Flexible dual-mode ammonia-impedance sensing patch (FDP) based on Ti3C2Tx MXene/graphene material and symmetric structure

The pursuit of simple, cost-effective, and efficient flexible ammonia sensors is an area of keen interest. This study aimed to create a highly sensitive, affordable flexible sensing patch (FDP) for immediate ammonia and impedance monitoring. Using a laser direct writing technique, symmetrical graphene patterns were crafted onto commercial kapton tape. These patterns were folded in half, allowing the lower layer to serve as an impedance sensor and the upper layer as an electrode for ammonia detection. The modified Ti3C2Tx MXene solution was introduced as the sensitive layer in response to ammonia gas, and we also explored how varying thicknesses of this sensitive layer affected the response results. Notably, the results highlighted that FDPs with two thicknesses (50 uL solution) offered optimal ammonia detection. With a detection limit of 150 ppb, impressive sensitivity (18.08%/ppm), exceptional linearity (0.996), and stability within the 0.5 ppm-20 ppm range, the overall performance of the FDP surpassed that of most reported ammonia sensor devices based on graphene materials. FDP was able to better characterize the shelf life of lamb at a cost of no more than $1.5. This study provides solutions for rapid ammonia detection and food quality assessment.