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November 17, 2022

Light Responsive Surfactants

Researchers at University of California, Santa Barbara have sent an experiment to the International Space Station National Lab looking at the boiling process. On Earth, bubbles dissipate, but in microgravity there are no forces to make that happen. Could light waves make that process occur?

Credit: U.S. National Science Foundation

ISS Projects – Light Responsive Surfactants

In your kitchen at home, when you boil something, the bubbles dissipate, but in microgravity there are no forces to make that happen. A project aboard the Cygnus NG-18 mission to the International Space Station is investigating ways to make that process occur. We'll explore in the U.S. National Science Foundation's "Discovery Files."

Most of the electricity produced in the United States is generated by boiling heat transfer. The process also plays roles in the heating and cooling of buildings, desalination, and distillation. Boiling heat transfer performance is directly related to the removal rate of bubbles generated during boiling.

This process is naturally driven by buoyancy; but it is difficult to control the size and frequency. If you could, it would significantly expand the achievable transfer rate, with the potential to improve the efficiency of power plants and reduce energy consumption.

Researchers from UC Santa Barbara aim to develop a new method to control, by exploiting liquids whose surface tension can be changed with light.

The microgravity environment of the ISS eliminates the interference of buoyancy, allowing a pure observation and understanding of this light-driven fluid motion.

Photo-responsive surfactants can reversibly switch their molecular conformation when illuminated with light, resulting in a tunable surface tension that can drive multi-phase fluid motion.

This light tuning method can be generalized to manipulate multi-phase fluid for applications including precision control in 3D printing and lab-on-a-chip microfluidics for biomedical and optical applications.

To hear more science and engineering news, including the researchers making it, subscribe to "NSF's Discovery Files" podcast.

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