Lignocellulosic Biomass-Based PVA Composite Films for Flexible Ammonia Sensors

This study presents the fabrication of flexible cellulose/lignin–PVA composite films for ammonia sensing in food packaging applications using red maple leaves as a renewable biomass resource. Cellulose and lignin were extracted through deep eutectic solvent (DES) treatment and incorporated into a poly(vinyl alcohol) (PVA) matrix to fabricate composite films. The lignin content was systematically adjusted to tailor the mechanical properties and flexibility of the films. Mechanical characterization was performed to identify the optimum film composition for sensing applications. Metal–organic frameworks (MOFs) were subsequently incorporated at different loadings to enhance ammonia sensing performance. The sensing capability of the developed composite films was evaluated through the detection of ammonia generated during meat spoilage, highlighting their applicability as sustainable sensing materials for intelligent food packaging and real-time freshness monitoring.