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pH sensing through a single optical fibre using SERS and CMOS SPAD line arrays.

TitlepH sensing through a single optical fibre using SERS and CMOS SPAD line arrays.
Publication TypeJournal Article
Year of Publication2017
AuthorsEhrlich K, Kufcsák A, McAughtrie S, Fleming H, Krstajic N, Campbell CJ, Henderson RK, Dhaliwal K, Thomson RR, Tanner MG
JournalOpt Express
Volume25
Issue25
Pagination30976-30986
Date Published2017 Dec 11
ISSN1094-4087
Abstract

Full exploitation of fibre Raman probes has been limited by the obstruction of weak Raman signals by background fluorescence of the sample and the intrinsic Raman signal of the delivery fibre. Here we utilised functionalised gold nanoshells (NS) to take advantage of the surface-enhanced Raman spectroscopy (SERS) effect to enhance the pH responsive spectrum of 4-mercaptobenzoic acid (MBA). However, the fibre background is still dominant. Using the photon arrival time-resolving capability of a CMOS single-photon avalanche diode (SPAD) based line sensor, we recover the SERS spectrum without a fibre background in a 10 s measurement. In this manner, pH sensing through a multimode fibre at a low excitation power that is safe for future in vivo applications, with short acquisition times (10 or 60 s), is demonstrated. A measurement precision of ± 0.07 pH units is thus achieved.

DOI10.1364/OE.25.030976
Alternate JournalOpt Express
PubMed ID29245776
Publication institute
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