Fibre optic time-resolved spectroscopy using CMOS-SPAD arrays

In vivo fibre optic fluorescence-based sensing is the use of synthesised fluorophores which interrogate the local environment via variation in their fluorescence emission, addressed through an optic fibre. However, the emission intensity is influenced by intrinsic factors such as photobleaching, quantitative factors like concentration dependency and background signals from autofluorescence of tissue and the delivery optical fibre. Many of these problems can be addressed by using time-resolved spectroscopy which measures variations in the fluorescent lifetime. We present a versatile fibre-based time-resolved spectrograph based on a CMOS SPAD line sensor capable of acquiring time and spectral resolved fluorescent lifetime data in a single measurement exploiting the time-correlated single photon counting (TCSPC) technique. It is shown that these TCSPC histograms enable the differentiation between autofluorescence of tissue and synthesized fluorophores, as well as the removal of unwanted fibre background through post-processed time-gating. As a proof-of-principle application the pH- dependent changes in fluorescent lifetime of 5-carboxyuorescein (FAM) are measured.

[1]  J. Lakowicz.  Principles of fluorescence spectroscopy , 1983 .

[2]  William M. Whelan,et al.  Optical Fiber Sensors for Biomedical Applications , 2010 .

[3]  Pedro A. S. Jorge,et al.  Optical fiber probes for fluorescence based oxygen sensing , 2004 .

[4]  Ute Resch-Genger,et al.  High-sensitivity detection of breast tumors in vivo by use of a pH-sensitive near-infrared fluorescence probe. , 2012, Journal of biomedical optics.

[5]  Toshihiko Imato,et al.  A ratiometric fluorescent probe for imaging hydroxyl radicals in living cells. , 2004, Chemical communications.

[6]  C. Bai,et al.  Development of fiber optic fluorescence oxygen sensor in both in vitro and in vivo systems , 2008, Respiratory Physiology & Neurobiology.

[7]  R. E. Bell,et al.  Exploiting a Transmission Grating Spectrometer , 2004 .

[8]  R. K. Henderson,et al.  A Single-Photon Avalanche Diode in 90-nm CMOS Imaging Technology With 44% Photon Detection Efficiency at 690 nm , 2012, IEEE Electron Device Letters.

[9]  Laura Marcu,et al.  Percutaneous fiber-optic sensor for chronic glucose monitoring in vivo. , 2008, Biosensors & bioelectronics.

[10]  S. Achilefu,et al.  Fluorescence lifetime measurements and biological imaging. , 2010, Chemical reviews.

[11]  Nikola Krstajić,et al.  256 × 2 SPAD line sensor for time resolved fluorescence spectroscopy. , 2015, Optics express.

[12]  T A Birks,et al.  Endoscopic sensing of alveolar pH. , 2017, Biomedical optics express.

[13]  R. Richards-Kortum,et al.  Fiber optic probes for biomedical optical spectroscopy. , 2003, Journal of biomedical optics.

[14]  B. Vojnovic.  Advanced Time‐Correlated Single Photon Counting Techniques , 2006 .

[15]  K. König,et al.  Fluorescence lifetime imaging by time‐correlated single‐photon counting , 2004, Microscopy research and technique.

[16]  Barry R. Masters,et al.  Fluorescence Lifetime Spectroscopy and Imaging: Principles and Applications in Biomedical Diagnostics , 2014 .