title: Characterization of a sulfonated polycarbonate resistive humidity sensor.
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.
authors: Departamento de Física e Química, Instituto de Ciências, Universidade Federal de Itajubá, Itajubá-MG, Brazil. carlarubinger@yahoo.com.br
authors: Carla P L
authors: CP
authors: Rubinger
authors: Hallen D R
authors: HD
authors: Calado
authors: Rero M
authors: RM
authors: Rubinger
authors: Henrique
authors: H
authors: Oliveira
authors: Claudio L
authors: CL
authors: Donnici
references: Environ Monit Assess. 2008 Jun;141(1-3):323-8
references: 17849229
references: Talanta. 2008 Apr 15;75(2):412-7
references: 18371900
references: Talanta. 2009 Apr 30;78(2):590-5
references: 19203629
references: Science. 2009 Feb 20;323(5917):1020-1
references: 19229026