Plant phytohormone electrochemical sensing: From functional materials and interfaces to multiplexed sensor design

Electrochemical monitoring of plant phytohormones offers a powerful route toward real-time assessment of plant stress and physiological status, yet remains technically challenging due to ultra-low analyte concentrations, strong matrix interferences, and the limited redox activity of several key hormones. Conventional analytical techniques provide high sensitivity but are incompatible with in situ, continuous, and field-deployable measurements required for precision agriculture. This review critically examines recent advances in electrochemical sensing strategies for major plant phytohormones, including salicylic acid (SA), abscisic acid (ABA), jasmonic acid (JA), and indole-3-acetic acid (IAA), with a focus on how material design, interfacial engineering, and sensor architecture address fundamental limitations. Hybrid nanomaterials, affinity-based and direct electrochemical transduction mechanisms, and flexible or wearable platforms were critically evaluated for their potential to enhance sensitivity, selectivity, and operational stability under realistic plant and environmental conditions. Beyond individual sensor performance, particular emphasis is placed on multiplexed architectures and data-driven integration with wireless platforms and artificial intelligence, enabling the simultaneous decoding of multiple hormonal signals and their temporal dynamics. By comparing design strategies, performance trade-offs, and remaining bottlenecks, this review provides a conceptual framework for the rational engineering of next-generation electrochemical phytohormone sensors and outlines key directions toward robust, field-ready monitoring systems for smart and sustainable agriculture.