Sourcing and channelling water—from Inca canals to Roman aqueducts—has always mirrored human progress. Today, solutions like reverse-osmosis desalination represent the latest step towards water security. Among the emerging methods designed to supply clean water where resources are scarce, atmospheric water harvesting stands out as one of the most promising.

While fog harps and desert-beetle-inspired Janus crystals have gained attention in recent years, this latest development is so compact it functions as everyday wearable tech: a jacket that pulls moisture straight from the air using an innovative, sustainable fabric. If matter has antimatter, this garment could be considered the functional opposite of a traditional raincoat.

Most atmospheric water-harvesting systems require either sprawling installations for passive dew condensation or bulky machinery that extracts moisture through energy-heavy ventilation and chilling units. The prototype built by the University of Texas takes a completely passive approach, setting itself apart through sheer portability: a flexible fabric that integrates directly into everyday clothing.

The American research team applied this textile fibre to a wearable jacket designed to absorb ambient humidity throughout the day and convert it into safe drinking water. Crucially, this goes well beyond a controlled laboratory exercise. In field trials, the garment generated between 400 and 900 millilitres of water daily, depending on surrounding humidity levels. In the right environment, a single jacket can supply nearly all of an individual’s basic daily fluid requirements.

Rather than trying to miniaturise conventional mechanical dehumidifiers, the research team focused on the molecular architecture of synthetic fabrics. According to Guihua Yu, professor at the Walker Department of Mechanical Engineering and co-lead author of the study published in Science Advances, the core objective was to fundamentally rethink how water-harvesting hardware is built.

Traditional desiccant materials often suffer from physical bottlenecks. While many chemical compounds readily capture moisture from the air, dense outer surfaces block internal fluid movement, significantly slowing both the absorption and release stages.

The Austin team resolved this limitation by engineering hierarchically open-porous fibres (HOP fibres). The principle behind the name is straightforward: these structures feature an open-pore outer surface linked to an internal capillary network. This setup allows water vapour to condense rapidly on the exterior before flowing directly into the textile's core.

As study co-author Keith Johnston points out, the breakthrough lies not just in synthesising a moisture-absorbing material, but in designing an uninterrupted transport channel that carries water from ambient vapour to a liquid phase on the fibre's surface, and straight into the core of the textile. This dynamic mechanism boosts performance between three- and tenfold compared to conventional absorption systems.

Beyond its performance, the fabric stands out for its sustainable source material. The water-harvesting jacket is manufactured using a sustainable hydrogel textile derived entirely from biomass. The fibres are synthesised from amphiphilic hydroxypropyl cellulose, a biodegradable polymer derived from plant cellulose. This is combined with lithium chloride, a hygroscopic salt that draws water vapour molecules from the air with remarkable efficiency.

The resulting garment can absorb up to 2.68 grams of water per gram of dry material at 60% relative humidity. Across humidity levels ranging between 20% and 80%, the textile delivered daily yields between 3.76 and 7.45 litres of water per kilogram of absorbent material.

Furthermore, the material reaches 80% of its total saturation capacity in just 19 to 20 minutes under moderate humidity, capturing water far faster than standard desiccants.

To turn this chemical formulation into a wearable garment, the team integrated four moisture-harvesting panels into the jacket's layout: two across the chest and two along the back. Once the hydrogel panels reach saturation during daily wear, they can be unzipped or detached and placed into a compact, foldable collection unit.

Inside this device, gentle heat from sunlight or low-power electric elements triggers the hydrogel to release its trapped moisture as vapour. This vapour condenses along internal channels and collects in an integrated reservoir. Laboratory testing confirms that the collected water meets World Health Organization drinking water standards and requires no additional chemical filtration before use.

The development of the jacket coincides with another breakthrough from the same team, published in Nature Water. In that study, the researchers introduced a portable, solar-powered water-harvesting unit based on technology that earned first prize at the National Collegiate Inventors Competition in the US.

• Fog nets and fog harps: Relying on passive condensation, these setups use bio-inspired mesh or parallel arrays of vertical wires to catch water droplets in fog-heavy coastal or mountainous areas, such as projects deployed in Chile.
• Superabsorbent polymers and hydrogels: Materials researched by institutions like MIT capture atmospheric vapour even in dry air before releasing liquid water through solar heating.
• Nanomaterials and biomimetic crystals: Technologies such as Janus crystals or membranes inspired by desert beetle shells and cactus spines, engineered by teams at New York University, optimise passive condensation without requiring external power.

Just one caveat. While widespread municipal adoption remains unlikely, these technologies hold genuine potential as dependable lifelines for remote communities, emergency response teams, and travellers in arid regions.

Source:

• SciTech Daily