Technologies for the 21st Century nanoManipulator Surface Images

	The nanoManipulator project nanoManipulation of a 20 nM gold particle Adenovirus particles Circuit tuning experiments Mixed molecular monolayer Surface of a compact disc Germanium grown on silicon
The nanoManipulator project	The nanoManipulator project is now under way at the University of North Carolina (UNC) at Chapel Hill. The project is developing an improved, natural interface to scanning probe microscopes, including Scanning Tunneling Microscopes (STM) and Atomic Force Microscopes (AFM). The purpose of a nanoManipulator is to scale the STM or AFM environments (on the nanometer scale) up to the human environment (on the meter scale) so that the researcher can use a virtual reality interface to interact with the environment at the atomic level. The required level of magnification is impossible for conventional optical microscopes that project magnified images. The STM provides its information as an elevation map that is then interpreted and rendered by the graphics portion of the system.   The nanoManipulator interface was conceived through a collaboration between UNC-Chapel Hill and the University of California at Los Angeles (UCLA). The effort commenced in 1991 with the development of a system to control an STM. Experiments conducted in 1993 led to the discovery of nanoWelding. The team works closely with users in biology, solid-state physics, and gene therapy to develop techniques and displays they could use to solve problems in their fields. The following examples illustrate the wide range of new capabilities that nanotechnologies are enabling:
nanoManipulation of a 20 nM gold particle	To the right, nanomanipulation of a 20 nM gold particle is shown as a sequence of pushes that move a colloidal gold particle across a micron-size field and into a gap etched in a gold wire. Force feedback during the pushes makes it possible to move the ball without destroying it and to avoid patches of surface contaminant. The ball starts in the circled position on the upper left image. Yellow lines trace the path of the ball, showing where high force was used to push it. The particle ends up in the gap as depicted in the lower-right image. Taking the two ends of the wire out to external contacts will allow measurement of the particle's energy states.
Adenovirus particles	Collaborators at the UNC Gene Therapy center have used the nanoManipulator to examine adenovirus particles. Since these particles are used as gene-delivering vectors in gene therapy, there is considerable scientific interest in learning how these particles stick to and move around on cell surfaces. A preliminary experiment, illustrated to the right, shows that particles have been moved around on a cleared area of mica substrate. The virus particles themselves were manipulated by pushing them together and pulling them apart.
Circuit tuning experiments	To perform an experiment in circuit tuning, the nanoManipulator was first used to cut a small gap in a 1-micron wire (shown to the right) while the impedance of the wire was measured. Once the impedance was infinite, the removed piece of wire was pushed back into the gap to tune the impedance from about 100 to about 1,000 Ohms. The wire in this image runs from the lower left to the upper right. The square in the center was machined first (leaving "snow piles" along the edges). Then the small gap in the upper left corner was formed, and finally the gap in the lower right corner. White contour lines indicate constant-height curves on the wire.
Mixed molecular monolayer	Three data sets of a mixed molecular monolayer of perfluorooctadecanoic acid and tetracosanoic acid deposited on mica are shown to the left. Color depicts the lateral friction of the sample with yellow areas indicating high friction and red low. The white lines are contours separating areas of high vertical adhesion from areas of low adhesion. The data sets on this one-square-micron sample were obtained by scanning with a Topometrix atomic-force microscope. The adhesion data set is misaligned and distorted because it was obtained on a separate, slower pass over the sample.
Surface of a compact disc	This image is a 5-micron area of the surface of a compact disc, with tracks running from the upper left to the lower right. The lateral force of the probe tip was measured along with the topography. A checkerboard pattern has been inlaid on the surface to indicate lateral force: areas of high force have a strong pattern, while areas with less force display no pattern. The researchers plan to use image and bump-map textures, together with color and contour lines, to indicate multiple data sets simultaneously. The PixelFlow graphics engine will enable them to do this rendering in real time.
Germanium grown on silicon	This image highlights germanium pyramids and domes grown on silicon. Color is from curvature information, using the black-body radiation spectrum. The gridlines are drawn on 100 nM boundaries. To the right is a close-up view of the preceding image, magnified and viewed from a different angle. The numbers show the distance in the plane and are vertical to the plane, indicating relative heights of the two bumps. These visualizations were performed for Hewlett-Packard's science labs.