Nicholas Pachon
I am a junior biomedical engineering student at the University of Southern California. In my free
time I love to run and hike, getting the chance to explore what nature has to offer.
Keywords: Biomimicry, Nature, Insects, Water
Suggested Multimedia:
Video of Stenocara beetle extracting water: http://www.youtube.com/watch?v=XsMJNNshPOs
National Geographic Article:
http://news.nationalgeographic.com/news/2001/11/1101_TVdesertbeetle.html
Abstract:
The Stenocara beetle is an insect found in the deserts of South Africa, thriving where
most organisms would perish. Using solely its body, the beetle can generate water from the air
around it in order to get its fill and survive in the harsh climate. With the application of
biomimicry, this method of water extraction is analyzed and applied to solve for human
problems, from water collection to drug delivery systems. Though some problems stand between
its implementation, the Stenocara beetle stands as a strong example of how powerful and
beneficial biomimicry can be.
The Beetle Architect:
An Application of Biomimicry for Water Extraction Processes
When looking at a beetle, one does not usually think that it can be the source of a
profound engineering development. However, nature, with time and repetition, fashions some of
the most efficient and creative methods in solving an issue that any organism may face, whether
it be cellular energy efficiency with ATP metabolism or a leaf’s specific shape and texture to
best retain water. In solving complex issues, engineers and scientists realized that they could
look to nature’s mechanisms to help formulate a response, thereby creating a new science.
Biomimicry, a relatively new but developing field, is the application of the processes found in
nature to human problems. Utilizing already existing methods, this science speeds up the rate at
which innovation occurs and problems are solved, while at the same time creating sustainable
and lasting solutions. An example of such an occurrence is found in the Stenocara beetle. What
was first an insect became a water-extraction marvel with the application of biomimicry.
In the harsh environment of the Namib Desert in Africa, organisms struggle to survive,
having to deal with the desolate
landscape and the lack of water in the
area. With “high winds, extreme
daytime temperatures and dense, earlymorning fog,” [1], it is hard to imagine
anything making its home in such an
environment, let alone thriving in it.
However, the Stenocara beetle is one
such creature that is able to do so and
does it with an ingenious method. With
the most difficult issue being the acquisition of water, the beetle developed a technique that uses
its body structure to collect and directly
Figure 1: Representation of how the beetle collects
feed itself water. Adapting the heavy
water from the air.
[2]
winds and fog to its benefit, the beetle tilts its body facing into the wind and allows droplets to
collect on the top of its abdomen, as detailed in Figure 1 [1]. Following the diagram, the water
then follows a path down the beetle’s back to its mouth, where it can then drink the fluid [1].
Simple and effective, it begged the question as to how the beetle was able to seemingly pull the
water right out of the air. The answer lies in the structure and composition of the insect’s back.
Under closer inspection, the Stenocara beetle’s skin demonstrates how creative and
effective nature can be. From the outset, it was immediately seen that the majority of the bug’s
Figure 2: A top and back view of
the Stenocara beetle.
[3]
back was covered in small bumps, pictured in Figure 2. The tips of these bumps were smooth
and hydrophilic, or water loving [1]. The rest of the
beetle’s back is coated in a waxy coating, making it a
hydrophobic surface or an area that repels water [1].
Combining the two characteristics, the Stenocara beetle is
thus able to extract the moisture from the morning fog to
drink from. The tips of the hydrophilic bumps collect tiny amounts of water from the fog being
blown past its body, continually building up the water on each tip. Once reaching a volume of
water that the peak of the bump cannot support, the resulting droplet begins its slide down the
insect’s back [4]. The droplet is carried across the back and into the mouth of the beetle,
continually moving as it is on the hydrophobic surface. In carrying out this process, the beetle
expends relatively little to no energy as the mechanism is built into its body, only having to lift
its abdomen to be able to gather the water. Comparing this structure to a plain waxy surface, the
mixed hydrophobic and hydrophilic surface was able to generate droplets with a diameter of
around four millimeters while the waxy surface only produced 1 mm diameter droplets [1].
