Equipment for Testing a Conductometric Gas Sensor in a Controlled Environment

To test the sensitive element of a conductometric gas sensor in a controlled environment a design was developed and the installation was assembled. The developed equipment is intended for carrying out technological, measuring and testing activities that require heating of samples in a controlled gas environment. The equipment contains a vacuum chamber into which the test gas is introduced; heating and measuring platform on which the gas-sensitive element under test is located; electronic control unit, which is used to set and control the temperature of the heating platform. The operating voltage of the unit is 220 V (50-60 Hz), the maximum power consumption is 750 W, the operating temperature range of the heating platform is 25-600 ℃, the time to reach operating temperature is up to 12 minutes. Research was carried out to determine the maximum duration of the experiment in the developed equipment at different chamber temperatures. The duration of the experiment is primarily limited by the durability of the chamber lid, made of polymethyl methacrylate, the melting point of which is 140 ℃. Tests of conductometric sensors are carried out at heating platform temperatures above 200 ℃. The results obtained showed the possibility of operating the equipment for 5 minutes even at a heating platform temperature of 400 ℃, which is more than sufficient to conduct the necessary tests. To carry out test tests on the developed equipmen, a gas-sensitive element of a conductometric nitrogen dioxide sensor based on oriented nickel oxide fibers and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) was used. Studies were carried out to determine the temperature dependence of the resistance of this material in the temperature range from 20℃ to 200℃ in air environment. The results obtained confirm the possibility of conducting studies of the sensory, thermoelectric and electrical properties of gas-sensitive elements using the developed installation with high accuracy.