Development of microfluidic device for in situ evaluate convective/diffusive movement of micronutrients through soil and rhizosphere around a living root

• Grant number: 24/19269-4
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: January 01, 2026
• End date: December 31, 2028
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Analytical Chemistry
• Principal Investigator: Helio Cesar Nogueira Tolentino
• Grantee: Júlia Adorno Barbosa
• Host Institution: Centro Nacional de Pesquisa em Energia e Materiais (CNPEM). Campinas , SP, Brazil

Abstract

Understanding nutrient transport in soil and the rhizosphere at the microscale is essential for improving input use efficiency and promoting sustainable agricultural practices. However, conventional experimental systems, such as soil columns and growth chambers, face significant limitations. These methods fail to capture the structural heterogeneity and natural opacity of soils, which hinder direct observation of microscale processes. Moreover, the interactions among nutrients, roots, and microorganisms are highly localized and dynamic, often distorted or not represented in low-resolution laboratory assays. The resulting loss of spatial and temporal precision, combined with the difficulty in reproducing realistic moisture, adsorption, and flow conditions, limits the ability of these systems to faithfully replicate in situ phenomena. This project proposes the development and application of a microfluidic platform integrated with synchrotron-based imaging to evaluate the convective and diffusive transport of calcium and phosphate ions in soil and near living roots. The work plan begins with the fabrication and physicochemical characterization of a microfluidic device (Prototype 1), including soil integration, sealing tests, and structural stability assessments under flow conditions. To ensure that undesirable leaching of soil components does not interfere with downstream analysis, LC/MS and ICP/MS will be used to detect the release of organic and inorganic species. Next, the effective diffusivity of ions will be estimated through image-based modeling using three-dimensional µ-XCT data acquired at the MOGNO beamline. With the device optimized, experiments at the CARNAÚBA beamline will enable spatial mapping of nutrient transport from soluble sources (KH2PO4 and CaCl2) and mineral particles (monetite and hydroxyapatite) under varying flow regimes and pH levels. In the second phase of the project, Prototype 2 will be fabricated and coupled to a Rhizomicrocosm system, enabling the investigation of nutrient transport in the presence of living Arabidopsis thaliana roots. The impact of the root system on local diffusion patterns will be analyzed using synchrotron imaging and computational modeling, providing spatially resolved insights into nutrient/root interactions. The developed platform may be applied in studies aimed at designing more efficient and targeted fertilizers, assessing how different types of soil influence nutrient mobility, and investigating retention or immobilization mechanisms induced by contaminants. Additionally, it enables long-term experiments that deepen the understanding of the chemical and biological processes governing nutrient availability in the rhizosphere, contributing to a more sustainable, knowledge-driven agriculture.