Calibration and Nonlinearity Compensation for Force Application in AFM based Nanomanipulation

Abstract — Both the extent and accuracy of force application in atomic force microscope (AFM) nanomanipulation are significantly limited by the nonlinearity of the commonly used optical lever with a nonlinear position-sensitive detector (PSD). In order to compensate the nonlinearity of the optical lever, a nonlinear calibration method is presented. This method applies the nonlinear curve fit to a full-range position-voltage response of the photodiode, obtaining a continuous function of its voltagerelated sensitivity. Thus, Interaction forces can be defined as integrals of this sensitivity function between any two responses of photodiode voltage outputs, instead of rough transformation with a single conversion factor. The lateral position-voltage response of the photodiode, a universally acknowledged puzzle, was directly characterized by an accurately calibrated force sensor composed of a tippless piezoresistive force sensor, regardless of any knowledge of the cantilevers and laser measuring system. Experiments using a rectangular cantilever (normal force constant 0.24 N/m) demonstrated that the proposed nonlinear calibration method restrained the sensitivity error of normal position-voltage responses to 3.6 % and extended the force application range. Index Terms — Atomic force microscope, nanomanipulation, force calibration, nonlinearity compensation. I

Block Phase Correlation-Based Automatic Drift Compensation for Atomic Force Microscopes

Automatic nanomanipulation and nanofabrication with an Atomic Force Microscope (AFM) is a precursor for nanomanufacturing. In ambient conditions without stringent environmental controls, nanomanipulation tasks require extensive human intervention to compensate for the many spatial uncertainties of the AFM. Among these uncertainties, thermal drift is especially hard to solve because it tends to increase with time and cannot be compensated simultaneously by feedback. In this paper, an automatic compensation scheme is introduced to measure and estimate drift. This information can be subsequently utilized to compensate for the thermal drift so that a real-time controller for nanomanipulation can be designed as if drift does not exist. Experimental results show that the proposed compensation scheme can predict drift with a small error. Future work is aimed at reducing the error even further through temperature feedback. Keywords - nanomanipulation, Atomic Force microscope, drift, Phase-Correlation Method, Neural Networ

Automatic Drift Compensation Using Phase Correlation Method for Nanomanipulation

Nanomanipulation and nanofabrication with an atomic force microscope (AFM) or other scanning probe microscope (SPM) are a precursor for nanomanufacturing. It is still a challenging task to accomplish nanomanipulation automatically. In ambient conditions without stringent environmental controls, the task of nanomanipulation requires extensive human intervention to compensate for the spatial uncertainties of the SPM. Among these uncertainties, the thermal drift, which affects spatial resolution, is especially hard to solve because it tends to increase with time, and cannot be compensated simultaneously by feedback from the instrument. In this paper, a novel automatic compensation scheme is introduced to measure and estimate the drift one-step ahead. The scheme can be subsequently utilized to compensate for the thermal drift so that a real-time controller for nanomanipulation can be designed, as if the drift did not exist. Experimental results show that the proposed compensation scheme can predict drift with a small error, and therefore, can be embedded in the controller for manipulation tasks

MICROCANTILEVER-BASED FORCE SENSING, CONTROL AND IMAGING

This dissertation presents a distributed-parameters base modeling framework for microcantilever (MC)-based force sensing and control with applications to nanomanipulation and imaging. Due to the widespread applications of MCs in nanoscale force sensing or atomic force microscopy with nano-Newton to pico-Newton force measurement requirements, precise modeling of the involved MCs is essential. Along this line, a distributed-parameters modeling framework is proposed which is followed by a modified robust controller with perturbation estimation to target the problem of delay in nanoscale imaging and manipulation. It is shown that the proposed nonlinear model-based controller can stabilize such nanomanipulation process in a very short time compared to available conventional methods. Such modeling and control development could pave the pathway towards MC-based manipulation and positioning. The first application of the MC-based (a piezoresistive MC) force sensors in this dissertation includes MC-based mass sensing with applications to biological species detection. MC-based sensing has recently attracted extensive interest in many chemical and biological applications due to its sensitivity, extreme applicability and low cost. By measuring the stiffness of MCs experimentally, the effect of adsorption of target molecules can be quantified. To measure MC\u27s stiffness, an in-house nanoscale force sensing setup is designed and fabricated which utilizes a piezoresistive MC to measure the force acting on the MC\u27s tip with nano-Newton resolution. In the second application, the proposed MC-based force sensor is utilized to achieve a fast-scan laser-free Atomic Force Microscopy (AFM). Tracking control of piezoelectric actuators in various applications including scanning probe microscopes is limited by sudden step discontinuities within time-varying continuous trajectories. For this, a switching control strategy is proposed for effective tracking of such discontinuous trajectories. A new spiral path planning is also proposed here which improves scanning rate of the AFM. Implementation of the proposed modeling and controller in a laser-free AFM setup yields high quality image of surfaces with stepped topographies at frequencies up to 30 Hz. As the last application of the MC-based force sensors, a nanomanipulator named here MM3A® is utilized for nanomanipulation purposes. The area of control and manipulation at the nanoscale has recently received widespread attention in different technologies such as fabricating electronic chipsets, testing and assembly of MEMS and NEMS, micro-injection and manipulation of chromosomes and genes. To overcome the lack of position sensor on this particular manipulator, a fused vision force feedback robust controller is proposed. The effects of utilization of the image and force feedbacks are individually discussed and analyzed for use in the developed fused vision force feedback control framework in order to achieve ultra precise positioning and optimal performance

Characterizing piezoscanner hysteresis and creep using optical levers and a reference nanopositioning stage.

