Ultrasoft, anti-dehydrated, and highly stretchable carboxymethylcellulose-based organohydrogel strain sensors for non-invasive real-time plant growth monitoring

Plant strain sensors, which enable real-time monitoring of plant growth, play a crucial role in improving both the quality and yield of various plants. However, current plant strain sensors often exhibit significant mechanical mismatches and poor interfacial compatibility with plant tissues, leading to inaccurate and unstable in situ monitoring. Herein, we present a novel ultrasoft, anti-dehydrated, and highly stretchable organohydrogel (UASOH) strain sensor composed of polyacrylamide (PAM) and carboxymethylcellulose (CMC) via a glycerol-induced hydrogen bonding enhancement strategy. The resultant UASOH exhibits low Young's modulus (18 kPa), exceptional stretchability (1448 %), and outstanding water retention capacity (maintaining 82 % water content after 50 days), enabling seamless contact and reliable long-term monitoring of living plants. The UASOH-based strain sensor features an ultra-wide stretchability range (0–900 %), and high sensitivity (gauge factor of 6.18), demonstrating state-of-the-art performance compared with previous reports. We further integrate the as-prepared sensor with a Bluetooth module to develop a wireless sensing system for non-invasive in situ plant growth monitoring under both ideal and abiotic stress conditions. Such a high-performance UASOH-based strain sensor and its integrated wireless sensing systems demonstrate significant potential for practical plant-monitoring applications.