A Self-Temperature-Modulated Quadrilateral Gas Sensor for Gas Identification

This article proposes a SnO2-based low-power quadrilateral gas sensor, which can realize different responses by self-temperature modulation using a single-layer electrode. Four detection channels are located on four edges and are integrated with a quadrilateral microheater to constitute the completed sensor. Under the premise of ensuring good electrical insulation, the heater and the detection electrodes are designed in parallel on the same layer, eliminating the need for the isolation layer and subsequent dry etching steps to expose the pad. This scheme can greatly simplify the fabrication process and save manufacturing costs. On top of that, temperature modulation is realized by designing the gradational width of the microheater metal line on the four edges to achieve different responses to gases. Six types of food-related gases (trimethylamine, ethanol, hydrogen sulfide, ammonia, ethyl acetate, and formaldehyde) were tested, and the four channels of the sensor show different performances to these stimuli, which can be utilized for gas identification. Moreover, six food species were also tested, showing that the sensor can efficiently differentiate the fruit, vegetables, and meats.