A changing climate is putting more pressure on the world’s supply of clean water. But an amphibian might have the answer.
A team of researchers at the University of Nevada, Las Vegas, has developed a material that harvests atmospheric water more efficiently than current technologies. And it’s all thanks to a frog.
Listen to the Deep Dive:
Frogs don’t consume food and water the way we do. Food is taken in orally, but the eyeballs fall inward to push it down the throat. Water, however, is absorbed through their skin.
It was this process that inspired a new ultra-absorbent material that came exclusively from studying hydrogels. The gels create a barrier that keeps out contaminants but allows water to pass through.
CAPTION: Jeremy Cho, assistant professor, Department of Mechanical Engineering
IMAGE: University of Nevada, Las Vegas
“A hydrogel is a soft polymeric material that can swell with water, meaning it is very permeable to water, just like skins in organisms,” says Jeremy Cho, one of the researchers on the team.
A hydrogen membrane and a liquid desiccant was the winning combination that permits rapid capture and large quantity storage for freshwater distillation.
“We observed that it could capture water at incredibly fast rates. We captured two to six liters per day per square meter of membrane area in Las Vegas air — the driest city in the United States,” Cho says.
The liquid desiccant attracts water and absorbs water vapor from the air, even when the relative humidity is as low as 10 percent.
The most challenging obstacle was to filter outside air particulates and contaminants. A hydrogel membrane was added between the desiccant and the air.
It sounds like an easy solution, but finding the just-right hydrogel took two years of experimentation resulting in two published papers. “It took a lot of careful hydrogel synthesis and experimentation to verify our theory,” he tells KUST Review.
| What’s new?
Though atmospheric water harvesting processes have been around for a long time, often repackaging old technologies, the team’s method is based on new tech.
“Our work is different in that we are not creating a new sorbent to be cycled, or relying on an old tech developed for a different application. We are presenting a new membrane-based method where water can be continuously captured into a liquid desiccant and released (distilled) in another location.
The segregation of processes is what’s key here as it allows you to separately optimize and control each process for better overall performance and efficiency. It gives us flexibility in how we can design a complete water-harvesting system. If we want to be solar or waste-heat or electrically powered, we can build different systems that still rely on the same membrane-based capture approach developed because of this flexibility,” Cho says.
| It’s not just for drinking
The majority of the market is focused on drinking water, which is only a fragment of overall water consumption, so the team initiated a start-up company with hopes its tech has a massive impact on sustainability and water sourcing.
Cho adds, “This approach was invented with water-stressed arid regions in mind, and sustainability has been part of the vision from the very beginning.”
This includes considering the current level of water stress and how their tech can impact water usage, conservation and regulation. Regulators are consistently looking toward lower consumption and water reclamation, and companies that look to environmental, social and governance factors when making investment calls are seeking to be water-neutral or water-positive.
Regulators in Nevada sometimes try to put off businesses from setting up there, based on their water-consumption forecasting. Cho and his team are hoping to eliminate this market barrier, enhancing the local economy.
| At what cost?
The problem is that these water solutions are more costly than tap water, but Cho says his team’s goal is to ensure their start-up company, WAVR Technologies, is focused on developing solutions to supply water to make up for these consumptive losses.
| Who is willing to pay the price?
Cho says there are many industries in Las Vegas looking for solutions, including real estate, hospitality, construction and high-tech manufacturing. “We’ve been talking to them, they’re all looking for a solution and are willing to pay for it. And from what we can tell right now, the amount they’re willing to pay seems to be achievable from a technoeconomic standpoint when we scale up our technology.”
“Climate change is real, and whether or not you accept the science that we are causing it, you are paying for it. In arid regions, it is extremely visible through our water resources, our utility bills, and our abilities to do business and live in our communities. We should be more responsible in how we use our water and do what we can to reclaim it. And whatever water we cannot reclaim, let’s consider sourcing that from the air—a hidden resource that surrounds us all,” Cho tells KUST Review.
The team at WAVR Technologies expects its first prototype to be ready by the end of 2025.
A research team from Japan and France has developed a new sort of mechanophore, a molecule that jumps into action when it experiences force, kind of like an assistant inside the softer hydrogel that wakes up to help and make them stronger.
