In Situ Decoding of Plant Ion Signals: Principles, Applications, and Challenges of Microneedle Sensing

A dynamic analysis of plant ion homeostasis is imperative for elucidating the mechanisms underlying stress resistance and enabling precision agriculture. However, conventional detection methods face challenges in simultaneously meeting the synergistic demands of in situ, real-time, minimally invasive, and high-resolution monitoring, which severely restricts advancements in this field. Microneedle sensing technology, with a focus on the "microneedle body-sensing unit-signal transmission" architecture, represents a significant paradigm shift from ex vivo destructive detection to in vivo minimally invasive dynamic monitoring. This article employs a systematic approach to elucidate the scientific implications and implementation challenges associated with in situ decoding of plant ionic signals. The proposed framework traces the technological evolution of microneedle sensing across the sensing, detection, and system layers, elucidating how it progressively overcomes key bottlenecks, including minimally invasive adaptation, specific recognition, and long-term, stable monitoring. Furthermore, typical applications of this technology in signal transduction analysis, stress-resistant variety screening, and precision field management are reviewed. It analyzes core challenges from two perspectives: fundamental research and industrialization. Ongoing advancements in material intelligence and system integration will position MN sensing technology as an indispensable tool in smart agriculture and plant physiology research. This technology provides critical support for addressing global food security challenges.