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Xuanhe ZHAO, et al.
Atmospheric Water Harvesting Window
https://www.eurekalert.org/news-releases/1086613
Window-sized device taps the air for safe drinking water
MIT engineers have developed an atmospheric water harvester that produces fresh water anywhere — even Death Valley, California.
by Jennifer Chu, MIT News
Today, 2.2 billion people in the world lack access to safe drinking water. In the United States, more than 46 million people experience water insecurity, living with either no running water or water that is unsafe to drink. The increasing need for drinking water is stretching traditional resources such as rivers, lakes, and reservoirs.
To improve access to safe and affordable drinking water, MIT engineers are tapping into an unconventional source: the air. The Earth’s atmosphere contains millions of billions of gallons of water in the form of vapor. If this vapor can be efficiently captured and condensed, it could supply clean drinking water in places where traditional water resources are inaccessible.
With that goal in mind, the MIT team has developed and tested a new atmospheric water harvester and shown that it efficiently captures water vapor and produces safe drinking water across a range of relative humidities, including dry desert air.
The new device is a black, window-sized vertical panel, made from a water-absorbent hydrogel material, enclosed in a glass chamber coated with a cooling layer. The hydrogel resembles black bubble wrap, with small dome-shaped structures that swell when the hydrogel soaks up water vapor. When the captured vapor evaporates, the domes shrink back down in an origami-like transformation. The evaporated vapor then condenses on the the glass, where it can flow down and out through a tube, as clean and drinkable water.
The system runs entirely on its own, without a power source, unlike other designs that require batteries, solar panels, or electricity from the grid. The team ran the device for over a week in Death Valley, California — the driest region in North America. Even in very low-humidity conditions, the device squeezed drinking water from the air at rates of up to 160 milliliters (about two-thirds of a cup) per day.
The team estimates that multiple vertical panels, set up in a small array, could passively supply a household with drinking water, even in arid desert environments. What’s more, the system’s water production should increase with humidity, supplying drinking water in temperate and tropical climates.
“We have built a meter-scale device that we hope to deploy in resource-limited regions, where even a solar cell is not very accessible,” says Xuanhe Zhao, the Uncas and Helen Whitaker Professor of Mechanical Engineering and Civil and Environmental Engineering at MIT. “It’s a test of feasibility in scaling up this water harvesting technology. Now people can build it even larger, or make it into parallel panels, to supply drinking water to people and achieve real impact.”
Zhao and his colleagues present the details of the new water harvesting design in a paper appearing in the journal Nature Water. The study’s lead author is former MIT postdoc “Will” Chang Liu, who is currently an assistant professor at the National University of Singapore (NUS). MIT co-authors include Xiao-Yun Yan, Shucong Li, and Bolei Deng, along with collaborators from multiple other institutions.
Carrying capacity
Hydrogels are soft, porous materials that are made mainly from water and a microscopic network of interconnecting polymer fibers. Zhao’s group at MIT has primarily explored the use of hydrogels in biomedical applications, including adhesive coatings for medical implants, soft and flexible electrodes, and noninvasive imaging stickers.
“Through our work with soft materials, one property we know very well is the way hydrogel is very good at absorbing water from air,” Zhao says.
Researchers are exploring a number of ways to harvest water vapor for drinking water. Among the most efficient so far are devices made from metal-organic frameworks, or MOFs — ultra-porous materials that have also been shown to capture water from dry desert air. But the MOFs do not swell or stretch when absorbing water, and are limited in vapor-carrying capacity.
Water from air
The group’s new hydrogel-based water harvester addresses another key problem in similar designs. Other groups have designed water harvesters out of micro- or nano-porous hydrogels. But the water produced from these designs can be salty, requiring additional filtering. Salt is a naturally absorbent material, and researchers embed salts — typically, lithium chloride — in hydrogel to increase the material’s water absorption. The drawback, however, is that this salt can leak out with the water when it is eventually collected.
The team’s new design significantly limits salt leakage. Within the hydrogel itself, they included an extra ingredient: glycerol, a liquid compound that naturally stabilizes salt, keeping it within the gel rather than letting it crystallize and leak out with the water. The hydrogel itself has a microstructure that lacks nanoscale pores, which further prevents salt from escaping the material. The salt levels in the water they collected were below the standard threshold for safe drinking water, and significantly below the levels produced by many other hydrogel-based designs.
In addition to tuning the hydrogel’s composition, the researchers made improvements to its form. Rather than keeping the gel as a flat sheet, they molded it into a pattern of small domes resembling bubble wrap, that act to increase the gel’s surface area, along with the amount of water vapor it can absorb.
The researchers fabricated a half-square-meter of hydrogel and encased the material in a window-like glass chamber. They coated the exterior of the chamber with a special polymer film, which helps to cool the glass and stimulates any water vapor in the hydrogel to evaporate and condense onto the glass. They installed a simple tubing system to collect the water as it flows down the glass.
In November 2023, the team traveled to Death Valley, California, and set up the device as a vertical panel. Over seven days, they took measurements as the hydrogel absorbed water vapor during the night (the time of day when water vapor in the desert is highest). In the daytime, with help from the sun, the harvested water evaporated out from the hydrogel and condensed onto the glass.
