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

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

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

Multi-Sensorial Interface for 3D Teleoperation at Micro and Nanoscale

International audienceThis paper presents the design of a new tool for 3D manipulations at micro and nanoscale based on the coupling between a high performance haptic system (the ERGOS system) and two Atomic Force Microscope (AFM) probes mounted on quartz tuning fork resonators, acting as a nano tweezers. This unique combination provides new characteristics and possibilities for the localization and manipulation of (sub)micronic objects in 3 dimensions. The nano robot is controlled through a dual sensorial interface including 3D haptic and visual rendering, it is capable of performing a number of real-time tasks on different samples in order to analyse their dynamic effects when interacting with the AFM tips. The goal is then to be able to compare mechanical properties of different matters (stiffness of soft or hard matter) and to handle submicronic objects in 3 dimensions

Haptic feedback in teleoperation in Micro-and Nano-Worlds.

International audienceRobotic systems have been developed to handle very small objects, but their use remains complex and necessitates long-duration training. Simulators, such as molecular simulators, can provide access to large amounts of raw data, but only highly trained users can interpret the results of such systems. Haptic feedback in teleoperation, which provides force-feedback to an operator, appears to be a promising solution for interaction with such systems, as it allows intuitiveness and flexibility. However several issues arise while implementing teleoperation schemes at the micro-nanoscale, owing to complex force-fields that must be transmitted to users, and scaling differences between the haptic device and the manipulated objects. Major advances in such technology have been made in recent years. This chapter reviews the main systems in this area and highlights how some fundamental issues in teleoperation for micro- and nano-scale applications have been addressed. The chapter considers three types of teleoperation, including: (1) direct (manipulation of real objects); (2) virtual (use of simulators); and (3) augmented (combining real robotic systems and simulators). Remaining issues that must be addressed for further advances in teleoperation for micro-nanoworlds are also discussed, including: (1) comprehension of phenomena that dictate very small object (< 500 micrometers) behavior; and (2) design of intuitive 3-D manipulation systems. Design guidelines to realize an intuitive haptic feedback teleoperation system at the micro-nanoscale level are proposed

AFM-Based Mechanical Nanomanipulation

Advances in several research areas increase the need for more sophisticated fabrication techniques and better performing materials. Tackling this problem from a bottom-up perspective is currently an active field of research. The bottom-up fabrication procedure offers sub-nanometer accurate manipulation. At this time, candidates to achieve nanomanipulation include chemical (self-assembly), biotechnology methods (DNA-based), or using controllable physical forces (e.g. electrokinetic forces, mechanical forces). In this thesis, new methods and techniques for mechanical nanomanipulation using probe force interaction are developed. The considered probes are commonly used in Atomic Force Microscopes (AFMs) for high resolution imaging. AFM-based mechanical nanomanipulation will enable arranging nanoscale entities such as nanotubes and molecules in a precise and controlled manner to assemble and produce novel devices and systems at the nanoscale. The novelty of this research stems from the development of new modeling of the physics and mechanics of the tip interaction with nanoscale entities, coupled with the development of new smart cantilevers with multiple degrees of freedom. The gained knowledge from the conducted simulations and analysis is expected to enable true precision and repeatability of nanomanipulation tasks which is not feasible with existing methods and technologies

Controlled surface manipulation at the nanometer scale based on the atomic force microscope

The object of this thesis is the development of theoretical and experimental methods for the controlled manipulation of surfaces at the nanometer scale, including the design, construction and experimental demonstration of an atomic force microscope (AFM) based manipulator. The transfer function description of an AFM system not only offers a theoretical dynamic characterization but, additionally, it is appropriate for the analysis of stability and controllability of different system configurations, i.e. different inputs and outputs. In this thesis, transfer functions are derived that correspond to a realistic model of the AFM sensor, including all its resonance modes and the tip-sample interaction. This theoretical description is then validated using the frequency response along an AFM cantilever. Different experimental and control techniques have been combined in the NanoManipulator system to optimize AFM lithography. Optical video microscopy allows a fast recognition of the sample and exact positioning of the AFM tip in the particular region of interest, while UV-laser ablation offers the possibility of noncontact manipulation of a wide range of materials, including biological specimens. Two different control approaches have been implemented in the NanoManipulator system: (i) automated control using a vector-scan module, and (ii) interactive control based on the use of a haptic interface. Using the NanoManipulator, the two different standard AFM lithography techniques based on dynamic methods (namely dynamic and modulated plowing) are compared by performing nanopatterning on thin resist films. The results reflect that modulated plowing, where the AFM tip is in permanent contact with the resist surface while the force is being modulated, offers the highest reliability, minimizing undesired side effects. The isolation and extraction of localized regions of human metaphase chromosomes represents a promising alternative to standard methods for the analysis of genetic material. The NanoManipulator is an excellent tool for such application, as it is here illustrated by comparing AFM based mechanical dissection and noncontact ablation on side by side chromosomes. The results are analyzed in situ using AFM imaging, revealing the high precision of mechanical dissection. Acoustical force nanolithography is a novel method for AFM based lithography where the cantilever is actuated using an acoustic wave coupled through the sample surface. The influence of acoustic wave frequency and magnitude, along with the preloading force of the cantilever are studied in detail. Acoustical force nanolithography can be used as a stand alone method or as a complement for the fine adjustment of manipulation forces

Feedback Control in an Atomic Force Microscope Used as a Nano-Manipulator

This paper offers a concise survey of the most commonly used feedback loops for atomic force microscopes. In addition it proposes feedback control loops in order to minimize the effect of thermal noise on measurements of weak forces, and to improve the manipulability of the AFM. Growing requirements to study and fabricate systems of ever-shrinking size mean that ever-increasing performance of instruments like atomic force microscopes (AFM) is needed. A typical AFM consists of a micro-cantilever with a sharp tip, a sample positioning system, a detection system and a control system. Present day commercial AFMs use a standard PI controller to position the micro-cantilever tip at a desired distance from the sample. There is still a need for studies showing the optimal way to tune these controllers in order to achieve high closed-loop positioning performance. The choice of other controller structures, more suitable for dealing with the robustness/performance compromise can also be a solution.