It’s all thanks to a naturally derived molecule called camphanediol. This molecule is tough in the heat, steady under UV light and ready to react when squeezed. Most mechanophores break down easily or need delicate chemical setups to work — but not this one.
When camphanediol gets stretched or pulled inside a hydrogel, it snaps certain chemical bonds in a very specific way. This releases mechanoradicals — tiny chemical sparks that can start new reactions. These sparks reinforce the material, similar to rebuilding muscle after a workout.
Tests showed that hydrogels with camphanediol generated over four times more of these strengthening sparks than regular versions. Additionally, the more it was stressed, the stronger it got, without resulting damage.
The findings could lead to smart materials that adapt and increase resilience on the fly, perfect for soft robots, medical devices and wearable tech.
From wearables for leaves to rose cyborgs, researchers are trying to weave electronics into greenery
There’s a human phenomenon known as “plant blindness.” Used to describe the human perception of plants as mere background noise, plant blindness was a useful evolutionary trait that kept the brain from being overwhelmed by the sheer volume of green surrounding us. But an evolutionary disregard for plants will need to be overcome as we turn to the natural world for solutions to our modern problems.
Anna-Maria Pappa is a researcher at Khalifa University. She says measures to enhance plant productivity and nutrient content are urgently needed — as is a fundamental understanding of plant development and how plants acclimate to environmental stresses:
Plants are increasingly becoming victims of human-caused climate changes, she says. But the classic kind of research in plant sciences that might offer answers can be invasive and may disturb the way plant cells communicate with each other.
Plants are renewable, large-volume and high-performing machineries that represent an untapped source for the production of advanced materials, electronics and energy technology.
– Eleni Stavrinidou
Her potential solution? “Real-time, non-invasive plant sensing can be achieved by placing sensors either on the surface of the plant or inserted inside them. Amalgamating plants and electronic materials makes it possible to combine electric signals with the chemical processes of the plant.”
Pappa calls this futuristic technological concept “e-Plants.” Her research uses conjugated polymers — a kind of organic semiconductor — to create electronic devices for bridging the gap between the biotic and the abiotic. Recent research has seen organic electronic materials used in biologically relevant ion sensing, ion pumps and neural activity transducers in humans.
They more seamlessly integrate with complex biological systems and offer more effective signal transduction of biological events. For e-Plants, they can be either “wearable,” where they are placed on the surface of leaves or stems, for example, or implantable.
Conjugated polymers are mixed conductors. The electronics surrounding us in our daily lives use electrons as the dominant charge carrier; biological systems use ions.
Conjugated polymers can use both, which makes them perfect for direct coupling with biological systems.
Plus, they’re flexible and light. The ease and versatility of integrating flexible polymers instead of hard metals into delicate biological structures is an obvious advantage on top of their other inherent advantages over conventional electronics, Pappa says.
“As in conventional bioelectronics devices, plant-integrated bioelectronics enable bidirectional communication through sensors that can translate plant biosignals to electronic readouts and actuators that can modulate their biological functions,” Pappa explains.
“The combination of ionic and electronic carriers aids signal transduction not only for sensing, but also for converting electronic signals into the specific delivery of chemicals. This could be a key measure for enhancing sustainable farming, which is the main pillar of the fast-growing agricultural revolution we are now facing.”
FLOWER POWER
Pappa’s research focuses on developing hydrogel materials from those polymers that can augment plant seeding and growth in environments that are not that favorable, but that’s not the only avenue for e-Plant technology.
A team of researchers from Sweden’s Linkoping University went down the implantable route, developing a molecule that can be absorbed and polymerized inside the plant, creating long threads throughout that conduct electricity.
Similar to dyeing a flower by feeding it a solution with food coloring, the researchers dissolved a molecule called ETE-S into a solution that was transported through the vascular system of a rose. The ETE-S polymerized throughout this network, turning it electronic.
They weren’t trying to sense anything across this rose, rather turn it into a supercapacitor, a fast-charging energy storage system that could be the future of batteries.
“The plant’s structure acts as a physical template, whereas the biochemical response mechanism acts as the catalyst for polymerization,” Eleni Stavrinidou, the team’s principal investigator, writes in Applied Physical Sciences.
