Recent research reveals that electrically charged liquid drops do not splash upon hitting a surface, a phenomenon that contrasts with neutral drops. This blog explores the mechanics behind this discovery, the experiments conducted, and its implications in various fields.
When a liquid drop is charged to a few thousand volts, it exhibits a fascinating behavior: it does not splash upon hitting a hard surface. This blog post delves into the recent discovery that electrically charged drops do not splash, contrasting sharply with the behavior of neutral drops. We will explore the mechanics behind this phenomenon, the experiments conducted to observe it, and its broader implications.
In a previous video, I discussed a remarkable phenomenon where a drop of liquid in a vacuum does not splash when it hits a hard surface; instead, it simply wets the surface. This discovery, made in 2005, was intriguing, but the story did not end there. In April 2025, a novel paper was published revealing that electrically charged drops also do not splash. This prompted me to investigate further: Do charged drops really avoid splashing, and if so, why?
To explore this question, I decided to conduct an experiment using my Whimsurst machine, a device capable of generating high static charges. By carefully controlling the voltage, I aimed to charge drops of isopropyl alcohol as they exited a syringe. The setup involved connecting one electrode to a needle and the other to a copper ring, which helped direct the charged drops as they fell.
The challenge was to charge the drops just enough to prevent them from spraying into a fine mist, which occurs when the charge is too high. After several trials, I managed to create a charged drop that would fall without breaking apart. I filmed both neutral and charged drops falling from a height of 400 millimeters to compare their behavior upon impact.
When a neutral drop hit the surface, it created a significant splash. In stark contrast, the charged drop fell without producing any splash at all. This was consistent regardless of whether the drop was positively or negatively charged. The results were astonishing: even a slight charge on the drop eliminated the splash.
The research paper I referenced indicated a clear correlation between the amount of charge on the drop and the splash produced. Specifically, drops with less than 0.1 nanocoulombs (nC) of charge did not splash. This leads us to the question: why does this happen?
As a drop impacts a surface, a lifting lamella forms due to trapped air beneath the liquid. In neutral drops, this lamella spreads out, leading to the formation of tiny droplets and a splash. However, in charged drops, an additional force comes into play. The charges on the drop are attracted to the surface, particularly when the surface is a dielectric material like glass. This attraction pulls the lamella down, allowing the drop to glide across the surface without creating air pockets, thus preventing a splash.
To further investigate, I dropped a charged drop onto a conductive surface, such as a metal plate. Contrary to the previous results, the charged drop splashed upon impact. This indicated that the charge dissipated upon contact with the conductive surface, allowing the lamella to spread and create a splash as it would with a neutral drop.
This discovery has significant implications across various fields. For instance, raindrops during thunderstorms carry some charge, which could influence how they spread mold spores upon impact. Similarly, understanding the behavior of charged droplets can enhance the efficiency of inkjet printers, where droplets are often charged to control their placement.
The findings suggest that the amount of static charge on droplets can complicate our understanding of splashing behavior. This raises questions about other scenarios where charge plays a role, such as in medical sprays or aerosol delivery systems. The ability to control splashing through charge manipulation could lead to advancements in these areas.
The recent discovery that electrically charged drops do not splash opens up new avenues for research and application. As we continue to explore the implications of this phenomenon, it is essential to consider how charge affects not only the behavior of liquids but also their interactions in various environments. I encourage readers to think about other potential applications of this knowledge and share their thoughts in the comments.
Thank you for joining me in this exploration of the science behind electrified drops. If you found this information enlightening, consider subscribing for more fascinating insights into the world of science.