Extracting larger amounts of water compared to a smooth surface offers the insect the capability
to make unattainable water a drinkable source. Now knowing how the beetle is able to harvest
the water and how efficient it is, engineers and scientists set out to mimic this ability.
Unfortunately, finding the mechanism that allows the beetle to perform this amazing feat
is only the initial part to repurposing it for human use. Here is the hardest facet of conducting
biomimicry, reapplying the technique that an organism uses while still retaining all the benefits
that it offers. While the beetle is born with this gift in its inherent body structure, people must be
able to replicate and mass-produce the same results in order for it to be any use. This is not an
arbitrary venture as current patterning methods for water extraction have great difficulty in being
either too complex to be a feasible commercial investment or the chemicals and materials used in
creating the patterns are limited in application [4]. Using the beetle as the model to base future
patterning techniques, an efficient method could be put to use, already trialed and proved
successful by allowing the beetle to survive in the deserts of Africa.
Realizing the potential significance of this concept, a lab led by Michael Rubner and
Robert Cohen sought to create a new material that could extract and channel liquid in an
effective manner. This lab, unlike the many others that attempted this feat, applied the principles
of biomimicry in finding their solution and copied the structure of the Stenocara beetle. First,
they created a base superhydrophobic coating material using a complex polyelectrolyte mix of
films with other chemicals and nanoparticles to cover a surface [4]. Once applied, they removed
spots of this coating in the same organization and pattern as the Stenocara beetle’s back, which
they then replaced with their own synthetic hydrophilic material. By doing this, they were able to
mimic the ability of the beetle, being able to take a fine spray of solution and coalesce it into
droplets on the hydrophilic regions [4]. Figure 3 is a photo taken of the sprayed water droplets in
Figure 3: Water droplets sprayed
onto the lab-created material.
[4]
order to better visualize what occurs.
The droplets are all organized on top
of the hydrophilic array; some droplets are larger than others as the spray concentration was
greater in that particular section. With the use of man-made materials and some ingenuity,
researchers were able to effectively replicate the effects of the Stenocara beetle’s body ability in
gathering water.
Moreover, conducting in a controlled environment that they could manipulate, the
researchers were able to improve upon the beetle’s technique by making it more versatile. This is
an important part of biomimicry, providing a working foundation that people can then improve
upon and enhance. In this situation, as the lab knew the specific characteristics of the synthetic
material they were using, known properties of the surfactant could be utilized or altered to
change its characteristics and incorporate new elements. By adding dyes that held a slight
positive or negative charge to the replicated surfactant, they were able to trap some of dye
beneath the structure and alter the surface properties [4]. The positively charged dye was able to
get underneath the superhydrophobic surface, not releasing until an added solution made the
surface hydrophilic. This new property gave the material the ability to act, “as a reservoir for
these chemicals which can be released…through subsequently created hydrophilic portals…”
[4]. Now able to hold and release material, the ways in which the substance can be applied in
situations are increased, requiring only adding a slight charge to the materials. Also, unlike the
beetle that worked primarily with water, this biomimicry-founded material could be effectively
used with over 240 types of polycation, polyanion, and water solutions [4]. Thus, not only were
they able to create a material that successfully copied the Stenocara beetle’s ability, the lab
improved off the design and gave several more unique and beneficial characteristics.
While achieved in the lab, the implementation of the material has a few obstacles to cross
before it can be used on a day-to-day basis. One of the largest difficulties is that the material
used is both very experimental and hard to replicate. Requiring unique plastics and chemicals
mixed in a specific manner, the material would be hard to make in a low-budget setting, as even
the equipment needed to make it would be a hindrance to acquire. Until the parts that make up
the material are relatively cheap, further research needs to be done that looks for other resources
to use or a cheaper fabrication method. The material also faces a problem in that it is very
environment dependent, requiring enough moisture for extraction to occur. The Stenocara beetle
always had the morning fog combined with the high winds to help it in its collection of moisture.
