Anyone who wants to make nanoparticles visible has a problem: they are so small that they are usually invisible under an optical microscope. Researchers at the Karlsruhe Institute of Technology (KIT) have now developed a sensor with which they can not only detect nanoparticles, but also determine their composition and track their spatial movement.
The novel fiber-based Fabry-Pérot resonator, in which the highly reflective mirrors are located on the end surfaces of glass fibers, now offers the possibility of deriving the hydrodynamic radius of the particle, i.e. the thickness of the surrounding water shell, from the three-dimensional movement. Due to the hydrate shell, nanoparticles can also be detected that would be too small without this shell. The researchers see potential applications for their resonator in the future detection of three-dimensional movement with high temporal resolution and the characterization of the optical properties of biological nanoparticles, such as proteins, DNA origami or viruses.
