From Sensors And Microsystems: Proceedings of the 9th Italian Conference: Ferrara, Italy, 8-11 February 2004

S.IPSALE
FINE Permeation Tubes, Messina, ITALY

N.DONATO
Dept. of Matter Physics and Advanced Technologies and INFM, University of Messina, ITALY

G. NERI, A.BONAVITA, G.RIZZO, S.GALVAGNO
Dept. of Industrial Chemistry and Materials Engineering, University of Messina, ITALY

Permeation tubes have been tested to supply calibrated gas-phase ethanol concentrations (from 1 to 500 ppm) for gas sensors calibration. Tests were also carried out to investigate the permeation dynamic of these devices changing the carrier gas flow and/or the temperature, with aim to develop a temperature-independent apparatus able to delivery constant gas concentration independently on the ambient temperature fluctuation.

1. Introduction

Calibration is an important step for the evaluation and validation of the performance of gas sensors. Different methods and techniques can be used for producing calibrated gas concentrations [1]. Among the others, permeation tubes show potential advantages for the wide range of compounds for which the method can be used [2]. They work best for liquids with low boiling points and for gases that are liquified at low pressures and room temperature. Hard-to-handle chemicals like nitrogen dioxide, ethyl mercaptan, acetaldehyde and alcohols are ideal for permeation tubes. Permeation tubes also offer high accuracy for a range of concentrations from more than 5000 ppm to less than 50 ppb.

A main drawback of these devices is the strong dependence of permeation rate with the temperature. To have high accuracy a careful control of the temperature, within 0.1 C, it is required. In this paper we report results related to the production of calibrated...

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Topics of Interest

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Chapter List Low Voltage Low Power Oscillator for Arrays of Quartz Microbalances Development of a Temperature-Independent Apparatus for Generating Calibrated Gas Flow with Permeation Tubes Cereal...