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

Abstract

Monitoring nitrogen utilization e ciency and soil temperature in agricultural systems for timely intervention is essential to monitor crop health, promote sustainable and precision agriculture, and reduce environmental pollution. Therefore, it is of vital signi cance to develop a multi-parameter sensor for effectively and accurately decoupled detection of nitrogen loss and soil temperature, which is yet to be reported. 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. By exploiting the laser-assisted synthesis, the highly porous 3D VO X -doped LIG foam composite is readily obtained by laser scribing of vanadium sul de (V 5 S 8 )-doped block copolymer and phenolic resin self-assembled lms. Compared with the intrinsic LIG, the heterojunction formed at the LIG/VO X interface provides the sensor with a signi cantly enhanced response to NO X and an ultralow limit of detection (LOD) of 3 ppb at room temperature. Meanwhile, the sensor can accurately detect temperature over a wide linear range of 10-110℃ with a small detection limit of 0.2℃. The encapsulation of the sensor with a soft membrane further allows for temperature sensing without being affected by NO X , presenting an effective strategy to decouple nitrogen loss and soil temperature for accurate soil environmental monitoring. The sensor without encapsulation but operated at elevated temperature removes the in uences of ambient relative humidity and temperature variations for accurate NO X measurements. The capability to simultaneously detect ultra-low NO X concentrations and small temperature changes paves the way for the development of future multimodal electronic devices with decoupled sensing mechanisms for health monitoring and precision agriculture.

Laser-induced direct graphene patterning: from formation mechanism to flexible applications

“…As a typical case of thermoplastic polymers, polyimide is the most common carbon source in early research of LIG [Figure 3A and B] due to its unique features in terms of material stability, high-temperature resistance, and flexibility [97,98] . With the rapid progress of LIG preparation, other common polymeric materials, such as PEEK [99] [Figure 3C], PDMS [47,100] [Figure 3D], phenolic resin [101] [Figure 3E], self-assembled block copolymer and resin composite [102,103] (such as the Kevlar fiber in Figure 3F), photoresists [104] , PTFE [105] , PES [106] , and resorcinol [107] , have been proven to be possible to fabricate LIG.…”

“…Copyright 2018, Elsevier. (F) The LIG pattern on the Kevlar fiber [102] . Copyright 2022, American Chemical Society.…”

“…Employing these advantages, various gas sensors for environmental monitoring and gas leakage detection have been studied in the past decade [137] . As exhibited in Figure 9B, a gas sensor was fabricated to detect hazardous gases, such as NO 2 [102,138] . On this basis, Stanford et al optimized the above structure, which is composed of LIG wire with large resistance and LIG electrode with small resistance [139] [Figure 9C].…”

“…By adjusting process parameters, the hole size and sensitivity can also be modulated. Besides, LIG method allows the preparation of sensors on different flexible substrates, such as polyimide, PDMS [138] , and textile [102] , thus significantly broadening application ranges. These resistive gas sensors are suitable for most gases (e.g, toxic, combustible, and inert gases).…”

“…Copyright 2019, American Chemical Society. (B) Photograph of the resistive gas sensor [102] . Copyright 2020, American Chemical Society.…”