Nov 8 2022Reviewed by Alex Smith
An innovative approach for separating bonded nano-components has been developed by physicists from Friedrich Schiller University Jena and their colleagues from Düsseldorf, Gothenburg, Lyngby, and Trieste.
Dr Falko Schmidt uses a heatable microscope lens to separate nano components from one another. Image Credit: Anne Günther (University of Jena)
Their approach is completely submerging the nano-components in a solvent just before they become unstable. By altering the solvent’s temperature in the experimental setup, they could separate the components in a controlled manner. In the journal Nature Physics, scientists describe their fruitful experiment.
Components Separate at the Critical Point of the Solution
We were looking for a solution to eliminate the undesirable static friction of the individual components in a nano electromechanical system (NEMS) rubbing against each other.
Dr Falko Schmidt, Institute of Applied Physics, University of Jena
Related StoriesChemical Nano-Analytics with Nano-FTIRHow Do Nano-Tex Fabrics Work? - New TechnologyNano-Tex Fabrics Use Nanotechnology To Eliminate Stains - New ProductThis static friction is termed stiction—a combination of the words static and friction—and is created by quantum-electrodynamic Casimir forces. These forces are caused by variations and will always drive the components to stick together.
The researchers devised a technique to reverse this impact by submerging the components in a critical solution—a mixture of water and oil—in which fluctuations also occur. The temperature can be used to regulate the strength of these fluctuations accurately.
The special feature here is that we don’t suppress the original fluctuations, but replace them with other, much stronger ones.
Dr Falko Schmidt, Institute of Applied Physics, University of Jena
The experiment used a heatable microscope objective to produce the intended effect. The scientists held a gold nanoflake atop a structured metallic substrate. The gold flake would normally adhere to the substrate.
When the surrounding liquid reaches the critical point - the temperature range where water and oil segregate—the fluctuations are sufficiently powerful that stiction is averted. According to the research team, this could be so efficient that bonded components could be detached and made moveable again.
A Long Road to Solving an Obvious Problem
The tests were carried out by Dr. Falko Schmidt while he was still at the University of Gothenburg, where he also created fresh, experimental strategies that ultimately yielded positive results.
We quickly came up with the idea for this project, as this problem was clearly evident from nano-manufacturing.
Dr Falko Schmidt, Institute of Applied Physics, University of Jena
However, the path to the solution was arduous and winding. Controlling the critical Casimir effect with the quantum-electrodynamic Casimir effect finally prevailed.
The goal is to use the concept of freeing micro and nanoelectromechanical systems from mechanical friction in the future, allowing for the development of new and more effective function-oriented nano-components.
Journal Reference:
Schmidt, F., et al. (2022) Tunable critical Casimir forces counteract Casimir–Lifshitz attraction. Nature Physics. doi.org/10.1038/s41567-022-01795-6.
Source: https://www.uni-jena.de/en
