Smartwatch-like wearables for crops offer real-time monitoring

British farmers may soon monitor their crops with wearable technology similar to smartwatches. Engineers have created miniature, tattoo-like leaf sensors and flexible stem bands that can detect distress signals in plants days before any visible signs of stress emerge.

Published in ACS Applied Materials & Interfaces, this innovation offers an immediate warning system for agricultural workers. Current methods like satellite imagery and drones provide regional data, assessing conditions that may affect fields in the future or damage that has already occurred. This new wearable system, however, offers a direct insight into how individual plants are responding to environmental pressures in real time.

The wearable devices are designed to operate continuously without an external battery. They generate electricity by harvesting microwatts of power directly from the moisture evaporating from the plant's surface. This is achieved using ultra-thin nanosheets of vanadium pentoxide and a graphene sieve. As moisture passes through, it generates an electrical current proportional to the moisture exchange, measuring the vapor pressure deficit (VPD) – a key indicator of how much water a plant is losing to the surrounding air.

In addition to the leaf sensor, a second device, a stretchable stem band inspired by the Japanese art of kirigami, tracks longer-term health. This band expands safely with the plant's growth, providing data on slower biological processes. Together, these technologies promise a more intimate and contextual level of information for each plant, helping farmers optimize crop health before problems become apparent.

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The leaf sensor is more of an early warning system showing how the plant is responding in the moment, before visible signs appear.