Biswas, Palas and Chiavaioli, Francesco and Jana, Sunirmal and Basumallick, Nandini and Trono, Cosimo and Giannetti, Ambra and Tombelli, Sara and Mallick, Aparajita and Baldini, Francesco and Bandyopadhyay, Somnath (2017) Design, fabrication and characterisation of silica-titania thin film coated over coupled long period fibre gratings: Towards bio-sensing applications. Sensors and Actuators B-Chemical, 253. pp. 418-427. ISSN 0925-4005

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In this paper we report on the application of over coupled long period fibre gratings (OCLPFGs) for detecting small changes in the surrounding refractive index (SRI). In addition, the optimization of a high RI(HRI) overlay deposited over the fibre for the adhesion of biological species is described. In this study, we utilised a sol-gel-based silica-titania thin film as HRI material deposited on the grating portion using the simple and versatile dip-coating (DC) technique. The OCLPFG-based sensor has been manufactured in such a way that the resonant band retains good visibility (close to the maximum coupling condition) in the transmission spectrum even after high thermal sintering of the coating material. Three different batches of OCLPFGs were produced using different withdrawal speeds and sol viscosities. By carefully tuning both the overlay thickness during the DC process and the RI of the sol-gel material during its preparation, it was possible to bring the sensor into the so-called transition mode working region, and thus maximize the sensing performance in terms of SRI changes. All devices were characterized as optical refractometers in the RI range of interest for a bio-sensing application (from 1.33 to 1.34) and, after a suitable bio-functionalisation process, one of them was used to implement a classical receptor-analyte biosensor. (C) 2017 Elsevier B.V. All rights reserved.

Item Type: Article
Subjects: Processing Science
Divisions: Fiber Optics and Photonics
Depositing User: Bidhan Chaudhuri
Date Deposited: 19 Jan 2018 09:01
Last Modified: 19 Jan 2018 09:01

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