Researchers from Penn State University suggested an approach of using freely-suspended nanoparticles to generate fluid pumping towards desired point sources
The field of active matter facilitates development of various applications in particle assembly, cargo and drug delivery, and sensing. Nanomotors, fluid pumps, and particle assembly strategies aid in development of these applications. However, there are several challenges in the field of active matter, especially for mechanisms that depend on chemical propulsion. One of the way to address the issue is by the use of external energy sources. Now, a team of researchers from Penn State University proposed a method of using freely suspended nanoparticles for generating fluid pumping towards desired point sources. The research was published in the journal Angewandte Chemie International Edition on December 13, 2018.
According to the researchers, the pumping rates rely on particle concentration and light intensity, which makes it highly controllable. The team used these directed flows to demonstrate the ability to reversibly construct and move colloidal crystals. According to Ayusman Sen, Distinguished Professor of Chemistry at Penn State and senior author of the paper, the method is simple and inexpensive and can improve drug delivery, chemical sensors, and fluid pumps. Moreover, the method encourages particles to gather and organize at a specific location within a liquid and. The particles can also be moved to new locations as desired.
The method initially involves adding a small amount of titanium dioxide or gold nanoparticles to a liquid that contains larger particles such as pollutants carrying a payload. A light is shone at a specific point in the liquid to heat up the metal nanoparticles. The heat is later transferred to the fluid and the warmer liquid then rises at the point of light and cooler water rushes in to fill the space vacated by the warm water and carries the larger particles with it. The larger particles randomly diffuse through the liquid when the light is removed. However, when the light is instead relocated, the larger particles move toward the new point of light and maintain their structure. Such dynamic assembly, disassembly, and movement of organized particles is expected to be a major implication for sensing and drug delivery.