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Sensors 2014, 14(3), 4060-4073;

A Fiber Optic Ammonia Sensor Using a Universal pH Indicator

Fiber and Integrated Optics Laboratory, Electronics Engineering Department, UAM Reynosa Rodhe, Universidad Autónoma de Tamaulipas, Carr. Reynosa-San Fernando S/N, Reynosa, Tamaulipas 88779, Mexico
Departamento de Ingeniería Eléctrica y Electrónica, Universidad Pública de Navarra, Edif. Los Tejos, Campus Arrosadia, Pamplona España 31006, Spain
Author to whom correspondence should be addressed.
Received: 27 December 2013 / Revised: 12 February 2014 / Accepted: 18 February 2014 / Published: 27 February 2014
(This article belongs to the Special Issue Photonic Sensors for Industrial, Environmental and Health Monitoring)
Full-Text   |   PDF [541 KB, uploaded 21 June 2014]


A universal pH indicator is used to fabricate a fiber optic ammonia sensor. The advantage of this pH indicator is that it exhibits sensitivity to ammonia over a broad wavelength range. This provides a differential response, with a valley around 500 nm and a peak around 650 nm, which allows us to perform ratiometric measurements. The ratiometric measurements provide not only an enhanced signal, but can also eliminate any external disturbance due to humidity or temperature fluctuations. In addition, the indicator is embedded in a hydrophobic and gas permeable polyurethane film named Tecoflex®. The film provides additional advantages to the sensor, such as operation in dry environments, efficient transport of the element to be measured to the sensitive area of the sensor, and prevent leakage or detachment of the indicator. The combination of the universal pH indicator and Tecoflex® film provides a reliable and robust fiber optic ammonia sensor. View Full-Text
Keywords: fiber optics sensor; ammonia sensor; optical sensor fiber optics sensor; ammonia sensor; optical sensor
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).

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Rodríguez, A.J.; Zamarreño, C.R.; Matías, I.R.; Arregui, F.J.; Cruz, R.F.D.; May-Arrioja, D.A. A Fiber Optic Ammonia Sensor Using a Universal pH Indicator. Sensors 2014, 14, 4060-4073.

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