A Single-Chip 4-Channel Quadrilateral MOx Gas Sensor with Different Sensing Materials for Food Discrimination

This paper proposes a single-chip 4-channel MEMS metal-oxide (MOx) quadrilateral gas sensor with gas discrimination ability. Four sensing channels with different sensing materials are positioned on four edges and share a common quadrilateral structured micro-heater, which can achieve low power and high integration. In2O3-Au, SnO2-Au, SnO2-Cu, and WO3-Au were sputtered as the sensing materials by shadow masks successively. The overall size of the sensor is 1.2×1.2 mm ² and the average power of each channel is as low as 8.69 mW. Test results show that the sensor can discriminate six types of food-related gases. Furthermore, principal component analysis (PCA) and support vector machine (SVM) classifiers were applied to distinguishing spoiled beef, pork, and shrimp, and SVM attained an accuracy of 100%.