NUS new e-skin takes precision farming to the next level | MEDICUS 2024 Issue 4

Leaf it to technology: NUS’ new e-skin takes precision farming to the next level
By Sruthi Jagannathan

Assoc Prof Lee Chengkuo (right), Asst Prof Chae Eunyoung (centre) and their colleague Ms Yang Yanqin (left) aim to revolutionise precision agriculture with a groundbreaking e-skin that monitors plant health // Credit: NUS

In the rapidly evolving landscape of agricultural technology, a breakthrough by scientists from the National University of Singapore (NUS) is setting new standards in the field of precision farming. They have developed a revolutionary plant monitoring system equipped with bio-compatible, transparent sensors that offer continuous, real-time data to optimise plant health and yield in varying environmental conditions.

These transparent, bio-compatible sensors or e-skin developed by the team can help farmers precisely and continuously monitor the physical conditions that plants are exposed to. The real-time data can offer valuable insights into how plant growth and yield can be optimised under dynamic environmental conditions.

The non-invasive, ultra-thin e-skin, which is ten times thinner than a single strand of human hair and in appearance much like a short strip of transparent sellotape, can be affixed to plant leaves, without causing any damage to the plant. It is a significant improvement over existing plant sensors that are often rigid and opaque, which restrict plant growth and visualisation when mounted onto leaves that need sunlight to thrive.

The team, jointly led by Associate Professor Lee Chengkuo from the Department of Electrical and Computer Engineering at the NUS College of Design and Engineering, and Assistant Professor Chae Eunyoung from the Department of Biological Sciences at the NUS Faculty of Science, improved the functionality of the e-skin by designing it as a multi-layered material, where two transparent outer layers sandwich a middle layer that can conduct electricity.

“Besides temperature, this digital-twin plant system can be utilised to continuously and non-invasively monitor physical characteristics of plants in various environments.”
Asst Prof Chae Eunyoung

This design ensures that more than 85 per cent of the light passes through the outer transparent layers, enabling unhindered food production and energy synthesis. It also takes into consideration the unique properties of plants with small and delicate leaves, to avoid any damage to the plant while mounting the sensors.

They also used simple lithography to pattern the e-skin with sensors that can sense different physical properties, including temperature and strain.

In a test-drive of their concept, the team mounted the e-skins on field mustard leaves to demonstrate that the sensor conforms to the surface curvature of the leaf and enables reliable and non-invasive monitoring of the two parameters.

A close-up of the e-skin mounted on the leaf // Credit: NUS

They also used simple lithography to pattern the e-skin with sensors that can sense different physical properties, including temperature and strain.

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The ability to measure leaf surface temperature is a unique feature of the e-skin that is lacking in conventional temperature sensors. “This feature allows us to collect data to understand how to mitigate heat stress on leaves caused by long-term exposure to heat, making it beneficial for precision farming of economically valuable crops,” said Lee.

The e-skin sensor is just one part of the team’s innovation. To clearly visualise the data recorded by the sensors, the team developed a ‘digital-twin’ plant monitoring system that can process the recorded data into digital output. As the name suggests, the digital images created by the monitoring system mirror the plant conditions precisely and in real time, enabling users to make timely adjustments to the plant environment to improve growth and yield.

With the temperature sensors that the team used in their test-drive, the digital-twin system can instantly translate temperature fluctuations on the leaf’s surface into colour changes in the digital images, prompting temperature adjustments to the indoor farming facility.

“Besides temperature, this digital-twin plant system can be utilised to continuously and non-invasively monitor physical characteristics of plants in various environments. This would enable quick analysis of such properties of new plant varieties, which has the potential to accelerate crop breeding processes,” added Chae.

As Singapore aims to locally produce 30 per cent of its edible greens by 2030, this innovative e-skin technology, complete with its digital twin monitoring system, could be a game-changer, potentially enabling local farmers to significantly enhance their crop production. Looking ahead, the team at NUS plans to integrate additional sensors into the e-skin, promising an even more comprehensive toolkit for precision farming that could accelerate crop breeding and bolster food security.

Adapted from NUS News: Elevating precision farming with innovative plant e-skin coupled with digital-twin monitoring system