2022-07-01 17:10


Conference: Bucharest University Faculty of Physics 2019 Meeting

Section: Optics, Spectroscopy, Plasma and Lasers

pH monitoring using an innovative fiber optic – surface plasmon resonance sensing platform

Iulia ANTOHE(1), Mathis THEBAUT(2), Izabela JINGA(1), Gianina POPESCU-PELIN(1), Iuliana IORDACHE(1) and Gabriel SOCOL(1)

1) National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, 077125 Bucharest-Magurele, Romania

2) Institut Universitaire de Technologie, 142 traverse Charles Susini, 13013 Marseille, France


Fiber optic-surface plasmon resonance, Platinum, Polyaniline synthesis, pH sensor

pH measurement is crucial in the fields of biochemistry, clinical medicine and environmental science [1]. In recent years, substantial efforts were invested towards improving the performance of pH sensors while reducing their cost. Fiber optic – surface plasmon resonance (FO-SPR) pH sensors have attracted increasing interests due to their many advantages, such as low-cost production, small size, immunity to electromagnetic interferences, remote sensing capability, and the safety for in vivo measurement [2]. In the FO-SPR technology, the light is guided through a metal (typically gold)-coated multimode FO to yield propagating plasmonic waves at the interface obtained with the analyzing environment (typically a liquid). Sensitive changes in the refractive index of light are then triggered by any biological interaction or chemical reaction occurring at this interface, which are further processed in a graph [3]. In this work, we report results on the fabrication and characterization of a SPR based pH sensor using coatings of platinum (Pt) and conductive polyaniline (PANI) layers over an unclad core of a FO. The thin platinum layer was coated using a magnetron sputtering technique, while the pH-sensitive polyaniline layer was synthetized using a relatively novel electroless polymerization method. The thicknesses of Pt and PANI layers were optimized to achieve the best performance of the sensor. The proposed FO-SPR pH sensor exhibits a fast and linear response in either acid or alkali solution (pH operational range 1 to 14).


[1] B.R. Mahdi et al., Current Trends in Natural Sciences, 5 (9), 55-61, 2016.

[2] T.H. Nguyen et al., IEEE Sensors Journal, 16(4), 881-887, 2016.

[3] I. Arghir et al., New Biotechnology, 32(5), 473-84, 2015.

This work was financially supported by The National Authority for Research and Innovation in the frame of Nucleus Programme - LAPLAS VI (contract 16N/08.02.2019) and by The Executive Agency for Higher Education, Research, Development and Innovation Funding (UEFISCDI), Project No. 15PCCDI/2017 (PN-III-P1-1.2-PCCDI2017-0172).