As there are no moving parts on the engineered material, it relies solely on external forces to be
near a moisture source. If it cannot get in contact with a source or not enough moisture is present,
then water extraction won’t occur and only negligible amounts of water will be built up [5].
Thus, it will most likely be tremendously location dependent or require an additional part that
would encourage moisture interaction with its environment.
Despite any shortcomings, with the developed material researchers can begin to fully
understand how to apply it to the problems that people face. Founded on the principle of being
able to absorb the moisture out of the air and collect it to get usable, significant quantities, the
material’s immediate use would be for the sequestration of water. With something as simple as
creating billboards of the material with a collection system attached, vast amounts of water can
be extracted from the surrounding air and be repurposed for drinking. Minimal treatment would
have to be conducted as well, as the hydrophilic parts would safely extract the water from its
surroundings. With the ability to change and resize as needed, this new material can be
repurposed to line virtually any object or structure, making it a water producer for anything from
individual drinking to watering agricultural fields [1]. The material wouldn’t need any coolant or
other heavy technological pieces to run due to it working solely off the design of its structure,
making it a perfect fit for inhospitable regions [4]. However, its application must be monitored as
it has the potential to leave a negative impact on the environment. The material may result in a
damaging effect upon the surrounding area due to it extracting large amounts of water from the
air, an effect that may not be determined until the material is employed in the real world. While
biomimicry shows useful and efficient solutions to problems, it is the way in which people apply
them that determines their overall sustainability and safety.
Copying the Stenocara beetle’s main skill of water extraction, the synthetic material’s
added abilities makes it versatile for other uses as well. As mentioned earlier, the multi-layered
material possessed the ability to store different chemicals inside a reservoir-like area, which can
then be released from the hydrophilic doorways. This can be applied in drug-delivery systems
that need the drug to be released only in specific areas, which the hydrophilic portals can help
control [4]. Another function is found in what are called lab-on-chip devices, being able to run
tests and other forms of analysis to the micro level [4]. Using the hydrophilic and hydrophobic
properties described, it is possible to create self-contained environments by building canals
across the system, using the water as an isolator. At this level, engineers and researchers could
begin to perform tests at a highly refined level of specificity, aiding future research and
endeavors in the scientific community.
The potential advances that biomimicry allows for appear endless. Organisms in nature
do not have the luxury of having a faulty adaptation, being either eliminated or existing with the
most efficient answer to a problem. From just a single beetle, a means was developed for
extracting and supplying water in an efficient and simple manner. Not only achieving this
advanced accomplishment, researchers were able to enhance the design of the process, giving the
created material medical purposes that can be explored. By just drawing inspiration from the
world around us, tremendous leaps can be made both in the scientific community and in the
growth of human welfare.
Works Cited
[1] Parker, Andrew R., and Chris R. Lawrence. “Water Capture by a Desert Beetle.” Nature (vol.
414) [Online]. Available: http://www.nhm.ac.uk/
[2] Nehring, Brad. (2011, April 27) Biomimicry: Using The Natural World To Benefit (And
Greatly Convenience) Humanity [Online]. Available: http://bradnehring.wordpress.com/
[3] Moyer, Justin. (2011, September 15) Imitation Is The Highest Form Of Flattery [Online].
Available: http://jmoyersmartsurfaces.blogspot.com/
[4] Zhai, Lei, Michael C. Berg, Fevzi Cebeci, Yushan Kim, John M. Milwid, Michael F. Rubner,
and Robert E. Cohen. (2006) "Patterned Superhydrophobic Surfaces: Toward a Synthetic Mimic
of the Namib Desert Beetle." NANO Letters (vol. 6.6) [Online]. Available: doi:
10.1021/nl060644q
[5] Lee, Anna, Myoung-Woon Moon, Hyuneui Lim, Wan-Doo Kim, and Ho-Young Kim. (2012)
“Water harvest via dewing.” Langmuir (vol. 28) [Online]. Available: doi: 10.1021/la3013987