DRIFT REDUCTION OF ORGANIC COATED GAS-SENSORS BY TEMPERATURE MODULATION

Drift effects and cross sensitivities hinder the application of chemic al sensors, especially with coatings based on organic or organically m odified substances. A temperature modulated mode of sensor operation ( AT-mode) is investigated to reduce drift and humidity influence on org anic gas-sensitive coatings. The transducers are interdigital capacita nce structures (IDC) with ring heater. As sensitive material a CO2 sen sitive organically modified heteropolysiloxane is used. Heteropolysilo xanes are well known materials for gas-sensing. They also have common weaknesses of organic sensor coatings. Different kinds and patterns of temperature modulation together with adapted signal-processing were u sed to reduce long time drift effects and diminish cross-sensitivities .