Vanadium Oxide-Doped Laser-Induced Graphene Multi-Parameter Sensor to Decouple Soil Nitrogen Loss and Temperature

Monitoring nitrogen utilization efficiency and soil temperature in agricultural systems for timely intervention is essential for crop health with reduced environmental pollution. Herein, this work presents a high-performance multi-parameter sensor based on vanadium oxide (VO_X )-doped laser-induced graphene (LIG) foam to completely decouple nitrogen oxides (NO_X ) and temperature. The highly porous 3D VO_X -doped LIG foam composite is readily obtained by laser scribing vanadium sulfide (V₅ S₈ )-doped block copolymer and phenolic resin self-assembled films. The heterojunction formed at the LIG/VO_X interface provides the sensor with enhanced response to NO_X and an ultralow limit of detection of 3 ppb (theoretical estimate of 451 ppt) at room temperature. The sensor also exhibits a wide detection range, fast response/recovery, good selectivity, and stability over 16 days. Meanwhile, the sensor can accurately detect temperature over a wide linear range of 10-110 °C. The encapsulation of the sensor with a soft membrane further allows for temperature sensing without being affected by NO_X . The unencapsulated sensor operated at elevated temperature removes the influences of relative humidity and temperature variations for accurate NO_X measurements. The capability to decouple nitrogen loss and soil temperature paves the way for the development of future multimodal decoupled electronics for precision agriculture and health monitoring.