lettuce agriculture

‘SmartFarm’ device harvests air moisture for autonomous irrigation

Image credit: Dreamstime

A solar-powered, fully automated device that can absorb air moisture at night and release it during the day for irrigation has been developed by a team of researchers from the National University of Singapore (NUS).

Dubbed SmartFarm, the device uses a moisture-attracting material to absorb air moisture at night when the relative humidity is higher, and releases it when exposed to sunlight. The water harvesting and irrigation process can also be fine-tuned to suit different types of plants and local climate for optimal cultivation.

“Atmospheric humidity is a huge source of freshwater but it has remained relatively unexplored,” explained project leader Professor Tan Swee Ching.

“In this work, we’ve tried to mitigate food and water shortage simultaneously. We created a hygroscopic copper-based material and used it to draw moisture from the air. We then integrate this material into a fully automated solar-driven device that utilises the harvested water to irrigate plants daily without manual intervention.”


The research team holding the prototype device

The key component of SmartFarm is a specially designed copper-based hydrogel that is extremely absorbent, and takes in moisture up to three times its weight. After acquiring moisture, the hydrogel changes colour from brown to dark green and finally to light green when it is saturated. It also releases water quickly under natural sunlight - one gram of the copper-based hydrogel releases 2.24 gram of water per hour.

The NUS team also tested the quality of the water that was collected using the copper-based hydrogel, and found that it meets the WHO’s standards for drinking water.

At night, the top cover opens to allow the copper-based hydrogel to attract atmospheric moisture. In the day, at a pre-set timing, the top cover closes to confine the water vapour allowing it to be condensed on the enclosure’s surface, particularly on the top cover.

Water droplets will be gradually formed and when the moisture stored in the copper-based hydrogel is completely released, the top cover automatically opens and water droplets which are wiped off by the parallel wipers fall onto the soil to irrigate the plants. The remaining water droplets on the walls of the device continue to provide a humid environment for healthy plant growth.

As a proof-of-concept, the NUS team successfully used the device to cultivate Ipomoea aquatica (commonly known as kangkong): a popular vegetable in Southeast Asia.

“The SmartFarm concept greatly reduces the demand for freshwater for irritation and is suitable for urban farming techniques such as large-scale rooftop farming,” Tan said. “This is a significant step forward in alleviating water and food scarcity in the near future.”

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