An ultra-sensitive flexible room-temperature H2S sensor enabled by PANI/MXene/Cu2O ternary nanocomposites for meat spoilage monitoring

Flexible PANI/Ti 3 C 2 T x /Cu 2 O H 2 S sensor achieves 0.456 ppb LOD, 24.72% ppm −1 sensitivity, and 55/35 s response-recovery at RT. • Enhanced sensing arises from synergistic charge transport, heterojunction amplification, and reduction of PANI. • A portable wireless system enables real-time H 2 S monitoring during shrimp spoilage for food safety warning. Hydrogen sulfide (H 2 S), a highly toxic gas released during meat spoilage, necessitates room-temperature real-time detection for accurate freshness assessment and potential health hazards mitigation. In this work, an ultra-sensitive flexible H 2 S sensor was developed by depositing a polyaniline/MXene/cuprous oxide (PANI/MXene/Cu 2 O) ternary nanocomposite onto a flexible substrate, and it operates reliably at room temperature. The sensing material was synthesized via in-situ polymerization of PANI on titanium carbide (Ti 3 C 2 T x ) MXene, followed by the strategic integration of Cu 2 O microparticles to construct a hierarchical heterostructure. The sensor exhibits a high response sensitivity of 24.72% ppm −1 , a low theoretical detection limit of 0.456 ppb, and fast response/recovery times of 55 s and 35 s. It also delivers good selectivity, repeatability, long-term stability, and mechanical flexibility. A signal acquisition circuit integrating an OPA333 precision amplifier and a microcontroller was assembled for real-time quantitative detection of H 2 S release during shrimp spoilage, enabling effective tracking of H 2 S accumulation and discrimination of freshness stages. The enhanced gas-sensing performance stems from the synergistic combination of the highly conductive Ti 3 C 2 T x network, the p-p heterojunction between PANI and Cu 2 O, and the reduction reaction of PANI with H 2 S, which facilitates rapid charge transport and effectively modulates the interfacial energy band alignment upon H 2 S exposure. This study provides an effective strategy for designing high-performance room-temperature flexible gas sensors for real-time meat freshness assessment. Download: Download high-res image (251KB) Download: Download full-size image