 ysics Department, and affiliation with ECE Department, WPI\n\nResearch Com
 mittee:\nProf. Ulkuhan Guler\nECE Department, WPI\nProf. Suat Ay\nECE Depa
 rtment, WPI\n\n
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