Investigation of a flexible, room-temperature fiber-shaped NH₃ sensor based on PANI-Au-SnO₂

A sensitive compound was successfully obtained by coating polyaniline (PANI) on the surface of composite nanoparticles consisting of Au-loaded tin dioxide, named as PANI-Au-SnO₂, using an in situ polymerization method. NH₃ sensors in thin-film and fiber-shaped forms were prepared by inkjet printing and impregnation methods, respectively, based on PANI-Au-SnO₂. The response characteristics of these NH₃ sensors developed from composite sensitive materials were investigated in detail. Results indicate an effective response of the sensors to NH₃ at room temperature. The thin-film sensor demonstrated a good linear relationship between the resistance change and NH₃ concentration within the range of 5-40 ppm, indicating its excellent repeatability and long-term stability. In comparison to the thin film sensor, the fiber-shaped sensor showed a consistently stable response to NH₃ even after 1000 cycles of repeated bending deformation. To demonstrate the practical application of the flexible fiber-shaped NH₃ sensor, a cap designed for NH₃ detection was fabricated by integrating the as-prepared sensor with a circuit board and an LED digital display. This assembly was incorporated into a commercially available ducktail cap, resulting in a wearable device capable of dynamically monitoring environmental NH₃ levels and displaying real-time values. This innovative application underscores the potential of these sensors in real-world scenarios, particularly in occupational safety, where workers might be exposed to harmful levels of NH₃. The cap could serve as a personal safety device, alerting the wearer to hazardous concentrations of NH₃, which is particularly relevant in industrial or agricultural settings.