Award Abstract #0216347
Acquisition of a Virtual Presence Surface Profiling Microscope for Nanomanipulation and Nanoassembly

NSF Org:	ECCS Division of Electrical, Communications and Cyber Systems
Initial Amendment Date:	August 6, 2002
Latest Amendment Date:	April 20, 2004
Award Number:	0216347
Award Instrument:	Standard Grant
Program Manager:	Lawrence S. Goldberg ECCS Division of Electrical, Communications and Cyber Systems ENG Directorate for Engineering
Start Date:	August 15, 2002
Expires:	July 31, 2005 (Estimated)
Awarded Amount to Date:	$159553
Investigator(s):	Robert Cohn rwcohn@uofl.edu (Principal Investigator) Mahendra Sunkara (Co-Principal Investigator) Bruce Alphenaar (Co-Principal Investigator) Francis Zamborini (Co-Principal Investigator)
Sponsor:	University of Louisville Research Foundation Inc 2301 S. Third St. Louisville, KY 40208 502/852-8367
NSF Program(s):	ELECT, PHOTONICS, & DEVICE TEC, MAJOR RESEARCH INSTRUMENTATION
Field Application(s):	0206000 Telecommunications
Program Reference Code(s):	OTHR, 9251, 9150, 7237, 0000
Program Element Code(s):	1517, 1189

ABSTRACT

Abstract

Since the invention of the scanning tunneling microscope (STM) in 1982 and the atomic force microscope (AFM) in 1986 there have been many vivid demonstrations of nanometer, molecular and even atomic -scale manipulation. Performing such experiments usually is non-trivial, tedious and labor intensive. Probably the most critical limitation to the wider use of nanometer-scale manipulation with commercial scanning probe microscopes (SPM) is their lack of real-time, interactive feedback. With current SPM's an object is found by scanning the surface to produce an image. Then the tip is positioned on or near the object. Mechanical forces are applied to move the object by typing in a tip motion command. The result of the operation is evaluated by re-imaging. This tedious procedure may need to be repeated countless times to achieve the objective (of say. bringing two nanoparticles on a surface into contact.) The SPM electronics do provide signals that could be used to make this process more interactive: however, traditional SPM interfaces are designed primarily to scan and collect an image, which can delay access to a single image data set by a few minutes. A related problem is that sight is not the best sense to use for all applications. For instance, even when two nanoparticles appear to be touching in the scanned image, they might instead be separated by a gap smaller than the width of the probe tip. Using the sense of touch it might be possible to feel when the particles are engaged. The increasing value and importance of nanometer-scale manipulation and assembly, both in fundamental and applied research, requires SPM interfaces that provide real-time interactivity.

A University of North Carolina research group developed the first such commercial interface to a SPM, which in now being marketed through 3rdTech. Inc. The interface provides the operator a "virtual presence" on the surface of the sample. The operator views the surface topography in three dimensions from a chosen perspective, illumination and shading. A six degrees of freedom joystick is used to position the tip and manipulate objects on the sample surface. The operator can scan the tip over the surface in a non-perturbing "tapping mode" and feel the topography through the joystick. Then the SPM is switched to "contact mode" to apply prescribed forces (again, through the joystick) to move or modify the object. Force versus position of the manipulation is recorded to provide a quantitative understanding of the effect of (either in-plane or out-of-plane) forces applied to the object. Thus, the force-feedback or "haptic" interface enables the operator to find objects on the surface, to correct for thermal drifts and hysteresis in the piezoscanner in-real time, and to immediately determine the positional change after a manipulation. This tactile sense, in particular, greatly enhances the capabilities of the SPM as a nanomanipulation tool. Accelerated three-dimensional image rendering further assists the operator in viewing objects as they are moved or modified.

The virtual presence SPM has been used to find the seam between two nanotubes and then to separate the nanotubes by pressing on the seam. Also, this SPM has been used to qualitatively feel (and also quantitatively measure) differences in how smoothly a nanotube rolls as it is pushed in different directions on a graphite surface. This result reflects the degree to which the atomic lattices of the graphite and the nanotube mesh. The virtual presence interface greatly enhances intuition, which is essential for using the SPM for fundamental discovery and for simplifying the custom assembly and fabrication of nanostructures.

A 3rdTech virtual presence SPM will be acquired and installed. It will be used regularly in several ongoing research studies, in a hands-on laboratory class in nanotechnology practice, and in outreach presentations to secondary schools and the general public. The instrument will significantly enhance the capabilities of the proposers to measure electronic and mechanical properties of nanotubes, nanowires, nanoparticles and biological materials, and to construct networks, clusters and suspended structures with these materials. General interest demonstrations of the instrument will vividly illustrate the current abilities of man to probe, interact with, and manipulate the nanoworld. These outreach activities can profoundly influence more students to pursue education in scientific disciplines and promote increased public support of science.

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