Model-Based Ultrafast High Resolution Nano-Interrogation

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Nanotechnology has the potential to revolutionize the human condition through fundamental contributionsto science and technology. The chances of realizing the full potential of nanotechnology have been buttressedby recent demonstrations of rational control and manipulation of matter at the atomic level. Yet, in spite ofthe remarkable feats achieved in its nascent years, nanotechnology has formidable challenges to overcome inthe areas of manufacturing methods, system design, and basic understanding. These challenges have to beovercome before the promise of this new paradigm becomes a reality.The goal of this proposal is to establish a paradigm for real-time use of models in Atomic Force Microscopy(AFM). The concept of using models in real-time has significant potential that has not received the deservedattention by atomic force microscopists as the related tools are primarily employed by engineers. Such aperspective facilitates interpretation of data since it provides a precise means of delineating the effects ofthe inherent dynamics of the system from the properties of the sample being probed. Thus it provides aneffective means of interpreting sample properties. In addition to the proposal goal of laying the foundationsof a new paradigm, specific aims of the proposal will result in a new ultrafast investigation tool for AFM,termed the Transient Force Detector (TFD). The prototype will yield hundred thousand features per seconddetection rates without compromising sample size and resolution. A particular advantage of the TFD is thatthe resolution of the detection process, dependent on the quality factor of the cantilever probe, is decoupledfrom the speed of the detection process. Issues of the loss of the probe signal and high resolution imagingbased on the likelihood that the probe is detecting the sample will be addressed. Use of models in realtimeis very well suited to explore model based imaging where a more detailed information is desired whencompared to detection. A finer characterization of the sample will result only if cantilever-sample interactionmodels amenable for real-time use are available. Based on averaging theory, a methodology is proposed toextract sample characteristics that include topography, local stiffness and local damping at the nanoscale.This includes a parallel operation where the sample characteristics will be gleaned by real-time models builton the results of the averaging analysis of the tip-sample dynamics. Observer theory based active modificationof the cantilever probe is presented. This systems viewpoint opens up new vistas for tailoring bandwidth,resolution and forces on the tip and sample. This enhanced flexibility is absent from the present set of toolson modifying the cantilever dynamics. The innovative methods to be developed in the proposed investigationwill be complemented by the existing and future experimental facilities. Preliminary proof of concept resultsindicate the vast potential of the model based imaging paradigm presented.Broader Impacts: Micro-cantilevers are being used in diverse areas with increasing impact and has in-fluenced science in a fundamental manner. The methods proposed are enabling technologies and will opendoors for investigating basic science issues by providing ultra-high bandwidth and resolution. The innovativecontributions of the proposals will directly impact most aspects of scanning probe microscopy, as the proposedmethods apply to most of the existing setups. For example, it will directly impact the extremely highdensity data storage (3 Tb/in2) and read out technologies as well as the array technologies employed by thebio industry. The experimental aspects of the proposed research will be accomplished in collaboration withAsylum Research, and Bioforce Nanosciences Inc. both leading biology related scanning probe microscope(SPM) company. This collaboration is expected to foster transfer of the theory and technology developedin this program between the academic institution of the PI and the SPM industry. The PI has successfullydisseminated the system and control theory viewpoints to the physics community that is heavily involved inscanning probe microscopy. Under this proposal goals the PI will continue to push the synergistic transfer ofknowhow between the two communities by exchanging student visits and presenting specialized workshops.A web based remote operation of SPMs is being explored by the PI in collaboration with Asylum Researchthat can be used for remote operation that will aid this effort.