Researchers have developed a simple, hand-cranked jar that uses nanoparticles to remove pathogens from drinking water in seconds, offering a solution for off-grid areas. The device activates through manual stirring, generating chemicals that destroy microbes without needing electricity or sunlight. It targets parasites, bacteria, viruses, and fungi, achieving high reduction rates in tests.
Xu Deng at the University of Electronic Science and Technology of China in Chengdu led the team in creating this proof-of-concept device to address challenges in decentralized water treatment. "We kept running into the same roadblock with decentralised water treatment," Deng explained. "Most point-of-use options either need electricity or strong sunlight, and they’re slow."
The invention features spherical silica nanoparticles coated with positively charged amine groups and gold nanoparticles that become negatively charged during stirring. Users add a small dose of this engineered powder to water in a jar with a crank handle. "A few turns of the handle creates gentle shear in the water and that motion ‘wakes up’ our nanoparticles," Deng said. This process generates reactive oxygen species on the nanoparticles' surfaces, which form electric charges and oxidize pathogens.
"Those reactive oxygen species punch holes in microbial membranes, so pathogens can’t survive or reproduce," Deng added. Once stirring stops, the powder settles, allowing clean water to be drawn from an outlet. The team tested it against 16 high-risk pathogens, achieving a 99.9999 percent reduction in Escherichia coli after 15 seconds of stirring at 50°C and the same for Vibrio cholerae in one minute. Overall, it inactivated more than 95 percent of tested microorganisms.
The particles are reusable after each cycle and provide hours of protection against recontamination. Costs are low, dominated by silica powder and plastic housing, with gold amounts insignificant. Chiara Neto at the University of Sydney praised the work: "It’s very clever, fantastic work." The findings appear in Nature Nanotechnology (DOI: 10.1038/s41565-025-02033-9). While promising for disaster zones and remote communities, the device has not yet been scaled to determine capacity per batch.