Researchers at the University of Konstanz have introduced a groundbreaking, contact-free technique for efficiently removing liquids from delicate microscopic structures. This innovative method employs vapor condensation to create surface currents, effectively transporting droplets away from surfaces without causing damage. The findings were published in the journal Proceedings of the National Academy of Sciences on January 13, 2026.
Microchips, integral components of modern technology, rely heavily on microscopic elements that must be meticulously manufactured and cleaned. Many of these processes involve exposing surfaces to various liquids, which need to be entirely removed after production. The research team, led by Stefan Karpitschka, has developed a solution that uses the principle of surface tension to facilitate this delicate task.
Understanding Surface Tension and Its Impact
Surface tension is a property inherent to all liquids, varying significantly from one substance to another. For example, water’s surface tension allows small insects, such as the water strider, to traverse its surface. In microfabrication, however, even minimal tension can pose risks to fragile structures.
As Karpitschka explains, the production of microchips involves numerous intricate steps, some of which require wet processing. For instance, silicon wafers must undergo etching in acidic solutions, necessitating thorough drying afterward. “Due to the small size and sensitivity of these objects, traditional methods like wiping or boiling off residual liquids are not feasible,” he noted.
Innovative Fluid Dynamics in Action
To address the challenge of liquid removal, the researchers turned to a technique that harnesses the Marangoni force, which operates on the principle of surface tension differences. Karpitschka describes the process as a “tug-of-war” between areas of varying tension, enabling the liquid to be moved in a controlled manner.
In their experimental setup, the team introduced additional liquid—specifically, alcohol, which has a lower surface tension than water. This vapor condenses on existing liquids, creating the necessary tension differential that generates currents. “By directing these currents across the surface, we can consolidate the residual liquid into larger droplets for easier removal,” Karpitschka explained.
The resulting method draws parallels to how raindrops accumulate and slide down a windowpane, but with precise control over the droplets’ paths. This advancement holds potential for diverse applications in fields that utilize micropatterned surfaces, allowing for efficient drying without compromising the integrity of micro- and nanomaterials.
This research, led by Ze Xu and his team, not only enhances the production process of microchips but also paves the way for advancements in various technologies that depend on delicate microstructures. The innovative contact-free liquid removal technique represents a significant step forward in the optimization of micro-manufacturing processes, promising improved efficiency and reliability in producing high-tech materials.