“Plants are renewable, large-volume and high-performing machineries that represent an untapped source for the production of advanced materials, electronics and energy technology.”
Research is also investigating harvesting electricity from photosynthesis.
During photosynthesis, plants use sunlight to split water atoms into hydrogen and oxygen.
The electrons released are used to combine with carbon to produce sugars, but researchers at the University of Georgia have developed a way to interrupt this pathway, capturing the electrons before they can be squirreled away into sugar molecules.
Ramaraja Ramasamy led the team in manipulating the proteins contained in thylakoids, the structures in plants responsible for capturing and storing energy from sunlight. The modified thylakoids were then immobilized on carbon nanotubes, which act as electrical conductors, funneling the electrons from plant cells and out along wires.
A team of researchers at the University of Cambridge discovered something similar. Using ultrafast transient absorption spectroscopy (lasers at speed), the team observed electrons moving through the photosynthetic process.
Image: Envato Elements
Dream date
By: Suzanne Condie Lambert
Sap could make date palms even more important to food security Read more›››
Sap extracted from date palms has long been a rich source of extra nutrition before and after fasts for people in North Africa.
Fawzi Banat and his Khalifa University team in collaboration with UAE University would like to see those nutritional benefits extended to the emirates and other parts of the world.
The researchers had a few problems to overcome, however, before date sap can find its way onto store shelves: First, the extraction process often kills the towering plants, which in the Middle East are culturally and economically significant.
Second, the sap quickly turns to alcohol, limiting its appeal in Muslim markets. The team has an answer for the second issue – a chemical added to the sap that prevents fermentation – and is working on the first.
Banat wants to make sure the collection process doesn’t harm the date palms, but the researchers now know what time of day and how often they extract it matters. They’re perfecting the process, learning how deep to drill and what part of the palm to drill into.
But perhaps the most important question: How does it taste? “It’s sweet and delicious. It is very good,” Banat says.‹‹‹ Read less
They identified what they described as a “leaky pathway”: The cell in which photosynthesis starts was leaking electrons. Gathering these electrons could be a way to generate renewable energy from a self-generating, carbon-sequestering source — a truly green energy.
While the photosynthesis process has been honed over millions of years of plant evolution, it could always be better.
Michael Strano is a self-described “plant hacker” at MIT. In 2014, his team managed to insert nano-machines into a plant’s chloroplasts. Before this (literal) breakthrough, there wasn’t a way to penetrate the cell wall of the structures used by plants for photosynthesis. Strano’s team coated their nano-machines with electrically charged molecules, which were absorbed by the chloroplasts.
They weren’t doing this just to see if they could. Chloroplasts use chlorophyll, a pigment that absorbs blue and red light and reflects green — hence, greenery. If a chloroplast can be “re-wired” to absorb a wider range of light wavelength, theoretically, it should see a boost in productivity. Strano’s nanobionic plants produced 30 percent more energy from sunlight than their control counterparts.
Combine this plant hacking with the techniques to harvest electrons and we could have veritable power plants at our disposal for all our energy needs.
FEED THE WORLD
The interplay between nanobionic approaches and electroactive plants, what Pappa calls “biohybrids,” could have large implications for agriculture, making plants a technically advanced system to tackle and adapt environmental stresses beyond their natural capacity, as well as to better complement modern urban ecosystems.
“Current research in this area is only the tip of the iceberg,” Pappa says. “This is despite the significant advances in the fields of bioelectronics and materials sciences, mainly for human applications.” Pappa’s own previous research has been focused on developing bioelectronics for in vitro applications in drug design and so-called “membrane-on-chip” devices that use conducting polymer electrodes and transistors to interface with human cell membranes.
“Considering the advancements in bioelectronics, material sciences, synthetic biology and artificial intelligence, a few plants could be used as model indictors to understand the fundamentals for optimizing and correlating productivity on a larger scale,” she says.
“Although they might appear as science fiction, plant-integrated technologies could be the future of not only agriculture, but also modern urban ecosystems, as light-emitting, energy-generating or -storing, -sensing and -communicating biohybrid plants,” Pappa says. “We need to harness the potential of plants if we want to realize the goal of zero hunger by 2030.”