Over this period, the device worked across a range of humidities, from 21 to 88 percent, and produced between 57 and 161.5 milliliters of drinking water per day. Even in the driest conditions, the device harvested more water than other passive and some actively powered designs.
“This is just a proof-of-concept design, and there are a lot of things we can optimize,” Liu says. “For instance, we could have a multipanel design. And we’re working on a next generation of the material to further improve its intrinsic properties.”
“We imagine that you could one day deploy an array of these panels, and the footprint is very small because they are all vertical,” says Zhao, who has plans to further test the panels in many resource-limited regions. “Then you could have many panels together, collecting water all the time, at household scale.”
This work was supported, in part, by the MIT J-WAFS Water and Food Seed Grant, the MIT-Chinese University of Hong Kong collaborative research program, and the UM6P-MIT collaborative research program.
https://www.livescience.com/technology/engineering/mits-high-tech-bubble-wrap-turns-air-into-safe-drinking-water-even-in-death-valley
MIT's high-tech 'bubble wrap' turns air into safe drinking water — even in Death Valley
Researchers at MIT have tested a new technology for turning water vapor in the atmosphere into drinkable water, even in extreme environments.
https://www.nature.com/articles/s44221-025-00447-2
A metre-scale vertical origami hydrogel panel for atmospheric water harvesting in Death Valley
Chang Liu, et al.
Water scarcity impacts over 2.2 billion people globally, especially in underdeveloped, landlocked or off-grid regions. Passive sorbent-based atmospheric water harvesting offers a promising solution by converting ubiquitous atmospheric moisture into liquid water. However, current approaches are limited by low water production (a few millilitres a day), the release of unsafe lithium ions and poor efficiency in conditions of low relative humidity. Here we report an atmospheric water harvesting window (AWHW) featuring a vertical origami hydrogel panel and a window-like solar still. This passive, metre-scale device was tested in Death Valley, producing 57.0–161.5 ml of water a day across a relative humidity range of 21–88%. The device has a lifespan of at least 1 year and delivers safe water with lithium ion concentrations below 0.06 ppm. Our AWHW sets a benchmark in daily water production and climate adaptability, representing an advance towards practical, scalable, safe and sustainable decentralized water solutions for the most water-stressed regions.
XUANHE ZHAO HYDROGEL PATENTS
ADHESIVE MATERIAL WITH TRIGGERABLE ON-DEMAND DETACHMENT -- US202508428
[ PDF ]
An adhesive material that provides fast and robust adhesion on wet surfaces, where the adhesion formed is detachable on-demand. The adhesive material is formed of one or more hydrophilic polymers or copolymers grafted with one or more amine coupling groups via a plurality of cleavable physical bonds and/or cleavable covalent bonds and one or more cross linkers. Application of the adhesive material on a wet surface causes the adhesive material to absorb liquid to thereby swell the adhesive material to form a layer of hydrogel, resulting in the formation of temporary crosslinks followed by covalent crosslinks with the surface. Introducing a triggering agent cleaves the cleavable physical bonds and/or cleavable covalent bonds to allow for non-traumatic detachment of the adhesive material from the surface.
SYSTEMS AND METHODS FOR ON-PERSON WEARABLE ELECTRONIC DEVICES -- US2023277159
[ PDF ]
Systems and methods are provided for on-person wearable electronic devices configured for extended periods of wear. A couplant may be provided that is made of a soft anti-dehydrating, and hydrogel-elastomer hybrid material. A bioadhesive may connect the couplant the electronic devices and the person. The couplant may serve as a coupling and transmission for information to or from the electronic device.
INTERPENETRATING NETWORKS WITH COVALENT AND IONIC CROSSLINKS -- US10383980 // US11033658
[ PDF ]
The invention features a composition comprising a self-healing interpenetrating network hydrogel comprising a first network and a second network. The first network comprises covalent crosslinks and the second network comprises ionic or physical crosslinks. For example, the first network comprises a polyacrylamide polymer and second network comprises an alginate polymer.
FAST-SWELLING, HIGHLY-SWELLABLE, ROBUST HYDROGEL BALLOONS -- US2021038871
[ PDF ]
An expandable hydrogel structure formed of a housing with a superabsorbent material disposed and sealed therein, particularly wherein the housing is fabricated of a hydrogel membrane with a plurality of macropores providing fluid communication between the superabsorbent material and an exterior of the housing. Exposure of the superabsorbent material to an expansion trigger expands the housing from an initial size to an expanded size that is at least about 50 times to at least about 100 times the initial size. One or more therapeutic agents can further be disposed within the housing to provide controlled release of the therapeutic agents from the expanded housing for extended periods.
PURE CONDUCTING POLYMER HYDROGEL AND HYDROGEL PRECURSOR MATERIALS HAVING EXTRAORDINARY ELECTRICAL, MECHANICAL AND SWELLING PROPERTIES AND METHODS OF MAKING -- US2020299466
[ PDF ]
Pure conducting hydrogel precursors and hydrogels formed of pure conducting polymer materials having a combination of high electrical conductivity, high stretchability, low Young's modulus, superior mechanical, electrical and electrochemical stability, and tunable swelling behaviors in wet physiological environments. The hydrogel precursors and hydrogels are fabricated by adding a polar organic solvent to an aqueous solution of the pure conducting polymer material, followed by controlled dry-annealing to form a hydrogel precursor which can be subsequently rehydrated to form a pure conducting polymer hydrogel which comprises at least 99% of the pure conducting polymer.
