Fakhreddine Landolsi

Nanoscale Friction Dynamic Modeling

Friction and system models are fundamentally coupled. In fact, the success of models in predicting experimental results depends highly on the modeling of friction. This is true at the atomic scale where the nanoscale friction depends on a large set of parameters. This paper presents a novel nanoscale friction model based on the bristle interpretation of single asperity contact. This interpretation is adopted after a review of dynamic friction models representing stick-slip motion in macrotribology literature. The proposed model uses state variables and introduces a generalized bristle deflection. Jumping mechanisms are implemented in order to take into account the instantaneous jumps observed during 2D stick-slip phenomena. The model is dynamic and Lipchitz, which makes it suitable for future control implementation. Friction force microscope scans of a muscovite mica sample were conducted in order to determine numerical values of the different model parameters. The simulated and experimental results are then compared in order to show the efficacy of the proposed model.

An AFM-Based Nanomanipulation Model Describing the Atomic Two Dimensional Stick-Slip Behavior

A new AFM-based nanomanipulation model describing the relevant physics and dynamics at the nanoscale is presented. The nanomanipulation scheme consists of integrated subsystems that are identified in a modular approach. The model subsystems define the AFM cantilever-sample dynamics, the AFM tip-sample interactions, the contact mechanics and the friction between the sample and the substrate. The coupling between these different subsystems is emphasized. The main contribution of the proposed nanomanipulation model is the use of a new 2D dynamic friction model based on a generalized bristle interpretation of one asperity contact. The efficacy of the proposed model to reproduce experimental data is demonstrated via numerical simulations. In fact, the model is shown to describe the 2D stick-slip behavior with the substrate lattice periodicity. The proposed nanomanipulation model facilitates the improvement and extension of each subsystem to further take into account the complex interactions at the nanoscale.Copyright

Adhesion and Friction Coupling in Atomic Force Microscope-Based Nanopushing

The use of the atomic force microscope (AFM) as a tool to manipulate matter at the nanoscale has received a large amount of research interest in the last decade. Experimental and theoretical investigations have showed that the AFM cantilever can be used to push, cut, or pull nanosamples. However, AFM-based nanomanipulation suffers a lack of repeatability and controllability because of the complex mechanics in tip-sample interactions and the limitations in AFM visual sensing capabilities. In this paper, we will investigate the effects of the tip-sample interactions on nanopushing manipulation. We propose the use of an interaction model based on the Maugis–Dugdale contact mechanics. The efficacy of the proposed model to reproduce experimental observations is demonstrated via numerical simulations. In addition, the coupling between adhesion and friction at the nanoscale is analyzed.

A singular perturbation analysis and control of a new nanomanipulator

Recently, we proposed a new probe suitable for fabrication and manipulation at the nanoscale. The proposed design possesses three axis actuation and sensing capabilities. In addition, it can be incorporated into atomic force microscopes to turn them into reliable nanomanipulators. In the present paper, we use singular perturbation analysis techniques to develop a suitable control strategy of the probe motion. A fast control is used to eliminate undesired oscillations of the tip-holder whereas slow control is employed to reduce tip positioning errors. Path tracking simulations are conducted to validate the proposed control strategy. In addition, effects of stick-slip disturbances on the probe performance are investigated.

A New AFM Cantilever Design for Manipulation at the Nanoscale

Prototyping and fabrication of nanodevices require subnanometer tolerances and highly accurate sensing and actuation. Improved control on manipulating matter at the nanoscale is of relevance in different fields such as the automotive industry, biotechnology and communication. Limitations of existing nanomanipulation systems include constrained motion of manipulator end-effectors. In the present paper, a new AFM probe design suitable for nanomanipulation is proposed. The design includes a nanomanipulation piezotube that allows actuation and sensing of the tip motion in three directions. In addition, a piezopatch is attached to the cantilever holder for in-situ stiffness tuning needed for manipulating large and sticky nanosamples. Design considerations and path tracking performance of the proposed manipulator are analyzed.Copyright

Effect of Interaction Modeling in AFM-Based Nanomanipulation

AFM-based nanomanipulation is very challenging because of the complex mechanics in tip-sample interactions and the limitations in AFM visual sensing capabilities. In the present paper, we investigate the modeling of AFM-based nanomanipulation emphasizing the effects of the relevant interactions at the nanoscale. The major contribution of the present work is the use of a combined DMT-JKR interaction model in order to describe the complete collision process between the AFM tip and the sample. The coupling between the interactions and the friction at the nanoscale is emphasized. The efficacy of the proposed model to reproduce experimental data is demonstrated via numerical simulations.Copyright

Vibrational AFM-Based Nano-Placing: Modeling and Simulation

Bottom-up fabrication presents the potential applications of improved materials and highly effective devices. Matter at the microscale can be manipulated using micro-placing techniques that rely solely on surface forces. These techniques can be used on rough substrates and allow for fast manipulation. In the present paper, we will investigate generalizing these techniques to manipulate nanoscale samples. The use of dynamic oscillations of the manipulator is proposed to allow for controlled release at the nanoscale. The effects of the adhesion and sample mass on the manipulation outcome are investigated. Simulations are conducted to help select the amplitude and the frequency of the vibrations and to improve the accuracy of the manipulation.Copyright