pH Measurements Using Leaky Waveguides

Victoria Wensley; Nicholas J Goddard; Ruchi Gupta

doi:10.1109/APSCON63569.2025.11144119

pH Measurements Using Leaky Waveguides

Victoria Wensley
, Nicholas J Goddard
, Ruchi Gupta

Chemistry

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

Abstract

Leaky waveguides (LW) are simple devices, requiring only a low refractive index layer on a higher refractive index substrate to act as an optical sensor. In this study, two types of LWs were used as pH sensors, the metal-clad LW (MCLW) and dye-doped LW (DDLW), using agarose as a pH-insensitive reference layer and chitosan as the pH-sensitive layer. The pH response of both layers was studied individually in both MCLW and DDLW formats and then as a stacked DDLW where the chitosan layer was deposited on top of an agarose layer. The agarose layer was found to be essentially insensitive to pH, while the measured pKa of the chitosan LW was found to be 6.33±0.18, which is in accord with the literature value of ~6.5. Using the stacked DDLW it was possible to reduce the sensitivity of the device to sample refractive index changes caused by composition by a factor of ~7.

Original language	English
Title of host publication	Proceedings of IEEE Applied Sensing Conference (APSCON 2025)
Publisher	Institute of Electrical and Electronics Engineers (IEEE)
Pages	335-338
Number of pages	4
ISBN (Electronic)	9798350379334
ISBN (Print)	9798350379341
DOIs	https://doi.org/10.1109/APSCON63569.2025.11144119
Publication status	Published - 4 Sept 2025
Event	3rd IEEE Applied Sensing Conference - IIT Hyderabad, Kandi Village, India Duration: 20 Jan 2025 → 22 Jan 2025 https://2025.ieee-apscon.org/

Publication series

Name	Proceedings of IEEE Applied Sensing Conference (APSCON)
Publisher	IEEE

Conference

Conference	3rd IEEE Applied Sensing Conference
Abbreviated title	APSCON 2025
Country/Territory	India
City	Kandi Village
Period	20/01/25 → 22/01/25
Internet address	https://2025.ieee-apscon.org/

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10.1109/APSCON63569.2025.11144119Licence: None: All rights reserved

1 Article

pH Measurements Using Leaky Waveguides with Synthetic Hydrogel Films
Wensley, V., Goddard, N. & Gupta, R., 14 Feb 2025, In: Micromachines. 16, 2, 15 p., 216.
Research output: Contribution to journal › Article › peer-review

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title = "pH Measurements Using Leaky Waveguides",

abstract = "Leaky waveguides (LW) are simple devices, requiring only a low refractive index layer on a higher refractive index substrate to act as an optical sensor. In this study, two types of LWs were used as pH sensors, the metal-clad LW (MCLW) and dye-doped LW (DDLW), using agarose as a pH-insensitive reference layer and chitosan as the pH-sensitive layer. The pH response of both layers was studied individually in both MCLW and DDLW formats and then as a stacked DDLW where the chitosan layer was deposited on top of an agarose layer. The agarose layer was found to be essentially insensitive to pH, while the measured pKa of the chitosan LW was found to be 6.33±0.18, which is in accord with the literature value of \textasciitilde{}6.5. Using the stacked DDLW it was possible to reduce the sensitivity of the device to sample refractive index changes caused by composition by a factor of \textasciitilde{}7.",

author = "Victoria Wensley and Goddard, \{Nicholas J\} and Ruchi Gupta",

year = "2025",

month = sep,

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doi = "10.1109/APSCON63569.2025.11144119",

language = "English",

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series = "Proceedings of IEEE Applied Sensing Conference (APSCON)",

publisher = "Institute of Electrical and Electronics Engineers (IEEE)",

pages = "335--338",

booktitle = "Proceedings of IEEE Applied Sensing Conference (APSCON 2025)",

note = "3rd IEEE Applied Sensing Conference, APSCON 2025 ; Conference date: 20-01-2025 Through 22-01-2025",

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}

Wensley, V, Goddard, NJ & Gupta, R 2025, pH Measurements Using Leaky Waveguides. in Proceedings of IEEE Applied Sensing Conference (APSCON 2025). Proceedings of IEEE Applied Sensing Conference (APSCON), Institute of Electrical and Electronics Engineers (IEEE), pp. 335-338, 3rd IEEE Applied Sensing Conference, Kandi Village, India, 20/01/25. https://doi.org/10.1109/APSCON63569.2025.11144119

pH Measurements Using Leaky Waveguides. / Wensley, Victoria; Goddard, Nicholas J; Gupta, Ruchi.
Proceedings of IEEE Applied Sensing Conference (APSCON 2025). Institute of Electrical and Electronics Engineers (IEEE), 2025. p. 335-338 (Proceedings of IEEE Applied Sensing Conference (APSCON)).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

TY - GEN

T1 - pH Measurements Using Leaky Waveguides

AU - Wensley, Victoria

AU - Goddard, Nicholas J

AU - Gupta, Ruchi

PY - 2025/9/4

Y1 - 2025/9/4

N2 - Leaky waveguides (LW) are simple devices, requiring only a low refractive index layer on a higher refractive index substrate to act as an optical sensor. In this study, two types of LWs were used as pH sensors, the metal-clad LW (MCLW) and dye-doped LW (DDLW), using agarose as a pH-insensitive reference layer and chitosan as the pH-sensitive layer. The pH response of both layers was studied individually in both MCLW and DDLW formats and then as a stacked DDLW where the chitosan layer was deposited on top of an agarose layer. The agarose layer was found to be essentially insensitive to pH, while the measured pKa of the chitosan LW was found to be 6.33±0.18, which is in accord with the literature value of ~6.5. Using the stacked DDLW it was possible to reduce the sensitivity of the device to sample refractive index changes caused by composition by a factor of ~7.

AB - Leaky waveguides (LW) are simple devices, requiring only a low refractive index layer on a higher refractive index substrate to act as an optical sensor. In this study, two types of LWs were used as pH sensors, the metal-clad LW (MCLW) and dye-doped LW (DDLW), using agarose as a pH-insensitive reference layer and chitosan as the pH-sensitive layer. The pH response of both layers was studied individually in both MCLW and DDLW formats and then as a stacked DDLW where the chitosan layer was deposited on top of an agarose layer. The agarose layer was found to be essentially insensitive to pH, while the measured pKa of the chitosan LW was found to be 6.33±0.18, which is in accord with the literature value of ~6.5. Using the stacked DDLW it was possible to reduce the sensitivity of the device to sample refractive index changes caused by composition by a factor of ~7.

U2 - 10.1109/APSCON63569.2025.11144119

DO - 10.1109/APSCON63569.2025.11144119

M3 - Conference contribution

SN - 9798350379341

T3 - Proceedings of IEEE Applied Sensing Conference (APSCON)

SP - 335

EP - 338

BT - Proceedings of IEEE Applied Sensing Conference (APSCON 2025)

PB - Institute of Electrical and Electronics Engineers (IEEE)

T2 - 3rd IEEE Applied Sensing Conference

Y2 - 20 January 2025 through 22 January 2025

ER -

pH Measurements Using Leaky Waveguides

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Research output

pH Measurements Using Leaky Waveguides with Synthetic Hydrogel Films

Cite this