City Research Online

Abstract

Optical, and especially fiber-optic techniques for the sensing of pH have become very attractive and considerable research progress in this field has been made over a number of years. The determination of the pH level across a broad range of applications today, e.g. in life sciences, environmental monitoring, industry and widely in biologically research is now accessible from such optical sensors. This arises because familiar sensors are often limited in terms of their response time and drift, which reduces the use of the current group of such fiber-optic sensors in wider applications. A new compact sensor design has been developed in this work, based on a specially-formed fiber-optic tip that was coated with a pH-sensitive dye, covalently linked to a hydrogel matrix to provide high stability. The sensor developed has a very fast response time (to 90% of saturation, Δt90) of < 5 seconds, a sensing uncertainty of about ± 0.04 pH units and given the covalently bonded nature of the dye, leeching is reduced and the probe is very stable over many days of use. During extended continuous use over ~12h in pH 7, this stability was confirmed, with drift of < 0.05 pH/h. Preliminary experiments in an important biological application, monitoring over pH levels from pH 5 to pH 8.5, are shown and discussed.

Publication Type:	Article
Additional Information:	Copyright, the authors, 2021 Society of Photo‑Optical Instrumentation Engineers (SPIE). One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this publication for a fee or for commercial purposes, and modification of the contents of the publication are prohibited.
Publisher Keywords:	pH measurement, fast response time, fiber-optic, optical fiber sensors, fluorescence, luminescence, biomedical measurements
Subjects:	Q Science > QD Chemistry Q Science > QH Natural history > QH301 Biology T Technology > TK Electrical engineering. Electronics Nuclear engineering
Departments:	School of Science & Technology > Engineering
SWORD Depositor:	Symplectic Administrator

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