Microneedle-based electrochemical sensors for in planta chemical sensing: From analytical principles to field deployment

Abstract

By 2050, the global population is projected to approach 10 billion, requiring substantial increases in crop productivity under growing land, water, and climate constraints. In this context, plant wearables have emerged as powerful AgriTech tools, highlighted by the inclusion of wearable plant sensors in the World Economic Forum's Top 10 Emerging Technologies report of 2023 and autonomous biochemical sensing in 2025. Among these technologies, microneedle (MN) electrochemical sensors provide minimally invasive access to plant biofluids and are rapidly becoming a promising platform for real-time chemical monitoring in living plants. In this review, we examine the key design requirements, analytical challenges, and applications of MN-based in planta sensors for monitoring nutrients, agrochemicals, phytohormones, growth precursors, and stress biomarkers. We first discuss the plant–MN interface, relating plant organs, biofluid composition, and tissue mechanics to MN design considerations. We then describe the principal MN architectures and electroanalytical techniques used to develop sensing platforms. Representative case studies illustrate how MN sensors can resolve the spatial and temporal dynamics of target analytes directly in plants, with emphasis on analytical performance under realistic or in vivo conditions. We further assess the main challenges limiting the translation of MN sensors from laboratory prototypes to autonomous systems suitable for field deployment. Finally, we outline opportunities arising from advances in flexible electronics, wireless communication, Internet-of-Things infrastructures, and artificial-intelligence-driven data analysis. Overall, this review provides an analytical framework for microneedle-based plant (bio)sensing and highlights their potential role in next-generation smart agriculture. We analyzed a collection of over 170 references (2016-2026) identified by database searches, pertinent keywords, and recognized contributions in this field.