APCOM

It doesn't happen everyday that someone is able to overcome diffraction, one of the basic limits of physics. Doctor Roberto Cerbino, who works in the Department of Chemistry, biochemistry and biotechnologies of Milano's Università degli Studi, together with Lady Doctor Veronique Trappe from the Department of Physics at University of Fribourg, managed to do it by developing an innovatory technique of dynamic microscopy. The result of their study has been published on the 'Physical Review Letters', which since 1958, the year of its foundation, is among the most prestigious quarterlies of the field.

The technique, named Differential Dynamic Microscopy (DDM), allows to measure by using a conventional microscope the movement of those objects that are so small that it's not possible to locate them individually through a microscope. As a matter of fact, both if the objects are smaller than the resolution limit of the microscope and if they are too many to be followed individually, their trajectory can't be perceived. Besides, diffraction prevents from distinguishing two or more objects when they are too close.

Thanks to a refined analysis of digital images, however, DDM technique allows to extract the signal produced by the objects by separating it from all the spurious components and as a consequence to carry out an indirect measure of the nanoparticles' shape and dimensions. The method is unbelievably simple, as it just requires a white-lighted microscope and a camera. "I hope that its easiness will help DDM to spread throughout all those laboratories that are already using the necessary equipment," claimed Doctor Cerbino. The applications might be many: just to name a few, the indirect measure of nano-objects, the measure of cells' elastic properties and the characterization of the ageing state of yogurt and dairy products.