A research team from Brave Analytics GmbH, in collaboration with a colleague from the Gottfried-Schatz Research Center and another from the Institute of Physics, all in Austria, has developed a device capable of characterizing nanoparticles in real time. The group published their work in the journal Physical review applied.
In recent decades, product engineers have increasingly added nanoparticles to products to give them desired properties – for example, to thicken or color paints. The types of nanoparticles used depend on many factors, such as their composition and shape, which are generally easy to determine. The size of the nanoparticles is also important to ensure consistency, but figuring out how big they are has proven to be more difficult. An approach called dynamic light scattering has been found to work well, but only with tiny nanoparticles. In this new experiment, the researchers created a device that can be used to determine the size of larger nanoparticles.
The new device is based on optofluidic force induction (OF2i). It consists of a transparent cylinder and a laser beam. In use, the cylinder is filled with water to which sample nanoparticles have been added – in this case, tiny bits of polystyrene. The laser is fired in such a way that the light spirals through the water, forming a whirlpool.
The laser light is used in two ways: to push the nanoparticles through the water and to track their movement. In such a setup, the acceleration experienced by a particular nanoparticle depends on its size. The researchers suggest that it resembles a sailboat. Two boats of the same size will be pushed at different speeds in the same wind force if they have different sized sails. And because the laser forms a vortex, the nanoparticles move in a spiral, making collisions less likely.
The light scattered after the nanoparticle bounces off can then be viewed with a time-lapse microscope, which can visualize the trajectories of the individual nanoparticles. By analyzing the shape of such trajectories, changes in velocity caused by the force exerted by the laser can be determined, thus revealing the size of the nanoparticles. Tests have shown that the device can measure nanoparticles in the range of 200 to 900 nm.
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Marko Šimić et al, Real-time nanoparticle characterization by optofluidic force induction, Physical review applied (2022). DOI: 10.1103/PhysRevApplied.18.024056
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Citation: Optofluidic force induction enables real-time characterization of nanoparticles (2022 September 9) Retrieved September 9, 2022 from https://phys.org/news/2022-09-optofluidic-induction-real-time-nanoparticle- characterization.html
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