Nanotech Tool: Electron Beam Used to Trap Gold Nanoparticles

By using an electron beam, researchers from Berkeley Lab and the National University of Singapore have developed a way to manipulate nanoparticles.

They used an electron beam from a transmission electron microscope to trap gold nanoparticles and direct their movement, and to assemble several nanoparticles into a tight cluster.

The scientists intended to find a new tool for nanotechnology, and believe their approach could indeed lead to a new way to build nanostructures one nanoparticle at a time.

The research was co-led by Haimei Zheng of Berkeley Lab's Materials Sciences Division. She and her team began by sandwiching a particle of gold with a 10 nm diameter between two transparent silicon nitride membranes.

This liquid-filled sandwich, known as an environmental cell, which was also created by the Lab, enables objects to be imaged with a transmission electron microscope at a sub-nanometer resolution.

They passed the electron beam through the cell and trapped the nanoparticle in the beam. The nanoparticle wildly bounced within the beam, but never escaped its confines.

When they moved the beam in any direction at a speed of about ten nanometers per second, the trapped nanoparticle was dragged across the membrane surface.

The researchers also managed to clump several gold nanoparticles together, by trapping them all inside the beam and then rapidly decreasing the diameter of the beam from 200 nanometers to 50 nanometers. They then again moved the new cluster of nanoparticles over the membrane surface by moving the electron beam.

Zheng and colleagues are now working to understand how the electron beam traps the nanoparticles. They also want to develop ways to automate the positioning and movement of nanoparticles, which is a key step toward the fast and efficient assembly of nanostructures.