title: A fiber optic ammonia sensor using a universal pH indicator.
abstract: 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.
authors.affiliation: 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. arodriguez@uat.edu.mx.
authors.forename: Adolfo J
authors.initials: AJ
authors.lastname: Rodríguez
authors.affiliation: Departamento de Ingeniería Eléctrica y Electrónica, Universidad Pública de Navarra, Edif. Los Tejos, Campus Arrosadia, Pamplona España 31006, Spain. carlos.ruiz@unavarra.es.
authors.forename: Carlos R
authors.initials: CR
authors.lastname: Zamarreño
authors.affiliation: Departamento de Ingeniería Eléctrica y Electrónica, Universidad Pública de Navarra, Edif. Los Tejos, Campus Arrosadia, Pamplona España 31006, Spain. natxo@unavarra.es.
authors.forename: Ignacio R
authors.initials: IR
authors.lastname: Matías
authors.affiliation: Departamento de Ingeniería Eléctrica y Electrónica, Universidad Pública de Navarra, Edif. Los Tejos, Campus Arrosadia, Pamplona España 31006, Spain. parregui@unavarra.es.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Arregui
authors.affiliation: 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. rfdominguez@uat.edu.mx.
authors.forename: Rene F Domínguez
authors.initials: RF
authors.lastname: Cruz
authors.affiliation: 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. darrioja@uat.edu.mx.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: May-Arrioja
mesh_terms: D000641:Ammonia / Q000032:analysis*; D005336:Fiber Optic Technology / Q000295:instrumentation*; D006863:Hydrogen-Ion Concentration; D055100:Optical Fibers; D012815:Signal Processing, Computer-Assisted; D013057:Spectrum Analysis
chemical_list: D000641:Ammonia