A new way to embed gold nanoparticles into 3D-printed hydrogels could improve medical implants, optical devices and even contact lenses for colorblindness.
Scientists at Khalifa University published their research in Materials & Design. It introduces an eco-friendly method that places nanoparticles exactly where they are needed, without waste or extra chemicals.
3D-printed materials with nanoparticles are not new: The particles have previously been mixed into the printing material or applied as a coating afterwards. Both approaches limit device performance.
This new approach allows for better control over nanoparticle placement, making it useful for drug delivery, biosensors and light-based medical treatments.
On a desert planet in a galaxy far, far away, the land is hot, dry and devoid of any large bodies of surface water. It is a parched world, desolate in that way only a planet illuminated by a pair of binary stars can be. Fantastical, yes; a pop-culture icon, also yes.
Listen to the Deep Dive
But there are two reasons to start with a description of Tatooine, the desert planet that appears in the Star Wars franchise: The technology seen here has become a reality, and we can test it in the real-world places that inspired the fictional landscape.
We’re talking moisture farming.
The moisture vaporators, also known as vapor spires in the Star Wars lingo, are devices used on Tatooine moisture farms to capture water from the atmosphere. Tall and slender, they were stationed at ground level and used refrigerated condensers to pull water from the air around them. Captured water was then pumped or gravity-directed into a storage cistern. These devices could collect 1.5 liters of water every day, even when the relative humidity of the air was only 1.5 percent. An amazing idea, and now becoming real as new technologies and materials emerge to harvest previously untappable water from the atmosphere.
The basic concept is simple. If you take an ice-cold glass of water outside on a hot day, you’ll quickly notice water droplets forming on the outside of the glass. If you cool warm, humid air, it loses its capacity to maintain its water content and you can produce and collect condensation, whether it’s on the outside of your glass or in a moisture vaporator straight out of science-fiction.
Rather than waiting for the rain, bring the rain to you
When clean drinking water comes out of the tap at home, it’s easy to think that it will always be plentiful, but fresh water is actually incredibly rare. Only 3 percent of the world’s water is potable, and two-thirds of that is stored away, frozen in glaciers, or otherwise unavailable for our use.
IMAGE: AI; KUST Review
Do not eat this packet
Almost everyone has bought something and found a packet of silica gel beads placed inside to absorb moisture while items are waiting to make their way to the customer. Read more›››
Silica is commercially available, inexpensive and a highly effective desiccant.
Silica can also be also used in water production via the conventional condensation approach.
Silica gel is one of the most commonly used materials in moisture harvesting, and Lisa Klein, professor of materials science and engineering at Rutgers University, has investigated using patterns on silica gel to facilitate water-droplet formation.
She conducted a series of experiments to condense water vapor on the hydrophilic pattern of silica gels. Although the pattern was hydrophilic, the gel itself was hydrophobic so the water droplets slide down the surface and collect in a container rather than absorb into the gel. This represents another potential area of investigation for harvesting water from the atmosphere. ‹‹‹ Read less
As a result, more than 1 billion people worldwide lack access to clean water year-round. Global warming may be melting those glaciers, but as humans continue to pump carbon dioxide into the atmosphere, weather and water patterns will change, combining to make less water available for people around the world. By 2025, predicts the World Wildlife Fund, two-thirds of the world’s population may be facing water shortages.
Technologies such as filtration, desalination and solar purification have been developed to use seawater or wastewater. However, because they depend on terrestrial water sources, these technologies are feasible only in coastal areas. Atmospheric water, however, is present everywhere, and the global water cycle enables a sustainable supply of water to the air, providing a resource equivalent to about 10 percent of all the fresh waterin lakes on Earth.
At 100 percent humidity, the air at 40 degrees Celsius contains about 51 milliliters of water per cubic meter of air. For the same humidity at 10 degrees Celsius, the air contains only 9.3 milliliters. Bring that 40-degree air down to 10 degrees and you should be able to extract that water difference. Scale that up and you could produce an awful lot of water on one of those sticky, hot Arabian Peninsula days.
Technologies already exist to catch fog or collect dew that condenses overnight, but pulling water directly from the air, without consuming lots of electricity, is still under development. Still, Ruzhu Wang, professor at Shanghai Jiao Tong University, says atmospheric water harvesting is accessible everywhere and can be easily co-operated with a renewable energy source for local needs.
