Sustainable, Flexible, and Ambient Temperature Operated Polyaniline-Based Chemiresistive Ammonia Sensor With Eco-Friendly Design

In this work, an eco-friendly, flexible and ambient temperature (∼27°C ± 2°C) operated ammonia (NH3) sensor has been developed using electrospun polyaniline (PANI) fibers deposited on an eco-friendly paper substrate having printed graphene-carbon (G-C) interdigitated electrodes (IDEs). The sensor was designed to detect ammonia (NH₃) over a broad concentration range of 0.5 to 500 ppm, targeting applications in environmental and healthcare monitoring. Structural, elemental and morphological properties of the sensing layer were characterized using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM), confirming the formation of well-aligned PANI fibers with entangled networks and rougher surface. The sensor exhibited excellent % response (1261% at 500 ppm), reproducibility and good repeatability over multiple cycles. Selectivity studies showed a multifold % response towards ammonia gas as compared to interfering gases such as CO2, CO, SO2, and NO2. The use of paper as a low-cost, eco-friendly substrate, combined with the scalable fabrication route, highlights the potential of this work for sustainable and disposable ammonia sensing platforms and environmentally-friendly sensing solutions.