Ammonium sensing in aqueous solutions with plastic optical fiber modified by molecular imprinting

F. Sequeira; D. Duarte; A. Rudnitskaya; M. T. S. R. Gomes; R. Nogueira; L. Bilro

doi:10.1117/12.2236941

30 May 2016 Ammonium sensing in aqueous solutions with plastic optical fiber modified by molecular imprinting

F. Sequeira, D. Duarte, A. Rudnitskaya, M. T. S. R. Gomes, R. Nogueira, L. Bilro

Proceedings Volume 9916, Sixth European Workshop on Optical Fibre Sensors; 99161I (2016) https://doi.org/10.1117/12.2236941
Event: Sixth European Workshop on Optical Fibre Sensors (EWOFS'2016), 2016, Limerick, Ireland

Abstract

We report the development of a low cost plastic optical fibre (POF) sensor for ammonium detection using molecularly imprinted polymers (MIP’s). The cladding of a 1 mm diameter PMMA fiber is removed, in which is grafted a molecular imprinted polymer (MIP), by radical polymerization with thermal initiation, that act as a selective sensing layer. For the polymerization, 2,2’-Azobis(2-methylpropionamidine)dihydrochloride (AAPH) is used as initiator, methacrylic acid (MAA) as a monomer, ethylene glycol dimethacrylate (EDMA) as a cross-linker, ammonium chloride (NH₄Cl) as a template and 30% of ethanol in water as a solvent. The sensing method consists of an intensity based scheme. The response to different concentrations of ammonium solutions in water has been evaluated at room temperature. Solutions with (0 - 0.6) M concentration, with the corresponding refractive indexes varying between 1.3325 - 1.3387, at 25°C were used. The response of the fiber with the original cladding, and after cladding removal has been monitored and compared to the response given by the developed sensor. The response is very fast, less than 1 minute and reversible, which allows the continuum use of the sensor. Further developments are focused in optimization of MIP grafting procedure and sensor performance, in order to increase sensitivity.

Citation Download Citation

F. Sequeira, D. Duarte, A. Rudnitskaya, M. T. S. R. Gomes, R. Nogueira, and L. Bilro "Ammonium sensing in aqueous solutions with plastic optical fiber modified by molecular imprinting", Proc. SPIE 9916, Sixth European Workshop on Optical Fibre Sensors, 99161I (30 May 2016); https://doi.org/10.1117/12.2236941

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