Subject Categories: Materials
Published online 9 January 2013
The cactus Opuntia microdasys, which grows in the Chihuahua Dessert, has elaborate spines for harvesting water from fog (pictured). This unique structural feature allows the cactus to survive in areas where water is scarce.
Lei Jiang and co-workers at the Chinese Academy of Sciences in Beijing1 have now studied the cactus spine closely and discovered why it is so efficient in harvesting water.
The researchers examined the cactus spine using a scanning electron microscope and found that its tip is covered with tiny oriented barbs. These barbs have a conical shape that not only increases the area for harvesting water, but also forces water droplets to move to the base of the spine.
The researchers also found grooves on the spine that become smoother as they get closer towards the base. This gradual decrease in roughness generates a force that pushes water towards the trichome, a unique feature on the cactus for absorbing moisture into the stem.
The researchers believe their findings could aid the development of artificial fog collectors. If successful, the technology could help supply water to humans living in highly arid areas.
The authors of this work are from:
Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China; National Centre for Nanoscience and Technology, Beijing, China; School of Chemistry and Environment, Beijing University of Aeronautics and Astronautics, Beijing, China.