Flexible PANI–PVDF Composite Membrane Ammonia Sensor for Chilled Meat Freshness Monitoring

With the increasing demand for food safety and quality monitoring, efficient freshness detection technologies are crucial. This study presents a flexible ammonia sensor based on polyaniline (PANI)-poly-(vinylidene fluoride) (PVDF) composite membrane integrated with silver electrodes for rapid chilled meat freshness assessment. A uniform PANI-sensitive layer was synthesized on the PVDF membrane via chemical polymerization, followed by screen-printing of highly conductive silver interdigitated electrodes. Leveraging PANI's high sensitivity to NH₃, the sensor enables real-time monitoring of ammonia released during meat storage, thus indirectly reflecting meat freshness. Experimental results demonstrate that the sensor exhibits excellent sensitivity (response >20% at 10 ppm of NH₃) and rapid response dynamics (<i>T</i> ₉₀ ≈ 240 s at 10 ppm of NH₃). By establishing correlations among sensor response, total volatile basic nitrogen (TVB-N) content, and storage time, an accurate freshness evaluation of chilled meat is achieved. Its simple fabrication, low cost, and easy integration provide an efficient and reliable technical solution for food freshness monitoring.