Sensor Array-Based Optical Portable Instrument For Determination Of Ph
Metadatos
Afficher la notice complèteAuteur
Martínez Olmos, Antonio; Capel Cuevas, Sonia; López Ruiz, Nuria; Palma López, Alberto José; Orbe Payá, Ignacio De; Capitán Vallvey, Luis FermínMateria
Full-range optical pH sensor array OLED display Digital colour detector HSV colour space Portable instrumentation
Date
2011-02-23Referencia bibliográfica
A. Martinez-Olmos, S. Capel-Cuevas, N. L´opez-Ruiz, A.J. Palma, I. de Orbe, L.F. Capit´an-Vallvey, Sensor Array-Based Optical Portable Instrument For Determination Of Ph, Sensors and Actuators B: Chemical (2010), doi:10.1016/j.snb.2011.02.052
Patrocinador
Ministerio de Ciencia e Innovación, Dirección General de Investigación y Gestión del Plan Nacional de I+D+i (Spain) (Projects CTQ2009-14428-C02-01 and CTQ2009-14428-C02-02); Junta de Andalucía (Proyecto de Excelencia P08-FQM-3535); Partially supported by European Regional Development Funds (ERDF)Résumé
A portable optical instrument is presented that makes it possible to determine pH with a
colorimetric sensor array. The use of four membranes containing acid-base indicators
makes it possible to cover the full range of pH using the H (hue) coordinate
measurements of the HSV colour space. pH sensitive membranes were directly cast
onto a plastic support to form a two-dimensional array, located between an OLED
display as the programmable light source and a set of digital colour detectors. The
resulting microcontroller-based system is immune to optical and electrical interferences.
A complete optical and electrical characterization and optimization of the hand-held
instrument was carried out. The instrument was used to determine pH using a simple
algorithm to select the sensor output that was programmed in the microcontroller. The
initial eleven candidate pH membranes were reduced to only four, which permit to
obtain reliable pH values. The pH response of the selected four sensing elements was
modelled, and calibration curves were applied to a validation set and real samples
obtaining positive correlations between the real and predicted data.