Cactus-Inspired New Material Can Absorb and Retain Large Amounts of Water

During the occasional desert rainfall, cacti immediately start sopping up and storing the storm’s valuable precipitation. Researchers have now created a material inspired by this natural phenomenon. The unique material, described in a study appearing ACS Macro Letters, imitates cactus roots’ ability to quickly absorb and retain huge quantities of water with least amount of evaporation. They say this material could lead to new and better medical devices, cosmetics, and other daily use products.

A newly developed material can mimic the absorptive capabilities of cactus roots after a storm. Credit: Johnny Coate/

Cacti, like all living things, need water to survive. Nevertheless, they flourish in some of the world’s driest places. The key is the plant’s shallow, but widespread root system that swiftly soaks up rainfall, which rarely penetrates more than just a few inches into the soil. During droughts, the roots dehydrate and shrivel, forming air gaps that stop water from escaping back into the soil. Fascinated by these characteristics, Sang Joon Lee, Hyejeong Kim, and Junho Kim were keen to create a durable material that could effectively absorb and store water, without altering other physical properties.

The research team aimed to duplicate the main features of the cactus root system. To replicate the cactus root and its outer covering, they created a material made up of cellulose fibers, microparticles, and agarose cyrogel.  Then, they created a cylindrical-shaped gel and freeze-dried it to develop a structure that imitates the layered composition of cactus root epidermis. Tests conducted in the laboratory reveal that the resulting cactus-root-inspired material (CRIM) can absorb water close to 930 times quicker than it loses through evaporation.

The researchers say the blend of microparticles, cellulose fibers, and cryogel is modifiable for specific needs. For instance, incorporating water-repellant microparticles to this system could create CRIMs beneficial in oil separation and other oil-based engineering procedures. They conclude that CRIMs could ultimately have a horde of applications in cosmetics, agriculture, and medicine.

The National Research Foundation of Korea funded the researchers.

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