A team of researchers from the Institute of Photonic Sciences (ICFO) in Barcelona has managed for the first time in history to capture and move a nano-object in 3D using only the force of light , thanks to nano-sized optical tweezers. The study has been published in the journal Nature Nanotechnology .
This technique “could revolutionize the field of nanoscience , since, for the first time, we have shown that it is possible to trap, manipulate in 3D and release a single nano-object without exerting any mechanical contact or other invasive action”, says Romain Quidant, ICREA professor and leader of ICFO’s Plasmon Nano-Optics group.
The researchers say that the problem is similar to if we imagine an elephant trying to catch a simple needle with its huge legs, which seems completely impossible. At the nanoscale, the elephants would be us, and the needle would be, for example, a single molecule. Our conventional means make us incapable of manipulating such extremely small objects, hence the use of laser light as a method to catch and manipulate objects in micrometric dimensions is so successful . The laser light focused on a small point creates an attractive force that draws the object to the place of focus.
The downside of this technique, invented in the 1980s, is that it was unable to catch objects smaller than a few hundred nanometers. To overcome this obstacle, the researchers have manufactured plasmonic nano-clamps with a mobile optical fiber at its end and a small gold aperture, which using a non-invasive laser with extremely small intensity, it is possible to manipulate in 3D very small samples, of barely a few tens of nanometers. The great potential of this technique resides in that both the capture and the monitoring of the trapped sample can be done through the optical fiber, so it could be used for many fields such as medicine or in the assembly of miniature electronic devices.
