Gas sensor array based on multiplex sensing electrodes and its application in recognition of Chinese baijiu with edible alcohol

To enhance the integration of metal oxide semiconductor (MOS) gas sensor array in electronic nose, a sensor array structure based on multiplex sensing electrodes was proposed. Four multiplex sensing electrodes were designed and fabricated on silicon substrate. A heterogeneous sensing material, consisting of SnO 2 thin film and aligned Co 3 O 4 nanofibers, was subsequently prepared on the substrate by magnetron sputtering and electrospinning. By combining different sensing electrodes, the surface-modification-type sensors of SnO 2 @Co 3 O 4 and Co 3 O 4 @SnO 2 and the heterojunction-type sensors of SnO 2 -Co 3 O 4 and Co 3 O 4 -SnO 2 were constructed and formed the gas sensor array. At the operating temperature of 270 °C, the sensors on the array exhibited distinctive responses to ethanol. Co 3 O 4 @SnO 2 exhibited the highest response of 48 to 50 ppm ethanol among all the sensors. Toward the same concentration of ethanol, SnO 2 -Co 3 O 4 and Co 3 O 4 -SnO 2 showed the shortest response time of 1 s, while Co 3 O 4 -SnO 2 additionally presented the shortest recovery time of 34 s. the four sensors also showed different selectivity responses to the gases of ethyl acetate, benzene, methanol and isopropanol. Besides, a hybrid model of CNN-transformer was used to analyze the collected gas response signals of Chinese baijiu with varying concentrations of edible alcohol. With the dataset from the sensor array, the model converged rapidly and achieved a recognition accuracy of 98%. These results confirmed that the sensor array based on multiplex sensing electrodes was an effective design for the integrated gas sensor arrays of electronic noses