Printed Chemiresistive In2O3 Nanoparticle-Based Sensors with ppb Detection of H2S Gas for Food Packaging

Cost-effective and disposable smart sensing technologies capable of monitoring packaged foods’ degradation are necessary for human health and the growing processed-food industry. Herein, highly sensitive and selective hydrogen sulfide (H 2 S) gas sensors were fabricated from solution-printed nanocomposites comprising indium oxide nanoparticles (In 2 O 3 NPs), graphite flakes (Gt), polystyrene (PS), and copper acetate monohydrate (CuAc). The standard In 2 O 3 NP-based sensor (SS, without CuAc) showed H 2 S detection ≈100 ppb under ambient conditions. The presence of CuAc resulted in a highly sensitive nanocomposite layer enabling the detection of lower than 100 ppb (<100 ppb) concentrations of H 2 S gas levels, far superior to the standard In 2 O 3 NP-based nanocomposite. Adding CuAc to the In 2 O 3 NP-based nanocomposite as a modifying additive leads to copper sulfide (CuS) formation owing to its reaction with H 2 S gas. CuS significantly enhances the nanocomposite layer’s conductivity and H 2 S reactions on the sensors’ surface, resulting in a substantial reduction in electrical resistance for sensors. The modified In 2 O 3 NP-based sensor presents remarkable enhancement in their selectivity toward H 2 S gas detection when evaluated against various hazardous vapors. Furthermore, the modified In 2 O 3 NP-based sensors possess good anti-humid property under highly humid conditions (≈80% relative humidity).