Application of conductor polymers as gas sensors

• Grant number: 97/07388-0
• Support Opportunities: Research Grants - Innovative Research in Small Business - PIPE
• Start date: June 01, 1998
• End date: November 30, 1998
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Milton Soares de Campos
• Grantee: Milton Soares de Campos
• Company: Toro e Toro Ltda. - ME
• City: Barretos

Abstract

The objective of this project is to use the rectification properties of conductor polymers for the construction of sensors for methane and ethylene gas. For this, two types of polymer will be used, which are very stable under environmental conditions, polypyrrole and polythiophene. Schottky diodes will be constructed using these polymers (doped with protonic acid), both in the planar configuration (with two metallic electrodes deposited by lithograph or silk screen on the same face of the polymer) and in the sandwich configuration. Metals with a work function that forms ohmic and blocking contacts with the polymer will be used. Studies of the electric current as a function of the DC voltage, both in the forward direction and reverse, in relation to humidity, temperature and gas concentration, will be carried out using doped and non-doped polymers. Their sensibility, reproducibility and stability will also be investigated. We expect to collect sufficient information for the construction of a sensor for ethylene and methane gas. Despite the agricultural sector being one of the most dynamic in the national economy, one of the serious problems still is the storage of agricultural produce. It is estimated that close to 25 per cent of the total production is lost yearly through decomposition and fires that occur in grain silos, probably caused by the formation of inflammable gases such as methane. In the case of the controlled stocks of fruit, their maturing is caused by the formation of a hormone which on decomposing forms the gas named ethylene. (AU)