International audienceA method using atomic force microscope (AFM) optical levers and a reference nanopositioning stage has been developed to characterize piezoscanner hysteresis and creep. The piezoscanner is fixed on a closed-loop nanopositioning stage, both of which have the same arrangement on each axis of the three spatial directions inside the AFM-based nanomanipulation system. In order to achieve characterization, the optical lever is used as a displacement sensor to measure the relative movement between the nanopositioning stage and the piezoscanner by lateral tracking a well-defined slope with the tapping mode of the AFM cantilever. This setup can be used to estimate a piezoscanner's voltage input with a reference displacement from the nanopositioning stage. The hysteresis and creep were accurately calibrated by the method presented, which use the current setup of the AFM-based nanomanipulation system without any modification or additional devices

Nanotribology and electrical properties of carbon nanotubes hybridized with covalent organic frameworks

Nanomanipulation of molecular materials such as carbon nanotubes (CNTs) or new covalent organic frameworks (COFs) is key not only for the study of their fundamental physicochemical properties, but also for building and probing nanodevices. Therefore, we have investigated the tribological properties of oxidized MWCNTs (ox-MWCNTs) and their hybridization with COF building blocks (ox-MWCNTs@COF) adsorbed on a mica surface. We used the AFM tip to apply torsional forces on individual nanotubes. Depending on the manipulation parameters, the lateral displacements of the AFM tip slide and/or bend nanotubes enabling the direct quantification of the nanotube-mica adhesion. We found striking changes in the behaviour of the lateral force needed to manipulate each carbon nanotube variant which indicates an increased adhesion of ox-MWCNTs@COF with respect to ox-MWCNTs (∼10x). In addition, the use of the AFM tip as a mobile electrode enabled the measurement of electrical transport through individual nanotubes that revealed a rectifying behaviour of the ox-MWCNTs@COF with high resistivity, which was in contrast with the near ohmic performance of ox-MWCNTsP. J.d.P. acknowledges support by grants from the Ministerio de Ciencia e Innovacion (FIS2017- 89549-R; “Maria de Maeztu” Program for Units of Excellence in R&D MDM2014-0377; and FIS2017-90701- REDT) and the Human Frontiers Science Program (HFSPO RGP0012/ 2018). R. M. ackowledges support by grant PID2019-110637RB-10

Crystallographic influences on the nanomanipulation of gold nanoclusters on molybdenum disulfide

This work investigates the manipulation behavior of thermally deposited gold nanoclusters with tens of nanometers in size on monocrystalline Molybdenum Disulfide (MoS2) surfaces. Using scan raster patterns in the order of several m, dozens of Au islands can be displaced with a single scan, revealing a directional locking effect caused by the epitaxial nature of the nanoparticle growth on the MoS2 surface. Statistical analysis of tapping mode manipulation scans using pyramidal and conical AFM tips along with MD simulations lead to the conclusion that frictional anitrosopy governs the direction of displacement, with the preference to move along the zigzag- or armchair direction of the hexagonally structured surface. It further investigates the manipulation behavior on CVD grown mono- and bilayer MoS2 with the goal of formation of gold nanowires. For this several nanomanipulation and nanoscratching techniques are deployed to exploit the unique movement behavior of gold islands on a crystalline surface

A force feedback haptic interface for atomic force microscopy

Integrating a force feedback haptic device with atomic force microscopy (AFM) improves the capability to investigate and manipulate the objects on a micro- and nanoscale surface. The haptic device provides the researcher with a sense of touch and movement by changing the position of the stylus or amount of force on it. The developed system\u27s concept is to provide the user a sense and feel and control of the AFM probe at the nanoscale. By positing the haptic stylus, the user generates reference to commands to the AFM probe. In turn, forces experienced by the probe are communicated to the haptic and transferred to the user. In order to ensure that the forces that act on the haptic and the probe are accurate, it is important to calibrate the normal and lateral forces that act on the tip of the probe. These forces are generated due to using a contact mode interaction between the probe tip and the sample surface. The haptic-probe coupled motion is tested to reach the desired results. Also, a low pass filter is used to remove the undesirable high frequency content from the input force to the haptic since it affects the interaction between the probe s tip and the sample s surface. To close, the sensitivities of haptic to the probe position, and displacement of the probe to the force on the haptic are discussed --Abstract, page iii