The problem, Wang writes in Joule, is that there are few commercial water-harvesting systems available.
But when those systems do become available?
“In general, any viable atmospheric water-harvesting technology must satisfy five primary criteria: It should be efficient, cheap, scalable, wide-band and stable enough to operate for a whole year or at least a monsoon season,” Wang writes.
None of the existing commercial atmospheric-water generators meets all five criteria. Wang says this is mainly due to the energy inefficiency of the process.
So, the ideal moisture harvester has a high water uptake, low-energy demand for water release, fast water capture/release cycling, high cycling stability and a low cost — a tall order but one that could be achieved with advances in material science.
Large-scale moisture farming is science-fiction today. But it may someday bring clean water to desert cities. CREDIT: AI; KUST Review
Living in a material world
Atmospheric water harvesting based on moisture harvesters captures vapor from the air via adsorption, where water molecules adhere to the surface of a material through chemical or physical interactions.
Researchers are looking at materials such as hydrogels and zeolites, as well as porous materials similar to this AI-generated image. IMAGE: AI; KUST Review
For chemical adsorption, the surface needs to adsorb water through strong chemical bonding; releasing the water requires a large energy supply.
Physical adsorption needs pores in the surface, where water molecules can pool and collect. Energy is still required to release the water, but at a significantly lower rate than chemical adsorption.
Porous materials capture the water from the atmosphere, but said pores need to be perfect; you can’t just place a sponge in the desert and expect water to collect.
Enter the metal-organic framework (MOF): a network of metal and organic materials that can easily trap water vapor, which is then released using energy captured from the sun.
Water load of options
But MOFs aren’t the only material vying for a slice of the water-harvesting pie: hydrogels and zeolites have also entered the ring.MOFs work great in areas with lower humidity, but they have a finite number of pores. Fill those, and your harvesting device stalls until they can be emptied.
CREDIT: AI; KUST Review
Combining the two: Fog and moisture farming
The United Arab Emirates has all the necessary ingredients for fog as dry desert conditions exist next to the warm seas of the Arabian Gulf, with moist air carried inland by the afternoon sea breeze cooled by the night desert surface. Read more›››
Tendrils of fog snake their way through the dunes in the early morning and could be captured by the fog-farming technologies already available. At the same time, the humidity that plagues the region during the hot months makes atmospheric-water generation viable.
Combining both approaches could reduce dependency on desalination and provide clean water for the many farms found far out in the desert.‹‹‹ Read less
Hydrogels, on the other hand, can expand to hold more water. The soft, pliable and thin material that makes up more than 90 percent of contact lenses prescribed in the United States is a hydrogel: a water-swollen polymeric material that maintains a 3D structure.
The 3D network of hydrophilic polymers can swell in water while maintaining its structure and is tunable, dynamic, biodegradable and, most importantly, capable of encapsulating huge amounts of water.
Let’s just use hydrogels, then. Well, they’re not the best in low-humidity areas — they like it muggy outside.
Although they may not be suited to the deserts of the Middle East, there are plenty of places with high humidity that are also water-stressed. Lima, Peru, is one such place.
Just south of Lima is the village of Bujama. Despite being in an area where air humidity reaches 98 percent, Bujama is almost a desert, and its people live in tough conditions with little access to clean water.
Researchers from the University of Engineering and Technology in Lima installed panels in advertising billboards that trap the humidity and transform it into drinking water for the people on the ground. These panels comprise filters and condensers and produced 96 liters of water a day in 2013.
People here may already have one solution to water scarcity, but that doesn’t mean hydrogels couldn’t also work in Bujama.
Zeolites are often considered “molecular sieves” as they can selectively sort molecules based primarily on a size-exclusive process. They are easy to manufacture and have a large internal surface area full of pores to adsorb the tiny quantities of water held in desert air — another contender for the low-humidity application.
Water is running out and we know that desalination is not the solution. It’s not just drinking water, it’s all the water used in industry, in agriculture.
