Scientists from RMIT University and the University of Melbourne have unveiled groundbreaking insights into the electrical properties of water, revealing that it generates an electrical charge up to 10 times stronger than previously understood when moving across surfaces.
This discovery, published in Physical Review Letters, could revolutionise surface design and pave the way for advancements in energy storage, fuel safety, and renewable technologies.
Led by Dr Joe Berry, Dr Peter Sherrell, and Professor Amanda Ellis, the research team observed a phenomenon known as “stick-slip” motion.
When water droplets encounter tiny bumps or rough spots on a surface, they build up force until they “jump or slip” past the obstacle, creating an irreversible electrical charge.
Unlike earlier assumptions that charge was generated only when liquid transitioned from wet to dry surfaces, this study shows that significant charge is created during initial contact, as water moves from dry to wet states — a process 10 times stronger than previously understood.
Dr Sherrell explained that while most people see rainwater dripping haphazardly on windows or car windscreens, few realise it generates small amounts of electrical charge.
“Importantly, this charge does not disappear.
“Our research shows it is generated at the interface and likely retained in the droplet as it moves,” he said.
The findings have far-reaching implications for industries reliant on fluid handling systems.
Dr. Berry highlighted the importance of understanding charge build-up in fuel containers, especially with the transition to renewable flammable fuels like hydrogen and ammonia.
“Electric shocks inside fuel containers could pose safety risks.
This knowledge may help us engineer coatings to mitigate charge build-up in new fuels,” he said.
Additionally, controlled electrification of surfaces could enhance energy storage devices by recovering electricity from liquid motion or speeding up charging rates.
The team conducted experiments using water droplets on Teflon (polytetrafluoroethylene), a common non-conductive material used in fluid systems.
They measured electrical charges ranging from 0 to 4.1 nanocoulombs (nC) during initial contact and observed oscillations between 3.2 and 4.1 nC as droplets alternated between wet and dry phases.
Specialised cameras captured individual frames of droplets sticking and slipping while simultaneous measurements tracked changes in charge.
PhD student Shuaijia Chen noted that while the generated charge is minuscule compared to everyday static shocks, its potential applications are significant.
“This discovery could lead to innovations enhancing or inhibiting charge creation in liquid-surface interactions across various industries,” he said.
The researchers plan to expand their studies to other liquids and surfaces to explore broader applications of stick-slip motion.
Potential areas include improving safety designs for fluid systems storing ammonia and hydrogen, as well as optimising energy recovery techniques.
Dr Sherrell pushes for collaboration with industry partners to translate these findings into commercial technologies, stating: “The rate and amount of charge generated by different materials may unlock new opportunities for practical applications.”
This breakthrough underscores the untapped potential of water’s electrical properties and its role in shaping future innovations in energy and safety systems.
