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Characterization of a Sulfonated Polycarbonate Resistive Humidity Sensor
Departamento de Física e Química, Instituto de Ciências, Universidade Federal de Itajubá, CP 50, 37500-903, Itajubá-MG, Brazil
Departamento de Química, ICEx, Universidade Federal de Minas Gerais, 31270-901, Belo Horizonte-MG, Brazil
* Author to whom correspondence should be addressed.
Received: 30 November 2012; in revised form: 12 January 2013 / Accepted: 15 January 2013 / Published: 5 February 2013
Abstract: In this work; resistive moisture sensors were obtained by dip coating sulfonated polycarbonate (SPC) onto silver interdigitated electrodes. Commercial polycarbonate was sulfonated with acetyl sulphate at two different sulfonation degrees corresponding to 9.0 and 18.0 mole %. Impedance spectroscopy was used to investigate the humidity sensing properties at controlled relative humidity (RH%) environments generated from standard saline solutions in the range of 11–90 RH%. For the highest sulfonated sample; in the RH% range investigated (11 to 90%); the sensor impedance changed from 4.7 MΩ to 18 kΩ. Humidity sensors made from sulfonated polycarbonate showed exponential decay behavior of the impedance at constant frequency with the environmental relative humidity. Sample 9SPC presented dielectric relaxation response for environmental humidity between 58 and 90 RH% while sample 18SPC presented dielectric relaxation response for the entire measured range between 11 and 90 RH%. Sulfonated polycarbonate could be a promising material for the fabrication of simple and cheap humidity-sensing sensors for the assessment of relative humidity of the surrounding environment, as suggested by experimental results.
Keywords: sulfonation; humidity sensors; impedance spectroscopy
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Rubinger, C.P.L.; Calado, H.D.R.; Rubinger, R.M.; Oliveira, H.; Donnici, C.L. Characterization of a Sulfonated Polycarbonate Resistive Humidity Sensor. Sensors 2013, 13, 2023-2032.
Rubinger CPL, Calado HDR, Rubinger RM, Oliveira H, Donnici CL. Characterization of a Sulfonated Polycarbonate Resistive Humidity Sensor. Sensors. 2013; 13(2):2023-2032.
Rubinger, Carla P.L.; Calado, Hallen D.R.; Rubinger, Rero M.; Oliveira, Henrique; Donnici, Claudio L. 2013. "Characterization of a Sulfonated Polycarbonate Resistive Humidity Sensor." Sensors 13, no. 2: 2023-2032.