MATERIALS AND DEVICES CONTAINING HYDROGEL-ENCAPSULATED CELLS --
US11850290
[ PDF ]
Provided herein, in some embodiments, are hydrogel-elastomer and hydrogel-alginate devices, compositions and associated methods to encapsulate living cells.
TOUGH HYDROGEL COATING AND METHOD OF MANUFACTURE -- US2019125934
[ PDF ]
Hydrogel-substrate laminate structures and tough biocompatible hydrogel coatings for various equipment such as medical devices and underwater equipment, in which robust interfaces are formed between the hydrogel coatings and the substrate/equipment surface(s). The hydrogel coatings provide a highly-hydrated, ultra-low friction structure that does not rupture or delaminate under stress. The hydrogel coatings may further incorporate a variety of therapeutic agents and/or sensing mechanisms to provide for environmental sensing and therapeutic agent release.
HYDROGEL-ELASTOMER HYBRIDS -- US11148389
Hydrogel-elastomer hybrids with interfacial bonding tougher than epidermis-dermis interfaces and functional micro-channels and micro-patterns can be created by pre-shaping both elastomers and hydrogels before bonding to conserve their micro-structures, modifying cured elastomer surfaces with benzophenone for chemical bonding with hydrogels, and harnessing dissipative properties of tough hydrogels to achieve robust interfaces.
EXTREMELY COMPLIANT YET TOUGH HYDROGEL SYSTEMS AS ULTRASOUND TRANSMISSION AGENTS -- US9878506 [ PDF ]
A method for making a tough and compliant hydrogel. A precursor hydrogel is made of a first polymer selected to maintain high elasticity and a second polymer selected to dissipate mechanical energy. The precursor hydrogel is stretched to a multiple of its original length to form a pre-stretched hydrogel. The pre-stretched hydrogel is allowed to relax and is soaked in a biocompatible solvent to reach equilibrium swelling of the pre-stretched hydrogel whereby shear modulus of the hydrogel is reduced.
MULTIFUNCTIONAL BONDING OF HYDROGELS -- US10954375 [ PDF ]
Chemically anchoring long-chain polymer networks of tough hydrogels on solid surfaces can represent a general strategy to design tough and functional bonding between hydrogels and solid materials, achieving interfacial toughness over 1000 Jm−2.
Stretchable, Robust and Biocompatible Hydrogel Electronics and Devices -- US2017136180 [ PDF ]
A tough biocompatible hydrogel having one or more drug delivery components, deformable conductors, and/or rigid electronic components incorporated therein in such a way that robust interfaces are formed between the hydrogel and the various components. The resulting hydrogel device provides a highly deformable hydrogel composite in which the reliability and functionality of the incorporated components are maintained even under states of large deformation, and from which one or more drugs can be delivered in a controlled and sustained manner regardless of the state of deformation.
Atmospheric Water Harvester Patents
APPARATUS TO HARVEST ATMOSPHERIC WATER VAPOR -- SA522432598
ATMOSPHERIC WATER HARVESTING USING FOG HARVESTING FABRIC -- US2025032977
PROCESS FOR PRODUCING WATER ACTIVATED BY PLASMA JET IN CONTINUOUS FLOW -- MX2022010074
Atmospheric water harvesting generator -- US11745117
DEVICE AND METHOD FOR PASSIVE COLLECTION OF ATMOSPHERIC CARBON DIOXIDE WITH A DOUBLE-WALLED HARVEST CHAMBER -- WO2023064317
Atmospheric Water Generator Utilizing Centrifugal Hydraulic Air Compressor -- US2021230846
UTILIZATION OF SOLAR SYSTEMS TO HARVEST ATMOSPHERIC MOISTURE FOR VARIOUS APPLICATIONS INCLUDING PANEL CLEANING -- US2021234503
System for condensation water initiatively discharges noresidue at harvest time -- CN208349912
DEVICES AND METHODS FOR COLLECTING, SANITIZING, AND DISPENSING CONDENSED FORMS OF ATMOSPHERIC WATER -- US2016244951
MOISTURE- HARVESTING DEVICE -- US2016089616 // WO2014184965
ATMOSPHERIC WATER VAPOR ENGINE -- US2014311144
EXTENDED ATMOSPHERIC WATER HARVESTING MODULE -- SG177029
Farmland water storage for preventing flood the drought and systematic
engineering for increasing groundwater recharge -- CN101418551
Process and apparatus for commercial farming of marine and freshwater hydrophytes -- US4209943 // WO8102660
SEA HARVESTING APPARATUS AND METHOD -- GB1393003
Process and apparatus for commercial farming of marine and freshwater macrophytes -- EP0035611 // CA1126028
COLLECTION OF CARBON EMISSIONS -- WO2009152853