Researchers
Zhao Pan, William G. Pitt, Yuanming
Zhang, Nan Wu, Ye Tao and Tadd T. Truscott from the Department of Mechanical
and Aerospace Engineering, Utah State University have discovered that moss
Syntrichia caninervis has the
ultimate water collection toolkit. The moss uses its leaves in ingeneous ways to
collect moisture.
The researchers show that the unique multiscale
structures of the hair of moss are equipped to collect and transport water in
four modes: nucleation of water droplets and films on the leaf hair from humid
atmospheres; collection of fog droplets on leaf hairs; collection of splash
water from raindrops; and transportation of the acquired water to the leaf
itself. Fluid nucleation is accomplished in nanostructures, whereas fog
droplets are gathered in areas where a high density of small barbs are present
and then quickly transported to the leaf at the base of the hair. Their observations
reveal nature's optimization of water collection by coupling relevant
multiscale physical plant structures with multiscale sources of water.
The key
to the plant's success is its small leaf hair point, or awn. These 0.5-2
mm-long hair-like structures at the tip of each leaf function like a Swiss Army
knife in their ability to collect water from a variety of size scales. Whether
the plant gets buckets of rain or only the occasional passing fog, the awn of
S. caninervis can exploit any available water resource using four specialized
tools.
Each awn
is covered in nano- and micro-scale grooves where water vapor will readily
condense. The grooves are just the right size and shape to condense water
molecules directly from moist air and to catch microscopic fog droplets. At a
larger scale, each awn also features elongated barbs that serve as collection
depots where condensed or collected water forms small droplets. When large
enough, the droplets move along the length of the awn toward the leaf --
sometimes at impressive speeds.
This
process of water collection, droplet formation, and rapid transportation to the
leaf is a critical function of the awns required to keep this moss alive. S.
caninervis is unique because its leaf surfaces must be wet for
photosynthesis to occur, and its root-like structures (rhizoids) do not collect
water from the soil.
The researchers
add "There are several exciting angles to this research. For example,
there are processes in industry where we need to extract moisture from a humid
environment. It might be possible to create a man-made version of the nano- and
micro-scale grooves we see in the awns and use that in a manufacturing setting."
Another
attraction is the plant's remarkable anti-splash properties. For several years researchers
have been exploring methods to reduce splashing in multiple settings, including
the common urinal. The concept is no trivial topic for the Splash Lab team.
They've demonstrated that urinal splash-back is a legitimate concern when it
comes to public hygiene and facility maintenance costs. The way clusters of S.
caninervis harness water droplets inspired a newly designed urinal
splash pad being developed by Truscott's Team.
Details of the research appears in the latest issue of journal Nature Plants