A team of researchers at Virginia Tech has discovered a way to make surprisingly large puddles of water jump, a phenomenon previously limited to droplets of just a few millimeters in diameter. The breakthrough, published in in the journal Nature, relies on the bursting of bubbles trapped within the water, and could have implications for everything from self-cleaning surfaces to advanced 3D printing techniques.
The research, led by Associate Professor Jiangtao Cheng, builds on observations of nature. Ph.D. Student Wenge Huang, who grew up observing dew on lotus leaves in South China, noticed that air bubbles frequently become trapped within water droplets. When these bubbles burst, the droplets would often detach from the leaf surface with a noticeable force. Huang’s prior research, published in Nature Physics in 2024, explored bubble-driven droplet actuation, laying the groundwork for this latest investigation.
The team hypothesized that the energy released during bubble bursts could be harnessed to propel larger volumes of water than previously observed. Their experiments confirmed this, demonstrating that water puddles up to one centimeter in width could be made to jump when a bubble inside them burst, particularly on surfaces that repel water – similar to the lotus leaves that initially inspired the research. Crucially, the size of the bubble directly correlated with the height of the jump; larger bubbles resulted in more forceful propulsion.
The key to this phenomenon lies in the efficient transfer of energy. According to the study, approximately 90 percent of the energy released by the bursting bubble is directed downwards, impacting the base of the droplet. This focused energy input overcomes the force of gravity, allowing the larger droplets to jump. The researchers found that the impacting momentum of the capillary waves scales linearly with bubble radius, while the droplet jumping height scales quadratically.
Bubbles at Work: Potential Applications
The implications of this discovery extend far beyond a scientific curiosity. The ability to actively control droplet movement opens up a range of potential applications. One area is surface cleaning, where self-propelled droplets could remove contaminants without the need for external forces. The phenomenon also has relevance to condensation heat transfer and hydrogen production, offering potential improvements in efficiency.
the research sheds light on the design of anti-icing and anti-frosting surfaces. Understanding how droplets detach from surfaces can inform the development of materials that resist ice and frost buildup. The energy released during the bubble burst isn’t just used for propulsion; it can also be harnessed. The study notes that the motion generated without fuel could be used in small-scale energy harvesters, with larger droplets potentially increasing energy output.
Cheng’s team has also explored the potential of this technology for particle manipulation. Water’s inherent stickiness allows it to pick up particles as it moves. The team has previously investigated this principle for COVID-19 sensing, and the ability to move larger volumes of water could expand the capabilities of this type of biosensing.
Perhaps the most promising application lies in the field of 3D printing. The precise control offered by bubble-burst-induced jumping could enable the deposition of materials with unprecedented accuracy, particularly at the micro- and nano-scale. The researchers included examples of this application in their published study, demonstrating the potential for creating highly detailed 3D structures.
“We have achieved, for the first time, the passive jumping of water puddle in the unprecedented centimeter scale on lotus-leaf-like surfaces, which has never been accomplished and reported in previous works,” Cheng said. “Through studying the synergistic interplay between bubble bursting, fluidic jetting and droplet jumping, this work reveals a previously unexplored mechanism of water wave impact in fluid-structure interactions and offers a promising strategy for droplet actuations and the directional printing of particles in additive manufacturing.”
