Flexible and Shape-Morphing Plant Sensors Designed for Microenvironment Temperature Monitoring of Irregular Surfaces

Flexible plant sensors play a critical role in smart agriculture due to their advantages in real-time monitoring physiological signals of plants, and are experiencing growth in recent years. Such devices are expected to be directly placed on surfaces of plant organs for better detection. However, most existing sensors based on the planar substrate are not able to adapt to nondevelopable surfaces of plants, and are unsatisfactory in biocompatibility. Herein, considering the complexity of the plant surface, flexible temperature sensors for leaves and fruits are developed. The leaf temperature sensor is based on the porous substrate, which is designed to minimize its effect on plant respiration, and is demonstrated to measure temperature changes accurately after long-time integration with a leaf. By mechanical design, the fruit temperature sensor realizes the transformation from a planar shape to a tridimensional shape, and is demonstrated to work on a variety of complex curved surfaces without loss of performance. The proposed shape-morphing structure expands the capabilities of current planar electronics, and links thin-film technology to spatial deformable devices. Results of the in vitro experiments show that these two proposed sensors hold promise to monitor microenvironment temperature in plant biology.