CAMBRIDGE, Mass — Two researchers at Harvard University have created a nanoscale grasping device ideal for measuring and manipulating molecular structures. Working in Harvard's division of engineering and applied sciences, Philip Kim and Charles Lieber equipped a scanning-probe microscope with carbon nanotube tips to form a tweezer-like structure.
The dual structure could add badly needed functionality to scanning-probe microscopes. For example, the tweezer structure can be closed with an applied electrical field to produce a device that grasps and moves molecules or atoms. The two-pronged tip can also be used to make direct electrical contacts to a specimen. Another application would be to use the structure for probing fluid motion by measuring the capacitive variations between the two tips as they move.
Nanotubes are specific carbon structures that grow in a spiral to create hollow tubes only 1 or 2 nanometers in diameter. The tubes are mechanically robust and are also good conductors of electricity, making them ideal for scanning-probe techniques. The method the Harvard researchers used allowed them to attach previously grown nanotubes to a gold electrode. An even finer version of the device is being considered, where the tubes would be directly grown on the gold electrodes using chemical vapor deposition.
