Monitoring stagnated droplets for orchard management using flexible, and printed sensors

Abstract

Every year, up to 40% of crops worldwide are lost because of pests and diseases, accounting for $220 billion in losses [1]. One major cause of these pest and disease outbreaks is the presence of stagnated water droplets remaining on leaf surfaces for extended periods, fostering a moist environment where fungal spores and pest eggs can develop [2]. This study presents the development of a printed and flexible capacitive sensor for early detection of stagnated droplets in the range of 50-500 µm for precision farming. The work includes finite element method (FEM) simulations to optimize sensor design and predict responses to droplet presence. Two sensing geometries were investigated, interdigitated electrodes (IDE) and fractal geometry-based electrodes with a dimension of 33×33 mm, initially with an electrode width of 500 µm, a gap between the electrodes of 250 µm, using electrostatic physics modelling with and without droplets. The fractal-based design demonstrates higher sensitivity due to its increased effective surface areas. The sensor was fabricated using screen printing of carbon ink on a PET substrate, enabling low cost and scalable production. Experimental characterization and sensor response measurements are planned as future work. By providing early warnings about stagnated droplets this work has the potential to reduce the use of pesticides and fungicides to prevent pest and disease outbreaks, leading to improved and sustainable crop management.