Devising technological solutions for gas sensors based on zinc oxide for use at critical infrastructure facilities

Abstract

This paper reports a study of a gas sensor based on nanostructured zinc oxide in order to establish the conditions for its production and operating characteristics under the influence of the target gas ethanol. The studied samples were produced by magnetron sputtering on direct current. The method of forming the device structure was chosen among others due to the fact that it has a high rate of deposition at low values of the working gas pressure, there is no overheating of the substrate, a low degree of contamination of the obtained films, the possibility of obtaining samples of uniform thickness on a large area of the substrate. A VUP-5M vacuum unit with an original material-saving magnetron was used to obtain the films. Studies of the effect of temperature on the resistance of a gas sensor based on ZnO have been carried out. It was established that the change in the resistance of the tested sample depends on the temperature of the substrate. The resistance of the gas sensor in atmospheric air decreases with increasing substrate temperature from room temperature (25 °C) to 200 °C. A further increase in temperature from 200 °C leads to an increase in the resistance of the structure until it stabilizes in the temperature range of 300–400 °C. It was established that the operating temperature range of the gas sensor based on ZnO is within 300–400 °C. The characteristics of the gas sensor based on ZnO were studied and the working temperature of the sensor was determined for the rapid identification of ethanol in atmospheric air at a target gas concentration of 500 ppm. It was established that for rapid operation of the instrument structure, the temperature of the substrate should be 400 °C, a decrease or increase in temperature leads to a decrease in the sensitivity of the sensor to the target gas. It was established that the gas sensor demonstrates stability and a consistent sensitivity response upon repeated exposure to the target gas

Design of ammonia sensor based on ZnO for analyzing hazards at critical infrastructure

“…In contrast to the results reported in [8,9], the ammonia gas sensor demonstrates a high efficiency of detecting the target gas under standard conditions (operating temperature 25 °С) and a low concentration of 25 ppm. In [8], a gas sensor based on ZnO demonstrates sensitivity to the target gas ethanol only when the substrate is heated to a temperature above 200 °С, which negatively affects its degradation resistance. In [9], a gas sensor based on ZnO demonstrates sensitivity to NH 3 of the target gas only at its concentration of 150 ppm.…”

“…The research of new inexpensive and effective sensors for monitoring and controlling the concentration of ammonia in the atmosphere is the need of the hour. The main performance characteristics of the sensor include sensitivity, selectivity, response and recovery time, stability upon repeated exposure to the target gas, ease of manufacturing, and low energy consumption [8]. Most of the commercially available gas sensors have high sensitivity only at elevated operating temperatures, therefore the instrument structures are equipped with microheaters [9].…”