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Sensors 2013, 13(1), 484-499;

Disposable Fluorescence Optical pH Sensor for Near Neutral Solutions

Department of Engineering Enzo Ferrari, University of Modena and Reggio Emilia,via Vignolese 905, Modena I-41125, Italy
Author to whom correspondence should be addressed.
Received: 31 October 2012 / Revised: 17 December 2012 / Accepted: 17 December 2012 / Published: 28 December 2012
(This article belongs to the Section Chemical Sensors)
Full-Text   |   PDF [567 KB, uploaded 21 June 2014]


The design, development and performance evaluation of a fluorescence-based pH sensor for on-line measurements is presented. The pKa of the sensing element has been calculated to be 7.9, thus the sensor is suitable for measurement of near neutral solutions. The sensor consists of a low-cost disposable polymer sensing probe, in contact with the solution under test, interrogated by an optoelectronic transduction system. The pH sensitive dye is based on fluorescein O-methacrylate, which has been covalently linked to a hydrogel matrix, realized through the use of HEMA (2-hydroxyethyl methacrylate), HDDA (1,6-hexanediol diacrylate) and PEGDA (polyethylene glycol diacrylate). The optical interrogation setup, together with the electronics, has been developed to acquire and process the fluorescence signal. The sensor works over a pH range between 6.5 and 9.0. In the range between 7.0 and 8.0, the sensor shows a linear behavior with a maximum linearity error of 5%. Thanks to the good performance of the sensing element and transduction system, the short term drift of the reading (measured over 40 min) is lower than 0.15%. The measuring system also exhibits good performance in terms of response time and reproducibility. View Full-Text
Keywords: optical sensor; pH sensor; fluorescence sensor; hydrogel; polymer matrix optical sensor; pH sensor; fluorescence sensor; hydrogel; polymer matrix
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).

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Ferrari, L.; Rovati, L.; Fabbri, P.; Pilati, F. Disposable Fluorescence Optical pH Sensor for Near Neutral Solutions. Sensors 2013, 13, 484-499.

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