Researchers find nanoscale humidity electricity
- Jun Yao and Xiaomeng Liu’s team at UMass Amherst reported in May 2023 that nanopores in many materials can harvest electricity from air humidity. (umass.edu) - The key design rule was pores smaller than 100 nanometers, which the researchers said lets water molecules create a charge imbalance across the film. (umass.edu) - The work appeared in Advanced Materials as “Generic Air-gen Effect in Nanoporous Materials for Sustainable Energy Harvesting from Air Humidity.” (nanowerk.com)
Researchers at the University of Massachusetts Amherst said a thin film filled with nanopores can generate a small, continuous electrical output from humidity in the air. The work, published in May 2023 in *Advanced Materials*, described what the team called a “generic Air-gen effect,” arguing that the mechanism should work across a broad range of inorganic, organic and biological materials, not just one specialized compound. (umass.edu) Jun Yao, an electrical engineer at UMass Amherst, said the idea grew out of earlier work showing electricity could be harvested from air with protein nanowires from *Geobacter sulfurreducens*. In the newer paper, Yao and colleagues said the broader requirement was not the specific material itself but the presence of nanoscale pores. (nanowerk.com) ### How is humidity supposed to make electricity here? The UMass Amherst team said the device uses a thin film whose top surface is exposed to air while the bottom is sealed. Water molecules move through the nanopores, but because the pores are extremely small, the molecules collide with the pore walls and create an uneven distribution of charge between the top and bottom of the film. (umass.edu) When electrodes connect the two sides, that charge difference produces current, according to Yao’s description of the mechanism. Jun Yao compared the effect to a cloud building up charge before lightning. He said the device can be thought of, in his words, as a small “man-made cloud,” though the output described in coverage of the work was only a fraction of a volt from a fingernail-sized prototype. (umass.edu) ### Why do the pores have to be so small? The researchers said the critical threshold is pores smaller than 100 nanometers. UMass Amherst said that cutoff matters because it is below the mean free path relevant to water molecules in air, so molecules are more likely to interact with the pore surfaces as they travel through the film. (advancedsciencenews.com) Xiaomeng Liu, the paper’s lead author, said that design rule opens the door to using many different materials. UMass Amherst and later summaries of the paper said nearly any material could in principle be used if it can be engineered with the right nanoporous structure. (umass.edu) ### Is this a brand-new field? Humidity-based electricity generation predates this paper. A 2020 *Nature* paper reported power generation from ambient humidity using protein nanowires, and later reviews have grouped such systems under moisture-enabled or humidity-driven energy harvesting technologies. The 2023 UMass Amherst paper’s claim was narrower and more specific: that the effect is generic across materials if the geometry is right. (umass.edu) That is the part that made the work notable and helped drive later coverage and renewed social-media attention. ### What are the limits of the claim right now? (umass.edu) The prototype described in news coverage produced only a small output, and outside researchers questioned how far the approach could scale. Smithsonian cited MIT materials chemist Donald Sadoway, who was not involved in the work, as saying it was not yet clear what practical power levels in watts or costs could be achieved. (nature.com) A 2026 review of humidity-driven energy harvesting said the field includes multiple mechanisms and materials, but it also framed durability, performance and scalability as central issues for real devices. That means the paper is best read as a mechanism and platform claim rather than proof of a ready-made power source for mainstream electronics. (umass.edu) ### So what should readers take from the “tiny artificial cloud” line? The “artificial cloud” comparison comes from Yao’s explanation, not from a claim that the device recreates weather. His point was that airborne water molecules can carry charge and that a controlled nanoscale structure can separate that charge in a predictable way. (smithsonianmag.com) The next place to look is the *Advanced Materials* paper, titled “Generic Air-gen Effect in Nanoporous Materials for Sustainable Energy Harvesting from Air Humidity,” and the follow-on review literature tracking humidity-driven energy harvesters. (nanowerk.com) (umass.edu) (pubs.rsc.org)
