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Proceedings Paper

Highly processable method for the construction of miniature conducting polymer moisture sensors
Author(s): Scott T. McGovern; Geoffrey M. Spinks; Gordon G. Wallace
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Paper Abstract

A polymer blend incorporating polyaniline (PAn) was used as a sensing medium in the construction of a resistance based humidity sensor. Aniline monomer was polymerised to PAn emeraldine salt (ES) in the presence of poly (butyl acrylate-co-vinyl acetate) and the processable blend was developed by redissolving 1-2 w/w% of the resulting sensing polymer residue in dichloromethane (DCM). Some of this residue was washed in ammonia solution to de-dope the PAn to emeraldine base (EB) to act as a protective layer on the surface of the sensing polymer. This residue was then washed with distilled water until a neutral pH was realised with the waste water, dried and redissolved in DCM at 1-2 w/w% to create a processable blend barrier polymer solution. The final sensor design utilised 125μm polyester insulated platinum wire as conducting electrodes that were dip coated in the PAn ES blend solution and dried in a desiccator. A protective coating was then applied by dip coating in the EB blend solution. The sensors had an overall final thickness of less than 200μm and showed high sensitivity to humidity, low resistance, and good reversibility without hysteresis. The EB protective layer was shown to give more stable and predictable responses to the sensors when placed inside curing epoxies. Polymer based thin film humidity sensors have the advantage that the high processability of the material allows for simple fabrication of a range of geometries including smaller sensor designs. Such sensors may find uses in detecting water content in a number of areas including composite materials, electronic textiles, food/electronics packaging and corrosion detection.

Paper Details

Date Published: 28 February 2005
PDF: 9 pages
Proc. SPIE 5649, Smart Structures, Devices, and Systems II, (28 February 2005); doi: 10.1117/12.582241
Show Author Affiliations
Scott T. McGovern, Univ. of Wollongong (Australia)
Geoffrey M. Spinks, Univ. of Wollongong (Australia)
Gordon G. Wallace, Univ. of Wollongong (Australia)

Published in SPIE Proceedings Vol. 5649:
Smart Structures, Devices, and Systems II
Said F. Al-Sarawi, Editor(s)

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