Scalable Photoactive NO 2 ‐Sensing Framework for Plant Health Monitoring

Abstract Conventional sensing platforms for plant health monitoring are often limited by high operating temperatures, rigid substrates, and poor compatibility with ambient, power‐constrained, or biologically sensitive environments. These limitations hinder their integration into emerging platforms such as smart agriculture and plant‐interfaced electronics, where mechanical flexibility, energy efficiency, and low thermal budgets are essential. This paper reports a scalable, thermally passive NO 2 sensor based on light‐activated 3D TiO 2 nanoarchitectures. Fabricated via sequential glancing angle deposition, the highly ordered porous nanoarchitectures exhibit tunable broadband light scattering and defect‐mediated sub‐bandgap activation under ambient light. Integrated with a wireless microcontroller and mobile application, the sensor enables autonomous NO 2 monitoring in real‐world conditions. Field deployment on Mentha suaveolens plants demonstrates real‐time tracking of gas‐induced physiological stress, establishing practical ecological relevance. This platform overcomes the key limitations of conventional sensors, offering a structurally tunable, spectrally adaptive, and fabrication‐scalable solution for light‐powered, bio‐integrated environmental monitoring.