Enhanced Characteristics of Nondispersive Infrared CO2 Gas Sensor by Deposition of Hydrophobic Thin Film

Abstract

This paper presents the NDIR CO2 gas sensor that has improved the sensitivity and also the accuracy by the deposition of thin hydrophobic film (Parylene-C film with 0.5 micrometer thick) onto the reflector surfaces of White-cell structure. After deposition of hydrophobic thin film, the sensitivity of sensor has been increased with averaged 10% and the estimated errors were reduced within 13 ppm to 143 ppm from 254 K to 324 K temperature ranges and from 0 ppm to 5000 ppm CO2 concentrations.

Keywords

• hydrophobic film
• NDIR gas sensor
• carbon dioxide gas sensor
• White-cell structure
• IR absorbance
• temperature compensation