High numerical aperture waveguide absorption filter for fluorescence detection

Simone Berneschi; Cosimo Trono; Romeo Bernini; Sara Tombelli; Ambra Giannetti; Francesco Chiavaioli; Gianluca Persichetti; Genni Testa; Barbara Adinolfi; Francesco Baldini

doi:10.1117/12.2522336

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11 April 2019 High numerical aperture waveguide absorption filter for fluorescence detection

Simone Berneschi, Cosimo Trono, Romeo Bernini, Sara Tombelli, Ambra Giannetti, Francesco Chiavaioli, Gianluca Persichetti, Genni Testa, Barbara Adinolfi, Francesco Baldini

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Proceedings Volume 11028, Optical Sensors 2019; 110280H (2019) https://doi.org/10.1117/12.2522336
Event: SPIE Optics + Optoelectronics, 2019, Prague, Czech Republic

Abstract

Filtering strategies are a crucial aspect for signal detection in many fluorescence based systems such as chemical and/or biochemical sensors. The design, fabrication and characterization of a new waveguide absorption filter for the optimization of the fluorescence signal collection, thanks to its high numerical aperture, is here presented. The absorption filter is designed to work as an optical waveguide in order to increase the optical path and, consequently, the absorption of the excitation light. A comparison of the performances of the absorption filter and a conventional interference filter, with particular emphasis on the angular dependence of the spectral features, is also reported. We experimentally demonstrate, for what regards the attenuation capability of the excitation signal, the failure of the interference filter for incidence angles greater than 15° and the validity of the absorbing waveguide filter for large incidence angles. Finally, preliminary results performed in fluorescence on an IgG labelled/ anti-IgG assay show the improvement in detected fluorescence intensity collected by means of the proposed absorption filter compared to that measured with the interference filter. This suggests that the filtering strategy based on the waveguide absorption filter can greatly simplify fluorescence detection systems and find interesting applications in different areas of sensing, from Point of Care Testing (POCT) to environmental monitoring.

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Simone Berneschi, Cosimo Trono, Romeo Bernini, Sara Tombelli, Ambra Giannetti, Francesco Chiavaioli, Gianluca Persichetti, Genni Testa, Barbara Adinolfi, and Francesco Baldini "High numerical aperture waveguide absorption filter for fluorescence detection", Proc. SPIE 11028, Optical Sensors 2019, 110280H (11 April 2019); https://doi.org/10.1117/12.2522336

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