By remotely heating water over a metal sheet with a laser, Leipzig University researchers were able to move minuscule volumes of liquid at will. The currents generated in this process can be utilized to manipulate and even capture small things.
Illustration of a gold nanoparticle trapped near a locally heated gold surface by hydrodynamic and van der Waals forces. Image Credit: Martin Fränzl/Leipzig University.
This finding will open the door to ground-breaking new solutions in nanotechnology, liquid manipulation in small systems, and diagnostics by allowing new types of sensor systems to detect the tiniest quantities of chemicals.
Martin Fränzl and Professor Frank Cichos of Leipzig University’s Faculty of Physics and Earth Sciences describe how this was accomplished in a recent paper published in the high-impact journal “Nature Communications.”
Martin Fränzl and Professor Frank Cichos have discovered that by burning a very thin metal sheet on one side of the channel with a concentrated laser beam, they can produce very powerful fluid flows even in the smallest of channels.
The flows emerge from an ultra-thin liquid layer, a few nanometers above the metal’s surface, and mix the liquid in the channel in a precise flow pattern. Fränzl used nanoparticles as tracers to measure the flow pattern.
The researchers not only discovered the source of these currents, but they also demonstrated that by intelligently mixing currents and regulating other forces—remotely—using lasers, they can catch, separate, and transport nano-objects.
This is fascinating, because it allows us to control how objects and fluids move at the nanoscale without moving the entire fluid in the channels.
Martin Fränzl, Faculty of Physics and Earth Sciences, Leipzig University
Similar methodologies are already being used to explore the production of protein aggregates implicated in the development of neurodegenerative illnesses in a project managed by the joint Transregio/Collaborative Research Centre 102 at Martin Luther University Halle-Wittenberg and Leipzig University.
Both researchers are especially interested in combining this laser-driven thermofluidic with machine learning techniques to create automated smart nanofactories—for nanoscale manufacturing, programmed material manipulation, and sensor technologies—that can optimize and adapt to new requirements based on the data they collect.
We believe that thermofluidics will help us develop new technologies and solutions that may be highly useful for new collaborative projects such as the µChem initiative, which combines physics, chemistry, biochemistry, and artificial intelligence in microenvironments.
Detlev Belder, Professor, Institute of Analytical Chemistry, Faculty of Chemistry and Mineralogy, Leipzig University
This opens the possibility of lab-on-a-chip applications.
The approach was created in partnership with b-ACTmatter, the Interfaculty Centre for Bioactive Matter, which is supported by the federal STARK program. STARK was established to aid in the restructuring of coal-mining districts. The goal of b-ACTmatter is to create new materials and technologies that contribute to an economy that is inventive, sustainable, and circular.
Journal Reference:
Fränzl, M & Cichos, F (2022) Hydrodynamic manipulation of nano-objects byoptically induced thermo-osmoticflows. Nature Communications. doi.org/10.1038/s41467-022-28212-z.