Flexible leaf wetness sensor based on laser-induced graphene for precision agriculture

The monitoring of leaf wetness is critical for the prevention of plant diseases and the optimization of agricultural practices. Current leaf wetness sensors, such as dew gauges, leaf-shape resistance sensors, and flexible aluminum sensors, offer varying degrees of accuracy and durability, yet each faces limitations in cost, practicality, and environmental robustness. This work explores the development of a low-cost, flexible leaf-wetness sensor designed to replicate the hydrophobic properties of the leaves of Strobilanthes crispa, Gynura procumbus and Alternanthera sessilis and provide periodic measurements of leaf wetness. Using a combination of capacitance-based interdigitated transducers fabricated using laser-induced graphene on Kapton tape and surface coatings with parylene C, the proposed sensor addresses the challenges posed by existing technologies while offering a simpler and scalable solution for agricultural environments. The sensor can quantify water wetness levels up to 80 μL with a worst-case error of 21 %, with an average sensitivity of 1.3 pF/μL. The accompanying data acquisition system enables reliable Wi-Fi transmission of sensor data, further enhancing the practical application of the sensor. Experimental results show that the sensor demonstrates reliable performance in simulated field conditions, with future work focused on improving long-term durability, large-scale deployment and refining manufacturing processes. • A low-cost, flexible leaf wetness sensor designed to provide real-time measurements of leaf wetness. • A capacitive sensor made from laser-induced graphene on Kapton tape and surface coatings with parylene C. • The sensor can quantify water wetness levels up to 80 μL with a worst-case error of 21 %, with an average sensitivity of 1.3 pF/μL