– Michael Rutman, co-CEO of Watergen
Desert countries especially would benefit from atmospheric water harvesting. CREDIT: AI; KUST Review
The zeolite can collect water vapor overnight, and heat from the sun can then be used to extract the water for use. However, compared to MOFs and hydrogels, the water capacity of zeolites is relatively low, and releasing the water requires a high energy consumption that, even when supplied by solar power, make zeolites a less efficient option.
In areas where water scarcity is a problem — and climate change is putting more areas at risk — it’s important to consider different technologies and approaches.
Condensing the problem
The billboard in Bujama is just one example of the condenser approach. Michael Rutman is co-CEO of Watergen, a company creating drinking water from air. Based in Israel, “which has a very similar climate to the UAE,” Watergen uses a system involving food-grade polymer condensers and filters to draw water out of the air around us.
“Adsorption can only generate so much water,” Rutman explains. “It also requires a much larger resource footprint than condensation, and much more energy. Metal-organic frameworks that don’t need quite so much energy input to draw the water out are under development, but the metal part of a MOF should also be a concern.”
Atmospheric water is everywhere. The trick is finding energy- and cost-efficient ways to tap it. IMAGE: AI; KUST Review
Rutman points out that an air conditioning unit does much the same thing as a Watergen condensing system: pull warm air out of the environment and cool it, producing water as a by-product. However, the heat exchanger material in an AC unit is usually made of metal, and that metal leeches into the resulting water.
“That’s why you don’t drink from your AC,” Rutman says, laughing. “An AC unit produces tons of water, but that water is contaminated with heavy metals. The Watergen systems use food-grade polymers in the heat-exchanger technology, so the water produced is immediately potable, but we also add minerals to further improve the quality.”
Watergen didn’t set out to save the world from its water problem; the company started by trying to make dehumidifiers more efficient and less power-hungry.
It was Michael Mirilashvili, an Israeli-Georgian businessman, who declared they were wasting this technology. Now president of Watergen, Mirilashvili realized these highly efficient polymers could be used to solve the world’s biggest problem and spent the past five years pivoting the company to producing water from the air for everyone.
Their system works, too. It works in areas of high humidity, such as Colombia and South Africa, but it also works in the driest of places, like Arizona in the U.S., where the average relative humidity is 38.5 percent.
Rutman says he believes mass use of atmospheric water generation is the future.
“Water is running out and we know that desalination is not the solution. It’s not just drinking water, it’s all the water used in industry, in agriculture. It can take 160 liters of water to make a pair of jeans, and 60 liters for a loaf of bread. All this water can be replaced by water produced from the air. I believe we’re less than ten years away from this point. Our pilot technology works, and it’ll work everywhere.”
Perhaps a tabletop box like this will some day supply drinking water for an average home. CREDIT: AI; KUST Review
Speaking of everywhere, we should also start thinking about portability.
Conventional water supply starts with a large centralized plant that distributes water to the population, but if a device were small enough to incorporate into a home, gaps in water supply could be plugged.
Make them even smaller and they could travel to all sorts of now-uninhabitable regions: the middle of the desert, the polar extremes, Mars?
Back down to Earth
Understandably, research institutes in the Middle East are particularly invested in this new type of technology. Many of the projects showing promise in the U.S. were funded by Saudi Arabia’s King Abdulaziz City for Science and Technology, including projects designed by Omar Yaghi, pioneer in the MOF space, and his teams.
Similar technology is behind an industry-funded project at Masdar City, a hub for sustainability research and innovation in the MENA, with whom Khalifa University does research.
“As freshwater scarcity is becoming a global challenge, a promising route to overcoming water shortage is to extract water from air with innovative atmospheric water production (AWG) technologies,” says Samuel Mao, director of Masdar Institute at Khalifa University. “KU’s research team at Masdar Institute is performing comprehensive assessment of different AWG approaches, and developing advanced technologies to enable water extraction from air with better energy efficiency and lower cost.”
Almost half of all people on Earth live in water-threatened conditions, with demand growing drastically, while supply remains constant, according to the World Health Organization.
The United Nations recognizes that access to clean water and sanitation is at the core of sustainable development, and ensuring access requires innovation. Atmospheric water generation could be the solution, and it’s already here.
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CAPTION: Jeremy Cho, assistant professor, Department of Mechanical Engineering
Image: Envato Elements
