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Open AccessArticle

Multispectral Depth-Resolved Fluorescence Lifetime Spectroscopy Using SPAD Array Detectors and Fiber Probes

1
National Institute of Optics, National Research Council (INO-CNR), Via Nello Carrara 1, 50019 Sesto Fiorentino, Italy
2
European Laboratory for Non-linear Spectroscopy (LENS), Via Nello Carrara 1, 50019 Sesto Fiorentino, Italy
3
Department of Information Engineering (DINFO), University of Florence, Via di S. Marta 3, 50139 Firenze, Italy
4
Dipartimento di Elettronica, Informazione e Bioingegneria (DEIB), Politecnico di Milano, 20133 Milan, Italy
5
Micro Photon Device SRL, Via Waltraud Gebert Deeg 3g, I-39100 Bolzano, Italy
6
Becker & Hickl GmbH, Nunsdorfer Ring 7-9, 12277 Berlin, Germany
7
Department of Physics, University of Florence, Via G. Sansone 1, 50019 Sesto Fiorentino, Italy
*
Author to whom correspondence should be addressed.
Sensors 2019, 19(12), 2678; https://doi.org/10.3390/s19122678
Received: 27 May 2019 / Revised: 10 June 2019 / Accepted: 12 June 2019 / Published: 13 June 2019
(This article belongs to the Special Issue Advanced Spectroscopy, Imaging and Sensing in Biomedicine)
Single Photon Avalanche Diode (SPAD) arrays are increasingly exploited and have demonstrated potential in biochemical and biomedical research, both for imaging and single-point spectroscopy applications. In this study, we explore the application of SPADs together with fiber-optic-based delivery and collection geometry to realize fast and simultaneous single-point time-, spectral-, and depth-resolved fluorescence measurements at 375 nm excitation light. Spectral information is encoded across the columns of the array through grating-based dispersion, while depth information is encoded across the rows thanks to a linear arrangement of probe collecting fibers. The initial characterization and validation were realized against layered fluorescent agarose-based phantoms. To verify the practicality and feasibility of this approach in biological specimens, we measured the fluorescence signature of formalin-fixed rabbit aorta samples derived from an animal model of atherosclerosis. The initial results demonstrate that this detection configuration can report fluorescence spectral and lifetime contrast originating at different depths within the specimens. We believe that our optical scheme, based on SPAD array detectors and fiber-optic probes, constitute a powerful and versatile approach for the deployment of multidimensional fluorescence spectroscopy in clinical applications where information from deeper tissue layers is important for diagnosis. View Full-Text
Keywords: SPAD; CMOS; fluorescence spectroscopy; fluorescence lifetime; depth-resolved fluorescence; tissue diagnosis; fiber optics SPAD; CMOS; fluorescence spectroscopy; fluorescence lifetime; depth-resolved fluorescence; tissue diagnosis; fiber optics
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MDPI and ACS Style

Lagarto, J.L.; Credi, C.; Villa, F.; Tisa, S.; Zappa, F.; Shcheslavskiy, V.; Pavone, F.S.; Cicchi, R. Multispectral Depth-Resolved Fluorescence Lifetime Spectroscopy Using SPAD Array Detectors and Fiber Probes. Sensors 2019, 19, 2678.

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