Interface-Engineered, Standalone, Flexible, and Robust Platform for Ammonia Sensing by Polypyrrole Anchored on Acrylic Acid-Grafted Ethylene Vinyl Acetate

A standalone, flexible ammonia sensor developed through γ-radiation induced grafting of acrylic acid (AA) onto ethylene vinyl acetate (EVA), followed by in situ pyrrole (Py) polymerization. This three-dimensional interfacial engineering approach creates a robust molecular architecture, overcoming limitations of conventional surface modifications by enhancing mechanical-electronic coupling. The method involves covalent anchoring of carboxylic groups to EVA, enabling tunable PPy integration. Spectroscopic and morphological analyses confirm strong interfacial stability and molecular-level integration. The sensors exhibit high sensitivity (0.093 ppm –1 at 2.5% grafting), excellent selectivity against common interferents, and tunable performance, with 25% grafting yielding superior stability (Only ∼17% sensitivity loss over 28 days). Electrical characterization reveals conductivity tuning across 7 orders of magnitude, maintaining functionality under deformation. Breath analysis demonstrates practical applicability for healthcare. This radiation-engineered platform offers a scalable, cost-effective solution for ammonia detection in environmental, industrial, and medical applications, establishing advanced design principles for flexible electronics through precise interfacial control.