Kim said the project was inspired by a conference three years ago, but he and Leiber did not begin to work together until last year.
The tweezers consist of two carbon nanotubes connected to electrodes on nanometer-sized glass tubes. Voltages applied to the electrode open and close the tweezers, allowing them to pick up and drop molecules.
According to the Science paper, carbon nanotubes are suitable for building blocks of the tweezers because they continue to be tough and to conduct electricity at very small sizes.
Scanning probe microscopes, which can also be used to manipulate molecules, are inferior to nanotweezers because they only have a single probe that can move the molecules.
Much of Lieber's other research focuses on nanoscale projects like this. He could not be reached for comment yesterday.
Kim is now a post-doctoral student in chemistry at the University of California, Berkeley. He is working to extend these nanotechnologies to build electrical and mechanical devices that will manipulate molecules.