Three-dimensional graphene on a nano-porous 4H-SiC backbone: a novel material for food sensing applications

Sensors which are sensitive to volatile organic compounds and thus able to monitor the conservation state of food, are precious because they work non-destructively and allow to avoid direct contact with the food, ensuring hygienic conditions. In particular, the monitoring of rancidity would solve a widespread issue in food storage. The sensor discussed here is produced utilizing a novel three-dimensional arrangement of graphene, which is grown on a crystalline silicon carbide (SiC) wafer previously porousified by chemical etching. This approach allows a very high surface-to.volume ratio. Furthermore, the structure of the sensor surface features a large amount of edges, dangling bounds, and active sites, which make the sensor, on a chemically robust skeleton, chemically active, particularly to hydrogenated molecules. The interaction of the sensor with such compounds is read out by measuring the sensor resistance in a four wire configuration. The sensor performance has been assessed on three hazelnut samples: sound hazelnuts, spoiled hazelnuts, and stink bug hazelnuts. A resistance variation of about DeltaR = 0.13 (0.02) Ohm between sound and damaged hazelnuts has been detected. Our measurements confirm the ability of the sensor to discriminate between sound and damaged hazelnuts. The sensor signal is stable for days, providing the possibility to use this sensor for the monitoring of the storage state of fats and foods in general.