More than thirty years ago, Bell Labs first proposed a device that used focused laser light to either attract or repulse objects. These devices have become known as optical tweezers and are now a key instrument in manipulating matter in both biology and quantum optic applications. But until recently, these devices couldn’t manipulate particles smaller than a few hundred nanometers.
The key technological breakthrough for enabling these optical tweezers to reach deeper into the nanoscale and become so-called “nanotweezers” has been plasmonics. Plasmonics is a field that exploits the surface plasmons that are generated when photons hit a metal structure. Those plasmons move along the surface of the material and create waves or oscillations of electrons.
Now researchers at the Indian Institute of Science (IISc) in Bangalore have added another wrinkle to plasmonics-based nanotweezers by integrating them with magnetic, helical microrobots to overcome some of the limitations these devices have had in trapping objects.