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A Study of The Viability of Poly(O-Methoxyanhine) Layer-by-Layer Films as Gas Sensors

Published online by Cambridge University Press:  10 February 2011

M. Raposo  and
O.N. Oliveira Jr.
M. Raposo
Affiliation:
Instituto de Física de São Carlos, Universidade de São Paulo, CP 369 - 13560-970 São Carlos, SP, Brazil Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2825 Monte de Caparica, Portugal
O.N. Oliveira Jr.
Affiliation:
Instituto de Física de São Carlos, Universidade de São Paulo, CP 369 - 13560-970 São Carlos, SP, Brazil
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Abstract

The electrical properties of layer-by-layer films of poly(o-methoxyaniline) (POMA) alternated with poly(vinylsulfonic acid) (PVS) have been investigated as a function of the surrounding atmosphere, in order to probe the sensitivity of POMA/PVS as a gas sensor. The POMA films have their conductivity increased with increasing humidity, near to one order of magnitude higher for 100% relative humidity when compared to nitrogen. The d.c. applied field may affect the POMA films, for these films become practically insulating if the field is applied for a prolonged time (typically 10-20 h) in humid air. In order to circumvent this problem, a.c. impedance measurements were conducted. For samples in nitrogen, oxygen and carbon dioxide, the real part of the complex impedance increases only when the frequency is lowered below 10 kHz. In a humid atmosphere, the onset for the real part occurs at higher frequencies than for dry atmospheres. Furthermore, at a fixed frequency in the range from 10 to 100 kHz this impedance component increases with the relative humidity.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 558: Symposium B – Flat-Panel Displays and Sensors-Principles, Materials… , 1999 , 345
Copyright
Copyright © Materials Research Society 2000

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References

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