Controlled manipulation of molecular samples with the nanoManipulator

Abstract

The nanoManipulator system adds a virtual-reality interface to an atomic-force microscope (AFM), thus providing a tool that can be used not only to image but also to manipulate nanometer-sized molecular structures. As the AFM tip scans the surface of these structures, the tip-sample interaction forces are monitored which in turn can yield information about the frictional, mechanical and topological properties of the sample. Computer graphics are used to reconstruct the surface for the user, with color or contours overlaid to indicate additional data sets. Moreover, by means of a force-feedback pen, which is connected to the scanning tip via software, the user can touch the surface under investigation to feel it and to manipulate objects on it. This system has been used to investigate carbon nanotubes, DNA, adeno- and tobacco-mosaic virus. Nanotubes have been bent, translated and rotated to understand their mechanical properties and to investigate friction on the molecular level. Using AFM lithography in combination with the nanoManipulator, the electro-mechanical properties of carbon nanotubes are being investigated. The rupture force of DNA has been measured and the elastic moduli of viruses are being studied. We discuss how some of the graphics and interface features of the nanoManipulator made these novel investigations possible.