Liquid metal-based plant electronic tattoos for in-situ monitoring of plant physiology

Flexible plant sensors, as a noninvasive and real-time monitoring method for plant physiology, are becoming crucial for precision agriculture. However, integrating flexible devices with plants are challenging due to their fragility and complex surfaces. In this study, we introduce a liquid metal-based plant electronic tattoo (LM-PET) that can harmlessly and continuously monitor the loss of water content and plant electrical signals, which are critical parameters for analyzing plant physiological status. The LM-PET achieves double-sided conductivity through soluble electrostatic spinning films and transferring technology, effectively addressing the issue of mismatch between the rigid interface of electronic devices and the surface of delicate plants. The fabricated tattoo electrode can adhere tightly to the leaf surface for a long time and can significantly broaden the scope of moisture monitoring, even in cases of severe wrinkling caused by water loss. At the optimum operating frequency of 100 kHz, the sensitivity of LM-PET can reach 25.4 kΩ%−1. Thus, LM-PETs can record the electrical signals generated when abiotic stresses threaten plants. They are also significant in providing a deeper understanding of the drought adaptation mechanisms of plants and developing drought-resistant varieties. They offer data-driven crop management and decision-making guidance, which is imperative for advancing precision agriculture. Overall, our findings provide valuable insights into the performance of agricultural inputs and facilitate real-time monitoring of plant growth and development.