Fibre-based sensing of physiological parameters with time-resolved single photon spectroscopy

Research output: Contribution to conferencePaperpeer-review


In the age of antimicrobial resistance, there is an unmet need for fast, accurate and less invasive diagnostic methods for lung diseases. The EPSRC-IRC Proteus project attempts to fill this gap, seeking to develop minimally invasive methods of identifying pulmonary infections and inflammation for patients in critical care in vivo. This is enabled by combining novel optical fibres with advanced detector technologies.
We present a system for endoscopic sensing in size restricted regions such as the alveolar space of the distal lung consisting of a miniaturised single optical fibre probe and an in-house made CMOS SPAD line sensor for time-resolved single photon detection. The line sensor offers simultaneously read-out of 256 single photon detector pixels for fast time resolved spectroscopy. The system is exemplified for pH sensing with both fluorescent markers in the visible spectral range and functionalised surface enhanced Raman scattering (SERS) reporters in the near-infrared spectral region. pH is a key physiological parameter and tightly regulated in the body but can be locally changed in inflammatory and cancerous environments.
Fluorescence emission and Raman scattering are normally influenced and superposed by various unwanted background signals, especially the fibre background in miniaturised endoscopic sensing. We demonstrate addressing these problems with time-resolved detection. For fluorescence-based sensing, the local environment is investigated via changes in the fluorescence lifetime, which is less sensitive to fluorophore concentration, photobleaching and tissue autofluorescence than simple fluorescent amplitude. For SERS applications, we demonstrate complete recovery of the usually weak Raman signal from the unwanted fibre background through time-gating.
Fibre-based time-resolved spectrometry is an extremely versatile technique, we will discuss further adaptation to a variety of applications in the field of Raman and fluorescence spectroscopy.
K. Ehrlich et al., "pH sensing through a single optical fibre using SERS and CMOS SPAD line arrays," Opt. Express 25, 30976-30986 (2017)
Original languageEnglish
Publication statusPublished - Sept 2018
EventPhoton 2018 - Aston University, Birmingham, United Kingdom
Duration: 3 Sept 20186 Sept 2018


ConferencePhoton 2018
Country/TerritoryUnited Kingdom
Internet address


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